Overview of PCB Pollution in Africa: E-Waste and Insights from International Pellet Watch

ABSTRACT

In this paper, literature from the last decade concerning the environmental levels of polychlorinated biphenyls (PCBs) in Africa is reviewed. Although data to determine general trends of PCBs across African countries were insufficient, high levels were observed in environmental and biological samples from some urban and industrial areas near electronic waste (e-waste) sites in Ghana, South Africa and Nigeria, in comparison to those in rural settings. Notably, atmospheric PCB concentrations showed a slow rate of decrease, particularly in a 10-year monitoring program (2008–2019), in which PCB levels ranged from 0.5 to 37.7 pg/m³, whereas more rapid decreases were observed in other areas globally. PCB levels in plastic resin pellets, which reflect pollution in coastal waters, in some African countries, namely, Tunisia and Senegal (554–3,384 ng/g-pellet, respectively), were comparable with, or slightly higher than, those in developed countries, i.e., the United States and France (178 and 2,230 ng/g-pellet, respectively). Nevertheless, due to inconsistent monitoring methods and limited data availability, temporal trends were still unclear. Improperly disposed PCB-containing equipment, like electrical transformers and capacitors, informal recycling and open burning of e-waste are significant contributors of PCBs in Africa. Even though there is no known PCB production in the region, the contamination levels mirror those in historically heavy-use areas, largely due to electrical equipment and inadequate e-waste handling practices. The understanding of temporal trends is hindered by the current gaps in data, which highlights that comprehensive monitoring and effective enforcement of global treaties such as the Stockholm Convention and the Basel Convention are urgently needed. To understand better and address the pervasive impact of PCBs in Africa, this review calls for sustained monitoring with follow-up intervals.

INTRODUCTION

Polychlorinated biphenyls (PCBs) are synthetic persistent organic pollutants (POPs) encompassing 209 congeners, each with distinct physical and chemical properties. Massively produced from the 1950s to the 1970s in industrialised countries such as the United States, France and Japan, the cumulative global production of PCBs reached approximately 1.3 million tonnes, of which approximately 97% were used in the Northern Hemisphere (Breivik et al., 2007). Their widespread utilization was driven by their excellent dielectric and heat transfer properties, making them indispensable in electrical equipment, particularly transformers and capacitors. However, owing to their toxicity, environmental persistence and propensity for bioaccumulation and biomagnification, PCB production was halted first in Japan in 1972 and then in the United States in 1977 and in other countries in 1993, which was then subjected to stringent regulations and banned or restricted under the Stockholm Convention and associated legislation (UNEP, 2001).

Despite these regulatory measures, PCBs continue to pose significant environmental challenges, particularly because of their long-range transport and transboundary movement through various means, which include the trade and disposal of electronic equipment that contains PCBs (Pozo et al., 2006). This has led to the presence of PCBs in regions where they were never produced, underscoring the need for comprehensive monitoring to determine and mitigate their sources.

The Stockholm Convention, established in 2001 and enforced in 2004, was a pivotal global agreement aimed at protecting human health and the environment from the adverse effects of POPs, including PCBs. Monitoring and regulatory efforts under the Convention have led to a decrease in PCB emissions in former-use regions; nonetheless, high levels of PCBs have recently been recorded in various parts of the world (Gioia et al., 2014). Transformer oils predominantly use PCBs, constituting 48% of their applications, whereas capacitors and open applications such as paints and sealants each comprised roughly 21%. Other enclosed uses accounted for 10% of PCB applications (Akinrinade et al., 2024).

In Africa, the major environmental PCB sources are transformer oil leakages, with other applications resulting in minimal emissions due to high costs. There is a lack of detailed import/export data and contamination assessments, which complicates the management of PCBs. Older transformers, pre-1986, are often contaminated, and transformer oils are sometimes misused as coolants or adulterated diesel (Debela et al., 2022). In Africa, data on non-Aroclor PCB sources are limited.

Numerous African countries imported significant quantities of PCB-containing equipment before the global ban, which resulted in substantial stockpiles and contaminated sites (Akinrinade et al., 2023). For instance, Eritrea and Congo imported thousands of transformers and capacitors, which have contributed to widespread PCB contamination (Debela et al., 2022). Additionally, informal recycling and disposal practices, such as open-air burning, have exacerbated PCB pollution, releasing these harmful chemicals into the environment (UNEP, 2010). This issue is compounded by Africa’s growing electronic waste (e-waste) crisis, which was driven by rapid technological adoption and insufficient waste management systems (Maphosa et al., 2020). Africa generates significant e-waste, with 2.2 million tonnes produced in 2016. The countries with the largest contributions are Egypt (0.5 Mt), South Africa and Algeria (0.3 Mt each) (Baldé et al., 2015). The average annual per capita e-waste generation in Africa is 1.9 kg, which is remarkably lower than those in Europe (16.6 kg) and the Americas (11.6 kg) (Baldé et al., 2017). However, locally generated e-waste is projected to increase considerably, and illegal transboundary imports from developed countries have remarkably increased, further exacerbating the problem (SBC, 2011; Bello et al., 2016). Reportedly, 80% of e-waste generated worldwide has been treated informally (Balde et al., 2017), especially in developing countries of Asia and Africa (Breivik et al., 2014), including Accra, Ghana (Wittsiepe et al., 2015; Tue et al., 2019); Delhi, India (Chakraborty et al., 2019); Lagos, Nigeria (Iwegbue et al., 2019); and Trang Minh and Bui Dau, Vietnam (Tue et al., 2010).

The International Pellet Watch (IPW) program has been instrumental in monitoring the global distribution of POPs, including PCBs. This program analyzes plastic resin pellets collected from beaches worldwide to assess the levels and sources of PCBs and other contaminants. Studies have shown that PCB concentrations in Africa vary considerably, with higher levels often found near urban and industrial areas. For instance, monitoring in Ghana has revealed elevated PCB concentrations in coastal waters and sediments, particularly near e-waste recycling sites (Hosoda et al., 2014). In this review, an overview of PCB pollution in Africa is provided, focusing on the findings from the IPW program. Moreover, this review aims to summarize PCB levels in environmental and biological matrices within African environments over the past decades, address critical areas of concern and highlight research gaps. By integrating the data from numerous studies and monitoring programs, this review seeks to offer a comprehensive understanding of the current state of PCB pollution in Africa and its environmental implications.

METHODS

The data for this review were compiled from peer-reviewed research articles indexed in the Web of Science, Google Scholar and Scopus databases. The search, spanning publications over the period from 2014 to 2024, utilized keywords such as ‘polychlorinated biphenyls’ (or ‘PCBs’), ‘Africa’, ‘sediment’, ‘water’, ‘biota’, ‘air’, ‘atmosphere’, ‘microplastics’, ‘e-waste’ and ‘e-waste management’, alongside names of various African countries. The initial search yielded 171 documents. The inclusion criteria focused on peer-reviewed articles that were published within the specified timeframe, were available in English and provided relevant data on PCBs or e-waste in Africa. Following a detailed screening process, 97 articles met these criteria and were selected for inclusion in this review. This selection process ensured that only the most relevant sources were included, enabling a comprehensive overview of PCB and e-waste pollution across Africa.

RESULTS AND DISCUSSION

PCB POLLUTION STATUS ACROSS AFRICA THROUGH IPW

Despite international bans, PCBs continue to present significant environmental and public health threats worldwide. Reportedly, there is no African country with a history of manufacturing PCBs. African countries have imported numerous pieces of electrical equipment containing PCBs, primarily from Europe, America and Asia (Debela et al., 2022). The importation and continued use of pre-1980 equipment, which are often poorly managed, are likely a major contributor to PCB pollution in the region. These devices, containing PCBs, were not phased out in numerous African countries, which led to ongoing environmental contamination and contributed to the PCB burden in these regions (UNEP, 2010). However, the common sources of PCBs in the African environment include unintentional use in industries such as paint manufacturing (Anh et al., 2021), leakage from electrical transformers, contaminated sites and the disposal and recycling of e-waste, especially at open burning sites (Ssebugere et al., 2019; Liu et al., 2023).

IPW has been pivotal in monitoring global PCB levels through the analysis of beached plastic pellets, providing valuable data on pollution trends and levels. In this monitoring plan contributors across the globe send pellets to IPW, where 13 PCB congeners are reported; Σ13 PCBs represent the sum of these congeners (PCBs-66, 101, 110, 149, 118, 105, 153, 138, 128, 187, 180, 170 and 206). Although piece-to-piece variation in PCB concentrations among the pellets from the same beaches, by using the median value from five subsamples, IPW categorises the concentration of PCBs into different pollution levels and has developed a comprehensive global database of PCB values (Endo et al., 2005; Ogata et al., 2009). Notably, Ogata et al. (2009) documented that this median correlates well with concentrations found in mussels, as observed by Mussel Watch, a monitoring program established in the 1970s (Ogata et al., 2009; Takada and Yamashita, 2016). Thus, PCBs in pellets reflect the pollution levels of PCBs in coastal waters from which the pellets were collected.

In a series of global studies carried out by IPW researchers between 2011 and 2021, a total of 247 locations worldwide, including 43 along the African coastline, were monitored, and PCB concentrations were reported (Fig. 1 and Table 1). They established the global background level of PCBs at 10 ng/g-pellet, above which any local or regional sources of PCBs are suspected. They also proposed and utilised five-level categories of PCB concentrations reflecting the magnitude of local PCBs sources, that is, extremely polluted, >500 ng/g-pellet; highly polluted, >200 ng/g-pellet; moderately polluted, >50 ng/g-pellet; lightly polluted >10 ng/g-pellet; and non-local pollution, <10 ng/g-pellet. Extreme and high pollution levels were observed in industrialised coastal regions of western Europe, the United States, Japan and Australia, and they were ascribed to legacy pollution.

Fig. 1 Median PCB concentrations in plastic resin pellets worldwide (ng/g-pellet) IPW monitoring data during 2011–2021.

Values are the sum of 13 congeners: PCBs-66, 101, 110, 149, 118, 105, 153, 138, 128, 187, 180, 170 and 206. The PCB concentrations were categorized into five pollution levels. The categories are as follows: <10 ng/g-pellet=non-locally polluted, 10–50 ng/g-pellet=lightly polluted, 50–200 ng/g-pellet=moderately polluted, 200–500 ng/g-pellet=highly polluted and >500 ng/g-pellet=extremely polluted (data obtained from Karapanagioti et al., 2011; Heskett et al., 2012; Ryan et al., 2012; Mizukawa et al., 2013; Hosoda et al., 2014; Zhang et al., 2015; Yeo et al., 2015; Le et al., 2016; Alidoust et al., 2021; Karlsson et al., 2021; Ohgaki et al., 2021).

Table 1 Median PCB concentration (ng/g-pellet) in plastic resin pellets in Africa and around the world (2011–2021) in previous studies

Country	Sampling Year	Σ13 PCBs* (ng/g- pellet)	N**	Refrence
North America
New Jersey	2011	432	2	Ohgaki et al. (2021)
California	2010	3.8–42	6	Van et al. (2012)
Los Angeles, California	2012	233	1	Ohgaki et al. (2021)
California	2018	23	3	“
San Francisco	2012	178	1	“
San Francisco	2016	104	1	“
Texas	2014	45	1	“
Texas	2019	7	1	Karlsson et al. (2021)
Latin America
Argentina	2008	0.91	2	Ohgaki et al. (2021)
Chile	2008	1.2	1	“
São Paulo, Brazil	2010	n.d.–12.75	56	Taniguchi et al. (2016)
Brazil	2012	61	1	Ohgaki et al. (2021)
Belize	2013	2.6	1	“
Puerto Rico	2016	301	1	“
Argentina	2019	10	1	Karlsson et al. (2021)
Costa Rica	2019	18	1	“
Jamaica	2019	27	1	“
Mexico	2019	16	1	“
Africa
South Africa	2011	16–113	9	Ryan et al. (2012)
South Africa	2012–2013	96–122	2	Ohgaki et al. (2021)
Kenya	2011	19	1	“
Kenya	2019	4	1	Karlsson et al. (2021)
Guinea	2014	58	1	Ohgaki et al. (2021)
Ghana	2009–2013	1–69	11	Hosoda et al. (2014)
Guinea	2019	84	1	Karlsson et al. (2021)
Ghana	2010–2015	8.8–143	6	Ohgaki et al. (2021)
Mozambique	2013	53	1	“
Morocco	2019	155	1	Karlsson et al. (2021)
Nigeria	2019	18	1	“
Republic of Congo	2019	104	1	“
Senegal	2019	3,384	1	“
Tanzania	2019	217	1	“
Tunisia	2019	554	1	“
Tunisia	2020	14–632	4	Barhoumi et al., (2023)
Europe
Greece	2008	5–230	4	Karapanagioti et al. (2011)
Portuguese coast	2008–2012	10–310	10	Mizukawa et al. (2013)
France	2010–2017	96–2,230	4	Ohgaki et al. (2021)
Spain	2014–2015	107–1,243	2	“
Netherlands	2014	243	1	“
Italy	2014	46	1	“
Poland	2019	13	1	Karlsson et al. (2021)
Turkey	2019	9	1	“
Middle East
UAE	2010	2	1	Alidoust et al. (2021)
Qatar	2015	23	1	“
Iran	2018	0.01–624	19	“
Asia
Vietnam	2007–2014	4–24	4	Le et al. (2016)
Vietnam	2019	2	1	Karlsson et al. (2021)
India	2007–2017	671–473	3	Ohgaki et al. (2021)
China	2009–2014	2.7–299	2	“
China	2014	21.5–232	2	Zhang et al. (2015)
Malaysia	2011–2016	0.15–21	3	Ohgaki et al. (2021)
Japan	2013–2017	2–901	11	“
Philippines	2016	126	1	“
Indonesia	2017	304	1	“
Oceania
Australia	2014	0.1–223	26	Yeo et al. (2015)
New Zealand	2014		6	“
Australia	2019	122	1	Karlsson et al. (2021)
New Zealand	2019	76	1	Karlsson et al. (2021)
Remote Island
Remote islands in Pacific, Atlantic and Indian Ocean		1.1–9.9	8	Heskett et al. (2012)
Seven Remote Islands	2001–2018	0.41–12	7	Ohgaki et al. (2021)

^*  Σ13 PCBs=sum of 13 PCB congeners (PCBs - 66, 101, 110, 149, 118, 105, 153, 138, 128, 187, 180, 170, and 206)

^**  N: number of samples/locations

The extensive dataset on PCB concentrations in Africa from numerous studies reported between 2012 and 2019 highlights the significant PCB environmental pollution levels faced by the continent. The data reflect varied PCB concentration levels across different African countries, with some regions exhibiting exceptionally elevated levels indicative of severe local pollution sources. For instance, Ryan et al. (2012) reported that PCB concentrations in South African pellets ranged from 16 to 113 ng/g-pellet in 2011, highlighting variable levels of environmental contamination. Moreover, a study by Hosoda et al. (2014) reported PCB concentration in plastic resin pellets from 11 beaches along the Ghanaian coastline, revealing remarkably higher PCB concentrations in urban areas like Accra and Tema (39–69 ng/g-pellet) compared with rural coastal towns (1–15 ng/g-pellet), which were relevant to global background level. This disparity indicates substantial local PCB inputs, particularly near e-waste scrapyards, where sedimentary PCB concentrations downstream from an e-waste scrapyard in Accra were notably higher, emphasising the critical role of e-waste as a significant source of PCBs in Ghana (Hosoda et al., 2014).

Karlsson et al. (2021) studied PCBs in 22 sites across the globe including nine African countries in 2019; they reported Senegal with the world’s highest concentration at 3,384 ng/g-pellet in 2019, far exceeding the levels seen in other countries around the world. Research findings documented that the high PCB levels in samples from Plage De Hann in Hann Bay—surrounded by industrial activities and close to the Mbeueuss landfill near Dakar—point to remarkable local pollution sources and inadequate waste management practices (Karlsson et al., 2021).

Additionally, countries such as Tanzania and Tunisia have reported high PCB levels, with concentrations of 217 and 554 ng/g-pellet, respectively. Tunisia, in particular, had been documented to have the second-highest PCB levels, with samples collected from the Gulf of Tunis in the vicinity of industrial zones. This remarkable pollution points to ongoing environmental concerns in Africa. However, the extent of PCB usage in Tunisia is still insufficiently documented (Karlsson et al., 2021).

In 1986, the importation of transformers or equipment containing PCBs into Tunisia was banned. Nevertheless, numerous transformers containing PCBs are still utilised or presently stored in unsatisfactory conditions (Barhoumi et al., 2014). Therefore, local sources of PCBs such as e-waste may exist in the area. Moreover, there are slightly increasing concentrations in samples from Guinea, which have been reported in samples collected in 2014 by Ohgaki et al. (2021) and collected in 2019 by Karlsson et al. (2021), with concentrations of 58 and 84 ng/g-pellet, respectively. Conversely, Kenya showed a drastic reduction in PCB levels from 19 ng/g-pellet in 2011 (Ohgaki et al., 2021) to just 4 ng/g-pellet in 2019 at the same range as PCB background levels, indicating possible improvements in environmental management or sample site being in a small town.

In Ghana, a longitudinal observation from 2009 to 2015 highlighted fluctuating PCB concentrations ranging from 1 to 143 ng/g-pellet (Hosoda et al., 2014; Ohgaki et al., 2021). This variability could be attributed to various levels of activity and the effectiveness of local environmental regulations over time. Furthermore, South Africa’s data suggest a trend of relatively high PCB contamination, maintaining levels from 16 to 122 ng/g-pellet, which underscores consistent environmental pressure from PCBs.

The high PCB levels in areas like Senegal, Tunisia and other parts of Africa underscore the critical need for enhanced regulatory frameworks and effective waste management strategies. Moreover, the IPW data reflect the broader issue of e-waste, which is a remarkable contributor to PCB pollution, especially in less developed regions that may lack the infrastructure to manage hazardous waste effectively (Hosoda et al., 2014; Karlsson et al., 2021; Ohgaki et al., 2021).

When comparing PCB levels reported in Africa with other global concentrations, the data from countries such as the United States, Europe and Japan with concentration ranges of 4–432, 9–2,230 and 2–901 ng/g-pellet, respectively (Ohgaki et al., 2021), reveal notable differences in pollution levels and trends. Although African countries like Senegal, Tanzania, Morocco and Tunisia exhibit alarmingly high PCB concentrations, more industrialised countries have shown a noticeable decrease in such pollutants over similar periods. For instance, in the United States, certain areas such as Cox Creek in Texas reported PCB concentrations as low as 7 ng/g-pellet in 2019, which contrasts with the 3,384 ng/g-pellet recorded in Senegal the same year. Furthermore, in European regions such as Normandy, France, where concentrations were 2,230 ng/g-pellet in 2017 and 1,945 ng/g-pellet in 2010, and in Barcelona, Spain, at 1,243 ng/g-pellet, the recorded pollutant levels are still lower when compared to the highest values observed in Africa.

In terms of PCB composition, the most common congeners were penta-, hexa- and hepta-CBs in pellets. This pattern is similar to what has been reported in pellets from other parts of the world (Mizukawa et al., 2013; Hosoda et al., 2014; Yeo et al., 2015; Karlson et al., 2021). Although the specific composition varied by location, CB-138 and CB-180 were dominant in most samples, particularly in those with high PCB concentrations in Africa from Senegal, Tunisia and Tanzania. In these samples, CB-138 made up more than 50% of the total PCBs in numerous cases.

This discrepancy emphasizes both the severity of local pollution and potential gaps in environmental regulation and waste management practices in African nations. The decrease in PCB levels in historically major producer countries can be due to stringent regulatory frameworks, advanced waste management systems and heightened public awareness regarding the environmental and health risks associated with PCBs. Over the decades, these countries have established robust environmental policies, which include bans on PCB production, restrictions on their use and comprehensive programs for the cleanup and remediation of contaminated sites.

Meanwhile, increasing PCB pollution in several African countries underscores the ongoing challenges that these nations face, including inadequate waste management practices and weak regulatory oversight (Akinrinade et al., 2024). The increase in PCB levels is not attributable to historical usage within Africa, which was limited, but is more likely exacerbated by external factors including the importation of e-waste and old equipment imported from more developed nations (Gioia et al., 2013).

Components such as capacitors and transformers found in electronic equipment waste can contain PCBs, which leach into the environment as these materials degrade (Debela et al., 2022; Akinrinade et al., 2024). This issue is particularly concerning for equipment manufactured before 1980, which remains in operation today. For instance, Sudan continues to employ 255 transformers containing PCBs, whereas Cameroon had an estimated 200 tonnes of such equipment still active as of 2014 (NIP, 2016; Patrie, 2016; UNEP, 2018). The situation is further exacerbated by improper disposal and informal recycling practices. For instance, in Gambia, decommissioned transformers are sold as scrap metal, whereas in Uganda and Zimbabwe, transformer oil containing PCBs is repurposed for activities such as welding and lubricants, posing considerable health risks (UNIP, 2016; ZNIP, 2016).

Despite these grave risks, the regulatory response across Africa is still inconsistent. Only about a quarter of African countries have established national legislation that specifically targets PCB management. Although some countries have included PCB regulations within broader environmental or chemical management laws, others lack specific legislation related to PCBs (Akinrinade et al., 2024). This regulatory gap impedes the effective management and elimination of PCB pollution. The disparity in regulatory enforcement, management capacity and e-waste management across the African continent highlights the critical need for comprehensive strategies. These should include enhanced legal frameworks, regional cooperation, increased capacity building and improved e-waste management to effectively address the PCB challenge in Africa.

OCCURRENCE OF PCBs IN AFRICA

SEDIMENTS AND SOILS

The dataset reported for PCBs in African soil and sediment is provided in Table 2. Moeckel et al. (2020) reported Σ32 PCB concentrations in the range of 6.5 to 830 ng/g at the Agbogbloshie (Ghana) e-waste site and the Kingtom domestic dumpsite. The site was reported to have extensive e-waste recycling operations, and researchers associated these high concentrations with high e-waste loads in the vicinity of sampling locations (Moeckel et al., 2020). A related study in Accra, Ghana, reported that e-waste recycling practices at scrapyards were shown to considerably influence PCB levels, with Σ13 PCB concentrations ranging from 0.14 to 32.2 ng/g between 2010 and 2012 (Hosoda et al., 2014). This highlights the critical issue of e-waste contributing to environmental pollution. The presence of PCBs in these locations is directly associated with improper disposal and recycling practices related to e-waste. Likewise, in Nairobi, Kenya, urban industrial activities elevated topsoil PCB levels up to 55.49 ng/g in 2015, contrasting sharply with rural sites, where levels did not exceed 9.64 ng/g (Sun et al., 2016).

Table 2 Occurrence of PCBs in environmental samples sediments, soils, and indoor dust (ng/g); atmosphere (pg/m³); and water (ng/mL) in African countries in previous studies and in other regions

Loction, Country	Sampling Year	Number of Samples	Sample Type	Number of congeners analyzed	ΣPCBs	Congenrs	Refrence
Sediment (ng/g)
Mediterranean Coast, Egypt	2013	10	sediment	Σ10 PCBs	15.1–37.5	PCB-18, 28, 44, 52, 101, 118, 138, 153, 180, 194	Salem et al. (2013)
Accra, Ghana	2010–2012	8	Sediment (e-waste scrapyard)	Σ13 PCBs	0.14–32.2	PCB-66, 101, 110, 149, 118, 105, 153, 138, 128, 187, 180, 170, 206	Hosoda et al. (2014)
Dakar, Senegal	2013	10	surface sediment	Σ28 PCBs	4–333	PCB-8, 18, 28, 44, 52, 60, 77, 81, 101, 105, 114, 118, 123, 126, 128, 138, 153, 156, 157, 167, 169, 170, 180, 185, 189, 195, 206, 209	Net et al. (2015)
Winam Gulf, Kenya	2015	9	sediment	Σ12 PCBs	0.0174–0.812	PCB-77, 81, 126, 169, 105, 114, 118, 123, 156, 157, 167	Omwoma et al. (2015)
KwaZulu-Natal, Umgeni River, South Africa	2014	15	surface sediment	Σ8 PCBs	102–427	PCB-28, 52, 77, 101, 105, 138, 153, 180	Gakuba et al. (2015)
Port Elizabeth Harbour,South Africa	2012	11	Surface Sediment	Σ6 PCBs	0.56–2.35	PCB-28, 52, 101, 138, 153, 180	Kampire et al. (2015)
Nairobi,Kenya	2015	59	top soil	Σ7 PCBs	n.d.–55.5	PCB-28, 52, 101, 118, 138, 153, 180	Sun et al. (2016)
Lake Victoria, Kenya	2014	6	sediment	Σ7 PCBs	2.2–96.3	PCB-28, 52, 101, 118, 138, 153 and 180	Oluoch-Otiego et al. (2016)
Accra, Ghana	2010	14	soil from open burning of e-waste site	Σ6 PCBs	3.4–83	dl PCBs-77, 81, 126,169, 105, 114	Tue et al. (2016)
Ogun River, Nigeria	2012	56	Surface sediment	Σ19 PCBs	323–2,003	PCB-1, 5, 18, 31, 44, 52, 66, 87, 101, 110, 138, 141, 151, 153, 170, 180, 183, 187, 206	Adeogun et al. (2016a)
Ona River, Nigeria		28			589–1,360
Port Elizabeth, South Africa	2014	42	surface sediment	Σ6 PCBs	1.6–3.06	PCB-28, 52, 101, 138, 153, 180	Kampire et al. (2017)
Klip and Jukskei Rivers, South Africa	2013	8	surface sediment	Σ7 PCBs	2.9–61	PCB-28, 52, 101, 118, 138, 153, 180	Rimayi et al. (2017)
Kinshasa, Congo	2016	9	surface sediments	Σ12 PCBs	3.46–52.9	PCB-28, 52, 101, 118, 149, 153, 105, 138, 128, 156, 180, 170	Kilunga et al. (2017)
Olifants River Basin, South Africa	2012	12	Sediment	Σ33 PCBs	0.16–2.0	PCB-18, 28, 44, 49, 52, 87, 95, 99, 101, 105, 110, 118, 128, 138, 146, 149, 151, 153, 156, 170, 171, 172, 174, 177, 180, 183, 187, 194, 195, 199, 205, 206, 209	Verhaert et al. (2017)
Msunduzi River, South Africa	2013	10	sediment	Σ8 PCBs	362–5,041	PCB-28, 77, 101, 52, 153, 105, 138, 180	Adeyinka et al.(2018)
			soil		379.9–2,442.7
Durban Bay, South Africa	2012	10	Sediment	Σ24 PCBs	6–110	PCB-8, 18, 28, 44, 52, 49, 44, 66, 101, 99, 87, 110, 151, 149, 118, 153, 105, 138, 187, 183, 187, 128, 180, 170, 206, 209	Vogt et al. (2018)
Mngeni River, South Africa		22			<LOQ–21
Lagos and Osun States, Nigeria	2016	10	sediment	Σ28 PCBs	4.19–8.58	PCB-8, 18, 28, 44, 52, 60, 77, 81, 101, 105, 114, 118, 123, 126, 128, 138, 153, 156, 157, 167, 169, 170, 180, 185, 189, 195, 206, 209	Igbo et al. (2018)
Kiambu to Mombasa, Kenya	ns	12	soil	Σ7 PCBs	9.90–20.8	PCB-28, 52, 101, 118, 138, 153, 180	Makokha et al. (2018)
Lagos, Nigeria	2015	48	soil (electricity generation facilities )	Σ7 PCBs	2–220	PCB-28, 52, 101, 118, 138, 153, 180	Folarin et al. (2018)
Gauteng Province, South Africa	2017	ns	Landfill Sediment	Σ7 PCBs	3–6.9	PCB-28, 52, 101, 118, 138, 153, 180	Sibiya et al. (2018)
Douala, Cameroun	2017	30	soils (Informal E-Waste Recycling Sites)	Σ30 PCBs	32.1–72.8	PCB-8, 28, 37, 44, 49, 52, 60, 66, 70, 74, 77, 81, 82, 87, 99, 101, 105, 114, 118, 123, 128, 138, 153, 156, 157, 167, 170, 179, 180, 189	Ouabo et al. (2018)
New Calabar River, Nigeria	ns	5	Surface sediment	Σ8 PCBs	210–2,160	PCB-1 ,5, 18 ,77,105, 156, 189, 194	Ilechukwu et al. (2018)
Onitsha Axis, Nigeria	2017	20	Sediment	Σ20 PCBs	0.001–13.2	PCB-5, 18, 31, 44, 52, 66, 87, 101, 110, 138, 141, 151, 153, 170, 180, 183, 187, 206.	Ibeto et al. (2019)
East of Oran, Algeria	ns	ns	surface soils	Σ7 PCBs	nd–19.34	PCB-28, 52, 101, 118, 138, 153, 180	Halfadji et al. (2019)
Niger Delta, Nigeria	2017	9	transformer oils	Σ14 PCBs	484–48,506	PCB-18, 28, 29, 43, 52, 101, 118, 138, 142, PCB-153, 170, 180, 194, 209	Aganbi, et al. (2019)
		5	soil		8.4–510
Umgeni River bank, South-Africa	2013	14	soil	Σ8 PCBs	113–543	PCB-1, 5, 18, 77, 105, 156, 189, 194	Gakuba et al. (2019)
Gauteng Province, South Africa	2017	7	landfill sediment	Σ7 PCBs	2.25–6.86	PCB-28, 52, 101, 118, 138, 153, 180	Sibiya et al. (2019)
Agbogbloshie, Ghana	2015	15	surface soils (e-waste site dumping site)	Σ32 PCBs	6.5–830	PCB-18, 28, 31, 37, 47, 52, 66, 74, 99, 101, 105, 114, 118, 122, 123, 128, 138, 141, 149, 153, 156, 157, 167, 170, 180, 183, 187, 189, 194, 206, 209	Moeckel et al. (2020)
Kingtom, Ghana	2015	10	surface soils (domestic dumpsite)		0.74–43
Swartkops, Port Elizabeth, South Africa	2017–2018	20	Sediments	Σ17 PCBs	70–3,800	PCB-18, 31, 52, 44, 66, 101, 87, 110, 151, 153, 141, 138, 187, 183, 180, 170, 206	Olisah et al. (2020b)
Sunday, Port Elizabeth, South Africa					80–1,710
Addis Ababa, Ethiopia	2018–2019	45	Soil (transformer dumpsite)	Σ6 PCBs	166–4,500	PCB-28, 52, 101, 138, 153, 180	Debela et al. (2020)
Lagos lagoon, Nigeria	ns	150	sediment cores	Σ14 PCBs	bdl–6.41	PCB-18, 28, 20, 52, 44, 105, 142, 118, 153, 101, 138, 180, 170, 194	Benson et al. (2020)
Niger river, Nigeria	2019	9	Surficial sediments	Σ28 PCBs	13.5–277	PCB-18, 28, 44, 52, 60, 77, 81, 101, 105, 114, 118, 123, 126, 128, 138, 153, 156, 157, 167, 169, 170, 180, 185, 189, 195, 206, 209	Irerhievwie et al. (2020)
Ase river, Nigeria	2019	9		Σ28 PCBs	nd–1,633
Forcados river, Nigeria	2019	9		Σ28 PCBs	6.9–78.6
Escravos River Basin, Nigeria	no data	25	Sediment around oil production facilities	Σ28 PCBs	226–31,900	PCB-8, 18, 28, 44, 52, 60, 77, 81, 101, 105, 114, 118, 123, 126, 128, 138, 153, 156, 157, 167, 169, 170, 180, 185, 189, 195, 206, 209	Iwegbue et al. (2020)
Nairobi River, Kenya	2008	3	sediments	Σ7 PCBs	<bdl–157.64	PCB-28, 52, 101, 118, 138, 153, 180	Ndunda et a., (2021)
Tanzania	ns	2	sediment	Σ7 PCBs	510.6	PCB-28, 52, 101, 118, 138, 153, 180	Folarin et al. (2021)
Volta Basin, Ghana	2019	80	sediment	Σ7 PCBs	0.042–5.320	PCB-28, 52, 101, 118, 138, 153, 180	Magna et al. (2022)
urban Dar es Salaam, Tanzania	2019	5	core sediment	Σ32 PCBs	0.19–5.8	PCB-18, 28, 31, 33, 37, 47, 52, 66, 74, 99, 101, 105, 114, 118, 122, 123, 128, 138, 141, 149, 153, 156, 157, 167, 170, 180, 183, 187, 189, 194, 206, 209	Nipen et al. (2022)
Edor River, Nigeria	2019	9	sediment (around a glass industry and power generating plant)	Σ28 PCBs	976–5,670	PCB-8, 18, 28, 44, 52, 60, 77, 81, 101, 105, 115, 118, 123, 126, 128, 138, 153, 156, 157, 167, 169, 170, 180, 185, 189, 195, 206, 209	Iwegbue et al. (2022)
Okpare River, Nigeria					1,440–6,340
Afiesere River, Niger delta, Nigeria					1,520–3,540
Tanzania	2020	18	Sediment	Σ6 PCBs	0.1–5.5	PCB-153, 105, 28, 156, 157, 167	Zhao et al. (2022)
Niger Delta, Nigeria	ns	18	soils	Σ28 PCBs	88.0–293	PCB-8, 18, 28, 44, 52, 60, 77, 81, 101, 105, 114, 118, 123, 126, 128, 138, 153, 156, 157, 167, 169, 170, 180, 185, 189, 195, 206, 209	Emoyan et al. (2022)
southwestern Nigeria	2019–2021	72	Surficial sediments	Σ22 PCBs	9.86–80.76	PCB-18, 28, 29, 43, 52, 77, 81, 101, 105, 118, 126, 138, 142, 153, 157, 167, 169, 170, 180, 194, 206, and 209	Apata et al. (2022)
Nairobi, Kenya	2020	25	sediment	Σ30 PCBs	3.1–157.1	PCB-31, 28, 52, 77, 95, 101, 123, 118, 114, 105, 126, 151, 149, 146, 153, 138, 167, 169, 187, 183, 177, 180, 170, 195, 194, 209	Vane et al. (2022)
Dakar Coast, Senegal	2018	12	surface sediment	Σ18 PCBs	5.93–25.75	PCB-18, 31, 28, 52, 44, 70, 101, 81, 123, 118, 114, 138, 126, 167, 157, 180, 169, 189	Cisse et al. (2023)
Ojutu River, Osun State Nigeria	2013	53	soil	Σ7 PCBs	1,020	PCB-28, 52, 101, 118, 138, 153, 180	Afolabi et al. (2023)
		5	sediment	Σ7 PCBs	649
Alaba, Lagos, Nigeria	2020	6	soil (electronic waste dumpsite)	Σ19 PCBs	94.5–274.5	PCB-1, 5, 18, 31, 44, 52, 66, 87, 101, 110, 138, 141, 151, 153, 170, 180, 183, 187, 206.	Ayoola et al. (2023)
Port Harcourt city, Nigeria	2019	20	soils	Σ28 PCBs	4.59–116	PCB-8, 18, 28, 44, 52, 66, 77, 81, 101, 105, 114, 118, 123, 126, 128, 138, 153, 156, 157, 167, 169, 170, 180, 187, 189, 195, 206, 209	Ossai et al. (2023)
Lagos lagoon, Gulf of Guinea	2019	54	Sediment	Σ27 PCBs	273–6,757	PCB-8, 18, 28, 44, 52, 60, 77, 81, 101, 105, 114, 118, 123, 126, 128, 138, 153, 156, 157, 167, 169, 170, 180, 185, 189, 195, and 206	Unyimadu et al. (2023)
Other Regions
Chicago, USA	2013	10	Surficial sediments	Σ209 PCBs	650–500		Peverly et al. (2015)
Songhua River, China	2014	11	Surficial sediments	Σ7 PCBs	0.59–12.4	PCB-28, 52, 101, 118, 138, 153, 181	Cui et al. (2016)
Seine River Basin, France	2013	12	Surficial sediments	Σ15 PCBs	500–2,370	PCB-18, 31, 28, 20,52,44,101,149,118,153,105, 138,180, 170, 194	Lorgeoux et al. (2016)
Thames River, England	2013	13	Surficial sediments	Σ7 PCBs	0.12–27.4	PCB-28, 52, 101, 118, 138, 153, 180	Lu 2017
Indoor dust (ng/g)
Durban, South Afirca	2012	10	indoor dust from homes	Σ3 PCBs	891	PCB-28, 153, 180	Abafe et al. (2015)
		11	indoor dust from offices		923
		13	indoor dust (university students office)		1,880
		3	indoor dust of e-waste recycling and electronic equipment repair facilities		161–593
Lagos, Nigeria	2014	16	indoor dust from cars	Σ6 PCBs	3.09–30.69	PCB-28, 52, 101, 153, 138, 180	Harrad et al. (2016)
		12	indoor dust from house		17.9–67.6
		18	indoor dust from offices		19.5–97.3
Cape town, South Africa	ns	1	indoor dust	Σ6 PCBs	272.6	PCB-28, 52, 101, 153, 138, 180	Folarin et al. (2018a)
Lagos, Nigeria	2015	48	indoor dust (office, electricity generation facilities )	Σ7 PCBs	21–2,200	PCB-28, 52, 101, 118, 138, 153, 180	Folarin et al. (2018b)
Abraka and Warri, southern Nigeria	2017	40	dusts (electronic repair workshop )	Σ28 PCBs	96.6–3,949	PCB-18, 28, 44, 52, 60, 77, 81, 101, 105, 114,118, 126, 128, 138,153, 156, 157, 167, 169, 170, 180, 185, 189, 195, 206, 209	Iwegbue et al. (2019)
Lagos, Nigeria	2017	15	house dust	Σ8 PCBs	3.8–61	PCB-28, 11, 138, 180, 153, 52, 118, 101	Akinrinade et al. (2021)
Port Harcourt city, Nigeria	2019	15	indoor dusts (homes and shops)	Σ28 PCBs	1.80–23.0	PCB-8, 18, 28, 44, 52, 60, 77, 81, 101, 105, 114, 118, 123, 126, 128, 138, 153, 156, 157, 167, 169, 170, 180, 185, 189, 195, 206, 209	Ossai et al. (2023)
			outdoor dusts		nd–57.4
Air (pg/m3)
11 countries in Africa	2009	ns	ambient air (rural and urban sites)	Σ7 PCBs	8–2,074	PCB-28, 52, 101, 118, 138, 153, 180	Bogdal et al. (2013)
Ghana	2011	16	Atmosphere (informal electronic waste recycling activities)	Σ190 PCBs	280–11,100		Hogarh et al. (2018)
Lake Victoria, East Africa	2003–2010	53	outdoor air _ urban	Σ18 PCBs	19.2–462	PCB-22, 28, 33, 52, 49, 47 70, 66, 101, 99, 110, 118, 105, 151, 153, 138, 158, 128, 157, 183, 174, 180, 206, 207	Arinaitwe et al. (2018)
Bizerte, Tunisia	2015–2016	60	Aerosol samples (roof of the Faculty of Sciences)	Σ20 PCBs	0.30–11.0	PCB-8, 18, 28, 52, 44, 66, 77, 101, 105, 118, 126, 128, 138, 153, 170, 180, 195, 206, 187, 209	Barhoumi et al. (2018)
Africa, 9 countries (Congo, Ghana, Ethiopia, Kenya, Mali, Mauritius, Morocco, Nigeria, and Sudan)	2008–2019	84	Air samples	Σ6 PCBs	0.006–0.724	PCB-28, 52, 101, 138, 153, 180	White et al. (2020)
Lagos, Nigeria	2018–2019	23	outdoor air _ urban	Σ8 PCBs	49–220	PCB-11, 28, 52, 101, 118, 138, 153, 180	Akinrinade et al. (2022)
Other Regions
Antarctica	2011–2014	33	oudoor air_ Remote	Σ20 PCBs	4.8–62	PCB-11, 28, 52, 77, 81, 101, 105, 114, 118, 123, 126, 138, 153, 156, 157, 167, 169, 180, 189, 209	Wang et al. (2017)
China	2016–2017	62	oudoor air_ Remote to suburban	Σ209 PCBs	9–6,856		Zhao et al. (2020)
Northern Vietnam	2013–2015	13	oudoor air_ Urban	Σ209 PCBs	170–1,100		Anh et al. (2020)
Patagonia, Argentina	2018	11	Ambient air	Σ38 PCBs	25	PCB-18, 17, 31, 28, 52, 49, 44, 95, 74, 70, 101, 99, 87, 110, 151, 82, 149, 118, 132, 153, 105, 138, 187, 183, 128, 177, 171, 156, 180, 191, 201, 170, 169, 208, 195, 194, 205, 206	Miglioranza et al. (2021)
Water (ng/mL)
KwaZulu-Natal, Umgeni River, South Africa	2014	15	surface water	Σ8 PCBs	6.91–21.69	PCB-28, 52, 77, 101, 105, 138, 153, 180	Gakuba et al. (2015)
River Nile, Egypt	2013	20	River water	Σ10 PCBs	14–20	PCB-28, 52, 44, 70, 101, 153, 118, 105, 138, 180	Megahed et al. (2015)
River Niger, Nigeria	2014	240	Surface water samples	Σ8 PCBs	0.0808–0.2883	PCB-11, 28, 52, 101, 118, 138, 153, 180	Unyimadu J et al. (2017)
Msunduzi River, South Africa	2013	10	water	Σ8 PCBs	6.49–141.7	PCB-11, 28, 52, 101, 118, 138, 153, 180	Adeyinka et al. (2018)
Lagos, Nigeria	2015	10	water	Σ12 PCBs	23	PCB-18, 28, 31, 44, 52, 101, 153, 118, 138, 149, 180, 194	Folarin et al. (2018b)
Buffalo River, South Africa	2015–2016	12	Surface water	Σ19 PCBs	0.185–2.329	PCB-1, 5, 18, 31, 44, 52, 66, 87, 101, 110, 138, 141, 151, 153, 170, 180, 183, 187, 206	Yahaya et al. (2018)
Port Elizabeth, Eastern Cape, South Africa	2017–2018	50	Surface water (vicinity of the power station)	Σ19 PCBs	0.0148–2.91	PCB-1, 5, 18, 31, 52, 44, 66, 101, 87, 110, 151, 153, 141, 138, 187, 183, 180, 170, 206	Olisah et al. (2019)
Niger Delta, Nigeria	2017	2	drainage water (vicinity of the power station)	Σ14 PCBs	990–2,950	PCB-77, 81, 105, 114, 118, 123, 126, 156, 157, 167, 169, 170, 180, 189	Aganbi et al. (2019)
		4	groundwater		160–560
Nairobi River, Kenya	2008	3	water	Σ7 PCBs	<bdl–0.79	PCB-28, 52, 101, 118, 138, 153, 181	Ndunda et al. (2020)
Tanzania	2020	25	Surface water (18 lakes)	Σ6 PCBs	6.0×10−4–2.0×10−2	PCB-153, 105, 28, 156, 157, 167	Zhao et al. (2022)
Nigeria	2020	12	water	Σ8 PCBs	<bdl–29	PCB-11, 28, 52, 101, 118, 138, 153, 180	Afolabi et al. (2023)
Alaba, Lagos, Nigeria	2020	4	water (electronic waste dumpsite)	Σ19 PCBs	3,040–5,820	PCB-1, 5, 18, 31, 44, 52, 66, 87, 101, 110, 138, 141, 151, 153, 170, 180, 183, 187, 206.	Ayoola et al. (2023)
Lagos lagoon, Gulf of Guinea	2019	18	Surface water	Σ27 PCBs	69.2–440	PCB-8, 18, 28, 44, 52, 60, 77, 81, 101, 105, 114, 118, 123, 126, 128, 138, 153, 156, 157, 167, 169, 170, 180, 185, 189, 195, 206	Unyimadu et al. (2023)
Other Regions
Sacramento river, USA	2002–2010	300	Surface water	Σ40 PCBs	0.12–6.7	PCB-8, 18, 17, 31, 28, 52, 49, 44, 95, 74, 70, 101, 99, 87, 110, 151, 82, 149, 118, 132, 153, 105, 138, 187, 183, 128, 177, 171, 156, 180, 191, 201, 170, 169, 208, 195, 194, 205, 206	David et al. (2015)
Tiber River and Estuary, Italy	2014–2015	21	Surface water	Σ32 PCBs	1.90×10−4–6.82×10−4	PCB-8, 28, 37, 44, 49, 52, 60, 66, 70, 74, 77, 82, 87, 99, 101, 105, 114, 118, 126, 128, 138, 153, 156, 158, 166, 169, 170, 179, 180, 183, 187, 189	Montuori et al. (2016)
Coastal area of Bangladesh	2015	28	Surface water	Σ209 PCBs	0.032–0.19		Habibullah-Al-Mamun et al. (2019)
Shanghai, China	2009–2013	53	Surface water	Σ14 PCBs	nd–0.039	PCB-77, 81, 105, 114, 118, 123, 126, 156, 157, 167, 169, 170, 180, 189	Wang et al. (2017)

Note: below detection limit (bdl); not specified (ns); not detected (nd); limit of quantification (LOQ)

A further study by Adeyinka et al. (2018) reported that PCB concentrations of Σ8 PCBs in the Msunduzi River, South Africa, were alarmingly high, with sediment levels reaching up to 5,041 ng/g and soil levels up to 2,442.7 ng/g. Gakuba et al. (2019) documented the concentration of Σ8 PCBs from 113 to 543 ng/g in the Umgeni Riverbank, South Africa. A later study by Olisah et al. (2020) in Port Elizabeth, South Africa, reported PCBs Σ17 PCBs ranging from 70 to 3,800 ng/g, in sediment, and indicated that PCB contamination is likely related to industrial discharges or stormwater runoff.

Meanwhile, Aganbi et al. (2019) reported a concentration of 17 PCB congeners ranging from 484 to an alarming level of 48,506 ng/g in the Niger Delta. Another study in Nigeria, Edor River in 2019, reported PCB concentration in sediments near a glass industry and power-generating plant containing Σ28 PCBs ranging from 976 to 5,670 ng/g, indicating industrial discharges as a major source of contamination (Iwegbue et al., 2021).

In a study by Ouabo et al. (2018), PCB concentrations in Douala, Cameroon, reflected contamination at informal e-waste recycling sites with Σ30 PCB levels from 32 to 73 ng/g. Sibiya et al. (2019) reported low concentrations in Gauteng Province, South Africa, where concentrations of Σ7 PCBs were 2.25–6.86 ng/g in sediments. Egypt’s Mediterranean Coast presented moderate contamination with Σ7 PCB levels from 15.13 to 37.49 ng/g as reported by Salem et al. (2013).

High PCB concentrations were later documented around glass industries and power-generating plants in Nigeria, with levels of up to 6,340 ng/g in 2019 of Σ28 PCBs by Iwegbue et al. (2022). This underscores the significant environmental risks posed by industrial activities. In urban settings like Lagos, Nigeria, soils from electricity generation facilities revealed PCB levels of Σ7 PCBs from 21 to 2,200 ng/g in 2015 (Folarin et al., 2018), further emphasising the impact of industrial emissions on urban soil quality. Ayoola et al. (2023) also reported that soil PCB levels of Σ19 PCBs ranged from 94.5 to 274.5 ng/g in e-waste sites in Alaba, Lagos, highlighting the severe environmental health risks associated with improper e-waste management. Nipen et al. (2021) reported a concentration of Σ32 PCBs from 0.19 to 5.8 ng/g in core sediment samples from Tanzania, Urban Dar es Salaam (Nipen et al., 2021). In Senegal, sediment from the Dakar region contained Σ18 PCB levels from 4 to 333 ng/g, as reported by Net et al. (2015), indicating variable pollution likely associated with urban runoff and nearby industrial activities.

Omwoma et al. (2015) reported Σ13 PCBs at concentrations ranging from 0.0174 to 0.812 ng/g in the Winam Gulf, Kenya, which suggests lower levels of contamination that reflect minimal industrial impact. Gakuba et al. (2015), studying the Umgeni River in South Africa, documented PCB levels from 102 to 427 ng/g in surface sediment. This urban–rural disparity emphasizes the influence of urbanisation and industrial activities on PCB contamination.

Verhaert et al. (2017) reported Σ33 PCBs in the Olifants River Basin in South Africa concentrations ranged between 0.16 and 2.0 ng/g dw in sediments (Verhaert et al., 2017). These levels are notably lower than those reported in surface sediments of the Ogun River in Nigeria, where reported Σ19 PCB concentrations ranged from 323 to 2,003 ng/g (Adeogun et al., 2016). Likewise, Σ28 PCBs concentrations in the Niger River’s surficial sediments ranged from 13.5 to 277 ng/g (Irerhievwie et al., 2020), with the Ase and Forcados rivers also indicating considerable levels of Σ28 PCBs up to 1,633 and 78.6 ng/g, respectively (Irerhievwie et al., 2020).

In most samples, hexa-chlorinated PCBs were the most abundant homologue group and accounted for nearly 40% at most sites, followed by penta- and hepta-congeners. Low molecular weight PCBs (including tri-CBs) showed very low concentrations in these studies, whereas they accounted on average for 15% of the total PCB burden in samples from Agbogbloshie. A similar trend has been reported in suburban areas around Nairobi, Kenya (Sun et al., 2016), which also showed similar tri-to-hepta- CB ratios.

Comparing these African data with those from other regions worldwide highlights interesting contrasts. For instance, in the Thames River, England, Σ7 PCBs in surficial sediments were reported to range from 0.12 to 27.4 ng/g (Lu et al., 2017), which is somewhat comparable to the lower concentrations observed in the Olifants River Basin but remarkably lower than those reported in the Escravos River Basin in Nigeria, where Σ28 PCBs reached up to 31,900 ng/g due to industrial activities (Iwegbue et al., 2020).

In China, the Songhua River, Cui et al. (2016) reported Σ7 PCB concentrations from 0.59 to 12.4 ng/g in surficial sediments (Cui et al., 2016), similar to the lower end of concentrations documented in African sediments but still lower than the more contaminated sites like the Escravos River Basin. Furthermore, in the Seine River Basin, France, Σ15 PCBs reported in surficial sediments ranged from 500 to 2,370 ng/g (Lorgeoux et al., 2016), which are considerably higher than many of the African sites, except for the highly contaminated Escravos River Basin.

By contrast, surficial sediments from the Chicago River in the United States reported Σ209 PCB concentrations between 650 and 500 ng/g (Peverly et al., 2015), indicating a heavy industrial influence comparable to or exceeding levels found in some African rivers such as the Niger and Ase.

These comparisons demonstrate that although PCB contamination is present across Africa, the levels in many regions are comparable to those found in highly industrialised regions such as the Seine River Basin in France and urban areas in the United States and the United Kingdom. However, certain hotspots like the Escravos River Basin in Nigeria show considerably higher contamination levels, underscoring the impact of localised industrial activities.

Overviewed studies in African countries underscore the diverse contamination levels across Africa, from lower concentrations in natural and rural settings to alarmingly elevated levels in urban, industrial and particularly e-waste handling areas. The consistent detection of PCBs across Africa calls for enhanced regulatory frameworks, rigorous environmental monitoring and robust waste management strategies to mitigate the impact of PCB pollution effectively. The data across Africa could reflect concerning levels of PCB contamination in regions with extensive industrial activities and inadequate waste management, particularly regarding e-waste; however, in general, owing to inconsistent monitoring methods and limited data availability, temporal trends remained unclear. The identification of specific hotspots and the stark regional disparities necessitate targeted environmental policies and enhanced regulatory frameworks to effectively mitigate PCB pollution. Enhanced monitoring, stricter waste management protocols and international cooperation are crucial to reducing PCB levels and protecting ecosystems and public health across Africa.

AQUATIC ENVIRONMENTS

Surface and ground waters from various African locations have been documented over the years to assess PCB concentrations, revealing significant regional disparities and potential pollution sources. The data span from 2013 to 2024, with studies that target both urban and remote areas (Table 2).

In a study by Gakuba et al. (2015) in South Africa, PCB levels in water samples from the Umgeni River in KwaZulu–Natal reported Σ8 PCBs ranging from 6.91 to 21.69 ng/mL, which are within typical urban industrial levels and above the stringent European Union limit of 0.1 ng/mL for PCBs in surface waters. Meanwhile, PCB concentrations in the Msunduzi River were reported to be as high as 141.7 ng/mL, indicating potential localised sources of PCB pollution or historical contamination affecting the river (Adeyinka et al., 2018). Contrastingly, the situation in Nigeria presents some of the highest PCB levels recorded in the region, particularly in areas associated with industrial activities. For example, the Niger Delta demonstrated extremely high concentrations—up to 2,950 ng/mL of Σ14 PCBs in drainage water near a power station, emphasizing industrial discharge as a significant source of pollution (Aganbi et al., 2019).

These concentrations are among the highest when compared with those reported by other African studies and suggest that industrial processes in the Niger Delta may be contributing disproportionately to PCB pollution. In urban settings like Lagos, Nigeria, water samples from an e-waste dumpsite reported by Ayoola et al. (2023) contained between 3,040 and 5,820 ng/mL of Σ19 PCBs, illustrating the severe impact of e-waste on water quality. Such levels are not only extraordinarily high but also indicative of the challenges faced by regions with heavy e-waste processing activities.

In a later study, Afolabi et al. (2023) reported PCB concentrations of Σ8 PCB < bdl −29 ng/mL in water samples collected from Kenya in a non-urban setting, highlighting lower PCB levels in less industrialized water bodies. In a separate study, Zhao et al. (2022) investigated Σ18 PCB in Tanzania from 18 lakes in the Eastern Rift Valley, documenting levels ranging from 6.0×10⁻⁴ to 2.0×10⁻² ng/mL. These findings indicate the presence of PCBs in aquatic environments, although at relatively low concentrations.

In another study in Nairobi, Kenya, Ndunda et al. (2020) reported PCB levels of seven congeners as undetectable to 0.79 ng/mL, PCBs 28, 138 and 153 were the most dominant contributing more than 50% to the total PCBs in sediments. These lower concentrations may reflect either effective management practices or lesser industrial and e-waste influences compared with places like Nigeria (Aganbi et al., 2019).

When comparing PCB levels in surface and groundwater from African regions with those from other parts of the world, some differences and similarities are evident. For instance, David et al. (2015) reported Σ40 PCBs in the Sacramento River, USA, ranging from 0.12 to 6.7 ng/mL in surface water, which overlaps with PCB levels observed in African surface waters, such as the Buffalo River, South Africa, where Σ19 PCBs were reported at 0.185 to 2.329 ng/mL (Yahaya et al., 2018). However, the levels in the United States were generally higher than those in African regions.

By contrast, studies from the Tiber River in Italy indicated Σ32 PCBs at much lower levels, between 1.90×10⁻⁴ and 6.82×10⁻⁴ ng/mL (Montuori et al., 2016), which are remarkably lower than most values reported across African water bodies. Likewise, Wang et al. (2017) reported Σ14 PCBs in surface water ranging from not detected to 0.039 ng/mL, which is lower than those documented in highly polluted areas such as the Lagos lagoon in Nigeria, where Σ27 PCBs ranged from 69.2 to 440 ng/mL (Unyimadu et al., 2023).

These comparisons suggest that although some regions outside Africa, such as the United States, show a similar range of PCB contamination in water, others, particularly in Europe and Asia, exhibit lower levels. This underscores the relatively high levels found in certain African water bodies.

The review data on aquatic environments in Africa suggests a complex pattern of PCB distribution across African waters, heavily influenced by local industrial activities, waste management practices and historical use patterns of PCB-containing equipment. The notable contrasts between areas such as the Niger Delta and Nairobi or Tanzania underscore the need for targeted environmental policies and remediation efforts tailored to the specific conditions and challenges of each region (Adebusuyi et al., 2022; Ayoola et al., 2023). Effective management and reduction of PCB sources, particularly in heavily polluted areas, will be vital for enhancing water quality and protecting aquatic and human health across the continent.

ATMOSPHERE AND INDOOR DUST

Table 2 summarizes the data reported on concentrations of PCBs in studies of atmospheric samples, as well as indoor dust in Africa from 2013 to 2024.

Studies on the emission of PCBs in West Africa revealed high concentrations especially in Gambia and Ivory Coast both with up to 300 pg/m³ and the lowest PCB contamination level was recorded in Ghana (9 pg/m³) (Gioia et al., 2011). In Durban, South Africa, a study by Abafe et al. (2015) indicated indoor PCB contamination reaching 891 ng/g in home dust and 923 ng/g in office dust. This reflects high human exposure to these POPs in indoor environments. Moreover, higher pollutant levels have been reported in enclosed settings such as university student offices, with dust samples showing concentrations of up to 1,880 ng/g, which is indicative of significant external or building-specific source infiltration (Abafe et al., 2015).

Harrad et al. (2016) reported PCB contamination in various indoor settings within Lagos, Nigeria, in 2014. Their study further documented widespread urban exposure, with PCB concentrations in car dust ranging from 3.09 to 30.69 ng/g, house dust from 17.9 to 67.6 ng/g and office dust from 19.5 to 97.3 ng/g. These findings emphasise the prevalence of PCBs in urban environments, attributable to a combination of indoor sources and infiltration from the urban atmosphere. Further data from Lagos by Folarin et al. (2015) documented PCB levels in indoor dust from electricity generation facilities ranging from 2 to 220 ng/g, underscoring occupational exposure risks. Akinrinade et al. (2021) reported PCB concentrations ranging from 3.8 to 61 ng/g that house dust in Lagos, Nigeria. The reviewed documents reinforce earlier observations, which indicate a persistent presence of PCBs in residential environments.

In the outdoor air, a study conducted in Ghana by Hogarh et al. (2018) revealed extremely high PCB levels, ranging from 280 to 11,100 pg/m³ in the air around informal e-waste recycling activities. These observations highlight serious air quality problems and potential health risks linked to unregulated e-waste handling. In East Africa, Uganda, from 2008 to 2010, Arinaitwe et al. reported PCB levels in urban outdoor air ranging from 4.4 to 48 pg/m³, reflecting the broader regional atmospheric contamination by PCBs. Likewise, in Bizerte, Tunisia, Barhoumi et al. (2019) reported PCB concentrations in aerosol samples collected from the roof of the Faculty of Sciences, which varied from 3.5 to 2.4 pg/m³, documenting the persistence of PCBs in the Mediterranean urban atmosphere.

These studies from various African regions emphasize the widespread distribution and variability of PCB contamination in dust and air, signalling significant environmental and public health challenges, particularly in urban and industrialised settings in Africa, despite no history of PCB manufacturing on the continent. Focused efforts to reduce sources and monitor hotspots have led to remarkable decreases in atmospheric PCB concentrations in the Northern Hemisphere; meanwhile, despite reductions in PCB emissions in previously active areas, several studies have noted high PCB levels in locations far from original sources such as Africa (Jaward et al., 2004; Gioia et al., 2008, 2011). High PCB levels were recorded off the West African coast on cruises on board research vessels in 2001, 2005 and 2008. Klanova et al. (2009) found that urban and industrial sites in several African countries, including South Africa, Senegal, Kenya, Egypt, the Republic of Congo, Ghana and Sudan, had monthly average PCB concentrations of 100 pg/m³ or higher, levels comparable with those in the United States and European cities.

Nevertheless, a recent study using over a decade of passive air monitoring (2008–2019) by the MONET network has provided the first comprehensive dataset for documenting long-term trends of POPs in the African atmosphere (White et al., 2020). This study specifically focused on PCB monitoring in nine African countries (Congo, Ghana, Ethiopia, Kenya, Mali, Mauritius, Morocco, Nigeria and Sudan). As of 2019, concentrations of these pollutants varied, with PCBs ranging from 0.5 to 37.7 pg/m³. The recent findings reveal a general decrease in the concentrations of PCBs, over the past 10 years, although decreases have been slow at some locations. Elevated concentrations at specific sites were primarily attributed to persistent local emissions, whereas the lower concentrations reported at Mount Kenya are thought to represent the continental background levels influenced by long-range atmospheric transport. Regarding PCB composition, PCB concentrations in Mount Kenya were dominated by PCBs 28 and 52 and the absence of higher chlorinated PCBs. PCB emission sources are generally congener-specific, with the less chlorinated PCBs being the most volatile and therefore most associated with revolatilization from landfills, poorly stored or disposed of waste and contaminated soil. Conversely, emissions of the more chlorinated PCBs have been attributed to combustion processes (White et al., 2020).

When comparing PCB levels in Africa to those reported globally, variations can be significant. In Antarctica, Wang et al. (2017) recorded Σ11 PCB levels ranging from 4.8 to 62 pg/m³ in remote outdoor air between 2011 and 2014, which are generally lower than many levels documented in Africa. Likewise, Zhao et al. (2020) reported that in China (2016–2017), Σ11 PCBs ranged from below detection limits to 249 pg/m³ in remote to suburban outdoor air, aligning with the lower spectrum of African levels yet below the higher values seen in Ghana. Another study by Anh et al. (2020) in Northern Vietnam also documented a range of Σ11 PCBs between 68 and 300 pg/m³ in urban outdoor air from 2013 to 2015, paralleling or slightly under some urban African figures (Anh et al., 2020). Moreover, Miglioranza et al. (2021) reported Σ38 PCBs in ambient air from Patagonia, Argentina, at approximately 25 pg/m³ in 2018-less than in Africa (Miglioranza et al., 2021). Overall, studies in Africa, particularly those documented from informal e-waste recycling in Ghana, have documented relatively high PCB concentrations than samples from outside Africa.

These comprehensive data emphasize the ongoing challenges of PCB contamination across Africa, driven by factors like e-waste recycling and inadequate waste management despite the slight decrease in PCB trend. Only a quarter of African countries have established national legislation targeting PCB management, and although some have incorporated PCB regulations within broader environmental or chemical management laws, others lack any specific PCB-related legislation (Akinrinade et al., 2024). To address these environmental and public health issues effectively, the continued monitoring and adaptation of regulations are crucial.

BIOLOGICAL SAMPLES/HUMAN

Table 3 presents a summary of the concentrations reported on human/biological samples from 2014 to 2023.

Table 3 Occurrence of PCBs in biological samples; biota (ng/g) and human samples (μg/L) in African countries in previous studies and in other regions

Loction, Country	Sampling Year	Number of Samples	Sample Type	Number  of congeners analyzed	∑PCBs	Congeners	Refrence
Biota (ng/g)
Dakar. Senegal	2013	10	Mugilcephalus, Sarotheroron melanotheron	Σ28 PCBs	nd–95	PCB-8, 18, 28, 44, 52, 60, 77, 81, 101, 105, 114, 118, 123, 126, 128, 138, 153, 156, 157, 167, 169, 170, 180, 185, 189, 195, 206, 209	Net et al. (2015)
			Perna perna		<bdl–1,228
Swartkops, South Africa	2012	24	Fish tissues (P. commersonnii) liver, muscle and fat	Σ7 PCBs	<LOQ–195	PCB-28, 52, 101, 118, 138, 153, 180	Nel et al. (2015)
			Fish tissues (Lichia amia)		<LOQ–91
			Fish tissues (A. japonicas)		<LOQ–198
Port Elizabeth Harbour, South Africa	2013	60	Mytilus galloprovincialis	Σ6 PCBs	14.48–21.37	PCB-28, 52, 101, 138, 153, 180	Kampire et al. (2015)
Arusha, Tanzania	2011	159	free-range chicken eggs	Σ7 PCBs	0.36–9.2	PCB-28, 52, 101, 118, 138, 153, 180	Polder et al. (2016)
Ogun River, Nigeria	2013–2014	107	fish (muscle tissue of tilapia species)	Σ15 PCBs	359–4,636	PCB-8, 18, 28, 44, 52, 60, 77, 118, 123, 138, 153, 170, 189, 206, 209	Ibor et al. (2016)
South Africa	2005–2009	90	six dolphin species	Σ21 PCBs	78.5–938	PCB-28, 37, 52, 77, 81, 101, 105, 114, 118, 123, 126, 153, 138, 128, 156, 157, 167, 169, 180, 188, 209	Gui et al. (2016)
Eleyele Reservoir, Nigeria	2014	6	Cichlid sp. (fish tissue); Tilapia guineensis	Σ7 PCBs	2,531.1	PCB-28, 52, 101, 118, 138, 153, 181	Adeogun et al. (2016a)
Eleyele Reservoir, Nigeria	2014	6	Cichlid sp. (fish tissue); Sarotherodon galilaeus	Σ7 PCBs	1,178.7	PCB-28, 52, 101, 118, 138, 153, 181	Adeogun et al. (2016b)
			Cichlid sp. (fish tissue); Oreochromis niloticus		891.8
			Cichlid sp. (fish tissue); Tilapia zillii		832.8
			Cichlid sp. (fish tissue); Hemichromis fasciatus		475.7
			Cichlid sp. (fish tissue); Sarotherodon melanotheron		333.2
Lake Victoria, Kenya	2014	6	fish (Oreochromis niloticus, Lates niloticus, and Rastrineobola argentea)	Σ7 PCBs	300–3,000	PCB-28, 52, 101, 118, 138, 153, 181	Oluoch-Otiego et al. (2016)
South Africa and Reunion Island	2013	89	albacore tuna (Thunnus alalunga)	Σ18 PCBs	0.0051–1.2677 ww	12 dl-PCB-77, 81, 105, 114, 118, 123, 126, 156, 157, 167, 169, 189 and 6 PCB-28, 52, 101, 138, 153, 80	Munschy et al. (2016)
Senegal	2013	30	edible fish	Σ6 PCBs	1–8	PCB-28, 52, 101, 138, 153, 180	Diop et al. (2017)
Zanzibar islands (Pemba and Unguja) and mainland (Mtwara), Tanzania	2016	48	milkfish livers (Chanos chanos), mullet (Mugil cephalus)	∑10 PCBs	<LOD–8.13 lw	PCB-28, 52, 74, 99, 101, 118, 138, 153, 180	Mwakalapa et al. (2018)
Onitsha Axis, Nigeria	2017	20	sharptooth catfish (Clarias gariepinus)	Σ20 PCBs	nd–94	PCB-7, 18, 28, 43, 52, 60, 77, 101, 105, 123, 126, 128, 137. 154, 170, 180, 185, 195, 200, 209	Ibeto et al. (2019)
Saldanha Bay, South Africa	2018	-	Mussels (C. meridionalis, M. galloprovincialis)	Σ11 PCBs	6.9 –6.7 dw	PCB-18, 28, 44, 52, 70, 110, 118, 138, 149, 153, 180	Firth et al. (2019)
South Africa	2017	21	Chokka squid (Loligo reynaudii)	Σ7 PCBs	4.8–9.2 lw	PCB-28, 52, 101, 118, 138, 153, 180	Wu et al. (2019)
Zanzibar, Tanzania	2018	65	fish and prawn	Σ16 PCBs	5.6–336	PCB-28, 52, 74, 99, 101, 105, 118, 128, 136, 138, 153, 156, 170, 180, 183, 187	Haarr et al. (2021)
Other Regions
Hokkaido, Japan	2002	47	red-crowned cranes (Grus japonensis), muscle tissues	Σ16 PCBs	27–1,600 lw	PCB-101, 105, 110, 114, 118, 123, 138, 149, 153, 156, 157, 167, 169, 180, 187, 189	Kakimoto et al. (2018)
South Carolina, USA	2014	76	5 dolphin prey fish species: Atlantic croaker (Micropogonias undulatus); red drum (Sciaenops ocellatus); spot (Leiostomus xanthurus), spotted seatrout (Cynoscion nebulosus) and striped mullet (Mugil cephalus).	Σ121 PCBs	5.02–232.20	PCB-138, 139, 141, 146, 153, 156, 157, 167, 169, 170, 171, 174, 176, 177, 178, 179, 180, 182, 183, 185, 188, 189, 191, 193, 194, 195, 196, 199, 201, 202, 205, 206, 208, 209	Fair et al. (2018)
Okinawa, Japan	2017–2019	22	oysters (Saccostrea mordax)	Σ19 PCBs	<LOD–4,100 lw	PCB-28, 52, 95, 101, 105, 118, 138, 153, 156, 157, 167, 178, 180, 189, 194, 202, 206, 208, 209	Mukai et al. (2020)
Gulf of Naples, Italy	2016–2019	42	mussels (Mytilus galloprovincialis)	Σ6 PCBs	0.30–37.3	dl PCB-28, 52, 101, 138, 153, 180	Esposito et al. (2020)
Human (μg/L)
16 Western and Central African countries	2013	575	Blood samples serum of African immigrants	∑18 PCBs	82–678	PCB-28, 52, 77, 81, 101, 105, 114, 118, 123, 126, 138, 153, 156, 157, 167, 169, 180, 189	Luzardo et al. (2014)
Agbogbloshie, Accra, Ghana	2011	58	Human blood (informal e-waste recycling workers)	Σ3 PCBs	0.002–0.078	PCB-138, 153, 180	Wittsiepe et al. (2015)
Tunisia	2012	54	Blood serum	Σ3 PCBs	26.08–119.1 lw	PCB-138, 153, 180	Artacho- Cordan et al. (2015)
Arusha,Tanzania	2012	95	Human milk (mother-infant couples)	Σ7 PCBs	<LOD–157	PCB-28, 52, 101, 118, 138, 153, 180	Müller et al. (2017)
Accra, Ghana	2014–2016	105	Human milk (e-waste recycling site)	Σ7 PCBs	<LOD–29.20	PCB-18, 28, 52, 101, 138, 153, 180	Asmoah et al. (2018)
Tema, Ghana	2017	17	Maternal blood, pergnant women	Σ12 PCBs	0.059 lw	dl PCB-81, 77, 123, 118, 114, 105, 126, 167, 156, 157, 169, 189	Bruce-Vanderpuije et al. (2019)
Accra, Ghana					0.096 lw
Agbogbloshie (e-waste recycling site), Accra, Ghana	2015	88	Human blood (e-waste workers)	Σ6 PCBs	0.03–14.7	PCB-28, 52, 101, 138, 153, 180	Kaifie et al. (2020)
		196	Human blood (not workers, control)		0.03–1.29
Kampala, Uganda	2018	30	Human breast milk	Σ18 PCBs	0.0133–1.297 lw	PCB-28, 52, 101, 138, 153, 180, 77, 81, 126, 105, 114, 118, 123, 156, 157, 167, 189	Matovu et al. (2021)
Accra, Ghana	2017	24	Human milk	Σ12 PCBs	1.50×10−4–2.13×10−1	PCB-81, 77,123, 118, 114, 105, 126, 167, 156, 157, 169, 189	Bruce-Vanderpuije et al. (2021)
Other Regions
Guangdong province, China	2017–2018	179	Human breast milk	Σ12 PCBs	1.419–2.598 lw	PCB-81, 105,114,123,156,157,167,189	Huang et al. (2019)
Germany	2016	99	Human breast milk	Σ20 PCBs	0.000–0.115 lw	PCB-11 ,14, 28, 52, 77, 81, 101, 105, 114, 118, 126, 138, 153, 156,1 57, 167, 169, 180, 189	Zhong-Min et sl. (2019)
New Jersey, USA	2016–2018	920	Human serum samples	Σ40 PCBs	0.256–0.350 lw	PCB-18, 28, 44,49, 52, 66, 74, 87, 99, 101, 105, 110, 114,118, 123, 128, 138, 146, 149, 151, 153, 156, 157, 167, 170, 172,177, 178, 180, 183, 187, 189, 194, 195, 196, 199, 206, 209	Du et al. (2020)

Note: below detection limit (bdl); not specified (ns); not detected (nd); limit of quantification (LOQ); lipid weight (lw); wet weight (ww)

Net et al. (2015) documented Σ28 PCB concentrations in aquatic organisms in Dakar, Senegal, reporting the highest concentrations in Perna perna species, up to 1,228 ng/g dw, and the lowest in Penaeus kerathurus, with levels ranging from undetectable to 95 ng/g. Following this, Diop et al. (2017) reported Σ6 PCB levels in 30 edible fish samples from Senegal, with findings showing concentrations between 1 and 8 ng/g.

In another study, in Swartkops, South Africa, reported by Nel et al. (2015) PCB levels in 24 fish tissue samples from three species (P. commersonnii, Lichia amia and A. japonicas). Σ7 PCB concentrations were reported from below the quantifiable limits to 198-ng/g dry weight (Nel et al., 2015). Meanwhile, Mytilus galloprovincialis from Port Elizabeth Harbor in 2013 exhibited levels from 14.48 to 21.37 ng/g, suggesting low to moderate pollution (Kampire et al., 2015).

In Arusha, Tanzania, free-range chicken eggs in 2011 contained PCBs ranging from 0.36 to 9.2 ng/g (Polder et al., 2016), whereas Ibor et al. (2016) reported significant contamination in tilapia muscle tissues, with concentrations reaching up to 4,636 ng/g in the Ogun River, Nigeria. The authors associated these high concentrations could be concerning for dietary intake. The Eleyele Reservoir in Nigeria, extensively studied in 2014, showed extraordinarily high PCB levels across various cichlid species, indicating heavy local pollution. For instance, Tilapia guineensis and Sarotherodon melanotheron recorded levels up to 2,531.1 and 333.2 ng/g, respectively (Adeogun et al., 2016). Lake Victoria in Kenya also has been reported to have high PCB levels in 2014, ranging from 300 to 3,000 ng/g in fish species like Oreochromis niloticus, reflecting significant aquatic ecosystem contamination (Oluoch-Otiego et al., 2016).

PCB levels from African regions demonstrate a wide range, with some values comparable to those reported in other parts of the world. For instance, in South Carolina, USA, Fair et al. (2018) reported Σ121 PCBs in dolphin prey fish species at levels ranging from 5.02 to 232.20 ng/g (Fair et al., 2018), which is higher than those found in fish tissues in Swartkops, South Africa (Nel et al., 2015b). Nevertheless, Mukai et al. (2020) documented levels of Σ19 PCBs in oysters from Okinawa, Japan (2017–2019), from below detection limits to 4,100-ng/g lipid weight exceeding those typically reported in African samples.

By contrast, red-crowned cranes from Hokkaido, Japan, have been reported to have Σ16 PCBs ranging from 27 to 1,600 ng/g lw (Kakimoto et al., 2018), which is somewhat similar to the levels observed in South Africa and Reunion Island’s albacore tuna, with Σ18 PCBs ranging from 0.0051 to 1.2677 ng/g ww (Munschy et al., 2016). This highlights the diversity in PCB contamination levels across different regions and species.

Human exposure to PCBs through consumption and environmental contact was evident in African countries. Agbogbloshie, Ghana, is an area well-known for its extensive e-waste recycling operations; Wittsiepe et al. (2015) have documented PCB levels in human blood from 58 individuals working in informal e-waste recycling sites; Σ7 PCBs ranged from 0.002 to 0.078 μg/L.

A further study conducted by Kaifie et al. (2020) at the Agbogbloshie e-waste site in Ghana documented significant variations in PCB exposure. They have reported Σ6 PCB concentrations samples from 88 individuals ranging from 0.03 to 14.7 μg/L in the human blood of e-waste workers and PCB levels from 0.03 to 1.29 μg/L from 196 participants not workers as control groups. The authors associated these concentrations with PCB exposure due to proximity to e-waste handling activities (Kaifie et al., 2020). Regarding PCB congeners, a significant difference was observed in the levels of lower chlorinated PCB congeners (PCBs 28, 52 and 101) between e-waste workers and the control group. Among the specific recycling tasks, workers involved in dismantling and burning e-waste exhibited the highest levels of PCBs 28 and 52. Moreover, e-waste workers demonstrated elevated levels of PCBs 138, 153 and 180, likely due to increased occupational exposure in their work environment.

Later study in the same location in Accra, Ghana, concentrations of Σ12 PCBs were reported by Bruce-Vanderpuije et al. (2021), where concentrations of PCBs 118, 105 and 156 were considerably higher among all congeners; Σ12 PCBs ranged from 1.50×10⁻⁴ to 2.13×10⁻¹ μg/L from 24 individual human milk. A related study in Accra by Asmoah et al. (2018) reported Σ7PCBs levels in human milk collected from 105 mothers at an e-waste recycling site, with mean concentrations of 3.64 μg/L. In samples from the largest electric and e-waste dump and recycling site in Accra, PCB-28 was reported as the most prevalent, accounting for 30% of the total PCBs in the milk samples, whereas PCB-101 was reported as the least prevalent, representing 1.74%.

In comparison, PCB levels in human samples from African regions and other parts of the world indicated notable differences. For instance, Huang et al. (2019) reported PCB levels in Guangdong Province, China (2017–2018); Σ12 PCBs were reported at levels ranging from 1.419- to 2.598-μg/L lipids in human breast milk (Huang et al., 2019), which were higher than those documented in some African locations included in the review. Conversely, in Germany, Zhong-Min et al. (2019) reported Σ20 PCB levels in human breast milk ranging from undetectable to 0.115 μg/L, a range that overlaps with the lower end observed in Africa but remains below the highest levels reported, such as in Ghana, where Σ7 PCBs reached up to 29.20 μg/L in human milk from e-waste recycling sites (Asmoah et al., 2018). This contrast highlights the geographical disparities in PCB exposure, with some non-African regions experiencing higher exposures comparable with or exceeding those documented in more contaminated African environments.

Studies performed across various African countries have documented the persistent and pervasive nature of PCB pollution, which impacts both wildlife and human populations. In some regions, particularly those affected by industrial activities such as e-waste recycling activities, PCB levels have been reported to be alarmingly high, reflecting environmental contamination.

E-WASTE MANAGEMENT IN AFRICA

In recent years, Africa’s demand for electrical and electronic equipment (EEE) has increased at a rate of 2.5% per annum. Besides the e-waste generated locally, numerous African countries import significant amounts of EEE (Maphosa and Maphosa, 2020). The growing consumption of EEE has accordingly led to an upsurge in e-waste produced on the continent (Asante et al., 2019; Lebbie et al., 2021).

Africa locally generates between 50% and 85% of its total e-waste, with the remainder originating from illegal cross-border imports from developed countries in the Americas, Europe and China. Monitoring the transboundary movement of e-waste into Africa is challenging; however, Ghana, Nigeria and Tanzania have been identified as key recipients from the EU/UK. Nigeria, particularly, imports significant volumes of used electronic and electrical equipment, with over 60,000–71,000 tonnes annually entering Lagos, primarily from the EU. Major African ports like Durban, in South Africa, Bizerte and Lagos serve as entry points for such e-waste, often bypassing international conventions through illegal practices like mislabelling (Lebbie et al., 2021; Maes and Preston-Whyte, 2022).

According to Forti et al. (2020), Africa generated 2.9 Mt of e-waste, which converts to 2.5 kg per capita in 2019. Although the per capita e-waste generation in Africa is the second lowest globally, more than 60% is obtained from imports from high-income countries such as the United States and Europe (Bimir, 2020; Forti et al., 2020). E-waste contains valuable materials, making recycling an economically viable opportunity. Consequently, the trade, repair and informal recovery of valuable materials from e-waste provides an important source of income for many economically disadvantaged populations. Moreover, e-waste presents a hazard to the environment, animals and humans because a large range of toxic chemicals (toxicants) are associated with e-waste and can be released from it, which poses serious risks to human health and the environment (Williams et al., 2008).

Few countries including South Africa and Egypt have limited infrastructure for formal e-waste recycling; however, these limited infrastructures co-exist with a huge informal sector (Maes and Preston-Whyte, 2022). Consequently, the recycling companies have faced difficulty in progressing and increasing the amount of e-waste recycled. Conversely, large countries including Nigeria, Kenya and Ghana continue to rely on informal recycling (Adanu et al., 2020; Forti et al., 2020). Currently, the informal sector, including collectors and recyclers dominates e-waste management in Africa. Additionally, government control of this sector is presently very negligible and unproductive, and there are a limited number of organised schemes for take-back or licensed services for sorting and dismantling e-waste (Bakhiyi et al., 2018; Maphosa and Maphosa, 2020).

Africa faces the challenge of managing both domestic and imported cross-border e-waste. This influx often includes waste misrepresented as ‘charitable donations’ or ‘second-hand goods’, leading to significant environmental and human health impacts (Baldé et al., 2017). In Ghana, for instance, only a portion of the imported 0.215 million metric tonnes of e-waste in 2019 was found to be potentially usable, with the majority requiring proper disposal. The illegal dumping and burning of non-functional e-waste further exacerbate ecological damage, highlighting the need for stricter regulation and improved recycling infrastructure (Okeke et al., 2024). Nearly all imported EEE in Africa comes from developed nations, and the lack of effective e-waste recycling laws has led to significant illegal waste imports processed through informal methods. Although some African countries have begun implementing e-waste legislation, enforcement remains weak, which results in continued challenges with e-waste management (Baldé et al., 2017).

CONCLUSION AND FUTURE PERSPECTIVES

This review highlighted the persistent presence of PCBs in African environmental matrices at concentrations comparable to or, in some cases, higher than those reported globally. Despite available data, comprehensive information on PCBs is lacking in many African countries. However, the IPW employed effective screening methods to understand trends in global samples, including those from Africa. Reviewed studies suggested a shift in PCB pollution levels from traditional regions e.g., the United States and Western Europe to African regions, where PCBs were neither produced nor widely utilized. The findings from IPW studies underscore the critical need for robust regulatory frameworks and effective waste management strategies in African countries to manage PCB pollution effectively. The global distribution of PCBs, as shown by their presence in plastic pellets on beaches worldwide, calls for a concerted international effort to tackle the sources, effects and management of PCBs in Africa.

Significant sources of PCBs in Africa include obsolete transformers and the ongoing importation of e-waste into Africa from Northern America, particularly Europe. The clandestine nature of these imports complicates global emission inventories and control strategies. Thus, efforts to curb the export of obsolete products and waste from developed countries are crucial, along with implementing robust waste management solutions to eliminate PCBs in Africa.

Effective e-waste management strategies are urgently needed and should include stringent legislation, public education and technological advancements. These strategies should not only aim to reduce PCB pollution but also foster sustainable practices that prevent the future accumulation of toxic substances. Furthermore, regular monitoring of PCB concentrations is needed, particularly in countries with dense industrial activities and open burning sites. Monitoring should extend to both rural and urban settings to understand spatial trends and human exposure. Consistent long-term monitoring at selected locations is also essential to track temporal trends and assess the effectiveness of PCB reduction measures. Considering that only a quarter of African countries have established national legislation targeting PCB management, and although some have incorporated PCB regulations within broader environmental or chemical management laws, others lack any specific PCB-related legislation (Akinrinade et al. 2024). This regulatory gap hinders the effective management and elimination of PCB pollution. Studies reviewed indicated that there is a substantial deficiency in follow-up studies and monitoring evaluating the efficacy of cleanup activities in Africa.

Research on PCB exposure is scarce, and analytical data are primarily available for limited countries in air, soil and sediments, with few studies examining human exposure near potential contamination sites. This information is crucial for understanding the public health implications of PCB exposure.

Lastly, the lack of continuous and consistent monitoring of PCBs in Africa may stem from insufficient technical and institutional capacity. PCB analysis remains cost-prohibitive for many African countries due to expensive equipment and labour-intensive sample preparation. Developing local analytical capabilities is essential for achieving PCB reduction or elimination goals. Overviewed literatures call for enhanced monitoring and stricter regulations to decrease the levels of PCBs and their associated risks.

ACKNOWLEDGEMENTS

We would like to express our sincere gratitude to all the members of our laboratory for their valuable feedback and assistance throughout the writing of this review. We would also like to extend our gratitude to Mr. Takashi Tokumaru for providing the photograph of the burning site in Africa utilized in our graphical abstract. His contribution has greatly enhanced the visual impact of our work.

CONFLICT OF INTEREST

The authors declare no conflicts of interest regarding the publication of this paper.

AVAILABILITY OF DATA AND MATERIALS

This review does not involve any original data or materials. All the data used in this review are derived from published literature and are cited in the main text or main tables. No additional data or materials are available.

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