Benzotriazole UV-stabilizers in beached plastic resin pellets collected across the world including remote islands: Evidence of plastic-mediated long-range environmental transport (LRET) of additives

ABSTRACT

This study analyzed benzotriazole UV stabilizers (BUVSs), including UVP, UVPS, UV329, UV9, UV320, UV350, UV326, UV327, UV328, and UV234, in beached polypropylene (PP) pellets. First, the efficiency of soaking extraction in hexane was confirmed. This extraction method was then applied to 37 PP pellet samples (each sample basically consisted of 50 pellets) collected from beaches worldwide (Europe, Africa, the Middle East, Asia, Oceania, and the Americas). Twenty samples had low levels of BUVSs that were <0.2 μg/g, while 14 samples exhibited high concentrations, ranging from >1 μg/g of BUVSs (sum of the 10 BUVSs) to 70 μg/g. These high concentrations were observed only for one or two BUVS (UV326, UV327, UV329, and UV328) in individual PP pellet samples. Piece-by-piece analyses of pellets from eight locations revealed sporadic and inhomogeneous occurrences of specific BUVSs. Pellets with high concentrations of BUVSs were industrially compounded with additives and/or were recycled, and they were even found on remote islands, such as, Macquarie Island, Hawaii Island, Ogasawara Island, and Hachijo Island. The concentrations of BUVSs in pellets from remote areas were similar orders of magnitude to those observed in anthropogenically impacted areas near industrial areas, such as Sydney or Tokyo. This study demonstrates that BUVSs, as plastic additives, travel in millimeter-sized plastics across thousands of kilometers without drastic desorption or degradation. The findings highlight the need for international regulation of plastics and associated chemicals.

INTRODUCTION

BUVSs are a class of chemicals used to protect materials from UV-induced photo-degradation. They are used as additives in plastics, rubber, paints, and other applications. This study focuses on 10 major BUVSs, as shown in Fig. S1. These compounds are persistent (Khare et al., 2023), and although they have a wide range of hydrophobicity, with log K_ow 3–8, most of them are hydrophobic with log K_ow >5. Therefore, BUVSs are bio-accumulative and are found in various organisms, including mussels (Nakata et al., 2012; Takano et al., 2024), fish (Nakata et al., 2009; Peng et al., 2017), crustaceans (Nakata et al., 2009; Peng et al., 2017), seabirds (Yamashita et al., 2021), sea turtles (Fukuoka et al., 2024), and seals (Lu et al., 2019). Some BUVs interact with hormone receptors, such as estrogen receptors (Sakuragi et al., 2021) and aryl hydrocarbon receptors (Nagayoshi et al., 2015; Kubota et al., 2022), disrupting endocrine and drug-metabolism systems. Due to their persistent, bio-accumulative, and toxic properties, some BUVSs (UV320, UV350, UV327, and UV328) have been regulated and/or monitored by governments and regional organizations (ECHA, 2020). Notably, UV328 has been listed as a persistent organic pollutant (POP) under the Stockholm Convention (UNEP/POPS/COP.11/31, 2023) for its persistent, bio-accumulative, and toxic properties as well as its capacity for long-range environmental transport (LRET). Regarding LRET, UV328 is present in cm/mm-size plastic debris (Rani et al., 2017) that is subjected to long-range transport with floating on surface water by ocean currents and wind (Andrade et al., 2021), which was supported by Tanaka et al. (2019; 2020) and Yamashita et al. (2021). This floating plastic-mediated LRET of UV328 was intensively discussed during the 17^th and 18^th meeting of the Stockholm Convention Review Committee (POPRC).

POPRC has evaluated LRET via air, water, and migratory species for a wide range of POPs (UNEP, 2023). They positively evaluated plastic-mediated LRET of hydrophobic additives. However, there are some statements that underestimate the importance of plastic-mediated LRET of additives and they can be utilized by industries to keep producing the chemicals of concern. Such underestimation was due to confusion of (a) μm/nm-size polymers with cm/mm-size olefin polymers, which behave differently in marine environments, i.e., the later ones undergo LRET by floating but the former ones do not undergo LRET due to sinking and (b) additives with adsorbed chemicals. Furthermore, assessments were mainly based on model calculations utilizing limited observations, e.g., leaching and bio-accumulation of hydrophobic additives from long-range transported plastics in environmental conditions was just speculated. Field data on long-range transport of BUVSs is still limited (Wania and McLachlan, 2024). Thus, this study analyzed BUVSs in plastic resin pellets stranded on beaches worldwide, including remote islands, to obtain more data on the plastic-mediated long-range transport of additives.

Plastic resin pellets are plastic particles with diameters of 3–5 mm that are shaped into balls, cylinders, plates, or disks. They are a kind of microplastic and are a feedstock of plastic products. Plastics are synthesized from petroleum in the form of pellets. These pellets are transported to factories where they are heated, melted, pressed, and molded into the final product, such as packaging, toys, and automobile parts. During transportation and handling, a portion of the pellets are spilled to the environments and eventually washed into streams and rivers and then the ocean (Kuriyama et al., 2002). In addition, plastic resin pellets are spilled from containers onboard at the harbors accidentally and/or storm events (Saliba et al., 2022; James et al., 2023). Regardless of their route, pellets enter the oceans from industrialized coastal zones, including river mouths and ports. Because olefin plastic pellets, i.e., polyethylene (PE) and polypropylene (PP) pellets are nonbiodegradable and buoyant, they are transported around the world. Therefore, PE and PP pellets have been found on beaches worldwide (Gregory, 1978; Morris, 1980; Shiber, 1982 and IPW website), including remote islands such as Hawaii, Cocos, St. Helena, the Canary Islands, the Galapagos, Macquarie, and Easter Island (Heskett et al., 2012; Ohgaki et al., 2021). All of these remote islands, some of which are deserts, are hundreds to thousands of kilometers from industrialized coastal zones where the pellets were manufactured or handled. The presence of pellets on these remote islands provides strong evidence of the long-range transport of resin pellets and millimeter-size microplastics. This study then analyzed pellets from these remote islands to determine whether they contained plastic additives.

Due to the hydrophobic nature of plastics, hydrophobic contaminants in seawater are adsorbed and become concentrated in plastic pellets (Mato et al., 2001; Rochman et al., 2013). Various persistent organic contaminants, including PCBs, organochlorine pesticides, PBDEs, PAHs, coprostanol, and triclosan, have been measured in resin pellets to understand the pollution status of coastal waters (Ogata et al., 2009; Karapanagioti et al., 2011; Mizukawa et al., 2013; Hosoda et al., 2014; Yeo et al., 2015; Le et al., 2016; Taniguchi et al., 2016; Yeo et al., 2017; Yamashita et al., 2019; Pozo et al., 2020; Alidoust et al., 2021; Ohgaki et al., 2021; Alidoust et al., 2024). For this type of monitoring, polyethylene (PE) has been utilized because of its higher affinity to hydrophobic compounds (Endo et al., 2005; Karapanagioti and Klontza, 2008). Because BUVSs are hydrophobic and have an affinity with plastics, our previous study in the same project measured PE pellets collected from 22 beaches for BUVSs (Karlsson et al., 2021). Most of the detected BUVSs in the PE pellets were ascribed to being sorption-derived. BUVSs are not typically compounded into PE virgin pellets, and strong indicators of this having occurred were not observed. However, BUVSs may be compounded into PP pellets because PP is more prone to weathering from UV radiation. Thus, this study focused on BUVSs detected in PP pellets and to assess if they were compounded into the plastics.

In this study, first, we examined the analytical method to measure additives in the plastic matrix. Then based on this, we analyzed the BUVSs in PP pellets from 34 beaches worldwide to understand the occurrence patterns and their origins, i.e., sorption or additives. By examining pellets from remote islands, we aimed to provide evidence of plastic-mediated LRET of BUVSs.

MATERIALS AND METHOD

BEACHED PELLET SAMPLES

Plastic resin pellet samples were collected from 34 sandy beaches worldwide. The samples were collected using solvent-rinsed stainless-steel tweezers or soap-rinsed fingers, stored in aluminum foil, and sent by airmail to the Laboratory of Organic Geochemistry in Japan. The pellets from Ghana were collected in different years. Detailed information about the samples is listed in Table S1.

STANDARD ANALYTICAL METHOD OF BEACHED PP PELLETS

All glassware and stainless-steel apparatus were rinsed with detergents, tap water, and solvents (methanol, acetone, and distilled hexane) and dried or kiln-baked at >500°C. Hexane was distilled for the analysis.

The distinction between pellets and plastic fragments was made through visual observation based on their characteristic shape (cylinder, disk, and ball). Photos of all the analyzed pellets were displayed in Supporting Information (Fig. S3). Pellet samples were sorted by polymer type using near-infrared spectroscopy (Plascan-W^TM, OPT Research Inc., Tokyo, Japan). Fifty pieces of PP pellets were randomly selected and analyzed. In locations where the total number of PP pellets was <50, all the pellets were analyzed (Table S1). Although no biofilm was typically observed on the pellet surface, biofilm removal was not conducted and pellets with biofilm, if any, were solvent-extracted all together. The pellets were soaked in 15 mL of hexane in a 30 mL glass vial for 24 hours. While the PP pellets themselves were not dissolved in hexane, BUVSs and the other hydrophobic monomers were extracted in hexane. The residual pellets were subsequently soaked in 15 mL of fresh hexane, with the extraction process repeated three times (24 h×3). Hexane extracts were then combined. The extracts were spiked with 50 μL of 2 ppm isotopically labeled surrogate standards (UVP-d₃, UVPS-d₉, UV329-¹³C₆, UV326-d₃, UV327-d₂₀, UV328-¹³C₆, and UV234-d₁₀). The extracts were roto-evaporated to dryness, redissolved in a small volume of hexane, and transferred to a 10 mL glass centrifuge tube. The hexane was evaporated under a gentle stream of nitrogen, and 50 μL each of pyridine and acetic anhydride were added to the centrifuge tube. Acetylation proceeded at 40°C for 14 hours. By adding 0.2 mL of 4M hydrochloric acid, the reaction was stopped, and acetylated BUVSs were extracted using hexane. The hexane was concentrated to ~0.5 mL and applied to a 10% H₂O deactivated silica gel column chromatograph (1 cm i.d. × 9 cm). BUVSs were eluted with 25 mL of 4% acetone (ACE)/dichloromethane (DCM) following elution with 15 mL of 25% DCM/hexane. The ACE/DCM eluents were concentrated to ~0.5 mL in a rotary evaporator and transferred to a 1 mL glass ampoule. The solvent was evaporated to dryness under a gentle stream of nitrogen and redissolved in a small volume (100–500 μL) of iso-octane containing injection internal standard (chrysene-d₁₂), which corrected evaporation at the injection port and injection volume, for determination by a gas chromatograph-mass spectrometer (GC-MS). GC-MS analyses were performed using an HP 5977 MS equipped with a GC 7890B. Detailed information about the operating conditions of the GC-MS and the monitored ions are available in Table S2 and Table S3. Five-point calibration lines ranging from 125 ppb to 2,000 ppb were used for routine measurements. All analytical values were recovery-corrected using surrogates spiked with the extracts at the beginning of the analytical procedure. Blank sample runs were performed together with all the sets of samples. (One set consisted of five samples.) The limit of quantification (LOQ) was calculated at three times blank values. LOQ ranged from ~0.08 ng for UV329 to 0.3 ng for UV326 per sample. For quality assurance and quality control, hexane extracts of 250 pieces of pellets (Tokyo) were taken up to 250 mL, and four replicates of 250 μL aliquots were analyzed. The relative standard deviation of the analytical values was 1%–14%. Aliquots spiked with native BUVSs standards were analyzed for BUVSs to test for recovery. The recovery ranged from 75% to 110%.

PIECE-BY-PIECE ANALYSIS

Piece-by-piece analysis of one sample of 25 pellets from Tokyo (Kasai seaside park; IPW-Sample ID: 19091100) was performed to check for variations in the concentrations of BUVSs. In addition, another seven samples (Kenya, Lebanon, Malaysia, Fujisawa, Tokyo, Costa Rica, and Zamami Is.), five pools consisting of five pellets, were also analyzed, as shown in Table S1.

MANUFACTURING PP VIRGIN PELLETS COMPOUNDED WITH BUVSs

To evaluate the extraction efficiency of soaking in hexane, PP virgin pellets compounded with BUVSs were manufactured according to industrial protocols. First, 300 g of PP powder (NOVATEC PP FY4) was thoroughly mixed with 0.3 g (x factor [f]: 0.97–1.07) each of UVP, UV329, UV326, UV327, UV328, and UV234 neat standard powder in a stainless-steel bowl. The standard powder was then mixed with 1,200 g of PP pellets (NOVATEC PP FY4), put into an extruder, heated at 180°C and extruded into 5 mm pellets. The extruded pellets were thoroughly mixed, heated and extruded again. The heating and extrusion process was repeated three times so that the distribution of BUVSs in the pellets was as homogeneous as possible. The PP pellets were soaked in hexane and distilled water, respectively, and analyzed for BUVSs. The concentrations of BUVSs were compared with their theoretical concentrations (200×f μg/g) to calculate the extraction efficiency. Furthermore, residual PP pellets after soaking with hexane were dissolved in toluene, as described in the next section, and analyzed for BUVSs.

DISSOLUTION-PRECIPITATION METHOD

To confirm whether soaking efficiently extracts BUVSs from the polymer matrix, the pellets were extracted with soaking in hexane and then the residual pellets were dissolved in toluene to analyze for BUVSs. The dissolutions and subsequent analysis were performed according to the methods described by Tanaka et al. (2023) and Vandenburg et al. (1997). A piece of an residual pellet and 3 mL of toluene were placed in a 10 mL glass centrifuge tube and heated to 125°C for complete dissolution. After dissolution, the toluene solution was spiked with isotopically labeled BUVSs as surrogate standards, and methanol was added so that the polymer precipitated. Following centrifugation at 2,000 rpm for 30 minutes, supernatant was taken. MeOH was added to the precipitated polymer, and after centrifugation, MeOH supernatant was taken. The extraction process with MeOH was repeated twice, and MeOH and toluene extracts were combined and roto-evaporated for gel permeation chromatography (GPC, 2 cm i.d.×30 cm; CLNpak EV-2000; Shodex, Japan) to separate BUVSs from oligomers using DCM as an eluent at a flow rate of 4 mL/min. During the retention time, from 11.5 to 25 minutes, a sample was collected as a monomer fraction. The monomer fraction was subjected to acetylation and analyzed for BUVSs by GC-MS, as described in the section “Standard analytical method of beached PP pellets.” All the analytical values were corrected with the recovery of the surrogates spiked just after dissolution with toluene.

RESULTS AND DISCUSSION

COMPARING EXTRACTION BY SOAKING IN HEXANE WITH THE DISSOLUTION-PRECIPITATION METHOD

The manufactured PP pellets were soaked in hexane and distilled water, respectively, and then analyzed for BUVSs. Though no significant amounts of BUVSs were detected in distilled water, substantial amounts of BUVSs were extracted in hexane. The concentrations of BUVSs ranged from 190±26 μg/g to 221±45 μg/g. Comparing these concentrations with the theoretical concentrations of individual BUVSs calculated from the weight of the spiked BUVSs standards and the weight of PP indicates that the extraction efficiency exceeded 83%, as shown in Table 1. Furthermore, residual pellets remaining after the soaking extraction with hexane were dissolved in toluene as described above and analyzed for BUVSs. Only trace concentrations of BUVSs, ranging from 0.128 μg/g to 1.72 μg/g, were found, corresponding to 0.06% to 0.9% of those originally contained in the pellets. These results clearly demonstrate that soaking in hexane efficiently extracts BUVSs in the polymer matrix.

Table 1 BUVSs concentrations determined by Soaking extraction compared to spiked

	Spiked (g)	Theoretical (μg/g)	Soaking in water			Soaking in Hexane			Residue
			Average* (μg/g)	Deviation*	%	Average* (μg/g)	Deviation*	%	(μg/g)	%
UVP	0.30	200	15.7	0.45	7.8%	190	26	95%	0.325	0.16%
UV329	0.30	200	0.03	0.01	0.01%	192	43	96%	0.171	0.09%
UV326	0.32	213	<0.003	—	<0.001%	217	15	102%	0.128	0.06%
UV327	0.30	200	<0.002	—	<0.001%	165	15	83%	0.162	0.08%
UV328	0.29	193	<0.002	—	<0.001%	180	21	93%	0.291	0.15%
UV234	0.30	200	<0.004	—	<0.002%	221	45	111%	1.716	0.86%

^*  Duplicate measurement

Efficient extraction by soaking was also confirmed for beached pellets, as described below. In the piece-by-piece analysis of BUVSs in beached PP pellets, a pellet was extracted by soaking with hexane and then the residual pellet was dissolved in toluene and analyzed for BUVSs. Although high concentration (46.3 μg/g-pellet) of UV326 was found in the soaking extracts of the beached pellet, no significant amounts of UV326 (0.4 μg/g-pellet, corresponding to <1%) were found in the residual pellets after soaking extraction. This confirms that soaking in hexane is efficient also for the pellets collected in the natural environment. Efficient extraction by soaking in hexane can be explained by a process where hexane can penetrate the polymer matrix, enabling it to extract BUVSs. This is consistent with the higher extraction efficiency of hydrophobic additives in plastic that use fish oil compared to distilled water or seawater (Tanaka et al., 2015).

CONCENTRATIONS OF BUVSs IN PP PELLETS AND CALCULATING THEIR ORIGINS

Among the 37 PP pellet samples analyzed, 14 samples showed high concentrations of BUVSs of >1 μg/g (the sum of the 10 BUVSs). Ten samples had extremely high concentrations of >5 μg/g, and 23 samples showed low levels of BUVSs<1 μg/g, as shown in Fig. 1 and 2. The highest concentrations of up to 70 μg/g were observed in Belize. Though high concentration of BUVSs in pellets from Belize may be related to the industrial activities in the area, heterogeneous distribution of the additives among pellets could be more responsible for the high BUVSs concentrations as discussed in the following sections. There has been little research on BUVSs in beached pellets. Santana-Viera et al. (2021) detected ~0.02 μg/g of BUVSs in pellet samples from the Canary Islands. Karlsson et al. (2021) reported concentrations of BUVSs that ranged from 0.09 to 2.79 μg/g in PE pellets collected from 22 beaches worldwide. No extremely high concentrations of BUVSs of >5 μg/g were observed. Most of the BUVSs were hydrophobic compounds with ~log K_ow 5 or higher that could be adsorbed by the pellets from sea water. Lower concentrations of BUVSs in PE and PP pellets found on urban coasts (e.g., Ghana 2015) had multiple additive components (e.g., UV329, UV326, UV327, and UV328) with equal ranges of concentrations (Fig. 2). This suggests that these BUVSs could be derived from sea water. This is consistent with the fact that multiple BUVSs were found in coastal waters and sediments in equal ranges of concentrations (Hu et al., 2021; Zhao et al., 2024).

Fig. 1 Concentrations of total BUVSs in polypropylene (PP) pellets on world beaches (μg/g-pellet)

Total BUVSs: sum of UVP, UVPS, UV329, UV9, UV350, UV320, UV326, UV327, UV328, UV234

Fig. 2 Total BUVSs concentrations (upper) and their compositions (bottom) in polypropylene (PP) pellets on world beaches

Higher concentrations of BUVSs >1 μg/g consisted of one or two compounds, e.g., UV327 in Ghana (2014), Belize, Taiwan, and Sydney; UV326 in Ogasawara Island, Matsue; UV326 and UV327 in Kenya, Tokyo, Macquarie, Hawaii, and Hachijo Islands; UV328 in PunTa Herradura; and UV329 and UV326 in Fujisawa (Fig. 2). This exclusive predominance of one or two additives cannot be explained by sorption from sea water because multiple BUVSs additives are present in equal orders of concentrations in coastal waters (e.g., Hu et al., 2021; Zhao et al., 2024). Instead, it could be derived from pellets that are industrially compounded with additives and/or recycled pellets. Specific additives are compounded at high concentrations to pellets, including compound or master batch pellets, for the industrial manufacturing of plastic products (Murphy, 2001). Recycled pellets can also contain high concentrations of specific additives. Brosché et al. (2021) reported the exclusive predominance of specific additives (UV326 and UV327) for some recycled PE pellets that were purchased from local industries across 23 countries. They measured BUVSs in PE recycled pellets. More UV stabilizers are required for PP pellets, since PP is more susceptible to weathering by UV radiation. Thus, the sporadic high concentrations of BUVSs observed in the beached PP pellets were likely to be derived from industrially compounded additives and/or recycled pellets.

The results of piece-by-piece analysis of pellets from a beach in Tokyo are shown in Fig. 3. Among 25 pieces of pellets from the beach, one pellet exhibited orders of magnitude higher concentration of BUVSs (UV326 at 46.3 μg/g) than the other pellets with ~1 μg/g. This is again indicative of industrially compounded additives and/or recycled pellets. Concentrations of UV326 in the recycled pellets ranged from 0.3 ng/g to 83.2 μg/g (Brosché et al., 2021) and covered the concentrations of UV326 (46.3 μg/g) in the pellets from the beach in Tokyo. Additionally, from seven locations, five pools consisting of five pellets were analyzed for BUVSs. As shown in Fig. S2, three locations, Kenya, Fujisawa, and Tokyo, had pellet pools having extremely high concentrations of BUVSs (UV326, UV327, and UV329) of up to 100 μg/g. As the analysis was made for the 5 pellets, the maximum concentration for a single pellet could be ~500 μg/g. These concentrations were higher than the highest concentrations reported for the recycled pellets (UV326, 83.2 μg/g; UV327, 56.2 μg/g; UV329, 9.55 μg/g). However, the reported concentrations of BUVSs in the recycled pellets were for PE pellets, which require less BUVSs due to their superior weathering properties to PP pellets. Thus, PP recycled pellets may contain more BUVSs. Industrial pellets (compound pellets) spiked with BUVSs must have a similar range of BUVSs (~100 μg/g) since Rani et al. (2017) detected 58.3 μg/g of UV326 and 36.9 μg/g of UV327 in a commercial plastic product. Moreover, master batch pellets generally contain much higher concentrations (0.25%–3%=2,500–30,000 μg/g) of BUVSs (Murphy, 2001). All these results are consistent with BUVSs that were derived from industrially compounded additives and/or recycled pellets. More research is needed on the origins of the BUVSs in the beached pellets and further analysis of PP recycled pellets and industrially processed pellets.

Fig. 3 Analytical results of piece-by-piece analysis of 25 PP pellets on a beach in Tokyo (Kasai seaside park, Japan)

Solid diamond >LOQ; Blank triangle <LOQ

LONG-RANGE ENVIRONMENTAL TRANSPORT OF PELLETS AND BUVSs

High concentrations of BUVSs were even found in pellets from remote islands, i.e., Macquarie Island (5.44 μg/g), Hawaii Island (5.64 μg/g), Ogasawara Island (5.00 μg/g), and Hachijo Island (25.4 μg/g), as shown in Fig. 2. Concentrations of BUVSs in pellets from remote islands (5–25.4 μg/g) were in similar orders of magnitude to those observed in coastal areas that are close to industrial areas, such as Sydney (1.97 μg/g) and Tokyo (16.5 μg/g), as shown in Fig. 2. Sporadic high concentrations were observed for only one or two BUVSs compounds (UV326 for Ogasawara Island, UV327 for Hachijo Island, and UV326 and UV327 for Hawaii Island and Macquarie Island). This pattern again suggests that they come from industrial compounding and/or recycled pellets. In addition to remote islands, sporadic high concentrations of BUVSs were observed in pellets from remote areas, e.g., PunTa Herradura in Mexico, where there are sea-turtle nesting sites and far (>100 km) from any city. Pellets from the site had high concentrations (1.2 μg/g) of BUVSs that consisted exclusively of UV328 at 1.0 μg/g with minor amounts of UV 326, suggesting additive origin. These observations from remote areas of BUVSs that were derived from industrial pellets or recycled pellets mean that the BUVSs were transported from industrial areas for long distances of hundreds to thousands of kilometers without drastic desorption or degradation. This is consistent with leaching behavior of the additives from PP resin pellets. No significant BUVSs were extracted with distilled water with 7.8% for UVP, 0.01% for UV329 and <0.002% for other hydrophobic BUVSs during the leaching test (Table 1). This is because the hydrophobic additives are trapped in the polymer matrix, so they could not be leached-out with seawater during their long-range transport. However, if these pellets or similar-sized plastic fragments containing the hydrophobic additives were to be ingested by wild animals in remote areas, oily digestive fluids, such as stomach oil, facilitate leaching and the bio-accumulation of the additives as Tanaka et al. (2015; 2018) demonstrated. Thus, pellets and plastic fragments of similar sizes can be considered to be long-range transporters of additives to wild animals in pristine environments. This is consistent with the bio-accumulation of UV328 in seabirds from remote islands, such as great shearwaters (Ardenna gravis) from Gough Island and blue petrels (Halobaena caerulea) (Yamashita et al., 2021).

CONCLUSION

It was demonstrated that soaking PP pellets in hexane efficiently extracted additive BUVSs compounded in pellets. Of the 37 samples analyzed, 14 exhibited higher BUVSs concentrations>1 μg/g with exclusive predominance of a few specific BUVSs, including UV326, UV327, UV328, and UV329. The samples showed large piece-by-piece variations. Pellets with high concentrations of BUVSs were industrially compounded with additives and/or were recycled. High concentrations of BUVSs, which were due to industrially compounded additives, were detected in remote areas, including Macquarie Island, Ogasawara Island, Hachijo Island, the Oahu Islands, and PunTa Herradura in Mexico. This finding provides evidence of plastic-mediated LRET of BUVSs.

ACKNOWLEDGMENT

The authors thank Bjorn Beeler, Sara Brosché, Therese Karlsson, International Pollution Elimination Network (IPEN), Camille Dressler, Joao Frias, Sherry Heileman, Takashi Tokumaru, Nola Parsons, Andile Mdluli, Mahiro Gomi, Mohamad Pauzi Zakaria, Jao Jia Horng, Masaki Kato, Kaede Asano, Atsuko Sugahara, Sharnie Connell, Chrissy Mclean, Ed Sobey, Ana Antillanca Oliva, Evan Mckenzie, Nobuyuki Daimon, Mami Takahashi, Mikiko Arikawa, Angela Hansen, Doug Young, Heidi Tait, Taj Powell, Elizabeth Bailey for collecting and sending the pellet samples and for their coordination. This study was funded by The University of Tokyo FSI – Nippon Foundation Research Project on Marine Plastics and JSPS Grant-in-Aid study (No. 20H00627).

SUPPLEMENTARY MATERIAL

Fig. S1, Target benzotriazole-type UV stabilizers (BUVSs); Fig. S2, Analytical results of pool-by-pool analysis of PP pellets on 7 beaches (5 pools, one pool consists of 5 pellets); Fig. S3, Photos of all the analyzed pellets; Table S1, Sample Information on polypropylene pellets from world beaches; Table S2, Instrumental conditions for BUVSs by GC-MS; Table S3, Monitor ions on SIM mode of GC-MS anaysis of BUVSs; Table S4, Concentrations of BUVSs in the beached polypropylene resin pellets (μg/g-pellet).

This material is available on the Website at https://doi.org/10.5985/emcr.20240027.

REFERENCES

•  Alidoust,  M.,  Saito,  Y.,  Takada,  H.,  Mizukawa,  K.,  Karlsson,  T.,  Brosché,  S.,  Beeler,  B.,  Karapanagioti,  H.K., 2024. A Unique Monitoring Method for Fecal and Sewage-Derived Chemical Pollution Utilizing International Pellet Watch Approach. Environ. Sci. Technol. 58, 4761–4771. doi: 10.1021/acs.est.3c08847.
•  Alidoust,  M.,  Yeo,  G.B.,  Mizukawa,  K.,  Takada,  H., 2021. Monitoring of polycyclic aromatic hydrocarbons, hopanes, and polychlorinated biphenyls in the Persian Gulf in plastic resin pellets. Mar. Pollut. Bull. 165, 112052. doi: 10.1016/j.marpolbul.2021.112052.
•  Andrade,  H.,  Glüge,  J.,  Herzke,  D.,  Ashta,  N.M.,  Nayagar,  S.M.,  Scheringer,  M., 2021. Oceanic long-range transport of organic additives present in plastic products: an overview. Environ. Sci. Eur. 33, 85. doi: 10.1186/s12302-021-00522-x.
•  Brosché,  S.,  Strakova,  J.,  Bell,  L.,  Karlsson,  T. Widespread chemical contamination of recycled plastic pellets globally. 2021, International Pollutants Elimination Network (IPEN). https://www.cag.org.in/sites/default/files/database/IPEN-Recycled-Plastic-Pellets.pdf (accessed 23 November 2024)
• ECHA, 2020. Estimating the number and types of applications for 11 substances added to the Authorisation List in February 2020. https://echa.europa.eu/documents/10162/13634/applications_for_11_substances_Authorisation_List_February_2020.pdf/66fd8424-5f57-9c33-f3e5-265f01f754ba (accessed 3 September 2024)
•  Endo,  S.,  Takizawa,  R.,  Okuda,  K.,  Takada,  H.,  Chiba,  K.,  Kanehiro,  H.,  Ogi,  H.,  Yamashita,  R.,  Date,  T., 2005. Concentration of Polychlorinated Biphenyls (PCBs) in Beached Resin Pellets: Variability among Individual Particles and Regional Differences. Mar. Pollut. Bull. 50, 1103–1114. doi: 10.1016/j.marpolbul.2005.04.030.
•  Fukuoka,  T.,  Mizukawa,  K.,  Kondo,  S.,  Kitayama,  C.,  Kobayashi,  S.,  Watanabe,  G.,  Takada,  H., 2024. Detection of benzotriazole-type ultraviolet stabilizers in sea turtles breeding in the Northwest Pacific Ocean. Mar. Pollut. Bull. 206, 116753. doi: 10.1016/j.marpolbul.2024.116753.
•  Gregory,  M.R., 1978. Accumulation and distribution of virgin plastic granules on New Zealand beaches. N.Z. J. Mar. Freshw. Res. 12, 399–414. doi: 10.1080/00288330.1978.9515768.
•  Heskett,  M.,  Takada,  H.,  Yamashita,  R.,  Yuyama,  M.,  Ito,  M.,  Geok,  Y.B.,  Ogata,  Y.,  Kwan,  C.,  Heckhausen,  A.,  Taylor,  H.,  Powell,  T.,  Morishige,  C.,  Young,  D.,  Patterson,  H.,  Robertson,  B.,  Bailey,  E.,  Mermoz,  J., 2012. Measurement of persistent organic pollutants (POPs) in plastic resin pellets from remote islands: toward establishment of background concentrations for International Pellet Watch. Mar. Pollut. Bull. 64, 445–448. doi: 10.1016/j.marpolbul.2011.11.004.
•  Hosoda,  J.,  Ofosu-Anim,  J.,  Sabi,  E.B.,  Akita,  L.G.,  Onwona-Agyeman,  S.,  Yamashita,  R.,  Takada,  H., 2014. Monitoring of organic micropollutants in Ghana by combination of pellet watch with sediment analysis: E-waste as a source of PCBs. Mar. Pollut. Bull. 86, 575–581. doi: 10.1016/j.marpolbul.2014.06.008.
•  Hu,  L.-X.,  Cheng,  Y.-X.,  Wu,  D.,  Fan,  L.,  Zhao,  J.-H.,  Xiong,  Q.,  Chen,  Q.-L.,  Liu,  Y.-S.,  Ying,  G.-G., 2021. Continuous input of organic ultraviolet filters and benzothiazoles threatens the surface water and sediment of two major rivers in the Pearl River Basin. Sci. Total Environ. 798, 149299. doi: 10.1016/j.scitotenv.2021.149299.
•  James,  B.D.,  Reddy,  C.M.,  Hahn,  M.E.,  Nelson,  R.K.,  de Vos,  A.,  Aluwihare,  L.I.,  Wade,  T.L.,  Knap,  A.H.,  Bera,  G., 2023. Fire and Oil Led to Complex Mixtures of PAHs on Burnt and Unburnt Plastic during the M/V X-Press Pearl Disaster. ACS Environ. Au 3, 319–335. doi: 10.1021/acsenvironau.3c00011.
•  Karapanagioti,  H.K.,  Endo,  S.,  Ogata,  Y.,  Takada,  H., 2011. Diffuse pollution by persistent organic pollutants as measured in plastic pellets sampled from various beaches in Greece. Mar. Pollut. Bull. 62, 312–317. doi: 10.1016/j.marpolbul.2010.10.009.
•  Karapanagioti,  H.K.,  Klontza,  I., 2008. Testing phenanthrene distribution properties of virgin plastic pellets and plastic eroded pellets found on Lesvos island beaches (Greece). Mar. Environ. Res. 65, 283–290. doi: 10.1016/j.marenvres.2007.11.005.
•  Karlsson,  T.,  Brosché,  S.,  Alidoust,  M.,  Takada,  H., 2021. Plastic pellets found on beaches all over the world contain toxic chemicals. https://ipen.org/sites/default/files/documents/ipen-beach-plastic-pellets-v1_4aw.pdf (accessed 15 February 2025)
•  Khare,  A.,  Jadhao,  P.,  Vaidya,  A.N.,  Kumar,  A.R., 2023. Benzotriazole UV stabilizers (BUVs) as an emerging contaminant of concern: a review. Environ. Sci. Pollut. Res. 30, 121370–121392. doi: 10.1007/s11356-023-30567-9.
•  Kubota,  A.,  Terasaki,  M.,  Sakuragi,  Y.,  Muromoto,  R.,  Ikeda-Araki,  A.,  Takada,  H.,  Kojima,  H., 2022. Effects of benzotriazole UV stabilizers, UV-PS and UV-P, on the differentiation of splenic regulatory T cells via aryl hydrocarbon receptor. Ecotoxicol. Environ. Saf. 238, 113549. doi: 10.1016/j.ecoenv.2022.113549.
•  Kuriyama,  Y.,  Konishi,  K.,  Kanehiro,  H.,  Ohtake,  C.,  Mato,  Y.,  Takada,  H.,  Kojima,  A., 2002. Plastic pellets in the marine environment of Tokyo Bay and Sagami Bay. Fish. Sci. 68, 164–171. doi: 10.2331/suisan.68.164.
•  Le,  D.Q.,  Takada,  H.,  Yamashita,  R.,  Mizukawa,  K.,  Hosoda,  J.,  Tuyet,  D.A., 2016. Temporal and spatial changes in persistent organic pollutants in Vietnamese coastal waters detected from plastic resin pellets. Mar. Pollut. Bull. 109, 320–324. doi: 10.1016/j.marpolbul.2016.05.063.
•  Lu,  Z.,  De Silva,  A.O.,  Provencher,  J.F.,  Mallory,  M.L.,  Kirk,  J.L.,  Houde,  M.,  Stewart,  C.,  Braune,  B.M.,  Avery-Gomm,  S.,  Muir,  D.C.G., 2019. Occurrence of substituted diphenylamine antioxidants and benzotriazole UV stabilizers in Arctic seabirds and seals. Sci. Total Environ. 663, 950–957. doi: 10.1016/j.scitotenv.2019.01.354.
•  Mato,  Y.,  Isobe,  T.,  Takada,  H.,  Kanehiro,  H.,  Ohtake,  C.,  Kaminuma,  T., 2001. Plastic Resin Pellets as a Transport Medium for Toxic Chemicals in the Marine Environment. Environ. Sci. Technol. 35, 318–324. doi: 10.1021/es0010498.
•  Mizukawa,  K.,  Takada,  H.,  Ito,  M.,  Geok,  Y.B.,  Hosoda,  J.,  Yamashita,  R.,  Saha,  M.,  Suzuki,  S.,  Miguez,  C.,  Frias,  J.o.,  Antunes,  J.C.,  Sobral,  P.,  Santos,  I.,  Micaelo,  C.,  Ferreira,  A.M., 2013. Monitoring of a wide range of organic micropollutants on the Portuguese coast using plastic resin pellets. Mar. Pollut. Bull. 70, 296–302. doi: 10.1016/j.marpolbul.2013.02.008.
•  Morris,  R.J., 1980. Plastic debris in the surface waters of the South Atlantic. Mar. Pollut. Bull. 11, 164–166. doi: 10.1016/0025-326X(80)90144-7.
•  Murphy,  J., 2001. Additives for Plastics Handbook, 2nd edition. Elsevier Science Ltd,, he Boulevard, Langford Lane, Kidlington, Oxford OX5 1GB, UK.c.
•  Nagayoshi,  H.,  Kakimoto,  K.,  Takagi,  S.,  Konishi,  Y.,  Kajimura,  K.,  Matsuda,  T., 2015. Benzotriazole Ultraviolet Stabilizers Show Potent Activities as Human Aryl Hydrocarbon Receptor Ligands. Environ. Sci. Technol. 49, 578–587. doi: 10.1021/es503926w.
•  Nakata,  H.,  Murata,  S.,  Filatreau,  J., 2009. Occurrence and Concentrations of Benzotriazole UV Stabilizers in Marine Organisms and Sediments from the Ariake Sea, Japan. Environ. Sci. Technol. 43, 6920–6926. doi: 10.1021/es900939j.
•  Nakata,  H.,  Shinohara,  R.-I.,  Nakazawa,  Y.,  Isobe,  T.,  Sudaryanto,  A.,  Subramanian,  A.,  Tanabe,  S.,  Zakaria,  M.P.,  Zheng,  G.J.,  Lam,  P.K.S.,  Kim,  E.Y.,  Min,  B.-Y.,  We,  S.-U.,  Viet,  P.H.,  Tana,  T.S.,  Prudente,  M.,  Frank,  D.,  Lauenstein,  G.,  Kannan,  K., 2012. Asia–Pacific mussel watch for emerging pollutants: Distribution of synthetic musks and benzotriazole UV stabilizers in Asian and US coastal waters. Mar. Pollut. Bull. 64, 2211–2218. doi: 10.1016/j.marpolbul.2012.07.049.
•  Ogata,  Y.,  Takada,  H.,  Mizukawa,  K.,  Hirai,  H.,  Iwasa,  S.,  Endo,  S.,  Mato,  Y.,  Saha,  M.,  Okuda,  K.,  Nakashima,  A.,  Murakami,  M.,  Zurcher,  N.,  Booyatumanondo,  R.,  Zakaria,  M.P.,  Dung,  L.Q.,  Gordon,  M.,  Miguez,  C.,  Suzuki,  S.,  Moore,  C.,  Karapanagioti,  H.K.,  Weerts,  S.,  McClurg,  T.,  Burres,  E.,  Smith,  W.,  Van Velkenburg,  M.,  Lang,  J.S.,  Lang,  R.C.,  Laursen,  D.,  Danner,  B.,  Stewardson,  N.,  Thompson,  R.C., 2009. International Pellet Watch: Global monitoring of persistent organic pollutants (POPs) in coastal Waters. 1. Initial phase data on PCBs, DDTs, and HCHs. Mar. Pollut. Bull. 58, 1437–1446. doi: 10.1016/j.marpolbul.2009.06.014.
•  Ohgaki,  T.,  Takada,  H.,  Yoshida,  R.,  Mizukawa,  K.,  Yeo,  B.G.,  Alidoust,  M.,  Hirai,  N.,  Yamashita,  R.,  Tokumaru,  T.,  Watanabe,  I.,  Onwona-Agyeman,  S.,  Gardiner,  P.,  Eriksen,  M.,  Kelly,  J.F., RodrÍGuez-Sierra, C.J., Colasse, L., Baztan, J., Barretto, F.P., Izar, G.M., Abessa, D., Zakaria, M.P., Kwan, C.S., Saha, M., Ryan, P.G., Weerts, S., Ofosu-Anim, J., Sabi, E.B., Akita, L.G., Tait, H., Eriksson, C., Burton, H., 2021. International pellet watch: Global monitoring of polybrominated diphenyl ethers (PBDEs) in plastic resin pellets. Environ. Monit. Contam. Res. 1, 75–90. doi: 10.5985/emcr.20210002.
•  Peng,  X.,  Fan,  Y.,  Jin,  J.,  Xiong,  S.,  Liu,  J.,  Tang,  C., 2017. Bioaccumulation and biomagnification of ultraviolet absorbents in marine wildlife of the Pearl River Estuarine, South China Sea. Environ. Pollut. 225, 55–65. doi: 10.1016/j.envpol.2017.03.035.
•  Pozo,  K.,  Urbina,  W.,  Gómez,  V.,  Torres,  M.,  Nuñez,  D.,  Přibylová,  P.,  Audy,  O.,  Clarke,  B.,  Arias,  A.,  Tombesi,  N.,  Guida,  Y.,  Klánová,  J., 2020. Persistent organic pollutants sorbed in plastic resin pellet—“Nurdles” from coastal areas of Central Chile. Mar. Pollut. Bull. 151, 110786. doi: 10.1016/j.marpolbul.2019.110786.
•  Rani,  M.,  Shim,  W.J.,  Han,  G.M.,  Jang,  M.,  Song,  Y.K.,  Hong,  S.H., 2017. Benzotriazole-type ultraviolet stabilizers and antioxidants in plastic marine debris and their new products. Sci. Total Environ. 579, 745–754. doi: 10.1016/j.scitotenv.2016.11.033.
•  Rochman,  C.M.,  Hoh,  E.,  Hentschel,  B.T.,  Kaye,  S., 2013. Long-Term Field Measurement of Sorption of Organic Contaminants to Five Types of Plastic Pellets: Implications for Plastic Marine Debris. Environ. Sci. Technol. 47, 1646–1654. doi: 10.1021/es303700s.
•  Sakuragi,  Y.,  Takada,  H.,  Sato,  H.,  Kubota,  A.,  Terasaki,  M.,  Takeuchi,  S.,  Araki,  A.,  Watanabe,  Y.,  Kitamura,  S.,  Kojima,  H., 2021. An analytical survey of benzotriazole UV stabilizers in plastic products and their endocrine-disrupting potential via human estrogen and androgen receptors. Sci. Total Environ. 800, 149374. doi: 10.1016/j.scitotenv.2021.149374.
•  Saliba,  M.,  Frantzi,  S.,  van Beukering,  P., 2022. Shipping spills and plastic pollution: A review of maritime governance in the North Sea. Mar. Pollut. Bull. 181, 113939. doi: 10.1016/j.marpolbul.2022.113939.
•  Santana-Viera,  S.,  Montesdeoca-Esponda,  S.,  Sosa-Ferrera,  Z.,  Santana-Rodríguez,  J.J., 2021. UV filters and UV stabilisers adsorbed in microplastic debris from beach sand. Mar. Pollut. Bull. 168, 112434. doi: 10.1016/j.marpolbul.2021.112434.
•  Shiber,  J.G., 1982. Plastic pellets on Spain’s ‘Costa del Sol’ beaches. Mar. Pollut. Bull. 13, 409–412. doi: 10.1016/0025-326X(82)90014-5.
•  Takano,  T.,  Sakurai,  R.,  Ota,  M.,  Nakaoka,  M.,  Kinjo,  A.,  Inoue,  K.,  Takada,  H.,  Mizukawa,  K., 2024. Dietary exposure experiments on the migration of chemical pollutants from microplastics to bivalves. Mar. Pollut. Bull. 206, 116740. doi: 10.1016/j.marpolbul.2024.116740.
•  Tanaka,  K.,  Takahashi,  Y.,  Kajiwara,  T.,  Matsukami,  H.,  Kuramochi,  H.,  Osako,  M.,  Suzuki,  G., 2023. Identification and quantification of additive-derived chemicals in beached micro–mesoplastics and macroplastics. Mar. Pollut. Bull. 186, 114438. doi: 10.1016/j.marpolbul.2022.114438.
•  Tanaka,  K.,  Takada,  H.,  Ikenaka,  Y.,  Nakayama,  S.M.M.,  Ishizuka,  M., 2020. Occurrence and concentrations of chemical additives in plastic fragments on a beach on the island of Kauai, Hawaii. Mar. Pollut. Bull. 150, 110732. doi: 10.1016/j.marpolbul.2019.110732.
•  Tanaka,  K.,  Takada,  H.,  Yamashita,  R.,  Mizukawa,  K.,  Fukuwaka,  M.-A.,  Watanuki,  Y., 2015. Facilitated Leaching of Additive-Derived PBDEs from Plastic by Seabirds’ Stomach Oil and Accumulation in Tissues. Environ. Sci. Technol. 49, 11799–11807. doi: 10.1021/acs.est.5b01376.
•  Tanaka,  K.,  Yamashita,  R.,  Takada,  H., 2018. Transfer of Hazardous Chemicals from Ingested Plastics to Higher-Trophic-Level Organisms, In: Takada, H. and Karapanagioti, H.K. (eds.), Hazardous Chemicals Associated with Plastics in the Marine Environment, pp. 267–280, Springer International Publishing, Cham.
•  Tanaka,  K.,  van Franeker,  J.A.,  Deguchi,  T.,  Takada,  H., 2019. Piece-by-piece analysis of additives and manufacturing byproducts in plastics ingested by seabirds: Implication for risk of exposure to seabirds. Mar. Pollut. Bull. 145, 36–41. doi: 10.1016/j.marpolbul.2019.05.028.
•  Taniguchi,  S.,  Colabuono,  F.I.,  Dias,  P.S.,  Oliveira,  R.,  Fisner,  M.,  Turra,  A.,  Izar,  G.M.,  Abessa,  D.M.S.,  Saha,  M.,  Hosoda,  J.,  Yamashita,  R.,  Takada,  H.,  Lourenço,  R.A.,  Magalhães,  C.A.,  Bícego,  M.C.,  Montone,  R.C., 2016. Spatial variability in persistent organic pollutants and polycyclic aromatic hydrocarbons found in beach-stranded pellets along the coast of the state of São Paulo, southeastern Brazil. Mar. Pollut. Bull. 106, 87–94. doi: 10.1016/j.marpolbul.2016.03.024.
• UNEP 2023: UNEP/POPS/POPRC.19/INF/14/Rev.1: Document on long-range environmental transport.
• UNEP/POPS/COP.11/31, 2023, Decision SC-11/11: Listing of UV-328. Annex in the Report of the Conference of the Parties to the Stockholm Convention on Persistent Organic Pollutants on the work of its eleventh meeting; Geneva, May 1−12, 2023; 125 pages.
•  Vandenburg,  J.H.,  Clifford,  A.A.,  Bartle,  D.K.,  Carroll,  J.,  Newton,  I.,  Garden,  M.L.,  Dean,  R.J.,  Costley,  T.C., 1997. Critical Review: Analytical Extraction of Additives From Polymers. Analyst 122, 101R–116R. doi: 10.1039/A704052K.
•  Wania,  F.,  McLachlan,  M.S., 2024. The Stockholm Convention at a Crossroads: Questionable Nominations and Inadequate Compliance Threaten Its Acceptance and Utility. Environ. Sci. Technol. 58, 13587–13593. doi: 10.1021/acs.est.4c06775.
•  Yamashita,  R.,  Hiki,  N.,  Kashiwada,  F.,  Takada,  H.,  Mizukawa,  K.,  Hardesty,  B.D.,  Roman,  L.,  Hyrenbach,  D.,  Ryan,  P.G.,  Dilley,  B.J., MuÑOz-PÉRez, J.P., Valle, C.A., Pham, C.K., Frias, J., Nishizawa, B., Takahashi, A., Thiebot, J.-B., Will, A., Kokubun, N., Watanabe, Y.Y., Yamamoto, T., Shiomi, K., Shimabukuro, U., Watanuki, Y., 2021. Plastic additives and legacy persistent organic pollutants in the preen gland oil of seabirds sampled across the globe. Environ. Monit. Contam. Res. 1, 97–112. doi: 10.5985/emcr.20210009.
•  Yamashita,  R.,  Tanaka,  K.,  Yeo,  B.G.,  Takada,  H.,  van Franeker,  J.A.,  Dalton,  M.,  Dale,  E., 2019. Hazardous Chemicals in Plastics in Marine Environments: International Pellet Watch, In: Takada, H. and Karapanagioti, H.K. (eds.), Hazardous Chemicals Associated with Plastics in the Marine Environment, pp. 163–183, Springer International Publishing, Cham.
•  Yeo,  B.G.,  Takada,  H.,  Hosoda,  J.,  Kondo,  A.,  Yamashita,  R.,  Saha,  M.,  Maes,  T., 2017. Polycyclic Aromatic Hydrocarbons (PAHs) and Hopanes in Plastic Resin Pellets as Markers of Oil Pollution via International Pellet Watch Monitoring. Arch. Environ. Contam. Toxicol. 73, 196–206. doi: 10.1007/s00244-017-0423-8.
•  Yeo,  B.G.,  Takada,  H.,  Taylor,  H.,  Ito,  M.,  Hosoda,  J.,  Allinson,  M.,  Connell,  S.,  Greaves,  L.,  McGrath,  J., 2015. POPs monitoring in Australia and New Zealand using plastic resin pellets, and International Pellet Watch as a tool for education and raising public awareness on plastic debris and POPs. Mar. Pollut. Bull. 101, 137–145. doi: 10.1016/j.marpolbul.2015.11.006.
•  Zhao,  M.-L.,  Ji,  X.,  Zhang,  J.,  Yang,  G.-P., 2024. Spatiotemporal variation, partitioning, and ecological risk assessment of benzothiazoles, benzotriazoles, and benzotriazole UV absorbers in the Yangtze River Estuary and its adjacent area. J. Hazard. Mater. 465, 133337. doi: 10.1016/j.jhazmat.2023.133337.