To explore the utility of artificial sweeteners (Acesulfame: ACE; sucralose: SUC; saccharin: SAC; cyclamate: CYC) as molecular markers and to establish a historical benchmark of the water pollution status in the 2010 decade, 272 surface water samples, including river water, sewage, and livestock wastewater, were collected from African (Ghana, Kenya, Mozambique, South Africa), Asian (Vietnam, Indonesia, Thailand, Philippines, Cambodia, Malaysia, India, and Japan) and Middle Eastern (Iran and Lebanon) countries during 2010–2019 and were analyzed for the artificial sweeteners by high performance liquid chromatograph with tandem mass spectrometer coupled with online solid-phase extractor. ACE was most frequently detected (87% of the samples) due to its widespread use and lower detection limit (2 ng/L). SUC was less frequently detected (51%) because of its lower sensitivity and detection limit of 100 ng/L, and less widespread use in some low-income countries, probably due to its higher price. SAC and/or CYC were abundant in surface waters of most countries, despite their biodegradable nature. This was ascribed to intensive usage of SAC and CYC and extensive inputs of untreated sewage to rivers due to limited installation of sewage treatment systems. Concentrations of the sweeteners were higher in urbanized rivers (~1 μg/L to ~100 μg/L) than those in corresponding suburban and rural sites, reflecting spatial patterns of sewage inputs. Furthermore, concentrations of the sweeteners were positively correlated with those of linear alkylbenzenes (LABs) for all countries except Malaysia. These results confirm the utility of artificial sweeteners as indicators of sewage inputs. SAC and CYC could be indicators of untreated sewage inputs. ACE has proved to be the most sensitive and reliable marker to assess inputs of sewage, i.e., both treated and untreated, to surface waters. However, ACE concentrations in secondary effluents and receiving waters in Tokyo decreased two orders of magnitude from 2011 to 2019, while sucralose did not show such a marked decrease. This is probably due to the upgrading of activated sludge treatment, i.e., introducing anaerobic-anoxic-oxic (A2O) treatment and resultant higher removal of ACE. Therefore, the measurement of multiple markers, including SUC, is recommended for long-term monitoring.

There has been little research on the pollution of drifted debris in terrestrial ecosystems in coastal areas compared to research focusing on aquatic environment and aquatic organisms. In this study, two species of terrestrial hermit crabs and three species of coastal plants were collected from a polluted site (Nita) and a control site (Furuzamami) in Zamami Island, Okinawa, and analysed to evaluate element contamination in order to evaluate the risk of drifted debris as a source of trace element pollution in terrestrial ecosystems. In both species of terrestrial hermit crabs, Cd was detected at significantly higher concentrations in both the muscle and hepatopancreas of individuals collected from the polluted site. In addition, Pb, often contained in polyvinyl chloride products along with Cd, had higher concentrations in the hepatopancreas of terrestrial hermit crabs in the contaminated site than in the control site. Among the three coastal plants, Pandanus tectorius was the most sensitive to trace element pollution via drifted debris. In general, plants tended to accumulate elements in accordance with their leachability from plastics. This result suggested that trace elements, leaching from drifted debris to soils, accumulated in the plants. These results indicate that leaching rates from drifted plastics have a greater effect on element accumulation in plants than in terrestrial hermit crabs. The degree of influence of the leaching rate of elements from drifting debris differed between the hermit crabs and plants. In addition, the accumulation of elements that were easily adsorbed by plastics was observed in each species. In the environment, drifted debris is potentially hazardous as a medium of contamination to organisms, as it adsorbs various elements during their transport in the ocean.

Organohalogen compounds (OHCs) are persistent environmental contaminants that can pose health risks to both humans and animals. This study aimed to assess the contamination levels of OHCs in dry and wet pet foods sold in Japan and evaluate their potential health implications for companion animals.

Results indicated that OHCs were widely present in all types of pet foods analyzed, with dry foods generally exhibiting higher contamination levels than wet foods. Polychlorinated biphenyls (PCBs), dichlorodiphenyltrichloroethanes (DDTs), chlordanes (CHLs), hexachlorocyclohexanes (HCHs), polybrominated diphenyl ethers (PBDEs), and decabromodiphenyl ethane (DBDPE) were detected in varying concentrations across different pet food types. The contamination profiles differed based on the raw materials and country of origin. Estimations of OHC concentrations from raw materials highlighted potential contamination sources beyond ingredient-related contributions, including the manufacturing process.

Moreover, risk assessments were conducted to evaluate the potential health risks posed by OHCs exposure through pet food consumption. While PBDEs, CHLs, and DDTs generally posed low risks, PCBs were found to be of concern, particularly in pet foods containing salmon as a primary ingredient. The results underscored the importance of considering the type of pet food and its raw materials when assessing exposure risks.