Persistent organochlorine residues in fish and sediments collected from Eastern Aegean coast: Levels, occurrence and ecological risk

Surface sediments as a sink and risk source for legacy POPs during waste management practices

Persistent organic pollutants (POPs) such as polychlorinated biphenyls (PCBs) and polybrominated diphenyl ethers (PBDEs) are globally recognized contaminants due to their persistence, bioaccumulative properties, and toxicity. Despite regulatory efforts, these compounds continue to enter the environment through improper waste management practices, including shipbreaking activities. This study investigates the PCB and PBDE contamination of marine sediments along a 30 km coastline in Aliağa, Türkiye, involving one of the world's largest shipbreaking yards. Sixteen surface sediment samples were analyzed for 46 PCB and 23 PBDE congeners. The results revealed Σ46PCBs ranging from 5.17 to 4750 ng/g and Σ23PBDEs from non-detectable to 5053 ng/g. Shipbreaking activities exhibited the highest concentrations, while the sediments sampled close to beaches had the lowest POP contamination. Source apportionment using principal component analysis (PCA) identified distinct contamination patterns, associating higher-chlorinated PCBs with shipbreaking and lower-chlorinated PCBs and PBDEs with land-based industrial emissions and urban runoff. Ecological risk evaluation showed that most sediment samples exceeded sediment quality guidelines, with some PCB and PBDE congeners posing moderate to high risks to benthic ecosystems. Particularly, PCBs 28 and 52 exhibited low to high risk for almost all sediment samples. This study emphasizes the urgent need for improved waste management practices, particularly for POP-containing materials, to mitigate ecological risks. Shipbreaking yards are identified as hotspots for legacy POP contamination, necessitating international collaboration and stricter enforcement of environmental regulations as shipbreaking operations encompass cross-country transfer of wastes. Findings highlight the critical importance of remediation strategies to protect marine environments.

The lingering menace: How legacy organochlorine pesticides still threaten our rivers and food chains

The bioaccumulation of organochlorine pesticides (OCPs) in aquatic organisms has been extensively explored in recent years due to associated ecological risks and potential threats to human health through food. This study aims to assess the bioaccumulation of organochlorine pesticides (OCPs) in 18 freshwater fish species from the Pearl River Delta, China. The observed OCP concentrations ranged from 0.69 to 43.15 ng/g wet weight, indicating low to moderate pollution levels. A linear mixed-effects model revealed the contribution of the feeding habits and geographic distributions at 58.67 and 0.67 % of OCP accumulation, respectively. Bottom-dwelling carnivorous fish species exhibited greater OCP residue levels than those in the upper layers of the freshwater. Estuarine organisms showed higher Dichlorodiphenyltrichloroethane (DDT) residue levels than those inland species. On the other hand, although there were no direct carcinogenic or exposure risks associated with OCPs in the study area, potential related hazards were observed. Consumers are, therefore, advised to select fish species from the middle and upper delta rather than bottom fish, shellfish, and shrimp. The current research provides valuable guidance for aquatic food consumption.

Concentrations and Human Health Risk of Organochlorines in Farmed Freshwater Products: Fish Ponds around Changsha, China

ABSTRACT

The present study was conducted to reveal the concentrations and patterns of organochlorine pesticides (OCPs) and polychlorinated biphenyls (PCBs) in seven species of freshwater food products (Procambarus clarkii, Ctenopharyngodon idellus, Parabramis pekinensis, Hypophthalmichthys molitrix, Cyprinus carpio, Aristichthys nobilis, and Carassius auratus) collected from aquaculture farms around Changsha, People's Republic of China. The OCPs and PCBs in the muscle tissue of these species were analyzed to assess the health risk associated with dietary intake. The mean concentrations of OCPs and PCBs were 6.38 to 15.90 and 3.18 to 5.12 ng g-1 wet weight, respectively. Heptachlor and δ-HCH were the main OCP contaminants in the tested samples, accounting for >74% of the total OCPs. PCB52 was the main PCB, accounting for >88% of the total PCBs. The bioaccumulation of OCPs and PCBs in these aquatic products depends upon the species. C. idellus had the highest concentrations of OCPs, and H. molitrix had the highest concentrations of PCBs. The mean lipid concentration in these freshwater species was 6.08 to 19.8% (dry weight) and was significantly correlated with the concentrations of OCPs and PCBs. The health risk from consumption of these freshwater species was assessed based on the hazard ratios and hazard quotient, and consumption of these products was determined to pose a carcinogenic risk.

HIGHLIGHTS

Occurrence, spatial distribution, source, and ecological risk assessment of organochlorine pesticides in Dongting Lake, China

The occurrence, distribution, sources, and ecological risks of organochlorine pesticides in Dongting Lake of China were investigated. The average concentrations of organochlorine pesticides (OCPs) in 22 surface water samples and 14 sediment samples were 90.07 ng/L and 80.65 ng/g dw, respectively. Sixteen types of OCPs, dominated by HCHs, DDTs and heptachlor, were detected in the Dongting Lake. The relationships of OCP residues between Dongting Lake and its tributary rivers have been discussed and the hydraulic connections with the Yangtze River and the Three Gorges Dam (TGD) were also considered. Results showed that the shortage of runoff, earlier dry season, and reduction of sediment deposition extremely deteriorated the hydraulic conditions, magnified the water cycle, and restrained the self-purification of OCPs. The ∑OCPs in surface water were concentrated in the inlets of Yangtze River, Lishui River, Zishui River, Yuanshui River, and Xiangjiang River. Moreover, the ∑OCPs in the outlet of the Yangtze River also maintained a high level, indicating that OCPs posed adverse effects on the Yangtze River. Risk assessments of OCPs in the surface water of Dongting Lake were estimated according to available water quality guidelines and health risk assessment models. The results indicated that OCPs in the surface water of Dongting Lake were safe for aquatic organisms and human health. In addition, sediment quality guidelines (SQGs) were also applied to evaluate the potential ecotoxicological risks of OCPs in sediments. The results presented that contaminants of γ-HCH; o,p'-DDD; and dieldrin in sediment had adverse effects on benthic organisms, indicating that fundamental solutions should be proposed to control OCP contamination in Dongting Lake.

Depth-distribution, possible sources, and toxic risk assessment of organochlorine pesticides (OCPs) in different river sediment cores affected by urbanization and reclamation in a Chinese delta

Sediment cores were collected in urban (0-50 cm), rural (0-40 cm) and reclamation-affected river (0-40 cm) environments in the Pearl River Delta. Concentrations of 16 organochlorine pesticides (OCPs) were determined in all collected samples to identify the depth-distribution, possible sources and ecotoxicological risks of OCPs in river sediments affected by urbanization and reclamation in a Chinese delta. The results showed that the top 10 cm of rural river sediments had slightly lower concentrations of the 16 OCPs compared to urban and reclamation-affected rivers, whereas the 30-40 cm sediment layers in the rural river showed higher levels of the 16 OCPs. However, higher OCPs levels were observed in the 20-30 cm sediment layers in the urban river than in the rural and reclamation-affected rivers. The principal OCPs in most deeper sediment layers were hexachlorobezene (HCB), the combination of aldrin, endrin and dieldrin (ΣDRINs) and the combination of α-HCH, β-HCH and γ-HCH (ΣHCHs). The predominant OCPs in surface sediments were HCB, ΣDRINs and the combination of p,p'-DDD, o,p'-DDT, p,p'-DDT and p,p'-DDE (ΣDDTs). Generally, OCP concentrations decreased with depth along sediment profiles at most sampling sites in the three types of rivers. The source analyses indicated that some sampling sites were still suffering from the recent use of hexachlorocyclohexanes (HCHs), dichlorodiphenyltrichloroethanes (DDTs) and aldrin. According to the soil quality thresholds of China, the levels of HCHs and DDTs at most sampling sites were below class Ⅰ criteria. Based on the sediment quality guideline quotient (SQGQ), the combined ecotoxicological risk of OCPs (γ-HCH, dieldrin, p,p'-DDD, p,p'-DDE and p,p'-DDT) in surface sediments (0-10 cm) was higher than deeper sediments, and the rural river sediments exhibited a higher combined ecotoxicological risk than the sediments in urban and reclamation-affected rivers.