Spatial-temporal analysis of HCHs in oysters along the Guangdong coast, China

Abstract

Listen

Translate article

Mussels are often used as sentinel organisms to monitor the presence of environmental contaminants.We measured the hexachlorocyclohexane(HCH) content in the soft tissue of oyster(Crassostrea rivularis Gould) samples collected from the Guangdong coast in 1989-1993 and 2003-2012 using gas chromatography.Using re-lated data taken from the Pollution Investigations Program along Guangdong's coastal zone during 1980-1985,we analyzed the residue levels,spatial and temporal trends,and composition of HCHs in oysters.In addition,we as-sessed the food safety and biological quality of HCHs in oysters.HCHs were detected in 92.3% of the samples at concentrations ranging from below the limit of detection to 42.4 ng/g(mean: 1.70 ng/g wet weight basis).HCH content has declined over time since the early 1980s,but the rate of decline slowed and levels have remained con-stant since the early 1990s.In general,the HCH content has decreased by 99.94% over the last 30 years.In the early 1980s,the HCH content in oysters in the Pearl River Estuary was much higher than in the East and west Guangdong coasts,but the difference in HCH content between these three coasts has gradually decreased over time.The composition of HCH compounds implies that the HCHs are primarily derived from historical usage,but the lower ratios of α-HCH/γ-HCH(0.53-1.11) indicate that there was likely fresh input of lindane between the 1990s and early 2000s.The HCH residue levels in all oyster samples were far below the maximum residue limit in China,although 75.0% of oyster samples collected in 1989 exceeded the requirement of the first grade of the Na-tional Marine Biological Quality Standard of China(GB18421-2001).The daily intake of HCHs by residents along the Guangdong coast via consumption of seafood products ranged from 0.11 to 83.62 ng/(kg·d),which is much lower than the Acceptable Daily Intake established by the Food and Agriculture Organization of the United Na-tions/World Health Organization.