PCBs contamination in seafood species at the Eastern Coast of Thailand

Abstract

Polychlorinated biphenyls (PCBs) are a large group of persistent organic substances spread throughout the world. The most toxic PCBs are those that are dioxin-like (dl-PCBs). Environmental studies on PCBs in Thailand are limited, especially with regards to dl-PCBs. This study is one of the first in this country that demonstrates contamination of seafood with PCBs and determines the levels of PCBs and total dioxin like activity in mussels, oysters and shrimp, from the Eastern Coast of Thailand. Sixty pooled samples of mussels and twenty-seven pooled samples of oysters were collected from cultivation farms and twenty-one pooled samples of shrimp were collected from fisherman piers. Qualitative and quantitative measurements of 49 PCB congeners was obtained by HRGC-ECD analysis and total dioxin-like activity using the CAFLUX bioassay. Total PCB concentrations varied between three species, ranging between 19 and 1100 ng g(-1) lipid adjusted weight, and the levels of PCBs in shrimp was three time higher than that in mussels and oysters. With respected to the pattern of PCB congeners, it implied that the source of PCBs exposure in this area could be from the regional contamination. The calculated CAFLUX bioanalytical equivalents (BEQs) values ranged between 0.8 and 18 pg BEQ g(-1) lipid adjusted weight, and showed a good relationship with the chemical-derived TEQs. Therefore, the CAFLUX bioassay can be used for effective screening of dioxin-like activity in marine species effectively.

Fig. 1

Sampling locations along the east coast of the Gulf of Thailand.

Fig. 2

Box plots of total PCB concentrations in mussels, oysters and shrimp collected at various locations from the Eastern Coast of the Gulf of Thailand, expressed either as dry weights (A), wet weights (B) or lipid adjusted weights (C). Each box represents the median and 25–75th percentiles. The whiskers represent the 10th & 90th percentiles. Circles represent the outliers.

Fig. 3

Congener specific distributions and concentrations (mean ± SD) of individual PCB congeners in mussels (A), oysters (B) and shrimp (C); and their isomer groups distribution (D). Isomer groups have been divided in lightly (Cl₃ and Cl₄), medium (Cl₅ and Cl₆) and heavily (Cl₇ and Cl₈₎) chlorinated.

Fig. 4

Score plot of principal component analysis of mussels (A), oysters (B) and shrimp (C) collected at various locations from east coast of the Gulf of Thailand.

Fig. 5

Statistical relationship between HRGC-ECD-derived MO-PCB TEQs and CAFLUX-derived BEQs of mussels (A), oyster (B) and shrimp (C) collected at various locations from east coast of the Gulf of Thailand.