Organochlorines in Hong Kong Fish

Muscle samples from 15 species of fish (n=1) purchased from markets in Hong Kong and 10 liver samples of tilapia (Tilapia mossambica) collected from the Shing Mun River were analysed for organochlorines (polychlorinated biphenyls, ΣDDTs, hexachlorobenzene, hexachlorocyclohexanes, chlordanes, mirex and dieldrin). Polychlorinated biphenyls (PCBs) were detected in 15 market fish samples but the levels were very low (around 1 ng g⁻¹). PCB levels in tilapia livers collected from Tai Wai (29.3–65.1 ng g⁻¹) were higher than those from Fo Tan (3.5–23.2 ng g⁻¹) suggesting that there may be some local point soucres. ΣDDTs were detected in all samples, ranging from 3.3 to 75.6 ng g⁻¹ in the market fish and from 7.1 to 88.8 ng g⁻¹ in tilapia. The DDE/DDT ratios in the market fish (0.12–0.75) showed higher variability than those of tilapia (0.30–0.46), suggesting that some of the market fish may have been collected from areas where DDT was recently used. Results of this preliminary study show that organochlorine levels in Hong Kong market fish are low and do not cause any concern for human consumption. An on-going monitoring program, however, is recommended.