| Global fish production has grown impressively, with the average per capita supply doubling from 8 kg in 1950 to 16.2 kg in 2002 (live weight equivalent). Overall, fish provided more than 2.6 billion people with at least 20 percent of the average per capita animal protein consumption. Many studies indicated that fish were good sources of proteins, n-3 polyunsaturated fatty acids, which were beneficial for human health. Balanced against this, however, fish consumption is the main routes for persistent halogenated hydrocarbons exposurment, which are potential risks to human health. Currently, China (mainland) has the largest fishery production in the world with an output of 44.3 million metric tons in 2002, accounting for 33.3% of the total global production. China has overtaken Thailand to become the world's largest exporter of fishery products since 2002. The main exporting destinations include Japan, Korea, the U.S., Germany, Canada, Hong Kong, Russia, etc. Despite the increasingly important impact of China's fishery products on the global population, the state of fish contamination by persistent halogenated hydrocarbons (PHHs) and associated human health risk have not been systematically assessed in China.This dissertation aimed to determine the levels and distributions of PHHs, including organochlorine pesticides (OCPs), polychlorinated biphenyls (PCBs), and polybrominated diphenyl ethers (PBDEs), in thirteen typical consumer fish of China (seven freshwater farmed fish, three seawater farmed fish, and three wild marine fish), assess the potential health risks associated with fish consumption, and provide preliminany advisories on consumption of fish from China.In all fish samples, DDTs, HCHs, PCBs, and PBDEs were the predominant PHH residues, with the median levels (ranges) being 6.0 (0.14-698.9), 0.50 (0.13-24.06), 0.10 (<0.02-7.65), and 0.15 (<0.0012-3.85) ng/g wet weight, respectively. DDTs levels in consumer fish of China are at the high end, HCHs levels at the moderate end, while PCBs and PBDEs levels at the low end of the globle ranges. Overall, the concentrations of DDTs were 1-2 orders of magnitude higher than those of HCHs, PCBs, and PBDEs. DDTs were about 67.3%, 97.5%, and 75.8% of the total PHH residues in freshwater farmed fish, seawater farmed fish, and wild marine fish, respectively, which reflected their historical usage in China and their characteristics. The present study indicated that seawater farmed fish accumulated more DDTs, PCBs, and PBDEs than freshwater farmed fish and wild marine fish. This probably indicated the impact of contaminant discharge from the Pearl River Delta of southern China on the coastal environment where most seawater farmed fish are raised. In addition, freshwater farmed fish contained higher HCHs than the other two types fish, which may be related with the usage of lindane in the agriculture soil near fish pond in China. No significant correlations among DDTs, HCHs, PCBs, and PBDEs were observed in consumer fish of China, indicating that PHHs have originated from the different sources.For DDTs, p,p'-DDE was the predominant component in freshwater farmed fish. Also, p,p'-DDD and p,p'-DDT were the main DDTs residues in seawater farmed fish, whereas p,p'-DDE and p,p -DDT were abundant congeners in wild marine fish. The ratio of (DDD+DDE)/∑DDTs was higher than 0.5 in some fish species, which indicated the possibility of recent input of DDTs in China. In addition, HCHs residues were dominated byα-HCH andβ-HCH in all fish samples, which may be due to large usage of technical HCHs in China or transformation ofγ-HCH (the main component of lindane) to other isomers. Moreover, PCB-153, PCB-31(28), and PCB-52 were the main PCBs congeners in Chinese consumer fish. For PBDEs, BDE-47, BDE-28, BDE-154, and BDE-100 were the predominant congeners.Our results suggested that the mean concentrations of DDTs, HCHs, and PCBs were much lower than the corresponding maximum residues limits (MRLs) or maximum levels (MLs) established by the Chinese government, and the action levels and tolerances developed by the United States Food and Drug Administration (USFDA). However, 0.5% and 13.8%, respectively, of the fish samples exceeded the advisory limits for human consumption recommended by the Chinese government and the European Union. The upper-bound values of estimated daily intakes (EDIs) of DDTs, HCHs, PCBs, and PBDEs for urban and rural residents of China were 45.5, 1.35, 0.46, and 0.30 and 15.9, 0.47, 0.16, and 0.10 ng/kg bw/d, respectively. The human daily intakes of DDTs and HCHs were far below the provisional tolerable daily intakes (PTDIs) and acceptable daily intakes (ADIs) recommended by the FAO/WHO. Compared with exposure via inhalation, fish consumption was the main routes, accounting for 30% and 70% of the total PBDEs intakes, respectively. In addition, the median total ? 10PBDEs intakes for nursing infants (6,611 and 7,090 pg/kg b.w./day for male and female, respectively) were much higher than other age groups (103-319 pg/kg b.w./day).PHHs in consumer fish of China are transported to China's trading partners through fishery production exportation, spreading the potential health impact outside China. Japan, Korea, and the U.S. are the top three countries receiving China's fishery products. The upper-bound outflows of DDTs, HCHs, PCBs, and PBDEs from China to the globe were 185, 5.51, 1.86, and 1.22 kg, respectively, in 2005. Japan accepted the largest upper-bound outflows of DDTs, HCHs, PCBs, and PBDEs at 48.0, 1.43, 0.48, and 0.32 kg, respectively, followed by Korea at 38.6, 1.15, 0.39, and 0.25 kg. The U.S. ranked third at 29.7, 0.88, 0.30, and 0.20 kg. Fish consumption assessments indicated that consumption of freshwater farmed and wild marine fish generally does not subject consumers to significant health risk as far as PHHs are concerned, while limited consumption of seawater farmed fish is advised.
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