Xiang-Zhou Meng

Organochlorine pesticides in seafood products from Southern China and health risk assessment

Seafood consumption is an important route of human exposure to organic contaminants. Residual levels of organochlorine pesticides (OCPs), including DDTs, hexachlorocyclohexanes (HCHs), heptachlor, aldrin, alpha-endosulfan, beta-endosulfan, dieldrin, endrin, endrin aldehyde, endrin ketone, methoxychlor, endosulfan sulfate, and heptachlor epoxide, were determined in a wide variety of seafood products collected from 11 coastal cities in southern China in June and October 2005. The results indicated that OCPs were predominated by DDTs and HCHs. The concentrations of other OCP components generally were low and were detectable in a small number of seafood samples only, probably reflective of the generally low levels of these OCPs in the study region and low bioaccumulation potentials in the species under investigation. Risk assessment against various standards clearly showed that seafood products were highly contaminated by DDTs and may pose health threat to local residents and the consumers all over the world. Furthermore, other OCP components, such as dieldrin and heptachlor, also impose lifetime cancer risk, especially to residents of coastal regions who often consume more seafood than those living inland. Therefore, continual monitoring of OCPs in various environment compartments, including biota and abiota, urgently is needed to mitigate effectively the impact of OCPs, particularly DDTs, on human health and the ecological environment.

Congener-specific distribution of polybrominated diphenyl ethers in fish of China: Implication for input sources†

A total of 390 individual fish, including seven species of freshwater-farmed fish, three species of seawater-farmed fish, and three species of wild marine fish, from China were analyzed to determine the concentrations and congener distribution of polybrominated diphenyl ethers (PBDEs). The levels of Sigma(10)PBDEs (sum of BDEs 28, 47, 66, 100, 99, 85, 154, 153, 138, and 183) in seawater-farmed fish (median, 13.6 ng/g) were significantly higher than those in freshwater-farmed fish (median, 10.1 ng/g) and in wild marine fish (median, 4.5 ng/g) on a lipid-weight basis. Lipid contents positively correlated with Sigma(10)PBDEs concentration (wet wt) in all fish species except for tilapia, bighead carp, bluntsnout bream, and common mullet; however, no significant relationship was found between fish length or weight and Sigma(10)PBDEs concentration except for one fish species. In general, BDE 47 was the dominant congener, with a mean contribution of 53.2%. Brominated diphenyl ether 209 was only detected in 14 samples, reflecting its low bioavailability or high degree of debromination. In addition, the ratios of BDE 47 to BDE 99 and of BDE 100 to BDE 99 in freshwater-farmed fish were significantly higher than those in seawater-farmed and wild marine fish. Freshwater-farmed fish had a relatively higher proportion of BDE 28, whereas seawater-farmed and wild marine fish contained more abundant BDE 66, BDE 100, and BDE 99. The difference in congener distribution might be indicative of different exposure pathways for PBDEs in three types of fish.

Distribution of polybrominated diphenyl ethers in fish tissues from the Pearl River Delta, China: Levels, compositions, and potential sources

Fish tissues from three different farming types (freshwater farmed, seawater farmed, and seawater wild fish collected from the Pearl River Delta of South China), including skin, gills, gastrointestinal tract (GIT), liver, and muscle, were analyzed for polybrominated diphenyl ethers (PBDEs). In general, the dry weight based concentrations of Sigma10PBDE (sum of BDE-28, -47, -66, -85, -99, -100, -138, -153, -154, and -183) in fish tissues followed the sequence of liver > gill > skin > GIT and muscle. The BDE congener profiles varied with fish species. Decabrominated diphenyl ether was detected in 37.4% of the total 187 samples, and this ratio may actually have been underestimated because the reporting limit for BDE-209 was considerably higher than those for other congeners. Decabrominated diphenyl ether was the dominant BDE congener in skin and GIT, and less abundant in gills, muscle, and liver. Except for skin, no significant difference in BDE-209 lipid-normalized concentrations was observed among fish tissues. These results suggest that BDE-209 can occur abundantly in the fish species under investigation, somewhat inconsistent with the results from most previous studies that reported low bioaccumulative potential of BDE-209. Combined with the likelihood that BDE-209 can be debrominated into lower brominated congeners that tend to be more toxic than BDE-209, the abundant occurrence of BDE-209 could continue to pose prolonged health risk to the ecological environment.

Hexabromocyclododecane in consumer fish from South China: Implications for human exposure via dietary intake

Levels of hexabromocyclododecane (HBCD) were determined in 12 consumer fish species from South China. The concentrations of the sum of HBCD diastereoisomers (ΣHBCD) ranged from nondetectable to 194 pg/g wet weight, with a detectable frequency of 70%. This was at the low end of the concentration range globally observed. Carnivorous fish species contained higher HBCD concentrations than herbivorous and detritivorous ones, suggesting the potential for biomagnification of HBCDs via the trophic chain. Moreover, ΣHBCD concentrations were higher in both freshwater and seawater farmed fish than in wild marine fish, indicating that human activities were probably an important input source of HBCD in aquaculture. Among the three diastereoisomers, α-HBCD dominated in most samples, with a mean relative abundance of 70%. In agreement with previous studies, a difference in the diastereomer patterns was observed from commercial products and several environmental media to biota samples. For farm-raised snubnose pompano, the concentrations of ΣHBCD were moderately linearly correlated with lipid contents but were not significantly correlated with fish body lengths and weights. In the worst-case exposure, the mean estimated daily intake of ΣHBCD via fish consumption for residents of South China ranged from 13 to 16 pg/kg body weight/d for various age groups, much lower than its lowest observed adverse effect level derived from a two-generation reproductive toxicity study on rats.