Organochlorine pesticide residues in aquatic ecosystem and health risk assessment of local agricultural community

Abstract

The study of organochlorine pesticide residues (OCPRs) such as HCHs, heptachlor and heptachlor expoxide, DDT and derivatives, total endosulfan, endrin and endrin aldehyde, and methoxychlor in aquatic ecosystem was conducted from June 2004 to February 2007 at Khlong 7 (canal), Rangsit aricultural area, Pathum-Thani Province. The OCPRs in various samples (sediment, water, plankton (phyot-and zoo-plankton), aquatic plant, shrimp, freshwater snail, and fish) were extracted using multiresidue extraction method and then analyzed by gas chromatography with micro electron capture ( [mu]-ECD) detector. The results showed that low concentrations of OCPRs in Khlong 7 aquatic ecosystem were found, in part per billion (ppb) levels. The average concentration of OCPRs compared in various matrices indicated that total endosulfan was the highest in water, aquatic plants (8 species), and fish (41 species). On the other hand, DDT and derivatives was the highest detected in plankton, and invertebrates (3 species). In particular, the distribution pattern of OCPRs in aquatic organisms was planktons < aquatic plants < vertebrates (fish) < invertebrates (shrimp and freshwater snail), respecitively. Generally, OCPRs distribution pattern in the physical environment was water < sediment. Even though organochlorine pesticides were banned in Thailand, the accumulation and transformation existed in the aquatic food web from the lowest up to the highest trophic level. Concerning human heath, this study thus assessed the human health risk of OCPRs associated with aquatic organisms consumption from Khlong 7, based on a plausible worst-case scenario. The results showed that some fish consumption of local population at Khlong 7 could be related to a cancer risk causing by [alpha], [beta]-HCH, heptachlor, heptachlor epoxide, aldrin, dieldrin, DDD, DDE, and DDT. Likewise, the consumptions of Lanchesters freshwater prawn Macrobrachium lanchesteri, freshwater snail Filopaludina mertensi, swamp morning-glory Ipomomea aquatica, neptunia Neptunia oleracea, and water lity Nymphaea lotus were at risk from [alpha], [beta]-HCH, heptachlor, heptachlor epoxide, aldrin, and dieldrin. Therefore, the authorities and local communities should have the appropriate strategies for the reduction of health risk.