Thesis (M.Sc.)--Chulalongkorn University, 2005

Fifty species of fish were collected during June 2004 to May 2005 at Khlong 7, Rangsit, Pathum Thani Province. Forty-two species were analyzed for accumulation and biomagnification of organochlorine (OC) insecticide residues. The compounds were [Sigma]BHC (alpha, beta, gamma and delta-BHC) [Sigma]Heptachlor (heptachlor and heptachlor epoxide), [Sigma]Endrin (endrin and endrin aldehyde), [Sigma]DDT (p,p'-DDE, p,p'-DDD and p,p'-DDT), [Sigma]Endosulfan (endosulfan I, endosulfan II and endosulfan sulfate), aldrin, dieldrin and methoxychlor. The major compounds detected in the fillets were [Sigma]DDT (<0.04-48.26 ppb) and [Sigma]Endosulfan (0.44-49.18 ppb), followed by [Sigma]Heptachlor (<0.02-26.51 ppb), [Sigma]BHC (<0.05-20.76 ppb), [Sigma]Endrin (<0.02-14.73 ppb), Dieldrin (<0.03-13.22 ppb), Methoxychlor (<0.02-13.18 ppb) and Aldrin (<0.02-9.88 ppb), respectively. [Sigma]DDT and [Sigma]Endosulfan concentrations in fillets increased with fish total bodylength. Biomagnification factor (BMF) values were 1.61-2.27 for [Sigma]DDT and 4.19-8.80 for [Sigma]Endosulfan from primary consumers, herbivorous and detritivorous fish to the top predatory fish. Based on the Thai and FAO/WHO maximum residue limits (MRLs), all OC residue concentrations were beloow the levels that have been suggested to cause the adverse effects on human and wildlife.