Biomarkers for monitoring environmental impacts of Organochorine pesticide residues on freshwater mussels

Abstract

Thailand is known as an agricultural country with more than 53% of the total area. uses of organochlorine pesticdes (OCPs) to control pests have been carried out intensively. Due to their persistence in the field and their abilities to be biomagnified through food chain, the extent of OCPs contamination in ecosystem is crucial for environmental monitoring program. In the study, we used freshwater mussels to monitor the OCPs contamination in a freshwater ecosystem at Khlong 7 canal Rangsit agricultural area. three species of freshwater mussels (Uniandra contradens ascia, Pilsbryoconcha exliis exilis and Hyriopsis (Limnoscapha) deswitzi) and the surrounding sediment were collected during March 2006 – March 2007. the concentrations of OCPs namely HCH, Heptachlor, aldrin and dieldrin, Endrin, Endosulfan, DDT, and methoxychlor were quantified by gas chromatography with micro-electron capture detector (GC-uEDDT). the results showed that low levels of OCPs residues were contaminated in sediment and mussels. the concentrations of HCH, DDT, Heptachlor and Endosulfan were the most prevalent OCPs with the range of 6.93 – 15.33 up/kg in sediment and 19.48 – 68.44 up/kg in mussels. there were significant diffierences in OCPs contamination arnong sampling periods with the highest levels found during June – November. the OCPs residues found in mussel tissue were below the maximum residue limits by the Ministry of Public Health of Thailand. vitellogenin (vtg) in mssel gonad and specific activity of glutathione-s-transferase (GST) in mussel hepatopancreas were determined by ELISA and spectrophotometry, respectively. it was found that the levels of vtg and GST in mussels showed seasonal difference and significantly correlatead with the levels of OCP residues in sediment and mussels. this indicates that the freshwater mussels living nearby the agricultural fiels could potentially be used as sentinel species for environmental contamination of organochlorine pesticides.