Potential release of PCBs from plastic scientific gear to fringing coral reef sediments in the Gulf of Thailand

A status on environmental contamination of the coral reefs on the islands of Samui and Katen of the western part of the Gulf of Thailand was investigated with a preliminarily analysis of bottom sediment samples. Coral reef bed sediments were characterized as relatively uncontaminated by human activities in terms of selected metals and PCBs. Potential release of PCBs to the ambient seawater from scientific equipment made of plastic materials placed into the coral reef waters for an extended period was investigated because the sedimentary PCBs concentrations were very low in the region. Eight plastics - acrylic, mono cast nylon, polycarbonate, polyethylene, polypropylene, ivory and grey-colored polyvinyl chloride, and Teflon^® - were subjected to leaching in seawater after being thoroughly washed with laboratory detergent and distilled water. All plastics were found to release PCBs at highly variable rates to seawater in the initial 60 days. Grey-colored PVC, Teflon, and polycarbonate after rinsing with n-hexane were found to release less than 50ng PCBs/kg of plastics and they could therefore be used to make scientific equipment to be deployed on the relatively PCBs-free coral reef beds.