UPTAKE OF CHRYSOTILE ASBESTOS FIBERS ALTERS GROWTH AND REPRODUCTION OF ASIATIC CLAMS

The effects of chrysotile asbestos on siphoning activity, shell and tissue growth, fiber uptake, and gill ultrastructure in adult Asiatic clams (Corbicula sp.) and on larval release and mortality patterns from reproductively active adults were evaluated in 96-h to 30-d experiments at 0-108 fibers/L. Adult siphoning activity was significantly (.alpha. = 0.05) depressed in 96-h asbestos exposures when no food was offered or after 30 d when food was available. Shell growth was significantly inhibited in accordance with reduced siphoning. Corbicula exposed to 108 fibers/L accumulated 69.1 fibers/mg dry weight if food was offered. Fiber uptake was not observed at lower concentrations in 96-h or 30-d tests. Adult clams exposed to 108 fibers/L for 30 d accumulated 147.3 and 903.7 fibers/mg in gill and viscera, respectively. Gill tissue was significantly altered at 108 fibers/L and fibers wre observed in gill locules and in ctenidial tissue. Fiber dimension analysis suggested that small, thin fibers were preferentially accumulated by both gill and visceral tissues. Significant increases in mortality of larvae exposed to asbestos and decreases in larvae released per milligram of adult dry weight were observed in reproductive adults exposed to asbestos at 104-108 fibers/L. Corbicula is an efficient accumulator of chrysotile asbestos and may be considered for use as an indicator of asbestos contamination.