Toxicity to estuarine organisms of leachates from chromated copper arsenate treated wood

The effects of chromated copper arsenate (CCA), used for treating wood in docks, pilings, and bulkheads, were studied in several estuarine organisms. Leaching of metals from treated wood into sea water was assayed by atomic absorption spectrophotometry. Fiddler crabs (Uca pugilator) were subjected to limb removal and were placed in containers with treated wood of various sizes or control wood. Limb regeneration rate was retarded in a dose-dependent fashion and mortality occurred with the treated wood, reaching 100% in the tank with the largest piece of wood. Embryos of the mummichog (Fundulus heteroclitus) were allowed to develop in culture dishes in which CCA-treated or untreated wood was soaking. Mortality was noted in the dishes with treated wood and to a smaller extent in those with untreated wood. Containers containing CCA-treated wood, control wood, or no wood were stocked first with the alga Ulva lactuca, the snails (Nassarius obsoletus). Chlorophyll content of the algae was reduced with the treated wood within a few days, and snails with the treated wood became moribund and died within a few days. In the controls containing untreated wood or no wood, no such effects were seen. Studies with individual or combination of two or three of the metals with snails and algae indicated that the copper was primarily responsible for the snail mortality and algal bleaching seen in the treated wood experiments. In all experiments, the toxicity of the wood decreased over time; when the experiments were repeated with the same pieces of wood, effects were diminished.