Toxicity of a a Chlorinated Benzene to Sea Urchin Embryos

The effects of chlorinated benzene compounds on marine animals are not well known. Until recently, only hexachlorobenzene (HCB) had received attention in pollution studies: In a report published by the National Academy of Sciences (1975) this substance is labelled a marine pollutant of special concern. Last year. Project scientists analyzed municipal wastewater samples for HCB and three other chlorobenzene compounds—para-dlchlorobenzene (p-DCB), ortho-dichlorobenzene (o-DCB) and 1,2,4-trichlorobenzene (1,2,4TCB); the results indicated that the latter three substances were present at levels at least one order of magnitude higher than that of HCB (Young and Heesen 1976). It has been shown that p-DCB can act as a mitotic poison, causing disorders of cell division that result in abnormal multinucleate cells (Biesele 1958). The study de-scribed here was a preliminary investigation of o-DCB's potential as a mitotic poison in the marine environment. Recently fertilized sea urchin eggs were exposed to an o-DCB concentration of about 21 mg/liter, and their development morphology and rate were observed during the subsequent 52 hours. The results showed that o-DCB has the potential to interfere with embryological development: Grossly abnormal sea urchin embryos were evident at about 28 hours past fertilization.