Embryotoxicity of irradiated and nonirradiated catalytic converter‐treated automotive exhaust

This study was undertaken to examine the relative embryotoxicity in chick embryos of photochemically reacted and unreacted diluted automotive exhaust emissions from a system equipped with a catalytic converter. Clean air controls and H₂SO₄ aerosol controls equivalent in concentration to those found in the catalytic exhaust atmosphere were also studied. From day 1 through day 14 of development, continuous exposure to nonirradiated exhaust resulted in decreased survival, lowered embryonic weight, a small increase in heartlbody weight ratio, and altered hematocrit and serum enzyme activities (LDH and GOT). Irradiated exhaust had little effect on survival or on embryonic weight but resulted in a higher liver/body weight ratio as well as altered hematocrit and serum enzyme activities. Interactions or cumulative effects of different compositions of exhaust atmospheres may play a role in differing biological responses between unreacted and irradiated exhaust. Sulfuric acid aerosol had a minimal effect on survival and resulted in only a slight decrease in embryonic weight and serum LDH activity, with no other apparent effects. In previous studies where the catalytic converter was not used, more pronounced effects on survival, increased heart/body weight ratio, elevated serum GPT activity, and liver discoloration were observed. Thus, the introduction of an oxidizing catalytic converter appeared to alleviate some but not all of the embryotoxic effects of automotive exhaust.