Comparison Of Toxicity Of Class-based Organic Chemicals To Fish And Algae Based On Discrimination Of Excess Toxicity

In this paper,the toxicity data of 949 chemicals to fish and 468 chemicals to algae were used to investigate excess toxicity between species.Results showed that most of the compounds have very close toxicity values.Close toxic effects indicate that most of the compounds share same mode of action.Similar relationships between log KOW and toxicities to fish and algae for baseline and less inert compounds suggest that they have similar critical body residues in the two species.Study on the toxic ratio shows that the chemicals exhibiting excess toxicity to fish also show excess toxicity to algae for most of the compounds.These compounds can be predicted as reactive compounds and undergo covalent binding to target molecules both in fish and algae species.Slight differences in excess toxicity for some compounds suggest that there is a difference of physiological structure and metabolism between fish and algae.Some reactive compounds(e.g.amino alcohols,diamines,polyamines and benzothiazoles)exhibit greater toxic effects for algae than those for fish because of relatively low bio-uptake potential of these hydrophilic compounds in fish as compared with that in algae.Esters exhibiting greater toxicity in fish than that in algae indicate that metabolism can affect the discrimination of excess toxicity from baseline level.Algae growth inhibition is a very good surrogate for fish lethality.This is not only because the overall toxicity sensitivity to algae is greater than that to fish,but also the excess toxicity calculated from algae toxicity can better reflect the reactivity of compounds with target molecules than fish toxicity.