A REVIEW OF TRICHLOROBENZENES IN DRINKING WATER
Report No FR0097

A PATEL

AUG 1990

SUMMARY

I OBJECTIVES

To review the information on the toxicity of TCB's with reference to drinking water and to discuss the setting of a drinking water guide level for these compounds.

II REASONS

TCB's have been detected in surface and drinking water. There is a need to provide water suppliers with sound guidance on the maximum levels of toxic substances that should be permitted in drinking water. The WHO is undertaking a review of drinking water guidelines for a number of substances. This review is part of the UK water industry's contribution to that process of establishing new guidelines based on a sound scientific assessment of the latest available data.

III CONCLUSIONS

The TCB's have very low taste and odour thresholds in water. The majority of toxicity data refer to the 1,2,4-isomer. The TCB's are of low to moderate acute and chronic toxicity. There is no evidence of carcinogenicity and little evidence of mutagenicity. None of the isomers were embryo-toxic or teratogenic.

IV RECOMMENDATIONS

The guideline values based on toxicity data are greatly in excess of the reported taste and odour thresholds for the TCB's in drinking water. The maximum permissible concentration for TCB's in water should be set on the basis of odour, which is detectable at the lowest concentration.

V RESUME OF CONTENTS

TCB's are widely used in industry have been detected in surface and drinking water. Significant volatilisation is expected from water. The TCB's are of low to moderate acute and chronic toxicity. They do not appear to be carcinogenic or mutagenic. There is no evidence to suggest they are teratogenic or embryo-toxic. Guideline values for drinking water are calculated using an uncertainty factor applied to a no observed adverse effect level from animal studies. However, these are in excess of the reported taste and odour thresholds for TCB's in water.

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