Breakdown products of parent compounds are common and can
account for a majority of the mass of pesticides detected.
These breakdown products, which are mostly non-regulated,
can have similar or greater toxicities than parent compounds.
A NAWQA study found that in the Iowa River, for example, breakdown
products of some herbicides are commonly 10 times the concentration
of the parent compounds. On the basis of these findings, city
officials in Cedar Rapids, Iowa, require monitoring and analysis
of herbicide breakdown products in the city water supplies.
Selected Triazine and Aceanilide Pesticides
and Metabolites in the Iowa River at Wapello, IA
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