Tissue and milk residues arising from the ingestion of single doses of diquat and paraquat by cattle

The fate of 14C‐diquat and 14C‐paraquat administered orally in single doses to cattle has been studied. In lactating cows, very little (<0.02%) of administered radioactivity appears in the milk, and then largely as metabolic products. Milk obtained in these trials contained levels of paraquat or diquat which in all cases were so low that it could safely be consumed by humans. Only small amounts (< 5%) of the administered radioactivity appears in the urine and in this case also largely as breakdown products. The bulk of the radioactivity appears in the faeces. In a calf slaughtered one day after dosage with 14C‐diquat very little (< 0.01 ppm ion) diquat or its metabolites were found in the muscle tissue. The organs involved in metabolism and excretion, the kidneys and liver, contained relatively small amounts (equivalent to 0·7 ppm and 0·2 ppm ion, respectively) of diquat and its metabolites.