There is only low potential for consumer exposure to paraquat via the diet as the vast majority of paraquat uses do not result in detectable residues (>0.05 mg/kg) in foodstuffs.
No risks from residues in food
Most uses of paraquat involve spraying weeds and not crops. Paraquat is biologically deactivated through strong adsorption to soil and cannot be taken up by plant roots. Consequently, for the vast majority of uses, no residues are expected in harvested crops. This has been confirmed over many years by analysis of crops harvested after the use of paraquat as an herbicide. There are a few situations where crops are treated directly when paraquat is used as a pre-harvest desiccant. These uses are approved by regulatory authorities who have confirmed such treatments do not leave residues at levels which represent a risk to consumers.
No risks from residues in livestock
Paraquat binds to plant tissues once it is in contact with foliage and is not easily absorbed by livestock, only approximately 15% of ingested paraquat is absorbed and this is readily eliminated via urine. There is no significant transfer to milk, meat or eggs. Similarly there is no practical health risk to livestock if they are accidentally fed on treated herbage.
- In their report of a periodic re-evaluation of residues for the Joint FAO/WHO Meeting on Pesticide Residues (JMPR), the World Health Organization (WHO) concluded that, “the intake of residues of paraquat resulting from uses considered by the current JMPR was unlikely to present a public health concern” (JMPR, 2004)
- In their RED facts document, the US Environmental Protection Agency (EPA) concluded that “the Agency has determined that there is reasonable certainty that no harm will result to infants and children or to the general population from aggregate exposure to paraquat dichloride residues” (US EPA, 1997)
- In their review report for paraquat the European Commission (EC) concluded “the review has established that the residues arising from the proposed uses, consequent on application consistent with good agricultural practice, have no harmful effects on human or animal health” (EC, 2003)