Dislodgeable residues of fenamiphos applied to turfgrass and implications for golfer exposure

The general public is concerned about exposure to pesticides applied to tur fgrasses, Such exposure may occur because of dislodgeable residues. A study was conducted to determine the dislodgeability of fenamiphos (ethyl-4-meth ythio-3-methylphenyl-iso-propylphosphoramidate), a nematicide, applied to t urfgrass and to assess the risk of exposure to that pesticide by dermal and incidental ingestion pathways, Dislodgeability was determined using golf b alls, golf sips, a golf club head, and damp cheesecloth following applicati on and irrigation (a required practice), through a 24-hr period after appli cation. A risk assessment model encompassing golfer behavior and realistic golf course exposure scenarios was used in conjunction with field data to a ssess risk. Fenamiphos was applied to bermudagrass (Cynodon dactylon L. x C . transvaalensis Burtt Davy) as a liquid at 1.125 g a.i. m(-2). Dislodgeabl e residues of fenamiphos decreased with irrigation and time. Approximately 3% of the fenamiphos applied was dislodged with the damp cheesecloth wipe i mmediately following application, but only 0.1% of the fenamiphos applied w as dislodged with the damp cheesecloth wipe following irrigation. The risk assessment model used in this study suggests that risk associated with derm al and incidental ingestion exposure to fenamiphos will decrease with time after application. Daily exposure immediately following pesticide applicati on may exceed the acceptable daily intake levels for chronic exposure. Howe ver, more realistic exposure models estimate doses well below the chronic r eference dose.