This project was undertaken in response to concerns raised by the NSW goverrrrnent

Department of Environment and Conservation (DEC, formerly EPA) regarding the

potential for the concentration of pesticide residues in cotton gin trash to pose a

"hazardous" risk. The assessment and characterization of waste is stipulated by waste

management guidelines (EPA, 1999), of which one of the 27 pesticides analyzed,

commonly used in cotton production, is characterized.

Monitoring of trash ginned from cotton during the 2002 season occurred over a two year

period at three gin sites from different valley's, including Namoi (Auscott Narrabri),

Wathagar (Namoi Cotton) and Mungindi(Namoi Cotton). In total, 14 pesticide residues

were detected in gin trash; 13 commonly used pesticides of cotton and DDE, a breakdown

product of DDT. The concentrations of these residues were then characterised for risk

using standard risk assessment methodology (Norton at o1. , 1992; ECOFR, A. M, 1999) and

the EPA guidelines (EPA, 1999). The degradation rate of the residues was also measured.

The concentrations of residues in gin trash were not found to pose a hazardous risk. The

nature of these chemical, being strongly bound to organic matter, also indicated that these

residues would not be available to cause toxic action. The total amounts of residues in gin

trash almost disappear except for DDE found only in samples from the Namoi Valley.

Based upon the characterization guidelines for chiorpyrifos (EPA, 1999), cotton gin trash

was found to be "Solid Waste", two management categories lower than Hazardous

Waste". There is no evidence to suggest these chemical residues detected should be

considered a risk of causing toxic action in the future. Furthemore, future classification

would be expected to reduce cotton gin trash to "inert" waste, because of decreased

pesticide use with increased use of Bollgard 11 cotton varieties.