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FFd�one. lly applied agrichemical residues as a nonpoint source of potential contamination was not iewing the environmental fate data ofagrichemicals used today, we find most of the half-xtremely short and are measured in hours. of pesticide residues in soil, air, surface water and groundwater is extremely complex and variable. Environmental models that attempt to predict pesticide behavior and transport in the environment are beyond the scope of this investigation. However,pesticides with long half-lives that may have been used or drifted onto the property decades ago, primarily DDT, may be of a slight concern. DDT was used extensively throughout the agricultural fields of the San Joaquin Valley and /) degradates of DDT can be found in nearly all these soils. Previous Exposure Assessments made on typical San Joaquin Valley soils suggest an extremely low probability of adverse health effects from soil DDT/DDD and DDE concentrations (if the concentrations even exist). It can be reasonably concluded that any DDT, DDE and DDD concentrations that may be present on the property will continue to degrade as reported in the published environmental fate data. The 0 environmental fate data for DDT and its degradates DDD and DDE are illustrated below: DDT. Common name: Agritan, Anofex, Azotox, et al. Half-lives in the environment: Air: 17.7 -177 h. Surface water: 73.9 h for a pond 1 in deep. Degradation half-life f about 10 yr average from loss rates determined in Lake Michigan. Groundwater: 16 d to 31.3 yr. Sediment: 3 to 5 yr Soil: 2-15.6 yrs based on observed rates of biodegradation in aerobic soils under field conditions. Avg. half life of-12 yrs in 3 different soils for -50 ppm in soil. (conversion of p,p'-DDT to p,p'-DDE). Environmental Fate Rate Constants or Half-Lives: Volatilization: Half-life of 3.7 d for water depth of 1 in, from soil w/h-1 of 578 h Oxidation: Photooxidation half-life of 168-8400 h in water, 17.7-177 h in air Hydrolysis: Estimated first-order half life of 22 yr Biodegradation: Aqueous aerobic half-life of 2-15.6 yrs DDE. Common name: DDE (p,p'-DDE; op'-DDE),product of DDT degradation. Half-lives in the environment: Air: Atmos. transformation lifetime est. to be < 1 d. Surface water: Hydrolytic half-life of >120 yr, est. half-life>300 d in lakes. Groundwater:N/A Sediment: N/A Soil: Field half life of 1000 d Biota: Elimination half-life of 340 d(rainbow trout), 300 d for birds. Environmental Fate Rate Constants or Half-Lives: Volatilization: N/A Oxidation: N/A �L�_ Page -4- Chesney Consulting