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'4 The science 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. As referenced below,although DDT was banned in 1972, its presence in San Joaquin Valley soils is indicative of its long half-life of 15.6 years. Consequently,there may be extremely small concentrations of DDT and its degradates in the subject property soils. Pesticides with long half-lives that may have been used or drifted onto the property decades ago, primarily DDT, may be of an extremely 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). The environmental fate data are presented below for DDT, and its degradates DDD and DDE. 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 m deep. Degradation half-life of about 10 yr-average from loss rates determined in Lake Michigan. Groundwater: 16 d to 31.3 yr. Sediment: 3 to 5 yr e 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: E Volatilization: Half-life of 3.7 d for water depth of 1 m, 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 f DDE. Common name:DDE(p,p'-DDE; o,p'-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:NIA 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 Hydrolysis:>120 yr DDD. Common name: DDD,TDE(tetrachlorod iphenyl ethane),product of DDT deg. Half-lives in the environment: Air: 17.7-177 h Surface water:2-15.6 yr. Groundwater: 1680-270,000 h based on anaerobic soil study data Sediment:N/A Soil: Field half life of 2-15.6 yrs based on observed rates of biodeg.of DDT Biota: 119 hr in mussels. Environmental Fate Rate Constants or Half-Lives: Volatilization: Aquatic approx. 1 mo. Oxidation: Aquatic half-life approx. 22 yr M Page -6- Chesney Consulting s l -