Laserfiche WebLink
<br />life in well-drained soils ranges from approximately 4 to 10 days. In studies conducted in <br />Colorado, Wilson et al. (1996) found that 2,4-D degraded to non-detectable levels in less than <br />35 days. <br />Under anaerobic conditions, the half-life of 2,4-D is estimated to be on the order of 6 months. <br />2,4-D is relatively immobile in soils. Adsorption in soils appears to increase with increasing <br />organic content and decreasing soil pH. Leaching to ground water is not a significant transport <br />' pathway except in warse soils with low organic content or very basic pH. If released to surface <br />' water or sediments, 2,4-D is readily biodegraded by native microorganisms. Its half-life in <br />surface water and sediment is reported to be on the order of 1 to 10 days. Its ground-water <br />half-life is reported to be up to 6 months. <br />Studies by Kennedy et al. (1972) and Tirey et al. (1993) identified the volatile compounds <br />resulting from the thermal decomposition of 2,4-D and other weed killers. The thermal <br />breakdown of 2,4-D produced carbon monoxide, carbon dioxide, hydrogen chloride, and <br />ammonia. Additional literature indicates that thermal destruction of 2,4-D may also produce <br />phosgene. Based on a literature review conducted by Dames & Moore during the preparation of <br />this SAP, dioxin would not be formed as a thermal degradation product of 2,4-D. None of the <br />identified thermal break-down products persists in the environment. Therefore, these <br />compounds are not targeted for investigation under this SAP. <br />(References: 2,4-D Industry Task Force Research Data. Obtained by Intemet at www.24d.org. <br />Extension Toxicology Network. 1996. 2,4-D Pesticide Information Profile. Obtained by Intemet <br />from Extoxnet.) <br />Bromacil (5-Bromo-3-Secbutyl Methyluracil) <br />Bromacil is broad spectrum weed killer used to control weeds in the agricultural industry and to <br />control weeds and brush along utility and highway right-of-ways. This weed killer is virtually <br />non-toxic to mammals, birds, and fish; and is not regulated as a hazardous substance. Pure <br />bromacil is a solid at room temperature. Typical formulations include granules, liquid ready-to- <br />use, pellets, and liquid soluble concentrates. Bromacil was first registered for use as a weed <br />killer in 1961, and was reregistered in 1982 and 1996. Environmental toxicological, fate, and <br />transport data for Bromacil is presented in Table 2. <br />~ In studies using laboratory animals, Bromacil was found to be slightly toxic by oral, dermal, and <br />inhalation routes. Bromacil is placed under Toxicity Category IV, the lowest of four categories, <br />,~ for oral, dermal, and inhalation exposure. The compound is in Toxicity Category III for eye <br />_ exposure. <br />' Bromacil has been evaluated as potential carcinogen and is classified as a Group C "possible" <br />human carcinogen. Risks due to dietary exposure have been determined to be very low. In its <br />1996 reregistration, EPA established more stringent worker protection standards to mitigate <br />potential chronic effects of Bromacil for handlers and applicators. Kennedy et al. (1972) found <br />that the thermal decomposition of Bromacil produced carbon monoxide, carbon dioxide, <br />hydrogen chloride, chlorine, and ammonia. None of the identified thermal break-down products <br />persists in the environment. Therefore, these compounds are not targeted for investigation <br />under this SAP. <br />' B&B Excavating, Inc., Edwards, Colorado December 17, 1998 <br />Montgomery Pit Facility 39210-003-034 <br />Draft Sampling and Analysis Plan 14 DAMES 8 MOORS <br />