Agricultural chemicals residue field

Acute aquatic tests duration, 133 species selection, 133 Advisory function of QAU, 114 Agricultural chemicals residue field trials program, quality assurance, 99-106... 

Soils may also become contaminated with industrial pollutants or with agricultural chemicals. For example, fields located close to industrial plants such as incinerators or metal smelters can gradually accumulate residues of combustion products and other chemicals from the fall-out from smoke plumes. Organo-chlorine pesticides, which are now largely banned, can persist in soils for many years and nitrates used in fertilisers can accumulate in soils which, under certain growth conditions, can result in high levels in certain crops. 

Dietary exposure to pesticides (or to xenobiotics in general) is determined by calculating the product of the amount of chemical in or on the food and the total quantity of food consumed. The quantity of chemical potentially consumed in foods can be estimated from data obtained from residue field trials, metabolism studies, and/or monitoring data. Information from these sources is then analyzed with one of several available models containing food consumption factors from surveys conducted by the United States Department of Agriculture (USDA). For calculation of... 

The total amount of renewable resources available around the world amounts to 170 GT/y (see Figure 10.6). Among them, 4.6 GT/y equivalent carbon are left in the fields as agricultural residues, while the world chemical industry currently consumes around 0.6 GT/y equivalent carbon (10% of the total current world... 

Macdonald et al. (2000) found that global use of technical HCH and historical measurements of alpha-HCH concentration in the atmosphere of Arctic region showed two significant declines, one in 1983 when China banned the use of technical HCH and another around 1990 when India banned technical HCH usage in agriculture. In an experiment conducted at a paddy field in southern India Tanabe et al. (1991), Ramesh et al. (1991) and Takeoka et al. (1991) noticed rapid volatilization of HCHs, low residues in the soil and paddy plant when compared to their presence in the atmospheric levels and rapid removal to the atmosphere. Such experiments and surveys indicate the prominence of India in the contribution toward global pollution of toxic chemicals. 

The application of synthetic pyrethroids in the pest management program has gained importance in recent years. In view of their moderate toxicity, these chemicals have been used for the control of field craft pest in abundance. Because of the low residual effects, these compounds have not caused any serious or undesirable health effects in agricultural farmers, occupational workers, or household workers. More information on synthetic pyrethroids, fumigants, and rodenticides is available in the literature.1,2... 

Fluometuron adsorbs to soil particles. Half-lives for degradation in soil and water are estimated at 12-17 days and 110-114 weeks, respectively. Breakdown in soil is mainly through photodegradation. Soil microbes also degrade fluometuron. In field studies in agricultural areas in California and Georgia, fluometuron residues were not detected in soil below 12 in. Roots more readily absorb fluometuron compared to leaves. Differences in the plant s ability to break down fluometuron should be considered in using this chemical in weed control. 

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