tailieunhanh - Pesticide profiles : Toxicity, environmental impact and fate - Chapter 3

Lớp cái nhìn tổng quan và bối cảnh mô tả chung Carbamate đã được phát triển thành thuốc trừ sâu thương mại trong những năm 1950. Mặc dù các thành viên của gia đình của hóa chất này có hiệu quả như thuốc trừ sâu, thuốc diệt cỏ và thuốc diệt nấm, họ phổ biến nhất được sử dụng như thuốc trừ sâu. Có lẽ thuốc trừ sâu carbamate được áp dụng rộng rãi nhất là carbaryl, đặc biệt là sử dụng cho các bãi cỏ và các khu vườn. Có khoảng 25 hợp chất carbamate khác hiện đang được sử. | chapter three Carbamates Class overview and general description Background Carbamates were developed into commercial pesticides in the 1950s. Although members of this family of chemicals are effective as insecticides herbicides and fungicides they are most commonly used as insecticides. Perhaps the most widely applied carbamate insecticide is carbaryl which is especially utilized for lawns and gardens. There are approximately 25 other carbamate compounds currently in use as pesticides or pharmaceutical agents. The carbamates have replaced chlorinated hydrocarbons as the pesticides of choice for controlling pests on agricultural crops such as citrus forage crops and cotton on garden vegetables and lawns and in the home. They control a wide variety of invertebrates . mites spiders and earthworms. The carbamates are generally applied to the soil and taken up by the plant. As a group carbamates are colorless and odorless compounds which are crystalline at normal temperatures 1 . They are stable when exposed to air light or heat during storage. Carbamates are derivatives of carbamic acid and have the general structure given in Figure 2 . Table lists the carbamates. Carbamate usage In 1987 herbicide production in the . was estimated to be 623 million pounds 3 . It was estimated that in 1987 carbamates represented of all herbicides used. Assuming that all herbicides produced were applied overall carbamate usage for 1987 was approximately million pounds 4 . Mode of action and toxicology Carbamates were originally identified in extracts of the calabar bean that grows in West Africa. These extracts contained a compound called physostigmine which is a methylcarbamate ester 5 . Many of the effects of carbamates have been documented from the study of this naturally occurring compound and its derivatives 5 . The primary way that insecticidal carbamates work on both target and non-target species is through the inhibition of the enzyme .

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