|
|Section2= |Section3= }} Dimethyl tetrachloroterephthalate (DCPA, Dacthal) is an organic compound with the formula C6Cl4(CO2CH3)2. It is a colourless solid, although commercial samples can be off white. DCPA is the dimethyl ester of tetrachloroterephthalic acid. It is used as a preemergent herbicide.〔(American Vanguard Dacthal Webpage )〕 It kills grass and many common weeds without killing sensitive plants such as flowers, fruits, vegetables, turf, and cotton.〔http://www.agri.state.id.us/Categories/Environment/water/waterPDF/gwreports/DCPA-PMP.pdf〕 DCPA was first registered for use in the United States in 1958. Production of DCPA was eventually discontinued by ISK Biosciences in 1998, but the large manufacturing company AMVAC began producing the product in 2001 for use in America.〔(【引用サイトリンク】url=http://southwestfarmpress.com/dacthal-returns-market-crops-use-patterns-remain-same )〕 Sigma-Aldrich also manufactures DCPA for use in the USA under the name Pestanal. In Australia, DCPA is the active ingredient in agchem company Farmalinx's herbicide called Dynamo 750. Currently, DCPA is only used for eggplant, kale, turnips, and sweet potatoes. ==Contamination== DCPA is released directly into the environment during its use as a herbicide. DCPA exists in both the vapor and particulate phases when exposed to the air. In the vapor phase, DCPA should react slowly with hydroxyl radicals with an estimated half-life of 36 days. Particulate-phase DCPA may be physically removed from air by wet and dry deposition. With a high Koc of 3900, DCPA is presumably immobile in soil, and thus may strongly attach to inorganic material in soil and other environments〔 In addition, its breakdown products, TPA (Tetrachloroterephthalic acid) and MTP (Monomethyl tetrachloroterephthalic acid), enter the environment after being formed through various processes. Studies have shown that DCPA can partially degrade through volatilization, as well as via photodegradation, but biodegradation is the primary route of DCPA degradation leading to MTP and TPA. Environmental Protection Agency testing in New York showed "measurable residues of DCPA and degradates" on land that had endured five years of treatment with DCPA, followed by three years of no treatment. DCPA is also prevalent in water and bioconcentration is seen in aquatic animals. DCPA accumulation was shown in fish at "several locations" in the United States.〔 Some of these locations included the Apalachicola, Colorado, Mobile, Savannah, and Pee Dee River Basins in both bass and carp. In the study done on these river basin locations, roughly 39% of the fish tested had stored DCPA concentrations that exceeded their limit of detection, and the male fish had higher stored concentrations of DCPA than their female counterparts. Fish collected from different locations throughout the United States are often contaminated by DCPA if they are near agricultural areas that use or have used it as an herbicide.〔(【引用サイトリンク】first1=Caroline )〕 Humans are exposed to DCPA through drinking well water, eating fish, and eating leafy and root vegetables. In some areas where agriculture is prominent, inhalation of air can be a means of exposure. DCPA is listed as a Group C Possible Human Carcinogen by the National Library of Medicine. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Dimethyl tetrachloroterephthalate」の詳細全文を読む スポンサード リンク
|