Atrazine United States

More controversially, endocrine disruption as a consequence of exposure to the herbicide atrazine (2-chloro-4-ethylamine-6-isopropylamine-s-triazine), one of the most widely used herbicides in the world, has also been hypothesized to explain various adverse biological effects in frog populations in the United States. Exposure to atrazine in the laboratory at high concentrations, far exceeding those found in the natural environment, has been reported to induce external deformities in the anuran species Rana pipiens, Rana sylvatica, and Bufo americanus (Allran and Karasov 2001). Studies by Hayes et al. have suggested that atrazine can induce hermaphroditism in amphibians at environmentally relevant concentrations (Hayes et al. 2002 Hayes et al. 2003). Laboratory studies with atrazine also indicated the herbicide... 

Hayes, T.B., Collins, A., and Lee, M. et al. (2002). Hermaphroditic, demasculinized frogs after exposure to the herbicide atrazine at low ecologically relevant doses. Proceedings of the National Academy of Sciences of the United States of America 99, 5476-5480. 

Although annual use of atrazine in the United States is about 35 million kg (Alvord and Kadlec 1996 Carder and Hoagland 1998), atrazine concentrations in human foods are negligible. Monitoring of domestic and imported foods in the human diet by the U.S. Food and Drug Administration between 1978 and 1982 showed that only 3 of 4500 samples analyzed had detectable atrazine residues. Two samples in 1980 contained 0.01 and 0.08 mg atrazine/kg and one in 1978, following a known contamination incident, contained 47 mg/kg (Reed 1982). 

DeNoyelles, F., W.D. Kettle, and D.E. Sinn. 1982. The responses of plankton communities in experimental ponds to atrazine, the most heavily used pesticide in the United States. Ecology 63 1285-1293. 

In the United States, about 80% of the 23 million kg of technical PCP produced annually — or about 46% of worldwide production — is used mainly for wood preservation, especially utility poles (Pignatello etal. 1983 Kinzell etal. 1985 Zischke etal. 1985 Choudhury etal. 1986 Mikesell and Boyd 1986 USPHS 1994). It is the third most heavily used pesticide, preceded only by the herbicides atrazine and alachlor (Kinzell et al. 1981). Pentachlorophenol is a restricted-use pesticide and is no longer available for home use (USPHS 1994). Before it became a restricted-use pesticide, annual environmental releases of PCP from production and use were 0.6 million kg to the atmosphere from wood preservation plants and cooling towers, 0.9 million kg to land from wood preservation use, and 17,000 kg to aquatic ecosystems in runoff waters of wood treatment plants (USPHS 1994). There are about 470 wood preservative facilities in the United States, scattered among 45 states. They are concentrated in the South, Southeast, and Northwest — presumably due to the availability of preferred timber species in those regions (Cirelli 1978). Livestock facilities are often constructed of wood treated with technical PCP about 50% of all dairy farms in Michigan used PCP-treated wood in the construction of various components of livestock facilities (Kinzell et al. 1985). The chemical is usually applied to wood products after dilution to 5% with solvents such as mineral spirits, No. 2 fuel oil, or kerosene. More than 98% of all wood processed is treated with preservative under pressure about 0.23 kg of PCP is needed to preserve 1 cubic foot of wood (Cirelli 1978). Lumber treated with PCP retains its natural appearance, has little or no odor, and can be painted as readily as natural wood (Wood et al. 1983). 

Several hundred-pesticide compounds of diverse chemical structures are widely used in the United States and Europe for agricultural and non-agricultural purposes (Fig. 10). Some are substitutes for organochlorines, which were banned due to their toxicity, persistence, and bioaccumulation in environmental matrices. According to a report published by the US-EPA, a total of 500,000 tons of pesticides was used in 1985 [144, 145, 148]. As far as specific pesticides are concerned, worldwide consumption of Malathion and Atrazine in 1980 amounted to 24,000 and 90,000 tons, respectively [149,150]. In the Mediterranean countries, 2100 tons of Malathion (active ingredient) were sprayed during the same period compared to 9700 tons in Asia [150]. 

Atrazine, one of the herbicides most widely used in the United States and European countries over the last 30 years, is employed for pre- and post-emergence weed control on corn, wheat, barley, and sorghum fields, and on railway... 

Outside Spain, the profile of pesticide contamination is fairly similar. For instance, Kolpin et al. [28] analysed pesticides in groundwater samples from the United States and found, in samples taken in 2001, triazine concentrations between 50 and 620 ng/L. In groundwater samples collected in Portugal between 2005 and 2008, atrazine and terbuthylazine were also detected [16]. 

The use volumes in the United States by major crops are shown in Figure 1.4 for atrazine and Figure 1.5 for simazine. 

Figure 1.4 Average atrazine use by crop in the United States for 2000-2002 (Doane Marketing Research, Inc.).

The rates used for atrazine in corn for most soil and rainfall conditions were up to 4 kg a.i./ha. This was very similar to the use rates of simazine. After introduction in 1958 in Switzerland and the United States, and by 1960 in several other countries, atrazine became an agricultural chemical of unprecedented dimensions. Atrazine s popularity and demand by growers of corn and sorghum have made it by far the most depended upon triazine ever developed. 

GS-13529, terbuthylazine A chlorotriazine similar to atrazine and simazine, terbuthylazine was first introduced to the scientific community in 1966. Terbuthylazine also provided broad-spectrum weed control in com. Studies comparing efficacy showed that generally atrazine was more effective than terbuthylazine on both broadleaf and grassy weeds. Since terbuthylazine was less efficacious than atrazine in weed control trials conducted in the United States in the late 1960s, it was not commercially developed for com in the United States. However, development for use in corn and vines continued for Europe and other countries where the weed control needs differed and the weed control differences between atrazine and terbuthylazine were not limiting. 

By the end of the 1950s, atrazine was introduced for weed control on railroad tracks and rights-of-way and in com production in Europe. The initial federal approval in the United States occurred in December 1958 when the US Department of Agriculture (USDA) registered Geigy Atrazine 50W for use in com and for nonselective weed control in noncrop areas. In 1959 Atrazine 80 W was registered, which in 1970 was trademarked as AAtrex and quickly became a leading herbicide in the United States. 

Geigy started production of simazine in 1956 in Schweizerhalle, near Basel, Switzerland 2 years later, atrazine also was produced. Use of triazines for weed control to improve crop yields grew quickly, and a production facility was installed at McIntosh, Alabama in 1959. Smaller production units were operated in Mexico, Brazil, and Australia, and important development work by Geigy led to improved production processes. In 1970 a continuous process production unit was built by Geigy Agricultural Chemicals in the United States. 

Commercial production of simazine started in 1956 at the Geigy Schweizerhalle plant near Basel, Switzerland. Two years later, atrazine also was produced. Smaller production units were placed in operation in Mexico, Brazil, and Australia. In the fall of 1960, manufacturing of the triazines was started in the United States in McIntosh, Alabama. Examples of production pathways are included in Figure 3.1. 

Generic producers and a number of companies registered and sold technical atrazine under their own trade names to other formulators. There are more than 140 atrazine products in the United States sold by 41 companies. 

Although simazine was the first triazine to be developed and marketed in corn as well as other crops, the more versatile atrazine quickly became the standard herbicide in corn. Simazine, however, has remained very valuable and is important on forage crops, ornamentals, turf, and several other vegetable, fruit and nut crops, including almond, apple, artichoke, avocado, berries, cherry, citrus, grape, hazelnut, peach, and walnut. There also remains a strong demand for simazine use in corn in some areas based on specific weed pressure. Simazine is manufactured and sold by several companies today in more than 25 countries around the world, with Brazil, the United States, Australia, and Japan ranked as the top four. 

The initial federal approval of an atrazine formulation in the United States occurred December 1, 1958, when the USDA registered Geigy Atrazine 50W for preemergence and postemergence control of several broadleaf weeds on corn and for nonselective weed control in noncrop areas. A wettable powder was the most popular choice for herbicide formulations at that time and could easily be sprayed uniformly across a field. 

On October 21,1959, a more concentrated wettable powder formulation, Atrazine 80 W, was registered and quickly became the leading com herbicide in the United States. Other formulations of atrazine, including various granulars... 

The next major crop use in the United States added to the Atrazine 80W label was weed control in sugarcane, approved by the USDA June 6, 1961. The 80 W formulation soon became the broadleaf weed control product of choice for sugarcane and remained so for many years until improved formulations of atrazine were developed. 

In subsequent years, additional uses were approved in the United States for Atrazine 80W fall application for quackgrass control in com (1961) macadamia nut, chemical fallow following wheat or ecofallow and perennial ryegrass (1962) southern turfgrass species for sod production (1963) pineapple (1964) sorghum and conifer (1965) and rangeland (1975). 

Other formulations were approved in the United States in 1965 for nonselective weed control in noncropland areas. Those formulations, which carried the Atratol brand, included a combination of atrazine, sodium chlorate, and sodium metaborate. This unique combination of ingredients, which became popular with highway departments, utilities, and railroads, provided quick bumdown of weeds and residual weed control. 

Ciba-Geigy also improved atrazine dry formulations, developing a 90% WDG - AAtrex Nine-O - that greatly minimized dust. Approved by the USEPA on December 10, 1975, it was the first WDG formulation sold in the United States. 

In the United States in 2005, approximately 88% of all atrazine was used on com, 8% on sorghum, 2% on sugarcane, and the remainder for minor uses. Atrazine is used by growers in more than 70 countries, with the top five being the United States, Brazil, Argentina, Mexico, and China. 

In US corn field trials, terbuthylazine was less efficacious than atrazine on certain broadleaf and grassy weeds. Therefore, terbuthylazine was not sold in the United States for use on com. Due to terbuthylazine s activity against algae, it was registered in the United States in 1986 for use as an algicide and microbiostat in water coolant systems. 

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