Atrazine history

The presence of chemical transformation products has shown rapid degradation of their parent compounds [9,13-16]. Repeated appUcation of some pesticides can also accelerate the degradation of the formed transformation products in the environment [17], and some examples of such transformation products and respective parent compounds are listed in Table 1. Carbendazim, 2-aminobenzimidazole, methyl isothiocyanate, and desmethyldiphenamid were degraded faster after repeated exposure of the respective parent compounds - carbendazim, benomyl, diphenamid, and metham-sodium [18-21]. DBA degradation was enhanced in soils with long-term exposure to atrazine (atrazine-history soil) compared to soils... 

Arthur EL, Anhalt JC, Anderson TA, Coats JR (1997) Enhanced degradation of deethy-latrazine in an atrazine-history soil of Iowa. J Environ Sci Health B 32(5) 599-620... 

This book is about the revolutionary impact of the triazines herbicides, likely the most important class of agricultural chemicals ever developed. For five decades the triazines have provided weed control in more than 50 crops around the world and have helped farmers boost yields and produce enough food to feed a rising global population. The triazine herbicides, and especially atrazine, are the most well-researched herbicides in history, with thousands of scientific studies on their safety to humans and the environment. Data from studies on the triazines have been evaluated extensively by regulatory authorities around the globe to ensure their safe use. 

Application versatility, combined with a high level of crop tolerance, led to atrazine being the most widely used corn herbicide in history. In fact, atrazine led the US com herbicide market within several years of its introduction. Illinois corn farmer surveys show a steady increase in the use of atrazine in corn from its debut in 1960, with 75-85% of com being treated with atrazine since 1975. 

Selective herbicides are relatively recent developments in the 5000-year history of sugarcane production. After 1945, when phenoxy herbicides were first sold, one person using 2,4-D in a backpack sprayer could accomplish the work of 15 others using hoes and with far more lasting results than simply severing weeds with a steel tool at the soil surface. While three herbicide families (triazines, phenoxys, and dinitroanilines) are of major importance in sugarcane production, the triazines, atrazine and ametryn clearly predominate. 

The interactions between y-triazines and microorganisms have been studied over nearly 50 years and new research has led to important discoveries. The isolation of pure cultures that are able to modify or completely mineralize y-triazines has led to the discovery of new genes and enzymes that are involved in the degradation and mineralization of y-triazines by soil bacteria. Studies carried out in soils with a history of repeated y-triazine applications indicate that rapid degradation and mineralization of atrazine developed in various soils (Barriuso and Houot, 1996 Bradley et al, 1997 Pussemier et al, 1997). 

In most column-leaching studies, the bulk of triazines remain near the soil surface. For instance, Kruger et al. (1993) found that in a 60-cm column of Iowa soil taken from a held with no previous pesticide history, approximately 1.2% of the 14C-atrazine was recovered in leachate over a 12-week period. By the end of the experiment, 77% of the 14C applied remained in the upper 10 cm of soil, and bound residue was the primary component. Both atrazine and degradation products (DIA > HA > DEA > DEHA > DIHA) were found in the top 10 cm of surface soil. 

Shaner, D.L. and W. B. Henry (2007). Field history and dissipation of atrazine and metolachlor in Colorado. J. Environ. Qual., 36 128-134. 

The lack of relevance of these data to humans is supported by 50 years of manufacturing and use history for atrazine and other triazine herbicides. To date there is no evidence linking atrazine exposure to any human health effects (Sathiakumar etal, 1992 Loosli, 1995 Neuberger, 1996). 

Guasch H, Sabater S. 1998. Light history influences the sensitivity to atrazine in periphytic algae. J Phycol 34 233-241. 

EPTC was degraded at an intermediate rate in butylate-history or carbofuran (2,3-dihydro-2,2-dimethyl-7 benzofuranyl methylcarbamate)-history soils. Previous carbofuran use did not reduce EPTC performance at Clay Center in 1984 (ljj). Prior soil treatment with atrazine (6-chloro-N-ethyl-N1-(l-methylethyl)-l,3,5-triazine-2,4-diamine), cyanazine (2-[[4-chloro-6-(ethylamino)-l,3,5-triazin-2-yl]] amino]-2-methylpropanenitrile), metolachlor (2-chloro-N-(2-ethyl-6-methylphenyl)-N-(2-methoxy-1-methylethyl)acetamide), alachlor (2-chloro-N-(2,6-diethylphenyl)-N-(methoxymethyl)acetamide) or cycloate (S-ethyl cyclohexylethylcarbamothioate) did not affect EPTC degradation. At Scottsbluff, EPTC degradation was equally enhanced in EPTC-history, vernolate-history, or butylate-history soils, but was not affected by the other pesticides. 

Foxtail spp. Control and Butylate Persistence with Butylate + Atrazine on a Butylate History Silty Clay Loam Soil on a Soil Near Avoca, NE... 

Elimination or Inhibition of Enhanced Biodegradation by Herbicide Tank Mixtures. In one field trial, tank-mixes of atrazine with EPTC significantly increased green and yellow foxtail control at 60 DAT. In the green foxtail field, which had been treated with EPTC for 4 years, the application of EPTC provided little weed control. When EPTC was applied at 4.5 and 6.7 kg ai/ha tank-mixed with atrazine at 1.7 kg ai/ha, green foxtail control increased from 15 to 52% and from 22 to 94%, respectively. EPTC had only been applied once before to the yellow foxtail field. EPTC alone provided 68 to 72% control and tank-mixtures with atrazine provided 83 to 91% control, respectively (Table V). Atrazine tank-mixes appeared to be more beneficial In the field with the longer previous history of EPTC use. 

Weed Control and EPTC Persistence from EPTC + Dietholate + Atrazine in Rotation with Various Herbicides on a Silty Clay Loam Soil, Otoe, NE Field history of EPTC in 1982 and EPTC + dietholate in 1983 EPTC + dietholate broadcast applied at 4.5 kg/ha on 5/8/85... 

Butylate + atrazine + metolachlor tank mixtures increased foxtail control compared to continuous butylate + atrazine use in a field with a 3 year history of butylate use (Table II). 

Atrazine is a selective herbicide. Severe contact dermatitis to atrazine has been reported in a farmer with a history of dermatitis caused by propachlor. This patient had a positive patch-test reaction to 1 1000 dilution of a commercial atrazine formulation [36]. 

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