Triazine herbicides cyanazine

Depending on the duration of heating yellow-green to dark green chromatogram zones were produced on a weakly colored background. The detection limits of the triazine herbicides cyanazine (h/Jf 25-30), simazine (h/Jf 30-35), atrazine (h/Jf 40-45), terbutylazine (h/Jf 45-50) and anilazine (h/Jf 60-65) were 20 ng substance per chromatogram zone. 

Beynon, K.I., Stoydin, G, and Wright, A.N. A comparison of the breakdown of the triazine herbicides cyanazine, atrazine, and simazine in soil and in maize, Pestic. Biochem. Physiol, 2 153-161,1972. 

Beynon, K.I., G. Stoydin, and A.N. Wright (1972b). The breakdown of the triazine herbicide cyanazine in soils and maize. Pestic. Sci., 3 293-305. 

As shown in Figure 30.6, the triazine herbicides cyanazine and prometryn have been used extensively in the Mississippi River Delta. Approximately 68% of cotton was treated with cyanazine prior to its 2002 phaseout and 40% with prometryn (Coupe et al., 1998). CAM, a major degradation product of cyanazine, occurred with the parent compound at about one-half the concentration of the parent compound, and its concentration increased relative to... 

This example illustrates the difficulty of showing pesticides mutagenic activity. For example, mutagenic activity was clearly expressed not in the sym-triazine herbicides atrazine and cyanazine, but in their transformation products formed in corn husks ... 

The triazine herbicides can be divided into four different structural classes chlorotriazines, methylthiotriazines, methoxytriazines, and atypical or asymmetrical triazines. The chlorotriazine group includes atrazine, simazine, pro-pazine, terbuthylazine, and cyanazine. The methylthiotriazine group includes ametryn, prometryn, and terbutryn. The methoxytriazine group will include prometon and secbumeton. Hexazinone and metribuzin were chosen to represent the atypical triazine group. The plant metabolism of the most researched member of each triazine group will be discussed in detail to cover all major biological and chemical transformations reported in the literature. 

Tierney and Talbert (1995) found that the best treatments for control of both ALS-resistant and susceptible common cocklebur were triazine herbicides (i.e., atrazine, cyanazine, and metribuzin). Tonks and Westra (1997) reported that mixtures including ALS inhibitors gave no better control of ALS-resistant kochia from Colorado and Kansas than the nonsulfonylurea herbicides alone. 

Smith, A.E. and A. Walker (1989). Prediction of the persistence of the triazine herbicides atrazine, cyanazine, and metribuzin in Regina heavy clay. Can. J. Soil Sci., 69 587-595. 

The triazine herbicides, with the exception of cyanazine, did not produce developmental or reproductive effects at maximally tolerated doses. Cyanazine produced developmental effects in rats and rabbits at the highest doses tested. Effects noted at doses that were toxic to the mothers were cyclopia and diaphragmatic hernia in rabbits and an apparent increase in the incidence of skeletal variations (i.e., anomalies) in rats (USEPA, 1994). 

Worldwide there have been a total of 20 commercialized triazine herbicides. Of the 20 triazines, 7 are currently registered for land use within the United States ametryn, atrazine, metribuzin, prometryn, simazine, terbutryn, and prometon. For purposes of this discussion, only dietary estimates for the 5 most widely used domestic triazines are presented since the USEPA revoked cyanazine tolerances in 2004, prometon is not used for food crops and terbutryn has very limited use. Additionally, propazine was used under USEPA Section 18 registrations in the 1990s, and in 2007 was registered for weed control in sorghum (USEPA, 2007). 

An important finding of USGS research was the occurrence of triazine herbicides in surface water. In a study by Thurman et al. (1991, 1994) measurable amounts of atrazine, the most frequently detected herbicide, occurred in 91% of the pre-planting samples, 98% of the post-planting samples, and 76% of the harvest samples. The atrazine degradation product DEA was found in many of the samples that contained atrazine. The frequency of detection or apparent order of stability of the herbicides and their degradation products is as follows atrazine, DEA, DIA, and cyanazine. This stability order is based on results of field-dissipation studies on atrazine and cyanazine (Meyer, 1994 Mills and Thurman, 1994). 

Triazine herbicides are particularly well suited for conservation tillage because they provide foliar and residual control of a broad spectrum of weeds. Atrazine, simazine, and metribuzin are used in com, atrazine and propazine in sorghum, metribuzin in soybean, and simazine reduces tillage required for weed control in many perennial and tree crops. Atrazine is also used extensively in chemical fallow cropping systems in rotations involving corn, sorghum, and wheat. Cyanazine was also used extensively in corn and cotton until 2002. 

Triazine herbicides such as atrazine and cyanazine are not tightly adsorbed to surface crop residue, allowing rainfall to wash intercepted herbicide into the soil. Low vapor pressures also avoid excessive vapor losses of residue-intercepted triazine herbicides. When atrazine was applied to corn-stalk residue, 52% of the herbicide washed off the stalk residue by the first 0.5 cm of simulated rainfall (Martin et al., 1978). After 3.5 cm of rain, 89% of the intercepted atrazine had washed off the residue. Similarly, in another study (Baker and Shiers, 1989), 75% of applied cyanazine washed off com-stalk residue with 0.7 cm of simulated rain, and an additional 11% was recovered from the residue. 

The toxic effects of some pesticide mixtures are additive, particularly when their toxic mechanisms are identical. The additive effects of the organophosphates chlorpyrifos and diazanon were demonstrated in one study. T Another study found the s-triazine herbicides atrazine and cyanazine to show additive toxic effects. Not all mixtures of similar pesticides produce additive effects, however. In one study, mixtures of five organophos-phate pesticides (chlorpyrifos, diazinon, dimethoate, acephate, and malathion) were shown to produce greater than additive effects when administered to laboratory animals. Another article discusses nonsimple additive effects of pyrethroid mixtures. Despite the similarities in their chemical structure, pyrethroids act on multiple sites, and mixtures of these produce different toxic effects. 10 ... 

We tried to obtain a herbicide binder from a tetrapeptide library. The herbicides diuron (DCMU) [3-(3,4-dichlorophenyl)-l, 1-dimethylurea] and atrazine (2-chloro-4-(ethylamino)-6-(isopropylamino)-s-triazine) are widely used for crop protection (Fig. 8.4). However, due to their widespread use, they contribute greatly to water pollution on a worldwide scale.24,25 Many risk characterizations or epidemiological studies on triazine herbicides (i.e., atrazine, simazine, cyanazine) have been reported including the clastogenic potentials of atrazine and simazine to Chinese hamster ovary cells26 or their carcinogenicity.27,28 The standard level of atrazine in... 

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