Simazine and atrazine

Atrazine and simazine arose principally as a result of their use in amenity situations but, since their ban for non-agriciiltiiral purposes, concentrations are generally declining. Fiowever, atrazine and simazine still have some agricultural uses (atrazine on maize and simazine on a wide range of crops), so the risk of pollution still exists when these pesticides are applied in either groundwater or surface water drinking water supply catchments. 

Until recently, the NRA has not participated during the approval process in assessing the potential environmental impact of pesticides. However, the NRA does supply monitoring data to MAFF and HSE for pesticide reviews. These occur once a pesticide has been approved for use for a certain length of time, or when further information is needed on an approved pesticide. In supplying these data, the NRA comments on any areas of concern. This contributed to the 1993 ban on the use of atrazine and simazine on non-cropped land. In January 1995 the NRA s National Centre for Toxic and Persistent Substances (TAPS) was made advisor to the DoF, on the potential impact on the aquatic environment of... 

Where both atrazine and simazine are released, the figure in aggregate is 350 grams. 

Supercritical fluid extraction (SFE) is generally used for the extraction of selected analytes from solid sample matrices, but applications have been reported for aqueous samples. In one study, recoveries of 87-100% were obtained for simazine, propazine, and trietazine at the 0.05 ug mL concentration level using methanol-modified CO2 (10%, v/v) to extract the analytes, previously preconcentrated on a C-18 Empore extraction disk. The analysis was performed using LC/UV detection. Freeze-dried water samples were subjected to SFE for atrazine and simazine, and the optimum recoveries were obtained using the mildest conditions studied (50 °C, 20 MPa, and 30 mL of CO2). In some cases when using LEE and LC analysis, co-extracted humic substances created interference for the more polar metabolites when compared with SFE for the preparation of the same water sample. ... 

In several AT studies, pesticide levels in the Ebro were found to be high. Hildebrandt et al. [50] found a homogeneous contamination pattern from atrazine (and also from simazine from May 2000) in intensive Rioja cultivation areas throughout the Ebro. Nearer to the delta, Barata et al. [72] found high levels of bentazone, methyl-4-chlorophenoxyacetic acid, propanil, molinate and fenitrothion in water, while Kuster et al. [71] found low concentration levels of atrazine and simazine at the delta, but high levels of other pesticides used in rice cultivation. Importantly, Hildebrandt et al. [50] found that levels of pesticides in groundwater... 

Glenn, S. and J.S. Angle. 1987. Atrazine and simazine in runoff from conventional and no-till com watersheds. Agric. Ecosys. Environ. 18 273-280. 

Kulshrestha, G., N.T. Yaduraju, and V.S. Mani. 1982. The relative toxicity of the s-triazine herbicides atrazine and simazine to crops. Jour. Environ. Sci. Health B17 341-354. 

Major chemical contaminants implicated in food safety include pesticides, herbicides, myeotoxins and antibiotics. These analytes have been targeted by numerous groups developing SPR biosensors. As these analytes are rather small (typical molecular weight < 1,000), inhibition assay has been a preferred detection format. Examples of chemical contaminants detected by SPR biosensors include pesticides atrazine and simazine (detection limits 0.05 ng/ml and 0.1 ng/ml respectively), mycotoxin Fumonisin B1 (detection limit 50 ng/ml ), and antibiotics Sulphamethazine, Sulphadiazine (detection limits 1 ng/ml and 20 ng/ml respectively). 

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. 

Carbon nanotubes could be also used in a format of disc. A comparison smdy showed that the double-disk system (comprising two stacked disks with 60 mg of CNTs) exhibited extraction capabilities that were comparable to those of a commercial Cig disk with 500 mg sorbent for nonpolar or moderately polar compounds. Moreover, the former system was more powerful than the latter for extracting polar analytes. The triple-layered CNTs disk system showed good extraction efficiency when the sample volume was up to 3,000 mL. Katsumata et al. [136] obtained very high enrichment factor for preconcentration of atrazine and simazine (3,900 and 4,000, respectively, for 200 mL of sample solution when only 30 mg of MWCNTs was used in the format of disk. 

The two most important compounds, atrazine and simazine, are used in two ways (B-78MI10700). At high concentrations they act as total herbicides, while at much lower concentrations they are used for selective pre-emergence weed control. The effectiveness of atrazine in maize has led to its being manufactured on the largest scale in the world... 

The first work in this field was probably that of Piletsky et al. [84] that described a competitive FILA for the analysis of triazine using the fluorescent derivative 5-[(4,6-dichlorotriazin-2-yl)amino]fluorescein. The fluorescence of the supernatant after incubation was proportional to the triazine concentration and the assay was selective to triazine over atrazine and simazine. The same fluorescent triazine derivative was applied to competitive assays using atrazine-imprinted films [70]. To this end an oxidative polymerization was performed in the presence of the template, the monomer(s) 3-thiopheneboronic acid (TBA) or mixtures of 3-amino-phenylboronic acid (APBA) and TBA (10 1) in ethanol-water (1 1 v/v) where the template is more soluble. The polymers were grafted onto the surface of polystyrene microplates. The poly-TBA polymers yielded a detection limit of 8 pM atrazine whereas for the poly-TBA-APBA plates it was lowered to 0.7 pM after 5 h of incubation. However, a 10-20% decrease in the polymer affinity was observed after 2 months. 

Hundreds of triazine-containing products continue to be reviewed, registered, and used throughout the world, with regular reregistrations and safety reviews. While several of the triazines have been recently reviewed, the most comprehensive of these reviews in multiple countries involved atrazine and simazine. 

Reviews by the Australian Pesticides and Veterinary Medicines Authority (APVMA) in 1997 and again in 2004 concluded that properly used and applied, atrazine and simazine are safe for humans and the environment [Australian Pesticides and Veterinary Medicines Authority (APVMA), 1997, 2004], The APVMA also reviewed additional data on potential effects of atrazine on amphibians and concluded that taken together, these data indicate that it is unlikely that atrazine is impacting adversely on populations of Australian amphibians at current levels of exposure (APVMA, 2004). 

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. 

The triazine herbicides have revolutionized agricultural production of corn and more than 40 other crops. The yield increases, less labor-intensive production, and use for erosion control in conservation tillage are all benefits of the tri-azines, especially atrazine and simazine. Registered since the late 1950s, atrazine is still a mainstay of corn production and likely the most studied herbicide by regulatory agencies. 

Terbuthylazine is another novel chloro-.v-triazinc that has found very important uses in Europe for control of weeds in corn, as well as vineyards and orchards. It was introduced at lower application rates than the early atrazine rates and was not registered for use in roads, railways, and noncropland. Terbuthylazine is used in combination with other herbicides and has continued to help replace some uses of atrazine and simazine in many countries of Europe. 

The metabolism of s-triazines has been the subject of extensive research since the 1950s to the present time. Much of this research has been the subject of review articles published over the years since s-triazines were introduced. The metabolism of -triazine herbicides in animals and plants and their degradation in soil were the subject of a review by Knuesli et al. (1969), later updated and revised by Esser et al. (1975) as a second edition. The metabolism of. v-triazines in plants was also reviewed by Shimabukuro et al. (1971a). Naylor (1976) published a review of herbicide metabolism in plants that included the. v-triazines. Lamoureux et al. (1998) reported on the identification of several plant metabolites of atrazine and simazine. 

Beynon et al. (1972a) compared the breakdown of cyanazine, atrazine, and simazine in soils and com. Residues of parent compound in leaf and stem tissue of corn plants 70 days after application at a rate of 1.5 kg a.i./ha to a medium loam soil were barely detectable. Cyanazine metabolized to chlorotriazines and hydroxytriazines, including their dealkylated derivatives. Atrazine and simazine metabolized to hydroxytriazines and unidentified polar components. 

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