Chemical Fact Sheet

Chemical Abstract Number (CAS #) 21725462
CASRN 21725-46-2
Analytical Method EPA Method 629
Molecular FormulaC9H13ClN6

Link to the National Library of Medicine's Hazardous Substances
Database for more details on this compound.

Use A pre and postemergence herbicide for control of annual grasses and broadleaf weeds. Early preplant, preemergence or postemergence for field corn. Weed control on fallow cropland. Outside US for soybeans, oil seed rape, peas and forestry.
Apparent Color White crystalline solid
Melting Point 166.5 - 167 deg C
Molecular Weight 240.7
Environmental Impact Cyanazine is released directly to the environment through its use and application as an agricultural herbicide. It can undergo surface runoff (via rainfall or irrigation), with subsequent transport to rivers and lakes, after being applied to fields as a herbicide. If released to soil, microbial degradation is reported to be the major environmental degradation process. Cyanazine has moderate mobility in soil; its detection in various ground waters demonstrates that it can leach. The half-life in soil typically ranges from 12 to 25 days; the USDA's lists a soil half-life of 14 days. If released to water, cyanazine may degrade through microbial degradation and catalyzed hydrolysis. Un-catalyzed hydrolysis is slow (200 days or more at 25 deg C and pH 5.5-9); natural water and soil constituents, such as humic and fulvic acid, may catalyze the chemical hydrolysis. Volatilization from water or soils is not expected to be an important fate process. If released to the atmosphere, cyanazine can exist in both the vapor and particulate phases; vapor phase cyanazine degrades readily by reaction with photochemically produced hydroxyl radicals (estimated half-life of 3 hours). Physical removal from the atmosphere occurs through wet and dry deposition. Occupational exposure to cyanazine occurs through dermal contact and inhalation of dust.
Environmental Fate Cyanazine was applied to plots having tile drains. Corn was grown in these plotsand water samples were collected from the tile outlets. Analyses of the water, using GLC and several different detectors and columns, indicated the presence of cyanazine amide in addition to unchanged cyanazine. Some hydroxycyanazine was observed in the soil. Terrestrial fate: Laboratory tests show that the nitrile group is hydrolysed in plants and soil to the corresponding carboxylic acid. The chlorine atom may also be replaced by a hydroxy group, which sometimes forms conjugates. These degradation products have not been detected in crops following field use. TERRESTRIAL FATE: Cyanazine is degraded in soil primarily through microbial activity . Catalyzed aqueous hydrolysis may contribute to its degradation in moist soil ; soil constituents such as humic and fulvic acid are potential catalytic agents . Cyanazine is reversibly adsorbed to soil particles ; the degree of adsorption varies with soil texture, water content, organic matter content and pH . A Koc value of 190 indicates moderate mobility in soil. Detection in various US ground waters demonstrates that leaching is potentially an important transport process. Field loss through rainfall runoff can amount to 0.07-1.0% of field application . Under field conditions, loss through volatilization or photodecomposition is minor . The half-life in soil typically ranges from 12 to 25 days ; the USDA'S Pesticide Properties Database lists a soil half-life of 14 days . TERRESTRIAL FATE: In 1967 to 1970 field trails, the half-life of cyanazine ranged from 1.3 to 5 weeks ; breakdown of cyanazine in soil occurred (at least partially) through hydrolysis of the nitrile group to the amide and then to the acid ; some hydrolysis of the 2-chloro group also occurred ; after 32 days, the major degradation product was the acid, together with small amounts of the hydroxy acid . In another cyanazine metabolite study, cyanazine amide and de-isopropylated atrazine were detected as soil degradation products ; it was proposed that hydrolysis preceded microbial degradation to yield the de-isopropylated atrazine . Persistence studies over a 20-week period at varying temperatures (5, 20, 35 and 50 deg C) found that cyanazine degraded within 10 weeks at 5 deg C and within 5 weeks at the higher temperatures ; the initial observed half-lives at the higher temperatures were 1.5-2.0 weeks ; it has been suggested that degradation of cyanazine at -10 deg C is not very likely . A half-life of 6 days was observed in a cornfield study in Quebec, Canada . AQUATIC FATE: The persistence and fate of cyanazine was studied in a model aquatic ecosystem ; after 35 days, only 18% of the initial cyanazine remained undegraded ; the following metabolites were identified : 60% N-deethylcyanazine, 0.8% cyanazine amide, 0.3% N-deethylcyanazine, 1.2% unknown polar metabolites, and 19% unextractable metabolites ; degradation of the triazine ring to CO2 proceeded slowly ; cyanazine and its metabolites did not bioconcentrate in the food chain . The exact degradation mechanism in water has not been determined with certainty, but may be a combination of microbial degradation and catalyzed hydrolysis. At 25 deg C and pH range 5.5-9, the un-catalyzed aqueous hydrolysis half-life is at least 200 days . Laboratory studies have suggested, however, that natural water constituents, such as humic and fulvic acid, may catalyze the chemical hydrolysis . Volatilization from water is not expected to be an important fate process; volatilization was not an important process in the model ecosystem study . ATMOSPHERIC FATE: Based upon an extrapolated vapor pressure of 1.38X10-7 mm Hg at 25 deg C , cyanazine can exist in both the vapor and particulate phases in the ambient atmosphere(2,SRC). It will degrade rapidly in the vapor phase by reaction with photochemically produced hydroxyl radicals with an estimated half-life of about 3 hr(3,SRC). Physical removal from air by wet deposition (dissolution in clouds, rainfall, etc) and dry deposition (particulate settling, etc) will also occur. Cyanazine has been detected in widespread rainwater monitoring studies ; degradation rates while associated with rainwater and clouds are unknown; these monitoring studies suggest that widespread atmospheric dispersal is possible .
Drinking Water Impact DRINKING WATER: Drinking water samples collected in Dresden, Ontario between 1982 and 1987 contained annual mean cyanazine levels ranging from <0.05 to 4.6 ug/l ; the highest reported level was 10 ug/l . In July 1986, 33 treated public water sources were analyzed for cyanazine following a rainstorm ; cyanazine was detected in 30 of 33 waters at levels of 0.12-20 ug/l . SURFACE WATER: Between 1983 to 1991, the US Geological Survey collected and analyzed more than 4000 water samples collected at 8 monitoring stations located on rivers and tributaries of the Lake Erie basin ; maximum cyanazine concns detected at the stations ranged from 1.36 to 24.77 ug/l ; most samples were below detection limits (0.05 ug/l) ; avg concn of positive detections ranged from 0.05 to 0.40 ug/l ; most detections occurred during agricultural use seasons indicating field runoff . During a Jan 1981 to Dec 1985 water monitoring analysis of the mouths of Grand, Saugeen and Thames Rivers (Ontario, Canada), cyanazine was detected at concns of the 1 ug/l magnitude in 8 of 96 Grand River samples, 5 of 143 Saugeen River samples, and 32 of 222 Thames River samples ; during a Jan 1986 to Dec 1990 water monitoring analysis of the mouths of Grand, Saugeen and Thames Rivers (Ontario, Canada), cyanazine was detected in 2 of 250 Grand River samples, 2 of 154 Saugeen River samples, and 3 of 70 Thames River samples . Water samples collected from the Sydenham River (Dresden, Ontario) between 1982 and 1987 contained annual mean cyanazine levels ranging from 0.5 to 3.6 ug/l ; the highest reported level was 10 ug/l . SURFACE WATER: Monitoring of the Des Moines River (Iowa) and an associated reservoir during Sep 1977 to Nov 1978 found the highest cyanazine concns (71-457 ng/l) during the agriculturally active months of May through Aug ; it was noted that agricultural runoff from the upstream watershed was a major source of river pollution ; levels during Sep to Dec were 2-151 ng/l and below detection limits during Jan to Apr . Cyanazine was positively detected in 15 water samples collected from various Swedish streams during 1985-1987 with max concns of 0.7 ug/l . Cyanazine was detected in 4 of 31 NJ surface water samples at concns of 0.025 to 0.07 ppb (sampling dates and locations not reported) . Monitoring conducted by the US Geological survey at 17 sampling stations on the Mississippi River and its tributaries during May to Jun 1988 detected cyanazine levels ranging from 17 to 647 ng/l . Water samples collected from the Cedar River (IA) from May 1984 through Nov 1985 were found to contain cyanazine at levels below 1 ug/l . GROUNDWATER: In a 1969 to 1978 monitoring analysis of well water from 237 wells from agricultural areas of Ontario, Canada, cyanazine was detected in only two wells at levels of 0.1-10 ug/l . Cyanazine was reportedly found at 1.1 ppb concn in one of 82 wells in a central PA study where the water level was about 75 below land surface ; it was also detected at low levels (0.1-1.0 ppb) in three wells in Iowa during springtime(2-3). According to the USEPA's Groundwater Data Base, cyanazine has been detected in groundwaters from IA, IL, MD, MN, PA and VT and concns ranging from 0.01 to 80 ppb . RAIN/SNOW: Collection of 14 to 24 rainwater samples at each of four US sites (West Lafayette, IN; Tiffin, OH; Parsons, WV; Potsdam, NY) in the spring and summer of 1985 resulted in cyanazine detections ranging from 0.1 (detection limit) to 1.0 ug/l ; cyanazine was found in nearly 35% of all samples collected . EFFL: In a study of two watersheds in GA, seasonal losses of cyanazine via field runoff have been reported to range from 0.07 to 1.0% of total field application .

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