Methazole

Avoid skin and eye contact. Keep away from food and feedstuffs.

SRP: The scientific literature for the use of contact lenses in industry is conflicting. The benefit or detrimental effects of wearing contact lenses depend not only upon the substance, but also on factors including the form of the substance, characteristics and duration of the exposure, the uses of other eye protection equipment, and the hygiene of the lenses. However, there may be individual substances whose irritating or corrosive properties are such that the wearing of contact lenses would be harmful to the eye. In those specific cases, contact lenses should not be worn. In any event, the usual eye protection equipment should be worn even when contact lenses are in place.

A tolerance is established for combined negligible residues of the herbicide methazole (2-(3,4-dichlorophenyl)-4-methyl-1,2,4- oxadiazolidine-3,5-dione) and its metabolites 1-(3,4-dichlorophenyl)-3- methylurea (DCPMU) and 3,4-dichlorophenylurea (DCPU) in or on cottonseed at 0.1 ppm.

LC50 Anas platyrhynchos (Mallard duck) oral 11500 mg/kg in 8 day diet

LC50 Colinus virginianus (Bobwhite quail) oral 1825 mg/kg in 8 day diet

LC50 Lepomis machrochirus (Bluegill) 4 mg/l/96 hr /Conditions of bioassay not specified/

LC50 Salmo gairdneri (Rainbow trout) 4 mg/l/96 hr /Conditions of bioassay not specified/

TERRESTRIAL FATE: METHAZOLE WAS DEGRADED TO 3-(3,4-DICHLOROPHENYL)-1-METHYLUREA & 3-(3,4-DICHLOROPHENYL) UREA OVER A 6-WK PERIOD FOLLOWING APPLICATION TO ELMWOOD SANDY LOAM SOIL COLUMNS. AFTER APPLICATION TO ELMWOOD SANDY LOAM SOIL COLUMNS, METHAZOLE LEVEL DECR TO 27% OF ORIGINAL AMT, OF TOTAL RADIOACTIVITY REMAINING IN THE SOIL COLUMNS AFTER 44 DAYS, APPROX 80% REMAINED ABOVE 6.35 MM.

TERRESTRIAL FATE: MOVEMENT OF METHAZOLE TAGGED WITH (14)C WAS STUDIED IN LAKELAND SAND, NACOGDOCHES SANDY LOAM, NORWOOD CLAY LOAM, & MILLER CLAY SOILS, VERY LITTLE (14)C WAS DETECTED IN LEACHATE. METHAZOLE WAS READILY CONVERTED TO 1-(3,4-DICHLOROPHENYL)-3-METHYLUREA (DCPMU) & 1-(3,4-DICHLOROPHENYL)UREA (DCPU) IN THE SOILS STUDIED, WITH 1-(3,4-DICHLOROPHENYL)-3-METHYLUREA BEING PRESENT IN LARGEST QUANTITIES.

Terrestrial Fate: Stabilized on attapulgite or montmorillonite clays.

TERRESTRIAL FATE: The results of degradation studies in four different soil types found that 14-C labelled chlormethazole degraded readily to 1-(3,4-dichlorophenyl)-3-methyl urea (DCPMU)(1); the degradation mechanism was not examined, but the degradation product is known to be a major degradation product resulting from aqueous hydrolysis or photodecomposition(2). Soil microorganisms can reportedly degrade chlormethazole to its major metabolites (including DCPMU)(3), but the relative importance of biodegradation in soil is unknown(SRC). The US Dept of Agric's Pesticide Properties Database lists a soil half-life of 14 days for chlormethazole(4). Chlormethazole applied to soil at agricultural rates degrades quickly and generally disappears within 30 to 60 days(3). Soil column leaching tests(1) and a measured Koc value of 2620(5) indicated that chlormethazole will leach very little in most soils(SRC). Chlormethazole will reportedly volatilize from inert surfaces, but much less so from foliar surfaces(3).

For more Environmental Fate (Complete) data for CHLORMETHAZOLE (6 total), please visit the HSDB record page.

The US Dept Agric's Pesticide Properties Database lists a Koc value of 3000 for chlormethazole(1). An experimental Koc value of 2620 has also been reported(2). According to a suggested classification scheme(3), these Koc values suggest that chlormethazole has low to slight mobility in soil(SRC). In soil column leaching tests using sand, sandy loam, clay loam and clay soils, very little chlormethazole leached below a 15 cm depth(4).

Based upon a water solubility of 1.5 mg/L at 25 °C(1), the BCF of chlormethazole can be estimated to be 490 from a regression derived equations(2,SRC). This BCF value suggests that bioconcentration in aquatic organisms may have some importance(SRC); however, it is reported that chlormethazole residues tend to dissipate quickly and do not bioaccumulate(3).

Based upon a vapor pressure of 1X10-6 mm Hg(1) and a water solubility of 1.5 mg/L at 25 °C(1), the Henry's Law constant for chlormethazole can be estimated to be 2.29X10-7 atm-cu m/mole (SRC). This value of Henry's Law constant indicates that chlormethazole is essentially nonvolatile from water(2). Chlormethazole will reportedly volatilize from inert surfaces, but much less so from foliar surfaces(3).

... Mildly irritating to the skin and eyes and chloracne was observed in rabbit-ear studies ... . It does not produce skin sensitization in guinea pigs. ... In 2 yr feeding trials in rats and mice a yellow-brown pigment (of unknown significance) occurred in the spleen or liver at levels >100 mg/kg diet. ... It is not a mutagen and not a teratogen in rabbits less than or equal to 60 mg/kg daily, but foetal toxicity was observed greater than or equal to 30 mg/kg daily. In a 3 generation study in rats NEL was 50 mg/kg diet, cataracts were observed greater than or equal to 100 mg/kg diet but no other ill-effect; in a 1 generation study no effect level for bobwhite quail and mallard duck was 3 mg/kg diet.

Feeding to rats and dogs at 500 mg/kg body wt for 90 days causes no changes in blood and urine status and no histopathological findings. ... Toxic to bees.

Methazole shows minimal toxicity to wildlife and fish.

Purebread albino rats and beagle dogs were fed methazole in the diet at levels up to and including 500 ppm for 90 days. There ws no hematologic, clinical blood chemistry, urinalysis, or histopathologic differences between test and control animals.

The rate constant for the vapor phase reaction of chlormethazole with photochemically produced hydroxyl radicals has been estimated to be 2.47X10-11 cu cm/molecule-sec at 25 °C which corresponds to an atmospheric half-life of about 15.7 hours at an atmospheric concn of 5X10+5 hydroxyl radicals per cu cm(1,SRC). Results of sunlight exposure studies indicate that chlormethazole is susceptible to photodecomposition(2); when thin films of 14-C labelled chlormethazole on glass plates were exposed to sunlight for 8 hr, nearly 60% of initial chlormethazole degraded while virtually no degradation occurred on dark controls(2); the decomposition products included 6,7-dichloro-1-methyl-2-benzimidazolinone, 5,6-dichloro-1-methyl-2-benzimidazolinone, and 1-methyl-3-(3,4-dichlorophenyl)urea(2); when aqueous solutions of 14-C labelled chlormethazole were exposed to sunlight for 7 days, approximately 65% of initial chlormethazole decomposed while only 20% degraded in dark controls(2); the same degradation products were identified(2); the major formation of the urea product in dark controls suggests a possible hydrolysis route of formation(2,SRC).

Chlormethazole's use as a herbicide releases the compound directly to the environment through applications in powders, sprays and other routes of application. If released to the atmosphere, chlormethazole will degrade rapidly in the vapor phase by reaction with photochemically produced hydroxyl radicals (half-life of about 15.6 hr). Particulate phase chlormethazole and aerosols released to air during applications of chlormethazole herbicides will be removed from air physically by dry and wet deposition. If released to soil or water, chlormethazole may degrade through photodecomposition, biodegradation and aqueous hydrolysis. The results of degradation studies in different soil types found that chlormethazole degraded readily to 1-(3,4-dichlorophenyl)-3-methyl urea; the degradation mechanism was not examined, but the degradation product is known to be a major degradation product resulting from aqueous hydrolysis or photodecomposition. Soil microorganisms can reportedly degrade chlormethazole, but the relative importance of biodegradation in soil or water is unknown. The US Dept of Agric's Pesticide Properties Database lists a soil half-life of 14 days for chlormethazole. Chlormethazole does not leach readily. Occupational exposure to chlormethazole occurs through dermal contact and inhalation of sprays, especially to workers applying the compound as a herbicide. (SRC)

1. SKIN CONTAMINATION SHOULD BE REMOVED PROMPTLY BY WASHING WITH SOAP AND WATER. CONTAMINATION OF THE EYES SHOULD BE TREATED IMMEDIATELY BY PROLONGED FLUSHING OF THE EYES WITH COPIOUS AMOUNTS OF CLEAN WATER. IF DERMAL OR OCULAR IRRITATION PERSISTS, MEDICAL ATTENTION SHOULD BE OBTAINED WITHOUT DELAY. /OTHER HERBICIDES/

2. INGESTIONS OF THESE HERBICIDES ARE LIKELY TO BE FOLLOWED BY VOMITING AND DIARRHEA DUE TO THE IRRITANT PROPERTIES OF MOST OF THE TOXICANTS. ... A. IF LARGE AMOUNTS OF HERBICIDE HAVE BEEN INGESTED, AND IF THE PATIENT IS FULLY ALERT INDUCE EMESIS WITH SYRUP OF IPECAC, FOLLOWED BY SEVERAL GLASSES OF WATER. DOSAGE FOR ADULTS AND CHILDREN OVER 12 YEARS: 30 ML; DOSAGE FOR CHILDREN UNDER 12 YEARS 15 ML. WHEN VOMITING HAS STOPPED, GIVE ACTIVATED CHARCOAL. ADD SORBITOL TO THE CHARCOAL SLURRY UNLESS DIARRHEA HAS ALREADY COMMENCED. IF, FOR SOME REASON, THE PATIENT IS NOT FULLY ALERT, PUT IN PLACE A CUFFED ENDOTRACHEAL TUBE TO PROTECT THE AIRWAY, THEN ASPIRATE AND LAVAGE THE STOMACH WITH A SLURRY OF ACTIVATED CHARCOAL. LEAVE A QUANTITY OF CHARCOAL, WITH SORBITOL, IN THE STOMACH BEFORE WITHDRAWING THE STOMACH TUBE. REPEATED ADMINISTRATION OF CHARCOAL AT HALF OR MORE THE INITIAL DOSAGE EVERY 2-4 HOURS MAY BE BENEFICIAL. /OTHER HERBICIDES/

2. B. IF THE AMOUNT OF INGESTED HERBICIDES WAS SMALL, IF EFFECTIVE EMESIS HAS ALREADY OCCURRED, OR IF TREATMENT IS DELAYED, ADMINISTER THE ACTIVATED CHARCOAL AND SORBITOL BY MOUTH. C. IF SERIOUS DEHYDRATION AND ELECTROLYTE DEPLETION HAVE OCCURRED AS A RESULT OF VOMITING AND DIARRHEA, MONITOR BLOOD ELECTROLYTES AND AND FLUID BALANCE AND ADMINISTER INTRAVENOUS INFUSIONS OF GLUCOSE, NORMAL SALINE RINGER'S SOLUTION, OR RINGER'S LACTATE TO RESTORE EXTRACELLULAR FLUID VOLUME AND ELECTROLYTES. FOLLOW THIS WITH ORAL NUTRIENTS AS SOON AS FLUIDS CAN BE RETAINED. FLUIDS SERVE TO SUPPORT EXCRETION OF THE TOXICANTS. D. SUPPORTIVE MEASURES ARE ORDINARILY SUFFICIENT FOR SUCCESSFUL MANAGEMENT OF EXCESSIVE EXPOSURES TO THESE HERBICIDES. /OTHER HERBICIDES/

LD50 RABBIT PERCUTANEOUS GREATER THAN 12500 MG/KG

LD50 Rat inhalation >200 mg/l/4 hr

As the federal pesticide law FIFRA directs, EPA is conducting a comprehensive review of older pesticides to consider their health and environmental effects and make decisions about their future use. Under this pesticide reregistration program, EPA examines health and safety data for pesticide active ingredients initially registered before November 1, 1984, and determines whether they are eligible for reregistration. In addition, all pesticides must meet the new safety standard of the Food Quality Protection Act of 1996. Pesticides for which EPA had not issued Registration Standards prior to the effective date of FIFRA, as amended in 1988, were divided into three lists based upon their potential for human exposure and other factors, with List B containing pesticides of greater concern and List D pesticides of less concern. Methazole is found on List B. Case No: 2400; Pesticide type: Herbicide; Case Status: No products containing the pesticide are actively registered ... The case /is characterized/ as "cancelled." Under FIFRA, pesticide producers may voluntarily cancel their registered products. EPA also may cancel pesticide registrations if registrants fail to pay required fees or make/meet certain reregistration commitments, or if EPA reaches findings of unreasonable adverse effects.; Active ingredient (AI): 2-(3,4-Dichlorophenyl)-4-methyl-1,2,4-oxadiazolidine-3,5-dione; Data Call-in (DCI) Date(s): 05/10/91; AI Status: The active ingredient is no longer contained in any registered pesticide products ... "cancelled."

A tolerance is established for combined negligible residues of the herbicide methazole (2-(3,4-dichlorophenyl)-4-methyl-1,2,4- oxadiazolidine-3,5-dione) and its metabolites 1-(3,4-dichlorophenyl)-3- methylurea (DCPMU) and 3,4-dichlorophenylurea (DCPU) in or on cottonseed.