Disulfoton

2021-11-12

Disulfoton is a manufactured substance used as a pesticide to control a variety of harmful pests that attack many field and vegetable crops. Disulfoton does not occur naturally. Pure disulfoton is a colourless oil with no identifiable odour and taste. The technical product is dark yellowish, and has an aromatic odour. It does not easily dissolve in water or evaporate to air. It is most likely to be present in hazardous waste sites with other wastes, either in drums or mixed with soil. [1] The molecular formula for disulfoton is C8H19O2PS3. [2]

Uses [1]

Disulfoton is used to protect small grains, sorghum, corn, and other field crops; some vegetables, fruit, and nut crops; and ornamental and potted plants against certain insects. Although it is used primarily in agriculture, small quantities are used on home and garden plants. Small quantities also are used for other purposes, such as mosquito control in swamps. The use of disulfoton has decreased in recent years.

In the Environment [1]

Disulfoton enters the environment principally when it is applied as a spray or as granules on field crops, vegetables, potted plants, and home gardens. Disulfoton also can enter the environment when it accidentally spills or leaks during storage and transport. Disulfoton may also enter the environment from hazardous waste sites. Environmental contamination by disulfoton mainly affects soil and water. Natural chemical reactions and bacterial attack remove disulfoton from soil and water. Such reactions form some by-products that are more toxic than disulfoton. Fish accumulate disulfoton in their bodies. The levels of disulfoton in fish can be hundreds of times higher than the level in water. Disulfoton binds moderately well to soil and typically does not travel deep into soil with rainwater.

Sources & Routes of Exposure [1]

Sources of Exposure

  • Breathing contaminated air;
  • drinking contaminated water; and
  • eating contaminated food.
  • Disulfoton is rarely detected in air.
  • Workers in industries that manufacture and formulate disulfoton are at a higher risk of exposure.
  • Workers who spray the pesticide in fields and some farm workers who enter the fields following spraying also are at a higher risk of exposure than the general population.
  • Among the general population, people who frequently use the pesticide in their homes and gardens are potentially at higher risk.
  • People who live near hazardous waste sites that contain disulfoton also are potentially at a higher risk of exposure.
  • Children playing at or near these hazardous waste sites may be exposed by touching and eating soil that contains disulfoton.

Routes of Exposure

The major routes of exposure to disulfoton are:

  • inhalation;
  • ingestion;
  • contact with skin/eyes

Health Effects [3]

Acute Toxicity

Disulfoton is very highly toxic to all mammals by all routes of exposure. It is labelled with a DANGER signal word. Whether absorbed through the skin, ingested, or inhaled, early symptoms in humans may include blurred vision, fatigue, headache, dizziness, sweating, tearing, and salivation. Symptoms occurring at high doses include defecation, urination, fluid accumulation in the lungs, convulsions, or coma. Death can occur if high enough doses lead to stoppage of respiratory muscles and/or constriction of the windpipes. Ingestion of high doses can lead to rapid onset of effects on the stomach while symptoms resulting from skin exposure may be delayed for up to 12 hours. Complete recovery from acute poisoning takes at least one week, but complete restoration of the blood to normal enzyme (cholinestrase) levels may take up to three months.

Chronic Toxicity

Disulfoton is rapidly absorbed through the skin. This chemical inhibits cholinesterase, and, as a result, may affect the eyes, respiratory system, and central nervous system. Continual daily absorption may cause flu-like symptoms, loss of appetite, weakness, and uneasiness. While repeated exposure to disulfoton may inhibit the cholinesterase enzyme and thus interfere with the nervous system, 30-day human exposures have not resulted in significant enzyme inhibition. Workers chronically exposed to organophosphates, of which disulfoton is a member, have developed irritability, delayed reaction times, anxiety, slowness of thinking, and memory defects. Chronic exposure of workers may also lead to cataracts.

Reproductive Effects

In a long-term reproduction study, 98.5% pure disulfoton was fed at doses ranging from 0.05 to 0.5 mg/kg/day to both male and female albino rats. At the high dose, the number of animals per litter was reduced by 21% in the first and third generations and a 10 to 25% lower pregnancy rate was noted. Some third-generation litters whose parents were exposed to this dose, developed fatty deposits and swelling in their livers. Exposed adults and litters had a 60% to 70% inhibition of red blood cell cholinesterase. This suggests that long-term exposures to high doses of disulfoton may cause reproductive effects in humans.

Teratogenic Effects

In one study, pregnant rats were given disulfoton (98.2% pure) at doses ranging from 0.1 to 1.0 mg/kg/day through a stomach tube during the sensitive period of gestation. Cholinesterase activity was decreased. In the foetuses, no developmental defects were seen except at high doses, where incomplete bone development was noted (4, 10). In another study, rabbits were given disulfoton (97.3% pure) during the sensitive period. At the higher doses (1.5 and 2.0 mg/kg/day), the mothers experienced tremors, incoordination, and death, while foetal growth was not affected. These studies indicate that disulfoton is very unlikely to cause birth defects in humans.

Mutagenic Effects

Studies have demonstrated that disulfoton is mutagenic to bacteria.

Carcinogenic Effects

Studies of rats and mice fed high doses for two years did not show significant tumour growth. The EPA has determined that there is no evidence that disulfoton is carcinogenic.

Safety [4]

First Aid Measures

  • General advice: Consult a physician. Show this safety data sheet to the doctor in attendance.
  • If inhaled: If breathed in, move person into fresh air. If not breathing, give artificial respiration. Consult a physician.
  • In case of skin contact: Wash off with soap and plenty of water. Take victim immediately to hospital. Consult a physician.
  • In case of eye contact: Flush eyes with water as a precaution.
  • If swallowed: Never give anything by mouth to an unconscious person. Rinse mouth with water. Consult a physician.

Exposure Controls & Personal Protection

Exposure Controls

  • Appropriate engineering controls should be used when handling disulfoton.
  • Avoid contact with skin, eyes and clothing.
  • Wash hands before breaks and immediately after handling the product.

Personal Protective Equipment

The following personal protective equipment is recommended when handling disulfoton:

  • Eye/face protection: Face shield and safety glasses Use equipment for eye protection tested and approved under appropriate government standards such as NIOSH (US) or EN 166(EU).
  • Skin protection: Handle with gloves. Gloves must be inspected prior to use. Use proper glove removal technique (without touching glove’s outer surface) to avoid skin contact with this product. Dispose of contaminated gloves after use in accordance with applicable laws and good laboratory practices. Wash and dry hands. The selected protective gloves have to satisfy the specifications of EU Directive 89/686/EEC and the standard EN 374 derived from it.
  • Body Protection: Complete suit protecting against chemicals, the type of protective equipment must be selected according to the concentration and amount of the dangerous substance at the specific workplace.
  • Respiratory protection: Where risk assessment shows air-purifying respirators are appropriate use a full-face respirator with multi-purpose combination (US) or type ABEK (EN 14387) respirator cartridges as a backup to engineering controls. If the respirator is the sole means of protection, use a full-face supplied air respirator. Use respirators and components tested and approved under appropriate government standards such as NIOSH (US) or CEN (EU).

Regulation [1,5,6]

United States

NIOSH: The National Institute for Occupational Safety and Health (NIOSH) recommends an exposure limit of 0.1 mg disulfoton/m³ of air for a 10-hour workday within a 40-hour workweek.

EPA: The Environmental Protection Agency recommends that no more than 10 parts of disulfoton per billion parts (ppb) of water be present in drinking water that children drink for periods of up to 10 days. Disulfoton in drinking water should not exceed 3 ppb for children or 9 ppb for adults if they drink the water for longer periods, and should not exceed 0.3 ppb for adults who will drink the water during an average lifetime. EPA has designated disulfoton as a hazardous substance, but it does not intend to cancel or restrict registration of pesticide products containing disulfoton. Federal regulations limit the amount of disulfoton that factories can release into wastewater. EPA requires industries to report releases or spills of 1 pound or more.

OSHA: The Occupational Safety & Health Administration has not established any regulation.

Australia

Safe Work Australia: Safe Work Australia has established a Time Weighted Average (TWA) concentration of 0.1mg/m³ for disulfoton over a 40-hour workweek.

References

http://www.atsdr.cdc.gov/phs/phs.asp?id=976&tid=205

http://en.wikipedia.org/wiki/Disulfoton

http://pmep.cce.cornell.edu/profiles/extoxnet/dienochlor-glyphosate/disulfoton-ext.html

http://www.sigmaaldrich.com/MSDS/MSDS/DisplayMSDSPage.do?country=AU&language=en&productNumber=45460&brand=FLUKA&PageToGoToURL=http%3A%2F%2Fwww.sigmaaldrich.com%2Fcatalog%2Fproduct%2Ffluka%2F45460%3Flang%3Den

http://www.cdc.gov/niosh/npg/npgd0245.html

http://www.safeworkaustralia.gov.au/sites/SWA/about/Publications/Documents/639/Workplace_Exposure_Standards_for_Airborne_Contaminants.pdf