Carbaryl, also known as 1-naphthyl methylcarbamate, is an insecticide with the molecular formula C₁₂H₁₁NO₂ and a molecular weight of 201.2 g/mol. It appears as a white crystalline solid that is slightly soluble in water and essentially odourless. Carbaryl was first registered in the U.S. in 1959 and remains widely used, with over 300 EPA-registered products currently on the market. Belonging to the carbamate class of insecticides, it works by interfering with an insect’s nervous system.
What is Carbaryl used for?
Carbaryl is commonly sold under trade names such as Sevin, Adios, Carbamec, Denapon, Hexavin, and Panam. Its primary application is as an insecticide on commercial crops, including corn, soybean, cotton, citrous fruits, pears, and nuts. It is also effective as a molluscicide and acaricide. Additionally, carbaryl is used in veterinary and household settings to treat pests like lice on livestock, poultry, pets, and even humans.
Carbaryl is used in veterinary applications to control parasites like lice on pets.
In the Environment
Soil: Carbaryl has a variable half-life (4–72 days), degrading faster in sandy, aerated, or flooded soils.
Plants: Average half-life is approximately 3.2 days on leaf surfaces.
Water: Though poorly soluble, carbaryl can persist under favorable conditions and is frequently detected in groundwater.
Air: Has a low potential to volatilise from treated surfaces.
Wildlife:
Birds: Practically non-toxic.
Fish: Slightly to highly toxic, depending on species.
Aquatic invertebrates (e.g., shrimp, oysters, tadpoles): Very highly toxic.
Bees: Carbaryl is extremely toxic and poses significant risks to pollinators and beneficial insects.
Sources & Routes of Exposure
Sources of Exposure
Occupational exposure during manufacturing, formulation, or application.
Drift from agricultural spraying into surrounding areas.
Detection at low levels in food and surface water.
Routes of Exposure
Inhalation
Skin absorption
Ingestion
Eye or skin contact
Health Effects
Acute Effects
Inhibits cholinesterase, leading to CNS symptoms: nausea, vomiting, blurred vision, convulsions, coma, and potentially respiratory failure.
May cause skin and eye irritation.
Animal studies indicate moderate to high acute toxicity by ingestion and moderate toxicity via skin.
Chronic Effects
Chronic exposure leads to cholinesterase inhibition, which is reversible.
Symptoms include headaches, memory loss, muscle cramps, and anorexia.
In rats, long-term exposure has caused kidney and liver damage.
EPA Reference Dose (RfD): 0.1 mg/kg/day based on animal studies.
Reproductive/Developmental Effects
No human data available.
In animals:
Dogs showed teratogenic effects, though not used for human risk assessment.
Rats showed reduced fertility, smaller litters, and higher offspring mortality across generations.
Cancer Risk
No evidence of carcinogenicity in humans.
Animal studies found no significant increase in tumour incidence.
EPA has not classified carbaryl for carcinogenic potential.
Safety
First Aid Measures
Swallowed: If poisoning is suspected, contact a doctor or Poisons Information Centre (Ph: 13 11 26).
Eye Contact: Irrigate eyes immediately with plenty of water for at least 15 minutes. Seek medical assistance.
Skin Contact: Remove contaminated clothing. Wash affected skin thoroughly with soap and water. Administer one atropine tablet every 5 minutes until dryness of mouth occurs. Seek urgent medical attention.
Inhalation: Move victim to fresh air. If not breathing, apply resuscitation using an alternative respiratory method (not mouth-to-mouth if poisoning is suspected). Administer oxygen if breathing is difficult. Give one atropine tablet every 5 minutes until dryness of mouth occurs. Seek immediate medical assistance.
First Aid Facilities:
Eyewash station
Safety shower
Standard washroom facilities
Exposure Control & Personal Protection
Engineering Controls
Carbaryl is toxic—even a single significant exposure may be fatal.
Ensure adequate ventilation at all times.
Prevent gas accumulation in confined spaces such as hollows or sumps.
Eliminate ignition sources.
Use the buddy system before entering confined spaces.
Automate atmospheric sampling where possible; direct any leak detection alerts to a command centre for response.
Follow all procedures and use protective equipment as outlined in the MSDS.
Personal Protective Equipment (PPE)
Clothing: Use PVC, nitrile, neoprene, or natural rubber aprons or splash suits as recommended.
Gloves: Use PVC, nitrile, neoprene, or natural rubber gloves.
Eye Protection: Wear chemical goggles or a face shield.
Respiratory Protection:
Avoid inhaling vapours.
Use respirators according to AS/NZS 1715/1716 standards.
When exposure exceeds limits, wear a self-contained breathing apparatus (SCBA) or airline respirator with a positive pressure air supply.
In unknown exposure environments, use SCBA or another device complying with international standards.
Regulation
United States
NIOSH: The National Institute of Occupational Safety & Health has set a Relative Exposure Limit (REL) for carbaryl of TWA 5 mg/m3.
OSHA: The Occupational Safety & Health Administration has set a Permissible Exposure Limit (PEL) for carbaryl of TWA 5 mg/m3.
ACGIH: The American Conference of Governmental Industrial Hygienists has set a Threshold Limit Value (TLV) for carbaryl of TWA 5 mg/m3.
Australia
Safe Work Australia: Safe Work Australia has set a Time Weighted Average (TWA) concentration for an 8-hour workday of 5 mg/m3 for carbaryl.
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