PRINCIPLES OF TOXICOLOGY - Biology East Borneo

362 PROPERTIES AND EFFECTS OF PESTICIDESnoted that certain fumigants have the ability to penetrate rubber and neoprene (often used for personnelprotective equipment).Methyl BromideMethyl bromide (Brom-O-Sol, Terr-O-Gas) has been in use as a fumigant since 1932 and is a colorlessand practically odorless compound (at low levels), with its low warning potential contributing to itstoxicity. At higher concentrations, the odor of methyl bromide is similar to chloroform. Fatalities havebeen reported during application and from early reentry into treated areas. Methyl bromide has beenused to treat dry packaged foods in mills and warehouses as well as used as a soil fumigant to controlnematodes and fungi.Methyl bromide is very irritating to the lower respiratory tract. It is thought that the parentcompound is responsible for the toxicity of the methyl bromide, with the mechanism of toxicitypossibly having to do with its ability to bind with sulfhydryl enzymes. Exposure to high concentrationsof methyl bromide can lead to pulmonary edema or hemorrhage, and those exposed typicallyexperience delayed onset (several hours after exposure). Symptoms of acute intoxication include thoseconsistent with central nervous system depression such as headache, dizziness, nausea, visual disturbances,vomiting, and ataxia. Exposure to very high concentrations can lead to unconsciousness. Incases of exposure to fatal levels of methyl bromide, death typically occurs within 4–6 h to 1–2 dayspostexposure; the cause of death is respiratory or cardiovascular failure resulting from pulmonaryedema. Dermal exposure to liquid methyl bromide can cause skin damage in the form of burning,itching, and blistering. Treatment of methyl bromide poisoning is symptomatic.Ethylene OxideEthylene oxide, also known as epoxyethane (ETO), is a sterilant and fumigant that exists as a colorlessgas and which has a high odor threshold. Ethylene oxide also is a severe mucous membrane and skinirritant. Dermal exposure at sufficient levels can result in edema, burns, blisters, and frostbite. Acuteintoxications can result in CNS depression characterized by headache, nausea, vomiting, drowsiness,weakness, and cough. Exposure to extreme concentrations of ethylene oxide can cause the developmentof pulmonary edema and cardiac arrhythmias.Sulfuryl FluorideSulfuryl fluoride (Vikane) (SO 2F 2), a colorless and odorless gas, is used as a structural fumigation.Fatalities have been reported from individuals entering buildings recently fumigated with sulfurylfluoride before reentry was allowed. The acute toxic effects from sulfuryl poisoning include mucousmembrane irritation, nausea, vomiting, dyspnea, cough, severe weakness, restlessness, and seizures.15.8 SUMMARYThis chapter has discussed the toxicology of some of the most commonly used groups of pesticides:• Organophosphate and carbamate insecticides• Organochlorine insecticides• Insecticides of biological origin• Herbicides• Fungicides• Rodenticides• Fumigants