The Pesticide Problem and Proposed Solution
Risk Assessment
Oscar Rodríguez Marrero
SCI275
February 27, 2011

The Pesticide Problem and Proposed Solution
The city council of Genericville has been presented with a proposal regarding the use of the pesticide Malathion within the city limits. This pesticide is used to control the mosquito population and is been registered for use in the United States since1956 (EPA). According to the US Environmental Protection Agency, the administration of the Malathion pesticide is not harmful to humans or the environment if applied in accordance to the product safety regulations. It the responsibility of the City Council members of Genericville to make and inform a decision that is in the best interest of the residents of Genericville, the city council members, and their visitors.
Due to an enlarged mosquito breeding area after a season of heavy rainfall, recent studies have been performed in our wetlands. There are projections that there could be 50 cases of WNV in Genericville this year with two fatalities. With a population of 100,000, this would mean that one out of every 2,000 people will likely become infected this year without the use of pesticides. The Malathion pesticide program could reduce the number of cases from 50 to five, with less than a 20% chance of a fatality. These numbers are too significant to ignore.
There is also the concern about the summer tourism and the Generic River, and how they could be affected if the mosquito infestation continues. It is believed by the community that if measures are not taken to control the mosquito population, the Genericville population will suffer economically, as many businesses have come to rely on summer vacationers.
The exposure of Malathion via air, water or food on bystanders is prejudicial only if exposed to exceeded doses of the pesticide. According to studies it will take continuous applications of the pesticide for this to accumulate in the human body (EPA). Studies showed that Malathion degrades very fast in the environment, preventing the pesticide to accumulate in animals or humans. Contact with Malathion can occur if exposed to a treated area shortly after the pesticide application. Common effects on humans after contact with the product are skin irritation and prolonged odor similar to the pesticide odor.
As today, there is no sufficient evidence that Malathion causes cancer in humans.
There also is no evidence that Malathion exposure is responsible for any human birth defects. There is also no evidence showing that this pesticide affects the ability to reproduce. However, Malathion can have potential health hazards if a person is exposed to higher doses. If a person who has been exposed to high amounts of Malathion receives proper treatment in a timely manner, they are likely to have a full recovery. It is my belief that these issues can be avoided by offering the community education programs and taking proper precautions against over-exposure (ATSDR).
In regard to the Generic River that runs through town, the Malathion breaks down quickly by the action of the water and the bacteria in the water. Therefore, it is unlikely that the river will be contaminated with high doses of Malathion that may be harmful to humans or animals. This would also apply to the wetlands along the banks of the river.

The Pesticide Handlers Exposure Database stated that there is a minimum risk of intoxication if proper use of protective gear is use when handling the pesticide. The protective equipment recommends for chemical sprayers are glove and protective clothing, also the use breathing equipment while spraying is required (EPA). Signs can be posted, and the public can be alerted weeks before spraying begins. Spraying can take place late at night, when most people are asleep. This should pose only a slight inconvenience on those who may be affected by the spraying.
After careful consideration and extensive statistical and toxicology research, it is my vote to approve the application program, and begin implementing the use of Malathion in Genericville. My evaluation has been done according to the four steps of risk assessment, and it is my belief that the potential risks to the community are relatively low, and can be avoided by taking the precautions mentioned above; therefore, the benefits of using the pesticide spray outweigh any possible negative effects.

Risk Assessment
Hazard identification
Common early signs or mild symptoms of acute cholinergic poisoning include miosis (pinpoint pupils), headache, nausea/vomiting, dizziness, muscle weakness, drowsiness, lethargy, agitation, and anxiety. Moderate or severe poisoning can result in chest tightness, difficulty breathing, bradycardia, tachycardia, hypertension, pallor, abdominal pain, incontinence, diarrhea, anorexia, tremor/ataxia, fasciculation, lacrimation, heavy salivation, profuse sweating, blurred vision, poor concentration, confusion, and memory loss. Life-threatening or very severe signs and symptoms, such as coma, seizures, respiratory arrest, pulmonary edema, loss of reflexes, and flaccid paralysis, can occur at high doses, such as in the cases of attempted suicide. Malathion also may be slightly irritating to the skin and eyes. In addition to acute poisoning, chronic effects such as peripheral neuropathy, neurobehavioral effects, and the development of allergic sensitivity have been reported, but these effects are not well documented.
Dose-response assessment
A controlled study in which male volunteers were administered daily capsules containing Malathion (purity not reported) in corn oil that provided an approximate dosage of 0.11 mg Malathion/kg/day for 32 days, 0.23 mg Malathion/kg/day for 47 days, or 0.34 mg Malathion/kg/day for 56 days. Plasma and erythrocyte cholinesterase was determined twice weekly before, during, and after administration of Malathion. Administration of 0.11 mg Malathion/kg/day for 32 days or 0.23 mg/kg/day for 47 days did not produce any significant depression of plasma or erythrocyte cholinesterase activity, nor did it induce clinical signs. In phase three, 0.34 mg Malathion/kg/day for 56 days caused a maximum depression of 25% in plasma cholinesterase approximately 3 weeks after cessation of treatment. A similar depression in erythrocyte cholinesterase was observed, but it occurred later. Routine blood counts conducted at the end of each study period did not detect any significant changes. No remarkable alterations in urinalyses were observed. In addition, male volunteers were exposed by inhalation to aerosol bombs that contained 0%, 5%, or 20% of Malathion for 2 hours/day for 42 days. Exposure concentrations were calculated as 0, 5.3, 21, and 85 mg/m3 by adjusting the application rate. These exposures did not result in changes in erythrocyte or plasma cholinesterase activity. The only effects noted were nasal and eye irritation at the highest concentration.
Exposure assessment
The general population is not likely to be exposed to large amounts of Malathion. However, some exposure to residues of Malathion is possible; as many studies show, Malathion has been detected in foods and atmosphere samples. Populations living within or near areas of heavy Malathion use are at increased risk for exposure to relatively larger amounts of Malathion through dermal contact with contaminated plants, by inhalation of the mist formed from the applied insecticide, or by ingestion of water or food borne residues. Dermal contact appears to be the major route of exposure. Ingestion also can be an important route, but inhalation has not been shown to be a significant route of exposure to Malathion.
Risk characterization
Many of the case reports cover people who have ingested Malathion unintentionally or have attempted suicide by ingestion. Other case reports involve private residents who have applied Malathion formulations improperly to their lawns and gardens or were exposed through inadequate packaging or spillage. In many cases, only minor symptoms developed, and were related more to the noxious odor than to the cholinergic effects. Most epidemiologic studies involve workers who were engaged in manufacturing, formulating, or applying Malathion. A few surveys of populations in areas where Malathion has been used to control mosquitoes or fruit flies also are available.

References

Agency for Toxic Substance & Disease Registry. (2005). Malathion. Retrieve from www.atsdr.cdc.gov

Environmental Protection Agency. (2011). Pesticide Handler Exposure Database. Retrieve from www.epa.gov