residence). Even if difficult to measure, the aesthetic benefits of controlling pests in homes, gardens, and lawns, must be sufficient for homeowners to use pesticide products despite reservations about their safety (Potter and Bessin 1998); close to 85% of US households contain at least one pesticide product in storage (Whitmore et al., 1993).
Control of household pests can potentially provide health benefits because insect allergens (including those present in cockroach excrement and body parts) contribute to asthma, particularly in children. The presence of domiciliary cockroaches is strongly associated with sensitization to cockroach allergens, and sensitization has been associated with the incidence of bronchial asthma (Duffy et al., 1998). About 70% of urban residents with asthma are sensitive to cockroach allergens. The high mortality and morbidity of inner-city children due to asthma are linked to exposure to cockroach allergens (Petersen and Shurdut, 1999). That cockroach control could reduce the incidence of asthma is suggested by the positive correlation between the degree of cockroach sensitivity and the number of cockroaches seen in infested dwellings by residents. Helm et al. (1993), for example, established a quantitative relationship between cockroach density and the amount of cockroach aeroallergens. However, particularly in multifamily households, reducing cockroach numbers does not always lower the incidence of asthma (Gergen et al., 1999).
The decision of whether to treat for cockroaches at present is determined not by an economic injury level (EIL), but rather by an aesthetic level. EILs cannot be calculated, because an economic value of human life cannot be easily assessed. No-observed-effect levels (NOEL) based on detectable levels of cholinesterase depression, however, can be established for the organophosphate agents used for cockroach control. Assessments of air and surface residues and biological monitoring have been used to evaluate multiple exposures of residents of homes undergoing crack and crevice treatment with organophosphates (summarized in Peterson and Shurdut, 1999). Maximum daily exposures were calculated at 2.4–8% of the reference dose (RfD) for children and less than 1% of the RfD for adults (RfD is the dose at or below which aggregate exposure every day over the course of a lifetime does not pose a significant risk). Use of chlorpyrifos, the agent of choice for crack and crevice treatment, was thought to result in minimal exposures and did not pose an appreciable risk to residents. Thus, even if aesthetic and health benefits are difficult to quantify, they still are expected to be offset by very low risk factors for chemical agents currently in use. On June 8, 2000, US EPA revised their risk assessment for this compound based on the mandates of the Food Quality Protection Act (FQPA) and eliminated chlorpyrifos for residential use. After December 31, 2001, retailers will not be able to sell any chlorpyrifos for home use except in baits with child-resistant packaging