Abstract:
Malaria is among the top causes of death in low-income countries. Because it is transmitted through a mosquito vector, programs to reduce or control these insects receive much attention. Recently, concerns have increased regarding possible chronic reproductive impairment following exposure to insecticides used in mosquito control. This project examines the human health benefits and potential human health consequences of indoor residual spraying (IRS), an increasingly popular method of insecticide use for malaria control.
Meta-analysis was used to aggregate the results of published trials on efficacy of IRS in reducing malaria prevalence in a region. Statistical analysis incorporating results of all these studies led to general conclusions about the impact of any IRS program, and provided insight as to what variables resulted in greater effects in one community over another—for example, the type of insecticide used, the initial malaria prevalence in the community, and the time frame of the program. Next, the potential chronic human health consequences were assessed through a review of chemical, toxicological and epidemiological studies. Research focused on two chemicals, lambda-cyhalothrin and DDT. Screening of chemical properties and toxicological studies indicate a potential risk for negative human health outcomes from exposure to both chemicals. Identification and critique of several epidemiological studies that link exposure to IRS with negative reproductive health outcomes verify this risk for DDT. Finally, a series of interviews with malaria control experts in Tanzania provided insight on the cumulative perceptions of decision-makers regarding both the benefits and the consequences illustrated in the previous sections, as well as a variety of other facets of malaria prevention.
While this project only presents a small portion of benefits and risks associated with using insecticides for malaria control, it is evident that the current risk assessment-risk management paradigm is not adequate for informing decisions on risk tradeoffs. The benefits and risks need to be considered holistically, not independently, in order to inform quality risk policies. Based on the case study of insecticide use for malaria control, a new framework is suggested in which risk tradeoffs are approached in an interdisciplinary, collaborative manner.
