Malaria Control Insecticide Residues in Breast Milk: The Need to Consider Infant Health Risks
Bouwman, Hindrik, Kylin, Henrik, Environmental Health Perspectives
BACKGROUND: In many parts of the world, deliberate indoor residual spraying (IRS) of dwellings with insecticides to control malaria transmission remains the only viable option, thereby unintentionally but inevitably also causing exposure to inhabitants. Because mothers are exposed to insecticides via various routes, accumulated residues are transferred to infants via breast milk, in some cases exceeding recommended intake levels. Except for dichlorodiphenyltrichioroethane (DDT), safety of residues of other insecticides in breast milk has not been considered during World Health Organization Pesticide Evaluation Scheme (WHOPES) evaluations. However, very little is known of the health risks posed by these chemicals to infants who, in developing countries, breast-feed for up to 2 years.
OBJECTIVE: We evaluated the need for WHOPES to include breast milk as a potentially significant route of exposure and risk to infants when evaluating the risks during evaluation of IRS insecticides.
DISCUSSION: We present evidence showing that neurologic and endocrine effects are associated with pyrethroids and DDT at levels equal or below known levels in breast milk.
CONCLUSIONS: Because millions of people in malaria control areas experience conditions of multiple sources and routes of exposure to any number of insecticides, even though lives are saved through malaria prevention, identification of potential infant health risks associated with insecticide residues in breast milk must be incorporated in WHOPES evaluations and in the development of appropriate risk assessment tools.
KEY WORDS: DDT, IRS, pyrethroid, vector control, WHOPES. Environ Health Perspect 117:1477-1480 (2009). doi:10.1289/ehp.0900605 available via http://dx.doi.org/ [Online 1 May 2009]
The unintentional exposure of people to sometimes unacceptably high levels of chemicals may (regrettably) be the only current and effective option available under certain circumstances. In 2004, an estimated 350-500 million people contracted malaria globally, of whom more than a million died (80-90% in Africa) [World Health Organization (WHO) 2007a; WHO and UNICEF 2005]. It is the cause of 18% of all deaths of children < 5 years of age in Africa and causes many other debilitations such as anemia, increased susceptibility to other diseases, and premature births. The WHO recommends three primary interventions for malaria control: diagnosis and treatment, insecticide-treated nets (ITN) and other materials, and indoor residual spraying (IRS) (WHO 2006b). For the foreseeable future, IRS with insecticides will remain one of the major methods with which to control malaria in many countries of Africa and elsewhere (WHO 2006b). The recommendations of insecticides are based on a process conducted by the World Health Organization Pesticide Evaluation Scheme (WHOPES) (WHO 2008), which includes the evaluation of human and environmental safety of these chemicals for use in malaria control (WHO 2006b). One of the IRS insecticides is dichlorodiphenyltrichloroethane (DDT), but 11 others are also recommended, with permethrin included as a treatment for ITNs (Table 1).
Table 1. Insecticides recommended by WHO, with associated parameters. Insecticide Type Use IRS dosage Maximum (g/[m.sup.2]) applied (g) per average dwelling at 42 [m.sup.2] Alpha-cypermethrin Pyrethroid IRS/ITN 0.02-0.03 1.26 Bendiocarb Carbamate IRS 0.1-0.4 16.8 Bifenthrin Pyrethroid IRS 0.025-0.050 2. …