Banned pesticide spikes in breast milk after spraying resumes, study finds.

Manacaa, MN, JO Grimaltb, J Sunyerd, I Mandomandoa, R Gonzaleza, J Sacarlala, C Dobañoa, PL Alonsoa and C Menendez. 2011. Concentration of DDT compounds in breast milk from African women (Manhiça, Mozambique) at the early stages of domestic indoor spraying with this insecticide. Chemosphere http://dx.doi.org/10.1016/j.chemosphere.2011.06.015.

Scientists studying the consequences of resumed use of indoor  spraying of DDT in Mozambique to control malaria report that the pesticide accumulates in breast milk after just one use, according to research published in Chemosphere.

The results are important because they shows how quickly the pesticide can accumulate in breast milk. Medical specialists nonetheless recommend that breast feeding should not be avoided as it provides many immune and nutritional benefits to the infant.

The findings suggest that after resuming DDT's use, monitoring pesticide levels is critical to provide information to the public  – who are exposed to the chemicals – and to policy makers who decide when and where the pesticide should be used.

DDT was historically used to control malaria-transmitting mosquitoes, but concern about its toxicity in wildlife and humans led to its ban in most of the world. Animal and human studies link the pesticide to effects such as hormonal disruption, cognitive deficits, and DNA damage.

Currently, about a dozen countries in sub-Saharan Africa still spray DDT in homes to kill or repel mosquitoes, because it is relatively cheap and effective. Since DDT and its major metabolic product DDE are distributed in fat tissues, they can build up in the food chain and in human tissues.

In this study, Maria Manaca and colleagues compared pesticide levels before and after a spraying ban on DDT. They collected human breast milk samples from women aged 15 to 47 in a rural area of Mozambique, Africa, at two separate times – once in 2002 when spraying was banned and again in 2006 after only one indoor spraying when the ban had been lifted. They statistically compared DDT and DDE levels in 40 pre-spraying samples and 48 after-spraying samples.

Before spraying, all the women but one had low, but detectable levels of DDT. After spraying, the average DDT levels increased three-fold when compared with before-spraying samples. Both p,p’-DDT – the type used in the spraying – and p,p’-DDE – the major kind produced when the body metabolizes DDT – rose.

Levels varied greatly among the women, depending on age and number of children. Breast milk from those with more children – even though they were older – had significantly lower pesticide levels, the researchers report. These results fit with prior studies that suggest the contaminants may pass from the mother to the infant through breast milk and placenta.

Despite the increase of DDT and DDE after spraying, the levels measured were still low compared with other African countries. For example, the p,p’-DDE levels had a median of 190 nanograms per gram of fat (ng/g lipids). This means that half the women had lower and the other half had higher levels. This median is lower than the reported 1,400 ng/g lipid reported in South Africa in 2002, and suggests a lower background level in Mozambique than in South Africa.

As DDT spraying continues in African countries, close follow-up and monitoring of DDT and DDE levels is needed to prevent very high exposure in local populations. Even in this study, one woman had p,p’-DDT levels of 3,300 ng/g lipids, suggesting some women may have extremely high exposure. Identifying those most at risk and avoiding such high exposure will lower the risk of adverse health problems in the women and their families.

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