Pregnancy and infancy are the periods of greatest vulnerability to the use of household insecticides. This is one of the findings of the first study of its kind to be carried out in Spain, which concludes that more than half of expectant mothers routinely use these chemical compounds.
Spanish researchers have described the use of domestic pesticides during pregnancy and the first year of life in nearly 2,500 women and children in Sabadell, Guipúzcoa and various areas of Asturias and the Valencian Community.
The study, published in Science of the Total Environment, also considers the socio-demographic and lifestyle factors most strongly linked to the use of these pesticides.
In 2003 and 2008, the authors monitored the women who agreed to take part in the project from the beginning of their pregnancy until birth and during their offspring's first few years of life.
"Pesticides are used in domestic environments to control infestations of insects or other living creatures," explains Sabrina Llop from the Higher Public Health Research Centre (CSISP) in Valencia, the leading author of the paper. "Exposure during pregnancy or infancy proves to have a negative impact on foetal growth and neurological effects, as well as increasing the risk of childhood leukaemia," she continues.
The results show that 54% of pregnant women used some kind of insecticide inside the home and 15% made use of a combination of two or three methods.
45% of women used some kind of insecticide in their bedrooms: 5% throughout the whole year, 75% seasonally and 20% on an occasional basis. The most frequently used method in the bedroom was the electric device at 62%.
47% of pregnant women used insecticides in the rest of the house, 7% throughout the whole year, 67% seasonally and 26% occasionally. The most widely used method by women in other areas of the house was insecticide spray at 69%.
2% of women used other kinds of measures to control infestations in their bedrooms and 5% in the rest of the house. These other measures included cockroach traps, powder insecticide and chemical methods such as wave devices. Only 1% of women used insect repellents during pregnancy.
10% of pregnant women used outdoor insecticides, such as in gardens or vegetable plots and yards with plants: 9% every month, 14% every 2-3 months, 20% three times a year and 57% occasionally.
"These results are significant because they enable this information to be used to come up with preventive measures, especially at vulnerable stages of life," Llop affirms.
The less educated, the more pesticides
"Multiparous women, born in Spain, with a lower level of education, who have a garden, whose residence is near crops, and/or from Sabadell or Valencia are the most likely to use household pesticides," Llop asserts.
The use of these pesticides continued during their offspring's first year of life, although 20% of the women stopped using them. Sprays were the method that the participants were most likely to stop using in their bedrooms: 53% during pregnancy and 26% during infancy. In contrast, the use of the electric device remained constant.
The main ways of being exposed to these substances are inhalation, skin contact and unintentional ingestion. In babies and children, ingestion of contaminated dust in the house is the most significant route of exposure to pesticides in the home.
The authors attribute this to babies spending more time at home and in general wearing fewer clothes than adults. In addition, their breathing zones are closer to the ground, where pesticide residue levels can be higher, and they are more likely to have close contact with plants, grass and other surfaces.
"Foetuses and children are especially vulnerable to pesticide exposure because their detoxification mechanisms and immune systems are not fully developed," Llop concludes.
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Llop, S. et al. Prenatal and postnatal residential usage of insecticides in a multicenter birth cohort in Spain, Science of the Total Environment 445-446 (2013) 273-280.