Exposure to the pesticide DDT may be linked to an increased risk of obesity, diabetes, high cholesterol and related conditions, according to new research in mice.
The mouse study, published in PLOS ONE, is the first to show that developmental exposure to DDT increases the risk of females later developing metabolic syndrome - a cluster of conditions that include increased body fat, blood glucose, and cholesterol.
While the pesticide has been banned in many regions, however worries over historical exposures and the fact that some countries still use the pesticide mean that research in to possible links between exposure to DDT and damage to human health and the environment continue.
Indeed, a recent study published in JAMA Neurology suggested historical exposures to DDT, and the persistence of the DDT metabolite DDE in the bloodstream of humans may be linked to the risk of developing Alzheimer’s disease .
Commenting on the current research that suggests DDT exposure may also be linked to metabolic syndrome and obesity, lead author Michele La Merrill of UC Davis said: "As mammals, we have to regulate our body temperature in order to live. We found that DDT reduced female mice's ability to generate heat. If you're not generating as much heat as the next guy, instead of burning calories, you're storing them."
"The women and men this study is most applicable to ... are currently at the age when they're more likely to develop metabolic syndrome, because these are diseases of middle- to late adulthood.”
La Merrill and her colleagues gave mice doses of DDT comparable to exposures of people living in malaria-infested regions where it is regularly sprayed. Such doses are similar to historical exposures of women and pregnant mothers around the world before the ban on DDT was put in place.
The team reported that exposure to DDT before birth slowed the metabolism of female mice and lowered their tolerance of cold temperature. This increased their likelihood of developing metabolic syndrome and its host of related conditions, they said.
However, the study found stark gender differences in the mice's response to DDT. Females were at higher risk of obesity, type 2 diabetes, and cholesterol, while in males, exposure did not affect obesity or cholesterol levels and caused only a minor increase in glucose levels.
“Our results suggest that perinatal DDT exposure decreases energy expenditure, and impairs the regulation of thermogenesis, glucose-, and lipid- homeostasis, which contribute to the development of insulin resistance and the metabolic syndrome in adult female mice,” the team concluding – noting that the differences in effect between sexes requires further research.
“Given that circulating DDT and DDE levels in our mice fell within the range of DDT and DDE found in serum of contemporary people living in northern Europe and in malaria-infested regions, and of the pregnant mothers of US adults who are currently in their mid-fifties this is an important observation.”
Source: PLoS One
Published online, open access, doi: 10.1371/journal.pone.0103337
“Perinatal Exposure of Mice to the Pesticide DDT Impairs Energy Expenditure and Metabolism in Adult Female Offspring”
Authors: Michele La Merrill, Emma Karey, et al