Pesticide Levels in Breast Milk Have Dropped Significantly, but Health Concerns Remain

Researchers at the University of Western Australia (UWA) and Murdoch University recently released a study whose findings show that levels of pesticides in breast milk have dropped significantly over the past forty years, though some major concerns remain. Published in the international journal Chemosphere, the research shows a 42-fold decrease in levels of pesticides detected in breast milk, and ties the reduction to government efforts to prohibit persistent organic pollutants (POPs) in Australia, which has lead to decreased exposure over time.

Led by UWA’s internationally renowned human lactation researcher Emeritus Professor Peter Hartmann, Dr. Donna Geddes and Murdoch’s Associate Professor Robert Trengove, the study is a testament to the positive impact banning pesticides can have on the health of individuals, especially vulnerable populations like infants, but also shows that there is a long way to go before our bodies are void of any bioaccumulated toxic residues.

Researchers often study breast milk because it can bioconcentrate, or accumulate, persistent organic pollutants (POPs). Multiple studies on breast milk have been performed throughout the years, many of them confirming the fact that common toxic chemicals, such as glyphosate and triclosan, build up in our bodies over time. Most people are unaware that they carry chemical compounds in their bodies, a natural phenomenon dubbed chemical “body burden.”

At any given time, hundreds of chemicals can be found in blood, urine, breast milk and even umbilical cord blood. Many of these chemicals enter our bodies through the foods we eat or drink, products we put on our skin and air we breathe. Before birth, people normally carry a body burden inherited from their mothers. Scientists believe the typical human being hosts close to 500 chemicals in various compartments in the body, mostly in fatty tissue. Many chemicals are broken down in our bodies and their metabolites are eliminated, but others linger in bodies for a lifetime and can increase the risk of certain diseases, such as cancer and Parkinson’s disease.

For this study, researchers recruited 40 breastfeeding mothers and performed mass spectrometry tests to determine the levels at which their human milk (HM) showed the presence of 88 different pesticides. While traditional POPs, such as organochlorines, organophosphates, carbamates and pyrethroids, were not detected in HM, the study revealed that 87.5 percent of mothers tested positive for dichlorodiphenyldichloroethylene (DDE), the toxic chemical dichlorodiphenyltrichloroethane’s (DDT)’s major metabolite.

DDT was banned in the U.S. in 1972, following a massive environmental movement spurred by Rachel Carson’s Silent Spring, which documents the adverse environmental effects resulting from the indiscriminate use of pesticides. Despite the fact that DDT was banned in the U.S. 43 years ago, concentrations of DDE have remained alarmingly high in many ecosystems, a fact supported by the prevalence of DDE in HM reported in this study.

Aside from the presence of DDE, the study does bring with it some positive findings, as researches point out that infants how have a daily intake of POPs 59-times below the amount that is considered safe. “It’s really good news,” said Professor Hartmann, Ph.D., while speaking to the problematic effects that the presence of pesticides can have on the growth and development of babies, “some of these compounds do mimic some of the body’s hormones… so it is a bit of a problem if they are at high levels.”

He also reiterated that his research showed that legislation to ban pesticides in the 1970’s has had positive impacts on health. “The restriction of sale of these pesticides has had an enormous effect in bringing the levels down to very good levels,” he said.

The study specifically looks to the banning of POPs in the 1970’s to explain the reduction in pesticides found in breast milk. Chemicals such as organochlorine pesticides, organophosphate pesticides, pyrethroids and carbamate pesticide were classified as persistent organic pollutants because they remain for long periods of time in the environment, eventually making their way up food chains, accumulating in the fatty tissues and animals and humans. Their legacy of poisoning the environment has been well documented, despite being banned for decades. Recent studies have linked these POPs to hormonal disturbances, abnormal sperm development, cancer, diabetes, obesity and environmental contamination.