Toxic chemicals in breast milk have been identified in mothers living near waste incinerators in the UK, a study has found.
The study looked at complex chemicals called polychlorinated biphenyls (PCBs) and dioxins. These are found in the fumes from burning waste and can persist in the environment for a long time. They can also accumulate in the fat in our bodies, with more than 90% coming from food.
Breast milk was donated by 194 first-time mothers living within about 12 miles (20km) of municipal waste incinerators in the UK.
Dr Pippa Douglas, who led the breast milk collections during her time at Imperial College London, said: “We recruited first-time mothers, so when they signed up to the study they were pregnant and likely to have no idea what life with a newborn baby would be like.”
The mothers also answered questions about their age, weight and the types of food that they ate, so these factors could be included in the analysis. The breast milk samples were analysed for dioxins and 150 samples were also analysed for PCBs, making it the largest study of its type in the UK.
Next the scientists compared the chemical analysis with the distance of the mothers’ homes from their nearest incinerators.
Ruthie Parsons, from Imperial College London and one of the authors, said: “When the results first emerged, I was initially surprised that proximity was not associated with the toxicity.”
But emissions from an incinerator chimney are affected by the prevailing winds. The team therefore looked at data on where particle pollution from the incinerator chimney reached the ground.
It was in this part of the analysis that they found an association between the particle pollution from the incinerators and PCBs and dioxins in breast milk, although all of the mothers had PCB and dioxin levels within the range found in other locations throughout Europe.
As these chemicals accumulate in our bodies over time, the scientists did a second statistical analysis looking at the mothers who had lived near the incinerators for more than five years. Again, they found the same association with particle pollution.
Prof Mireille Toledano of Imperial College London, who led the research team, said: “While diet is generally recognised to be the main source of PCBs and dioxins in the human body, our study raises the possibility that municipal waste incinerator emissions do make a small additional contribution to the pollutants in breast milk.”
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Prof Anna Hansell from the University of Leicester, who was also part of the team, said: “To some extent we are reassured that the range of levels in breast milk was not higher than found in the general population of mothers. These compounds can last for years in the environment and in the body and may well come from other sources, so we can’t say for certain using this type of study that the current operation of incinerators is responsible for the small increases we have seen. We need more monitoring of dioxins and PCBs from incinerators, both in the chimneys and the wider environment. Without both, it is not easy to tell whether the incinerators are the source.”
Parsons, who worked with a group of 20 mothers, said: “They spoke a lot about the vulnerability of pregnancy and their responsibility for doing the right thing for their child. The main thing that came across from mums is that knowing more about the chemicals that are in their milk will not stop them from breastfeeding. However, they want to know all of the information.”
Hansell added: “Breast milk remains the best choice for your baby – we know there are a lot of definite benefits to a child’s health. These outweigh the potential, and unclear health risks of contaminants in human milk at the levels that we detected. In our previous work we looked at the health of babies around 22 UK incinerators – the rationale being that babies in development and first year of life would be the most vulnerable. We did not find any strong evidence for adverse effects.”