Spanish Study Finds Pesticides, PCBs, and Other Pollutants in Breast Milk Samples

A study published in Environment International has measured what is actually in the breast milk of a group of Spanish nursing mothers, and the answer is a long list of environmental pollutants. The researchers tested samples for persistent organic pollutants, pesticides, plasticizer-related chemicals and metals, and found traces of many of them.

The context matters. Breastfeeding is recommended to begin within an hour of birth and continue for at least six months. Breast milk supplies nutrients, immune factors and growth factors, and breastfed children are more likely to be protected against excess weight gain later in life. They also tend to have lower risks of respiratory infection, diarrhea, anemia and hypertension. For mothers, breastfeeding is linked to lower rates of breast, uterine and ovarian cancers, osteoporosis, cardiovascular disease and type 2 diabetes. The concern here is that pollutants accumulated over a woman's lifetime can pass into her milk, including chemicals that disrupt hormones, affect brain development, and alter the infant gut microbiome.

DDT turned up in every sample, at up to about 900 pg/mL of milk, or 2 ng/g of fat, similar to levels reported in other European countries. Its metabolite DDE reached up to 62,000 pg/mL, about 70 ng/g of fat. Hexachlorobenzene appeared at roughly 300 pg/mL and 11 ng/g of fat. Oxy-chlordane was found in about half the samples, up to about 200 pg/mL and 7 ng/g of fat, lower than recent Norwegian and Swedish figures of up to 30 ng/g and lower than a 2002 Spanish study.

Nine of 11 PCB congeners were detected, with PCB-153 highest at about 800 pg/mL. The flame retardant congener BDE-47 appeared in every sample, while BDE-153 was around 10 pg/mL. Earlier studies reported higher PBDE levels, which fits a decline over recent decades. Most PFAS compounds were undetectable, though PFOS showed up in almost 90 percent of samples.

Other findings: chlorpyrifos in up to 40 percent of samples, at up to 150 pg/mL and 11 ng/g of fat, far below levels reported in Iran and India, which exceeded 2,000 pg/mL and about 70 ng/g of fat. BPA was present in about 90 percent of samples at roughly 2 ng/mL, and TBBPA in half, at up to 0.02 ng/mL or 13 ng/g of fat. Mercury appeared in 12 percent of samples, near the detection limit, and methylmercury was never found, whereas up to 60 percent of Italian samples had shown it. Aluminum, arsenic, copper, chromium, manganese and lead were found in all samples, though several are essential elements, and arsenic, chromium and mercury were detectable as toxic elements in up to 15 percent.

The study also looked at who carried more. HCB, PCBs and other persistent pollutants were higher in older mothers, likely reflecting cumulative exposure, while PFOA was found more in younger mothers. DDT and DDE were higher in lower-income mothers. Arsenic, chromium and manganese were higher in passive smokers. Higher body mass index correlated with DDT, DDE and HCB, which accumulate in fat. Spanish-born mothers appeared to have higher PCB levels than mothers of other nationalities. Diet and the use of creams and makeup showed no correlation.

The most concerning result concerns infants. Those younger than one month, those between one and six months, and those older than nine months were estimated to be exposed to BPA, PFASs and PCBs above tolerable daily or weekly intake levels. The authors say it is essential to understand how these chemicals move through an infant's body in order to set proper limits.

They stress that the problem is not unique to breast milk. Infant formula and baby food also contain pollutants, presumably from the manufacturing chain. In their words, biomonitoring and food monitoring are clearly needed, both to control pollutants in children's food and to raise awareness among inspection authorities.