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Page 2 of 20 Andjelkovic et al. J Environ Expo Assess 2024;3:23 https://dx.doi.org/10.20517/jeea.2024.22

observed in 2006. The daily dietary intake of POPs via human milk was estimated for nursing infants of 1 month
[intake of 260 mL milk/kg body weight (bw)] and compared with either health-based guidance values (HBGV) or
the reference point (margin of exposure, MOE). The exposure assessment in a worst-case scenario revealed no
concern for most POPs. However, the infants were exposed to levels of 60 pg total WHO2005-TEQ/kg bw/week,
indicating a possible risk during their life. Based on the MOE approach, 95th percentile of concentration can result
in a health concern for congeners BDE-99 and BDE-153.

Keywords: Human milk, WHO monitoring, persistent organic pollutants, brominated flame retardants, exposure
assessment

INTRODUCTION
Human milk is the optimal food for infants, offering practical benefits for mothers as well. Breastfeeding
supports maternal health by reducing the risk of ovarian and breast cancer, while also promoting sensory
and cognitive development in infants. It protects against infectious and chronic diseases, lowers infant
[1]
mortality from illnesses such as diarrhea and pneumonia, and aids in faster recovery during sickness .
While breastfeeding provides significant health benefits, it can also serve as a source of exposure to
environmental contaminants. Among these, polybrominated diphenyl ethers (PBDEs), which share a
structural similarity with polychlorinated biphenyls (PCBs), are notable. PBDEs consist of a diphenyl ether
core with various combinations of bromine atoms, though they are believed to degrade more readily in the
environment compared to PCBs. In fact, PBDE levels in American women’s human milk samples are
reported to be up to 100 times higher than those found in European samples . Similarly, concentrations of
[2]
other contaminants, such as dichloro-diphenyl-trichloroethane (DDT) and its metabolite dichloro-
diphenyl-dichloroethane (DDE), have declined in regions where their use has been banned, particularly in
human milk. However, other organochlorine pesticides (OCPs), which were once widely used as
agricultural and domestic pesticides, remain present in the environment over time. Although their use is
now prohibited in the European Union due to their toxicity and persistence, they are still detected in human
[3]
milk, particularly in countries where their use has not yet been fully phased out .

These contaminants, commonly grouped as persistent organic pollutants (POPs), are now considered
ubiquitous contaminants in human populations worldwide, and recent investigations have revealed
significant variability in POP concentrations in human milk, even within the same individual. Studies have
shown fluctuations in POP levels on a daily and monthly basis . Furthermore, geographic location is a
[4]
major factor influencing the accumulation of POPs. Proximity to agricultural areas, waste incineration sites,
and other pollution sources are key factors influencing an individual’s body burden of these chemicals.
Since humans are at the top of the food chain, POPs gradually build up over time, leading to what is known
as a “lifetime body burden”. These findings highlight the complexity of human exposure to POPs, which,
despite generally being detected at low levels, remains a global concern due to their persistence and
bioaccumulation [2,3,5-11] .

The maternal body burden of POPs depends on several factors, including age, geographical location,
background exposure, and number of pregnancies and lactations, which are among the most important.
Background exposure is commonly the consequence of low-level contamination of food commodities and
water. Among women with typical background exposure levels (i.e., no episodes of acute high exposure),
age and past lactation are key factors. Age serves as a marker of cumulative exposure, while prior lactation is
linked to reduced POP concentrations - particularly for PCBs and DDE - in breast milk .
[12]