WHO/UNEP global surveys of PCDDs, PCDFs, PCBs and DDTs in human milk and benefit-risk evaluation of breastfeeding

Abstract

Since 1987, the World Health Organization (WHO) carried out global surveys on polychlorinated dibenzo-p-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs) and polychlorinated biphenyls (PCBs) in human milk. This study presents a review of the three most recent surveys from 2000 to 2010, including DDT. The objective was to identify global quantitative differences and provide baseline information for 52 countries or provide time-trends for countries with previous data. Individual human milk samples were collected following a WHO-designed procedure and combined to form a national pooled sample. Here, we report global levels for PCDDs, PCDFs, PCBs and the sum of o,p'-DDT, p,p'-DDT, o,p'-DDE, p,p'-DDE, o,p'-DDD and p,p'-DDD (ΣDDTs). A concise risk-benefit evaluation related to human milk contamination with these persistent organic pollutants (POPs) was also done. Large global and regional differences were observed. Levels of PCDDs and PCDFs were highest in India and some European and African countries. PCB levels were highest in East and West Europe. The highest levels of ΣDDTs were found in less industrialized countries. A temporal downward trend for PCDDs, PCDFs and PCBs is indicated. A risk-benefit assessment indicates that human milk levels of PCDDs, PCDFs and PCBs are still significantly above those considered toxicologically safe, while ΣDDTs are below or around those considered safe. With respect to potential adverse health effects, a more dominant role of in utero exposure versus lactational exposure is indicated. If potential adverse effects are balanced against positive health aspects for (breastfed) infants, the advantages of breastfeeding far outweigh the possible disadvantages. Our observations provide a strong argument to plea for further global source-directed measures to reduce human exposure further to dioxin-like compounds.

Keywords: Benefit–risk; Breastfeeding; DDT; Dioxins; Human milk; PCBs.

Fig. 1

Participating countries in the WHO/UNEP human milk global surveys and levels of dioxin-like compounds expressed in TEQs (Van den Berg et al. 2006)

Fig. 2

Participating countries in the WHO/UNEP human milk global surveys and levels of ΣDDTs

Fig. 3

Results of the WHO/UNEP surveys for PCDDs and PCDFs in TEQs (pg/g lipid) in pooled human milk samples from different countries. The dotted red line represents the calculated safe level of these compounds for the breastfed infant (color figure online)

Fig. 4

Results of the WHO/UNEP surveys for DL-PCBs in TEQs (pg/g lipid) in pooled human milk samples from different countries. The dotted red line represents the calculated safe level of these compounds for the breastfed infant (color figure online)

Fig. 5

Results of the WHO/UNEP surveys for the sum of the indicator PCBs in ng/g lipid in pooled human milk samples from different countries. The dotted red line represents the calculated safe level of these compounds for the breastfed infant (color figure online)

Fig. 6

Results of the WHO/UNEP surveys for the sum of DDT-like compounds in μg/kg lipid in pooled human milk samples from different countries. The dotted red line represents the calculated safe level of these compounds for the breastfed infant (color figure online)

Fig. 7

Relationships between PCDD, PCDF, PCB and DDT levels in pooled human milk samples from the WHO/UNEP surveys

Fig. 8

Decline rates of PCDD, PCDF and PCB in some selected countries that have been studied during subsequent WHO/UNEP human milk survey periods (2000–2003 and 2005–2010)