Polybrominated dibenzo-p-dioxins and dibenzofurans (PBDD/Fs) in e-waste plastic in Nigeria.

Plastics from cathode ray tube (CRT) casings were sampled in Nigeria and analysed for their polybrominated dibenzo-p-dioxin and dibenzofuran (PBDD/F) content. PBDD/Fs, consisting mainly of PBDFs, were detected in BFR containing plastic with a median (mean) concentration of 18,000 ng/g (41,000 ng/g). The PBDD/Fs levels were highest in samples containing PBDEs, but the levels of PBDFs were two orders of magnitude higher than the levels reported in the technical PBDE mixtures and where frequently exceeding 1000 µg/g of PBDE content. These higher levels are likely to arise from additional transformation of PBDEs during production, use, recycling, or storage, but the processes responsible were not identified in this study. PBDD/Fs in CRT casings containing1,2-bistribromophenoxyethane (TBPE) were dominated by tetrabrominated dibenzo-p-dioxin (TBDDs) with concentrations around 10 µg/g of the TBPE content. The PBDD/Fs in CRT casings containing tetrabromobisphenol A (TBBPA) were found at concentrations around 0.1 µg/g of TBBPA levels. Casings treated with TBPE or TBBPA often contained PBDEs (and PBDF) as impurities-probably originating from recycled e-waste plastics. It was estimated that the 237,000 t of CRT casings stockpiled in Nigeria contain between 2 and 8 t of PBDD/Fs. The total PBDD/F contamination in polymers arising from total historic PBDE production/use is estimated in the order of 1000 t. TEQ values of CRT samples frequently exceeded the Basel Convention's provisional low POPs content of 15 ng TEQ/g. Due to the significant risks to health associated with PBDD/Fs, more detailed studies on the exposure routes from PBDD/Fs in stockpiles are needed.

Phthalates and their metabolites in breast milk--results from the Bavarian Monitoring of Breast Milk (BAMBI).

Phthalates have long been used as plasticizers to soften plastic products and, thus, are ubiquitous in modern life. As part of the Bavarian Monitoring of Breast Milk (BAMBI), we aimed to characterize the exposure of infants to phthalates in Germany. Overall, 15 phthalates, including di-2-ethylhexyl phthalate (DEHP), di-n-butyl phthalate (DnBP), di-isobutyl phthalate (DiBP), di-isononyl phthalate (DiNP), three primary metabolites of DEHP [mono-(2-ethylhexyl) phthalate (MEHP), mono-isobutyl phthalate (MiBP), and mono-n-butyl phthalate (MnBP)], and two secondary metabolites of DEHP were analyzed in 78 breast milk samples. We found median concentrations of 3.9 ng/g for DEHP, 0.8 ng/g for DnBP, and 1.2 ng/g for DiBP, while other parent phthalates were found in only some or none of the samples at levels above the limit of quantitation. In infant formula (n=4) we observed mean values of 19.7 ng/g (DEHP), 3.8 ng/g (DnBP), and 3.6 ng/g (DiBP). For MEHP, MiBP, and MnBP, the median values in breast milk were 2.3 µg/l, 11.8 µg/l, and 2.1 µg/l, respectively. The secondary metabolites were not detected in any samples. Using median and 95th percentile values, we estimated an "average" and "high" daily intake for an exclusively breast-fed infant of 0.6 µg/kg body weight (b.w.) and 2.1 µg/kg b.w., respectively, for DEHP, 0.1 µg/kg b.w. and 0.5 µg/kg b.w. for DnBP, and 0.2 µg/kg b.w. and 0.7 µg/kg b.w. for DiBP. For DiNP, intake values were 3.2 µg/kg b.w. and 6.4 µg/kg b.w., respectively, if all values in milk were set half of the detection limit or the detection limit. The above-mentioned "average" and "high" intake values corresponded to only about 2% to 7%, respectively, of the recommended tolerable daily intake. Thus, it is not likely that an infant's exposure to phthalates from breast milk poses any significant health risk. Nevertheless, other sources of phthalates in this vulnerable phase have to be considered. Moreover, it should be noted that for infants nourished with formula, phthalate intake is of the same magnitude or slightly higher (DEHP) than for exclusively breast-fed infants.

Integrated Exposure Assessment Survey (INES) exposure to persistent and bioaccumulative chemicals in Bavaria, Germany.

The Integrated Exposure Assessment Survey (INES) was started in the year 2005. Altogether 50 healthy adults living in Bavaria, Germany, were included into the study. Monitoring was conducted in accordance with relevant routes of human exposure (inhalation, ingestion) and integrated different pathways (indoor air, food, house dust). This approach consisted of a combination of external measurements of contaminants with the determination of these substances or their metabolites in body fluids. The target substances were phthalates, perfluorinated compounds (PFC), polychlorinated biphenyls (PCBs), polychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs), and polybrominated diphenylethers (PBDEs). This paper gives a brief description of the objectives and the concept of INES as well as methods of sampling and analyses of target compounds. Some preliminary results of biomonitoring data for PFC and phthalates as well as of the dietary intake of DEHP will be discussed.

Digestive tract absorption of PCDD/Fs, PCBs, and HCB in humans: mass balances and mechanistic considerations.

Gastrointestinal absorption of polychlorinated dibenzo-p-dioxins (PCDDs), dibenzofurans (PCDFs), biphenyls (PCBs) and hexachlorobenzene (HCB) from food was investigated in seven individuals aged 24 to 81 years with different contaminant body burdens using a mass balance approach. The difference between the ingested and excreted amounts of the chlorinated compounds was defined as net absorption. No analyzed compound was absorbed completely, and some were excreted to a greater extent than ingested, resulting in a net excretion. The absorption behavior was predominantly controlled by blood lipid levels: good correlations were obtained between the net absorption and the lipid-based concentrations in the blood for almost all of the persistent compounds studied. Expressed in international toxicity equivalents (I-TEq), the maximum absorption of PCDD/Fs among the volunteers was 63% and, for the three oldest volunteers, a net excretion of I-TEq was found. The high absorption levels of many compounds could not be explained on the basis of diffusive gradients estimated from the difference between the lipid-based food and blood concentrations; the diffusive gradient was consistently negative. Adding a factor to account for the reduction in the lipid content of the food during passage through the digestive tract did not resolve this problem. To explain this discrepancy, a "fat-flush" theory was postulated, which hypothesizes that the fat compartment of the absorbing tissue expands due to the uptake of dietary fat, resulting in a decrease of this compartment's lipid-based concentrations below the food's, hence facilitating absorption. The fat-flush hypothesis provides a theoretical basis for a two-step model of organic pollutant transfer in the gastrointestinal tract, with absorption and excretion as distinct processes occurring at different locations.