Per Ola Darnerud

The food additive nitrite (E249, E250) is commonly used in meat curing as a food preservation method. Because of potential negative health effects of nitrite, its use is strictly regulated. In an earlier study we have shown that the calculated intake of nitrite in children can exceed the acceptable daily intake (ADI) when conversion from dietary nitrate to nitrite is included. This study examined time-dependent changes in nitrite levels in four Swedish meat products frequently eaten by children: pork/beef sausage, liver paté and two types of chicken sausage, and how the production process, storage and also boiling (e.g., simmering in salted water) and frying affect the initial added nitrite level. The results showed a steep decrease in nitrite level between the point of addition to the product and the first sampling of the product 24 h later. After this time, residual nitrite levels continued to decrease, but much more slowly, until the recommended use-by date. Interestingly, this continuing decrease in nitrite was much smaller in the chicken products than in the pork/beef products. In a pilot study on pork/beef sausage, we found no effects of boiling on residual nitrite levels, but frying decreased nitrite levels by 50%. In scenarios of time-dependent depletion of nitrite using the data obtained for sausages to represent all cured meat products and including conversion from dietary nitrate, calculated nitrite intake in 4-year-old children generally exceeded the ADI. Moreover, the actual intake of nitrite from cured meat is dependent on the type of meat source, with a higher residual nitrite levels in chicken products compared with pork/beef products. This may result in increased nitrite exposure among consumers shifting their consumption pattern of processed meats from red to white meat products.

We identified factors that are important determinants of body burdens (breast milk levels) of polychlorinated biphenyls (PCBs), dioxins (polychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs)) and polybrominated diphenyl ethers (PBDEs). PCBs, PCDD/Fs and PBDEs were analysed in breast milk from up to 325 first-time mothers in Uppsala, Sweden, who delivered between 1996 and 2006. Hierarchical clustering was used as a method for identification of groups of compounds with common sources of exposure and similar toxicokinetics. Based on correlations between levels of single compounds/congeners in breast milk, distinctly separated clusters were formed, strongly dependent on structural similarities of the organohalogen molecules. In a multiple regression model, levels of PCBs (except PCB 28), PCDD/Fs and BDE-153 were positively associated with age of the mother and weight loss after delivery and inversely associated with pre-pregnancy BMI (body mass index) and weight gain during pregnancy. Higher levels of mono-ortho PCB TEQ, non-ortho PCB TEQ and BDE-153 in milk were found among women with high physical activity. Women who were breastfed during infancy and grew up on the Baltic coast of Sweden, with high availability of contaminated fish from the Baltic sea, had higher levels of PCBs and PCDD/Fs in breast milk indicating that exposure early in life from breast milk and contaminated fish may still affect body burdens at the time of pregnancy. The importance of current consumption of fatty Baltic fish as a source of exposure was supported by the positive association with breast milk levels of mono-ortho PCB TEQ, PCDF TEQ and BDE-153. The results show that, in contrast to the lower brominated PBDE congeners, the hexa-brominated BDE-153 resembles the chlorinated compounds with regards to determinants in breast milk. This suggests that some of the PBDEs may have toxicokinetic properties and that are similar to the PCBs and PCDD/Fs. Our results show that a few simple advices to women regarding weight changes in connection with pregnancy and consumption of contaminated fatty fish during the whole lifetime may lower the levels of dioxins in breast milk by up to 60%.

Summary: Brominated flame retardants (BFR) are endocrine disrupters in experimental systems, both in vitro and in vivo. Although BFR effects on thyroid hormones are well confirmed, studies of effects on oestrogen/androgen systems are fewer but today growing in numbers. The effects of BFR on other hormone systems are still unknown. Hormonal effect levels in animals start from ca 1 mg/kg b.w., but there are exceptions: effects on spermatogenesis, suggesting hormonal causes, have been observed at a low dose (60 μg/kg b.w.) of a polybrominated diphenyl ether (PBDE) congener, BDE‐99. It could be concluded that hormonal effects are of importance in risk assessment, and in some cases where effects are seen at low levels safety margins may be insufficient. One additional uncertainty is the lack of reliable human data that could be used to support animal BFR observations. In spite of the recent regulation of PBDE production, levels of both PBDE and of other BFR groups are still present in environmental samples. Thus, we have to deal with the possible effects of human BFR exposure for times to come. In order to reduce BFR exposure, the routes of exposure should be carefully examined and ways to reduce levels in major exposure routes considered.