Octabromodiphenyl ether - porphyrogenicity after repeated administration to rats

Update of the risk assessment of polybrominated diphenyl ethers (PBDEs) in food

The European Commission asked EFSA to update its 2011 risk assessment on polybrominated diphenyl ethers (PBDEs) in food, focusing on 10 congeners: BDE-28, -47, -49, -99, -100, -138, -153, -154, -183 and ‑209. The CONTAM Panel concluded that the neurodevelopmental effects on behaviour and reproductive/developmental effects are the critical effects in rodent studies. For four congeners (BDE-47, -99, -153, -209) the Panel derived Reference Points, i.e. benchmark doses and corresponding lower 95% confidence limits (BMDLs), for endpoint-specific benchmark responses. Since repeated exposure to PBDEs results in accumulation of these chemicals in the body, the Panel estimated the body burden at the BMDL in rodents, and the chronic intake that would lead to the same body burden in humans. For the remaining six congeners no studies were available to identify Reference Points. The Panel concluded that there is scientific basis for inclusion of all 10 congeners in a common assessment group and performed a combined risk assessment. The Panel concluded that the combined margin of exposure (MOET) approach was the most appropriate risk metric and applied a tiered approach to the risk characterisation. Over 84,000 analytical results for the 10 congeners in food were used to estimate the exposure across dietary surveys and age groups of the European population. The most important contributors to the chronic dietary Lower Bound exposure to PBDEs were meat and meat products and fish and seafood. Taking into account the uncertainties affecting the assessment, the Panel concluded that it is likely that current dietary exposure to PBDEs in the European population raises a health concern.

The effects of hexachloronaphthalene on selected parameters of heme biosynthesis and systemic toxicity in female wistar rats after 90-day oral exposure

Hexachloronaphthalenes (HxCNs) are the most toxic congeners of polychlorinated naphthalenes, a group of compounds lately included into the list of persistent organic pollutants (POPs). This study presents the effects of 90-day intragastric administration of HxCN to female Wistar rats at doses of 0.03, 0.1, and 0.3 mg/kg body weight. The study examined selected parameters of the heme synthesis pathway, oxidative stress, hepatic cytochromes level, and basic hematology indicators. A micronucleus test was also performed. The subchronic exposure of rats to HxCN resulted in disruption of heme biosynthesis, hematological disturbances, and hepatotoxicity. The highest dose of HxCN inhibited aminolevulinic acid dehydratase (ALA-D) and uroporphyrinogen decarboxylase (URO-D). Accumulation of higher carboxylated porphyrins in the liver and increased excretion of 5-aminolevulinic acid in the urine was observed after a dose of 0.1 mg/kg body weight. The most sensitive effect of HxCN in rats was very strong induction of hepatic CYP1A1 activity, which was observed after the lowest dose. The highest dose of HxCN induced significant thrombocytopenia, thymic atrophy and hepatotoxicity, expressed as hepatomegaly and hepatic steatosis.

Selected oxidative stress parameters after single and repeated administration of octabromodiphenyl ether to rats

OBJECTIVES

Octabromodiphenyl ether (OctaBDE) was used as a flame retardant applied mostly in the manufacture of plastics utilized in the electrical and electronic industries. Owing to its long half-life and being regarded as an environmental pollutant, OctaBDE, like other polybrominated diphenyl ethers, has been classified as a persistent organic pollutant (POP). This study was carried out to assess the effects of oxidative stress (redox homeostasis) induced in rats by OctaBDE.

MATERIAL AND METHODS

Female Wistar rats exposed intragastrically to OctaBDE at single (25, 200 or 2000 mg/kg b.w.), or repeated (0.4, 2, 8, 40 or 200 mg/kg/day) doses during 7-28 days were used in the experiment. Selected oxidative stress parameters were determined in the liver and blood serum.

RESULTS

Administration (single or repeated) of OctaBDE to rats resulted in the impaired redox homeostasis, as evidenced by the increased levels of reduced (GSH) and oxidized (GSSG) glutathione in the liver, the reduced total antioxidant status (TAS) in serum and the increased concentration of malondialdehyde (MDA) in the liver. After multiple doses of OctaBDE, elevated activity of glutathione transferase (GST) in the liver was also noted.

CONCLUSIONS

After repeated administration of OctaBDE at the lowest dose (0.4 mg/kg/day), changes were observed in the parameters (MDA, TAS, GSSG) indicative of oxidative stress.