EFSA study: Bioaccumulation and toxicity of mineral oils

On February 23, 2017 the European Food Safety Authority (EFSA) published a new study on “Bioaccumulation and toxicity of mineral oil hydrocarbons in rats – Specificity of different subclasses of a broad mixture relevant for human dietary exposures” in the journal EFSA Supporting Publications. The study is authored by scientists from the French National Institute for Agricultural Research (INRA), the Official Food Control Authority of the Canton of Zurich, Switzerland, and the Norwegian Institute of Public Health (NIPH). The study investigated the accumulation and toxicity of mineral oil saturated hydrocarbons (MOSH) in animals (female Fischer 344 rats) in two series of experiments. MOSH are commonly found in food, with recycled paperboard food packaging being an important source.

The first series of experiments involved a broad MOSH mixture representative of the entire range of MOSH (about C₁₄ to C₅₀) to which humans are exposed via the diet. Rats were fed the MOSH mixture at 40, 400, and 4000 mg/kg feed. MOSH were analyzed in the animals’ liver, spleen, adipose tissue, and the carcass after 30, 60, 90, and 120 days of exposure, as well as after 90 days exposure followed by 30 days depuration. In the second series of experiments, three MOSH mixtures were tested: 1) Mainly branched and cyclic MOSH, ~27% of hydrocarbons exceeded n-C₂₅ (short S-C25); 2) exclusively branched and cyclic MOSH ranging from n-C₂₅ to n-C₄₅ (short L-C25); and 3) L-C25 mixed 1:1 with a wax of similar mass range (n-alkanes from C₂₃ to C₄₅; short L-C25W). Rats were fed the MOSH mixtures at 400, 1000, and 4000 mg/kg feed for 120 days.

The scientists found that accumulation of MOSH always occurred mainly in the liver and to a lesser extent in adipose tissue and spleen. Concentrations in the tissues appeared to increase far less than proportionally with the dose. The authors thus deem linear extrapolation from high to low doses questionable, because low dose tissue concentrations would consequently be underestimated. In adipose tissue, the accumulated MOSH corresponded to the most volatile part of the administered mixture, whereas in the liver, the most volatile and the highest boiling part of the mixture were nearly absent. After exposure was stopped, MOSH concentrations decreased significantly in the liver, but not in adipose tissue. Further, MOSH exposure resulted in a significant increase in absolute and relative liver and spleen weights. This effect was dose-related and also dependent on the mixture tested: Increase of liver weights for the broad MOSH mixture at the highest dose; increase of both liver and spleen weights for L-C25 and L-C25W, but not for S-C25.

The German TV station ARD reported on EFSA’s new mineral oils study ahead of its publication in August 2016 (FPF reported). The EFSA study’s authors together with other colleagues from the mentioned institutions published two peer-reviewed studies describing their experiments in further detail: In October 2016 on comparing accumulation of MOSH in rats to humans (FPF reported) and in January 2017 on accumulation of wax components in rat liver.

References

Cravedi, J.P., et al (2017). “Bioaccumulation and toxicity of mineral oil hydrocarbons in rats – specificity of different subclasses of a broad mixture relevant for human dietary exposures.” EFSA Supporting Publications 14(2):EN-1090 (published online February 22, 2017).