Dioxin and heavy metals сontamination of reindeer offal from Russian Far North regions

Reindeer herding is vitally important agricultural sector in Russian Far North regions. Meat, liver, kidneys and other offal are highly consumed by indigenous people and go for export, therefore problem of reindeer products safety related to chemical contamination is of both scientific and practical interest. Here, we report levels of dioxins, dl-PCBs, cadmium and mercury in reindeer meat, liver and kidneys determined in 704 individual samples of meat, liver and kidneys of reindeers ( Rangifer tarandus tarandus and Rangifer tarandus sibiricus ) from 8 main reindeer-herding regions of Russia within the broad geographical range from western to eastern border of the country, including Kola Peninsula, Nenets Autonomny Orkrug and Yamalo-Nenets Autonomny Orkrugs, Taymir Peninsula, Kamchatka and Chukotka. Stable organic pollutants, including dioxins (polychlorinated dibenzo-para-dioxins and polychlorinated dibenzofurans) and dioxin-like polychlorinated biphenyls, were determined by high-resolution chromatography-mass spectrometry and expressed as WHO toxic equivalents (WHO-TEQ). Toxic elements were determined by mass spectrometry with inductively coupled plasma. Dioxin pollution has shown clear geographical distribution. It reaches the highest level at the Kola Peninsula and decreases to the East. Heavy metal pollution did not show any geographical trends. In particular, dioxins concentration in reindeer liver varied from 42.2±10.6 pg WHO-TEQ/g of fat in Kola Peninsula to 1.2±0.6 WHO-TEQ/g of fat in Chukotka. We have also investigated сadmium and mercury levels in different feed samples (lichen, mushrooms, compound feed and forage grain). Literature analysis showed a significant decrease of dioxin levels in reindeer liver over the last 15 years, while cadmium and mercury content in reindeer liver and kidneys has increased dramatically. Causes of clear geographical distribution of dioxin pollution and significant rise of heavy metal contamination need further research. It was shown that cadmium poses the highest health risk. Consumption of reindeer offal in six out of 8 investigated regions may lead to cadmium intake exceeding the tolerable intake level more than threefold. In the meantime, consumption of reindeer meat poses no health risk related to any of the investigated contaminants. Taking into account growing interest to reindeer liver processing for food production, it is usable to take into account our data on possible risk of longtime consumption of reindeer offal.