Chemical analysis of materials used in pig housing with respect to the safety of products of animal origin

Bedding, environmental enrichment materials and disinfectant powders in pig farming are meant to ensure a hygienic bedding environment or allow pigs to perform explorative behaviour. To our knowledge, no legal regulation exists, that established maximum contents for undesirable substances, such as toxic metals, dioxins or trace elements in these materials, although oral ingestion could be expected. In the present study, a total of 74 materials (disinfectant powders n = 51], earth/peat n = 12], biochar n = 8], recycled manure solids n = 3]) were analysed for their content of various toxic metals, trace elements, dioxins and polychlorinated biphenyls. The data suggest that, in some samples, trace elements like iron, copper and zinc might have been added intentionally in order to induce physiological effects (iron supply to piglets, copper and zinc as growth promoter in pigs). Moreover, some materials contained high levels of lead, cadmium or arsenic. Consequently, if farm animals repeatedly consume environmental enrichment and bedding materials or disinfectant powders in considerable amounts and these quantities are added to the daily ration, the amount of ingested undesirable substances and trace elements might exceed the maximum levels set for complete feedstuffs, and an elevated transfer into food of animal origin might occur. Future studies are required to address the possible quantitative contribution in the light of feed and food safety. Finally, the excretion of undesirable substances with manure needs to be considered due to their possible accumulation in soils.