Enzyme assays and toxicity of pig abattoir waste in Eisenia andrei

Due to high global demand, large amounts of abbattoir waste are generated from pork production. Mismanagement of abattoir waste on agricultural lands can result in soil and water contamination with pathogens and contaminants like metals and nutrients. Therefore, possible effects on soil organisms prior to application should be evaluated. Thus, the aim of this study was to determine the effects of fresh pig abattoir waste (PAWf) and waste after stabilization processes on E. andrei through tests of avoidance behavior, acute toxicity and chronic toxicity. In order to do this, the waste was evaluated fresh (i.e., non-treated), and after aerated composting (PAWa), natural composting (PAWn) and vermicomposting (PAWv). In addition, we used a natural soil with no history of agricultural use as control soil. The evaluation was based on avoidance behavior, mortality, initial and final earthworm weight, and reproduction, in addition to a set of enzyme assays formed by acetylcholinesterase, lipid peroxidation, catalase and glutathione S-transferase measured over time. The ecotoxicological results showed that PAWf and PAWa increased AChE activity at different experimental periods, while PAWn decreased activity at 14 days compared to the control. PAWf and PAWa increased TBARS levels at 7 and 14 days, respectively. CAT activity decreased at 3, 7 and 14 days in PAWv, while GST activity increased at 3 days in PAWa and at 3 and 14 days in PAWf compared to the control. In the acute toxicity test, PAWa and PAWn had a toxic effect on E. andrei, resulting in 100% mortality at 14 days of exposure. Based on our findings, pig abattoir waste should undergo vermicomposting prior to agricultural application to soils.