Click on “Download PDF” for the PDF version or on the title for the HTML version.

If you are not an ASABE member or if your employer has not arranged for access to the full-text, Click here for options.

The probability and severity of an adverse event can be analyzed by quantitative exposure assessment (QEA). This methodology was applied to model the human health risks associated with the combustion of specified risk material (SRM) derived meat and bone meal (MBM) in a combustion facility. The identification of MBM and SRM as significant factors in the spread of bovine spongiform encephalopathy (BSE) has resulted in restrictions on their use and movement, and this has led to a requirement for alternative enduses for these products.

A stochastic (Latin Hypercube sampling) simulation model was developed to assess the exposure and hence the risks associated with the use of SRMderived MBM in a combustion facility. The model simulates the potential infectivity pathways that SRMderived MBM follows, including its production from animals potentially infected with subclinical BSE and subsequent processing of the material with segregation and heat treatments. A failure probability was included to take account of suboptimal operating conditions. Two scenarios, reflecting the infectivity risk in different animal tissues as defined by the European Commissions scientific steering committee (SSC), were performed with 100,000 iterations of the model.

Model results showed that the societal exposure to humans resulting from the combustion of SRMderived MBM is extremely small (mean values ranging from 7.57 106 ID50/year to 8.38 105 ID50/year). The resulting societal risks are significantly less than the background societal risk of approximately 2.5 cases of sporadic CJD in Ireland each year. A sensitivity analysis revealed that the species barrier had a large impact on exposure calculations and hence should be the focus of further scientific investigation to reduce our uncertainty about this parameter. The model predicts that material spillage into untreated effluent represents the biggest risk to humans, indicating that efforts for risk mitigation should be focused on reducing the potential for spillage.