Biosolids Applied to Land Advancing Standards and Practices (2002) / Chapter Skim
Currently Skimming:
7 Integration of Chemical and Pathogen Risk Assessment
7 Integration of Chemical and Pathogen Risk Assessment
Pages 322-334
The Chapter Skim interface presents what we've algorithmically identified as the most significant single chunk of text within every page in the chapter.
Select key terms on the right to highlight them within pages of the chapter.
From page 322... ...
EPA conducted risk assessments for chemicals to establish concentration limits and loading rates but deemed microbial risk assessment to be too immature for developing risk-based limits for pathogens. Instead, EPA established treatment and site restrictions to reduce the concentrations 322
|
From page 323... ...
For infectious agents, however, acquired immunity can be a major modifier of population risk. An exposed population is likely to be an unknown mixture of those with acquired immunity and those without.
|
From page 324... ...
Whatever the pathway, secondary transmission can expand the population at risk beyond those involved in the original exposure scenario. Hence, the likelihood of secondary transmission is an issue that must be addressed generally in pathogen risk assessments, as contrasted with those for chemical exposures.
|
From page 325... ...
However, the need for data for execution of calculations based on these approaches is also greater than that for static risk assessments. When secondary infection is possible, risk is by definition manifested at a population level and risk calculations are dynamic in nature.
|
From page 326... ...
The importance of secondary transmission depends in part on the level of acquired immunity to the pathogen in the community. In assessing the likelihood of secondary transmission, it is clear that the use of the dynamic modeling approach to fully assess the risks of the pathogen component of biosolids for all pathogens and all exposure scenarios would be a complex undertaking.
|
From page 327... ...
This same challenge exists for mixtures of chemical agents alone, as discussed in EPA's "Supplementary Guidance for Conducting Health Risk Assessment of Chemical Mixtures" (EPA 2000~. This document offers valuable guidance on the assessment of risks arising from the chemical mixtures found in biosolids.
|
From page 328... ...
Introducing risks from pathogens to the process of integrating diverse outcomes in the risk characterization step would seem to present no new challenges beyond the implications of acquired immunity and secondary infection discussed previously. However, despite progress in integrating risks for mixed chemical exposures, the possibility of pathogen-pathogen or chemical-pathogen interactions between the components in either inhibiting or enhancing the adverse effects expected from individual exposures presents an array of unexplored issues in the context of risk assessment.
|
From page 329... ...
Exposed populations can be monitored or studied at particular times and locations to assess the relation between any abnormal health conditions and the biosolids exposure experienced. Any information gained from studying health outcomes is collected and fed back into the risk assessment to support or improve the risk-management process, as indicated by the vertical line on the far right of the figure.
|
From page 330... ...
330 Biosolids~pplied lo La7`d:~4dvanez~g Siarldards arid Practices Environmental Hazard Surveillance Opportunities , Quality Control Compliance Audits Raw Sewage Sludge 'A 1 Packaging and Transport Potential Exposure Class A/B ~ Potential Exposure 1 Compliance Audits ~ Land Application }_ Class A/B ~ Potential L+ Exposure ~ 1 Environmental Transport Off-site contaminants ~ Potential Exposure 1 Human Exposure Study Opportunities J ~ FIGURE 7-1 Processing, transport, and land application of biosolids with options for hazard surveillance and studies of human exposures.
|
From page 331... ...
The committee found that although the chemical-speciSc risk assessments conducted to establish the Part 503 regulations can be improved by using new risk-assessment methodology, the remaining uncertainty for complex mixtures of chemical and biological agents is sufficient to preclude the development of nsk-management procedures that can reliably result in acceptable levels of risk. Some form of treatment-process quality assurance and ongoing surveillance must be done to ensure that effects not anticipated by the agent-specif~c risk assessments do not occur.
|
From page 332... ...
Another development of importance is the recommendation of the Presidential/Congressional Commission on Risk Assessment and Risk Management to diminish reliance on assumption-laden procedures for arriving at agent-by-agent and medium-bymedium mathematical estimates of risk in favor of stronger interaction with stakeholders in achieving and sustaining practical reductions in risk. Recommendation: Is Allied in Chapters 5 and 6, future risk assessments of biosolids compot~erlts should be conducted using the most current methods and data.
|
From page 333... ...
However, He committee believes that the differences in point of view and approach underling its response to the various elements of the charge accurately reflect He countervailing currents in the broader nsk-assessment community and the differences in perspective among those directly involved in the management of biosolids risks. The overall objective of the process, which this report is a part of, is to better assess and manage the risks associated wig He land application of biosolids in the United States.
|
From page 334... ...
1998. Risk of pulmonary tuberculosis relative to silicosis and exposure to silica dust in South African gold miners.
|
Key Terms
This material may be derived from roughly machine-read images, and so is provided only to facilitate research.
More
information on Chapter Skim is available.