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DEVELOPMENT AND REVIEW OF MONITORING METHODS AND RISK ASSESSMENT MODELS USED TO DETERMINE THE EFFECTS OF BIOSOLIDS LAND APPLICATION ON HUMAN HEALTH AND THE ENVIRONMENT
Citation:
HERRMANN, R. F., M. W. BRODER, AND M. W. WARE. DEVELOPMENT AND REVIEW OF MONITORING METHODS AND RISK ASSESSMENT MODELS USED TO DETERMINE THE EFFECTS OF BIOSOLIDS LAND APPLICATION ON HUMAN HEALTH AND THE ENVIRONMENT. Presented at BOSC Review, Cincinnati, OH, January 23 - 25, 2006.
Description:
Development and Review of monitoring methods and risk assessment models for biosolids land application impacts on air and land
Ronald F Herrmann (NRMRL), Mike Broder (NCEA), and Mike Ware (NERL)
Science Questions .
MYP Science Question: What additional models, tools and methods are needed to identify, measure and assess aggregate exposure pathways and risks?
Research Questions: What approaches should be used in order to characterize releases to the air and soil during land application of class B biosolids? How should human exposure measurements be conducted to determine contaminant transport during land application? Can models be developed to address pathogen risk from land application so that risk assessment can move away from process dependant technologies?
The Research
Each year municipal wastewater treatment plants in the United States produce about 11 million dry tons of processed sludge. With landfill capacity decreasing and incineration unpopular, beneficial reuse by land application has increased to account for about 60 percent of biosolids produced yearly. The number of health related complaints from residents living near biosolids land application sites has continued to increase. Many of these complaints occur during or just after application. USEPA asked the National Research Council (NRC) in 2002 to provide independent technical review of the existing biosolids regulations (40 CFR Part 503) and the development of the chemical and pathogen standards as they pertain to human health. In response to their recommendations we have developed a multileveled approach to answering questions around land application. NRMRL is investigating methods for looking at the fate of pathogens and chemicals during application and how the processing and application method of the biosolids affects this transport and long term fate. NERL is investigating and developing tools for assessing human health exposures protocols. NCEA is working on developing problem formulation and risk analysis models for land application of Class B biosolids.
NRMRL has conducted a field scale evaluation in North Carolina (2004) of various air and land sampling methods in order to assess and optimize the techniques. From this initial study, limitations of some of the methods were brought to our attention. Because of these observations, we have been able to focus more on certain sampling techniques and work on improving sample size either in terms of sample numbers or actual mass of material sampled. Also the composition of the test biosolids used in the study was very different from what we had observed from tours at other facilities. Therefore, the importance of understanding what is being applied, such as; biosolids physical composition, pathogen and chemical loads, and method of biosolids application are areas that we need to address in order to determine release of airborne and soil-bound contaminants.
NERLs' focus is to identify, and if necessary, develop exposure measurement tools needed to investigate human health effects related to land application ofbiosolids. Their objective is to recommend monitoring protocols for measuring human exposure to contaminants ITom biosolids land application, surface disposal, and reclamation practices. NERL will be hosting a Biosolids Exposure Measurement Workshop that addresses these issues in early 2006.
NCEA is reviewing the availability of models and data for assessing exposure and risk of infection from exposure to biosolids-borne pathogens. Current regulations apply risk based criteria to the regulation of chemicals in biosolids, but apply technology-based process criteria to establish pathogen reduction levels and vector attraction reduction. This process may allow for substitution of risk. based criteria for existing process-based criteria which would help to address the uncertainty about the protectiveness of existing regulations. The first step is problem formulation. The problem formulation includes three components: identification of the valued entity and desired condition (what needs to be protected and from what?), development of conceptual models (scenario by which the stressor reaches the receptor) and an analysis plan that lays out the approach to conducting assessment of risks from exposure to pathogens originating from Class B biosolids. Alternatively, if the findings are that currently available methods are inappropriate or that data are lacking, the problem formulation will help to define future research to address existing deficiencies.
Impact and Outcomes
This research is designed to optimize air and soil sampling methods so that protocols can be developed for sampling during and post application for determination of contaminant loads. These protocols will be used to help construct more effective models for assessing pathogen risk from various types of land application processes. In the future these sampling protocols may be used by the states and other regulating bodies in order to address the effectiveness oflocal class B biosolids land application practices. As a result researchers, regulators and others will have improved approaches to characterize releases from biosolids land application. Used as input to risk assessments (including pathogens risk assessment using existing or improved models) this release data can be used to determine human health risks attributable to facilities. Exposure monitoring protocols can be used in conjunction with or as an alternative to risk assessment modeling depending on site-specific conditions. These are improved approaches to characterizing releases and determining resultant exposures and risks that should result in more effective protection of human health.