Hazard endpoint

Physical hazard endpoint Assessment metric Measurement metric... 

Fourteen formulations of chemical alternatives were submitted to EPA under confidentiality and they were assessed based on numerous human health and ecotoxicity endpoints in addition to bioaccumulation potential and environmental persistence. They were also screened for potential exposure to workers, users and the aquatic environment. Where data gaps existed, EPA experts used models and chemical analogs to estimate the hazard for a particular endpoint. The literature and test data reviews were published in the final report, Environmentally Preferable Options for Furniture Fire Safety Low Density Furniture Foam . In addition, each hazard endpoint was ranked with a concern level (High, Moderate or Low) based on the criteria used by the EPA s New Chemicals Program to rate the concern level of new chemicals submitted under the Toxic Substance Control Act (TSCA). As seen in Figure 8.2, where the hazard endpoint rankings are bold, the value is based on experimental data. Where the hazard endpoints are presented in italic font, the value is estimated based on models or chemical analogs. In this way, detailed hazard information was summarized and presented in a clear and concise format. 

Establish the hazard endpoints that will be used to evaluate a chemical. 

Table 8.1 Threshold values for each organic chemical hazard endpoint included in the Green Screen v1.0. 

Defining positive as the absence of hazard. Using Clean Production Action s Green Screen, the ideal chemicals are defined as those that have low hazard for all relevant hazard endpoints as exemplified by Benchmark 4. While it is anticipated that the majority of chemicals will not ciurently reach Benchmark 4, it is stiU important to have a vision of what good (and... 

Hewitt M et al. (2007) Structure-based modelling in reproductive toxicology (Q)SARs for the placental barrier. SAR QSAR Environ Res 18(l-2) 57-76 Mekenyan O et al. (2003) In silico modelling of hazard endpoints current problems and perspectives. SAR QSAR Environ Res 14(5-6) 361-371... 

The hazard endpoint time scale th describes the length of time required for the contaminant to pose a hazard. There are many different time scales associated with various toxicity levels (e.g., TLV-C ceiling limit values are never to be exceeded, TLV-STEL values are not to be exceeded in a 15-min period, etc.). Time scales associated with flammability hazards reflect the maximum local concentration (and also typically including peak-to-mean concentration ratios) and for reasons discussed above are considered representative of dispersion model averaging times of around 20 s. 

For a given release scenario, estimate the state of the released contaminant after it has depressurized and become airborne (including any initial dilution). The initial mole fraction of hazardous components will be applied to the final reported concentrations and hazardous endpoint concentrations throughout the process. If source momentum is important (as in a jet release or for plume rise), other models are available that can address these considerations. Disregarding the dilution due to source momentum will likely result in higher concentrations downwind, but not always. 

While the assessments of the chemicals in the 14 mixtures indicated that the alternatives had a lower level of concern for persistence, bioaccumulation, and toxicity compared with pentaBDE, each chemical was of concern for at least one of the key hazard endpoints and had at least some potential routes of exposure. 

In cases where detailed mechanisms of action do not exist, there is often an understanding that the presence of certain functional groups may result in a hazardous endpoint. Where the possibility exists to simply remove these... 

The relationship between a chemical s structure and its biological action has been studied extensively for over a century (16). In cases where there is not a complete understanding of the mechanism/mode of action or where the influence of functional groups is not known or obvious, there is a vast body of knowledge on how different structural features within a class of chemicals may correlate with various levels of hazard. Structure-activity relations (SAR) or their mathematical treatment. Quantitative SAR (QSAR) have been developed for myriad endpoints including cancer, developmental and reproductive effects, aquatic toxicity, boiling points, water solubility and many others hazard endpoints. An instructor therefore has many opportunities to incorporate the concept of SAR at several points in the curriculum. 

Time scale for a contaminant cloud to reach hazard endpoint distance Xh, time... 

Based upon the principles of green chemistry and designed to evaluate the inherent hazards posed by chemicals, the Green Screen method proved to be useful in evaluating the hazards posed by decaBDE and the phosphorous-based flame retardants (and their breakdown products) and relatively simple to apply once the hazard endpoints and levels of concern were established. Of the three flame retardant compounds commonly used in TV enclosures and evaluated in the Green Screen, bisphenol A diphosphate (BRADP) and decaBDE only... 

The suite of adverse human health effects noted in Table 21.1 occurs within various affected human population subsets and within the criteria set forth above. They are included on the basis of the available evidence, including evidence for their importance as hazardous endpoints, scaled as to severity, duration of adverse impacts, and affected numbers in human populations likely to sustain toxic harm. 

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