Chemicals handling risk assessment

U.S. EPA may list a waste as hazardous for any and all of the above reasons. The majority of listed wastes fall into the toxic waste category. To decide if a waste should be a toxic listed waste, U.S. EPA first determines whether it typically contains harmful chemical constituents. An appendix to RCRA contains a list of chemical compounds or elements that scientific studies have shown to have toxic, carcinogenic, mutagenic, or teratogenic effects on humans or other life forms. If a waste contains chemical constituents found on the appendix list, U.S. EPA then evaluates 11 other factors to determine if the wastestream is likely to pose a threat in the absence of special restrictions on its handling. These additional considerations include a risk assessment and study of past cases of damage caused by the waste. 

SuperChems Expert 161 is a code developed by Arthur D Little Inc. for risk assessment consequence analysis, which also has a relief system sizing option. The code has a physical properties package that can handle highly non-ideal properties. It can also consider the effect of chemical reaction in the relief system piping. The code uses the DIERS drift flux methods for level swell and has the option of a rigorous two-phase slip model for the. relief system capacity. 

Abstract In this chapter relatively recent European Commission risk assessment reports for three potential PBT/vPvB chemicals are used as examples to illustrate scientific uncertainty in the risk assessment process, and how science and policy interact when such uncertainty is handled. The studied risk assessment reports are for pentabromodiphenylether (Penta), octabromodiphenylether (Octa), and decabromodiphenylether (Deca) and the analyses focus on the scientific basis for assessing the risk of potential PBT and vPvB properties as described in these documents. The purpose of this effort is to contribute to a discussion aiming at clarifying the nature of science-policy interactions, and improving the transparency of the risk assessment process. 

Under OSHA hazard communication standard 29 CFR 1910.119, employers are required to carry out an assessment to evaluate the risk to health from any chemicals handled and establish what precautions are needed to protect employees. A written record of the assessment should be kept and details made available to employees. The design engineer should consider the preventative aspects of the use of hazardous substances. Points to consider are... 

Among a few specific methods of handling pollution problems, quantitative techniques for assessing environmental risks due to contamination of environmental media by unwanted chemicals are becoming increasingly popular. Many ptqters and presentations such as [10] mention application of this type of risk assessment studies being carried out in the USA, Canada and Western European countries. 

With or without an MSDS, however, caution in chemical handling should be observed. As a general guideline, worker and student exposures to laboratory chemicals should be kept to a minimum. Because so many laboratory chemicals are hazardous to humans in some way, conservative risk assessment should be employed. Persons in the laboratory should assume that personal protection is required whenever they are working with chemicals. Chemicals of unknown toxicity initially should be treated as toxic with respect to exposure during work performed in the laboratory. For work with chemicals of known toxicity, appropriate precautions should be taken. When working with mixtures of chemicals, the risk of the mixture as a whole should be assumed at least to equal the risk for the most toxic component of the mixture. 

Great efforts have been made to develop methods for quantitative assessments of dermal absorption. For risk assessment of chemical mixtures, many challenges are encoimtered (1) lack of quantitative data for chemical mixtures because most of the data are measured with individual chemicals (2) even for individual chemicals, only limited data acquired under comparable experimental conditions, and many data acquired imder incomparable conditions are not useful for the uigent need for risk assessment of dermal absorption (3) lack of fundamental methodology to handle thousands of chemicals and nulhons of their combinations. It is impossible to mechanistically study all of the chemicals and their combinations. This problem is likely to worsen with the increasing number of chemicals required to be evaluated. 

Smith RL (1991) EPA Region 3 Guidance on handling chemical concentration data near the detection limit in risk assessment, http //www.epa.gov/reg3hwmd/risk/human/info/guide3. htm, Last modified date March 8th 2007, US EPA, Accessed May 2009... 

Concerning the physical-chemical risks, the employer has to take technical and organizational actions on the basis of the risk assessment in order to protect workers from fire and explosion hazards. The type of measures depends on the nature of the hazardous chemical agents and should be appropriate to the operation, including storage, handling, and segregation of incompatible materials. In order of priority the particular measures are... 

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