Despite the numerous studies on welding fumes, incomplete information still exists regarding the causality and possible underlying mechanisms associated with welding fume inhalation and pulmonary disease. The use of animal models and the ability to control the welding fume exposure in toxicology studies could be utilized in an attempt to develop a better understanding of how welding fumes affect pulmonary health.
Research continues to support the theory of endocrine disruption. Endocrine disruption is defined as the ability of a chemical contaminating the workplace or the environment to interfere with homeostasis, development, reproduction, and/or behavior in a living organism or it's offspring. Certain classes of environmentally persistent chemicals such as polychlorinated biphenyls (PCBs), dioxins, furans, and some pesticides can adversely effect the endocrine systems of aquatic life and terrestrial wildlife. The University of Tennessee, Knoxville (UTN), developed a method for hazard scoring chemicals for the aquatic ecosystem. The Indiana Clean Manufacturing Technology and Safe Materials Institute at Purdue University (CMTI) later expanded the scoring system to include terms for worker hazard as well as terms for contamination of soil and air quality, and for stratospheric ozone depletion. We call the CMTI chemical hazard score the Purdue score. At West Virginia University, two improvements of the Purdue chemical hazard score are developed, a normalizing of the term for soil contamination, and addition of hazard score terms for ecosystem endocrine disruption. The results of incorporating endocrine disruption terms into the hazard scoring equations resulted in increased hazard rankings, often substantially increased, for 26 endocrine disrupting chemicals (EDCs) among 200 Superfund chemicals. Because data suggesting human endocrine disruption from such chemicals is still controversial, no endocrine disruptor term has been added to the human toxicity portions of the chemical hazard scoring system at this time. The third product of this work is assembly of a current consolidated list of (1) established or probable, mostly synthetic, industrial chemical and medication EDCs and (2) suspect (less certain) synthetic and natural (phytoestrogen) possible endocrine disrupting chemicals, with the goal of contributing to future development of quantitative structure activity relationship software for predicting whether an untested chemical is likely to be an endocrine disruptor. We conclude that enough endocrine disrupting chemicals are now identified to make an attempt at developing structure activity estimates of disrupting potential worthwhile. Further, we conclude that within a group of 200 chemicals of concern to the US EPA, the addition of endocrine disrupting terms to the Purdue score substantially increases its representativeness in reflecting ecological exposure hazard. We have developed this enhanced Purdue score risk management tool to be of assistance to industry.
There is a huge and changing number of chemicals in commerce for which workplace exposure criteria have not been assigned. Assigning an exposure criterion by an expert committee is resource-intensiveÐnot soon available for the large majority of chemicals in current use. In the absence of assigned criteria, we have provided a regression method to estimate a ®rst-screen estimate of a`TLV/WEEL-equivalent' inhalation time-weighted average exposure criterion for a pure chemical (or chemical group) from a measure of a non-stochastic toxic exposure to elicit a chronic or sub-chronic health eect, known as a lowest observable adverse eect level (LOAEL) or a (highest) no observable adverse eect level (NOAEL). Results are presented for six data sets for which both a threshold limit value (TLV) or workplace environmental exposure level (WEEL) exposure criterion is presently assigned, and a LOAEL or NOAEL measure of toxic health eect was available from the United States Environmental Protection Agency Integrated Risk Information System data base. The results can be applied as a ®rst estimate of exposure to substances for which no TLV or WEEL (TLV/WEEL) exists, and also serve as a mechanism for identifying substances for potential re-evaluation of their exposure limit, based on their relative position about the prediction models.
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