These studies are being conducted to evaluate potential human exposure for manufacturing compounds that have high production, increasing use and/or structural similarity to other known toxicants. There is limited environmental and occupational exposure data available in the scientific literature to assess the acute exposure/ response relationship, and potential chronic long-term adverse effects of EGEHE exposure. Validation of passive (diffusive) and active (pumped) sampling methods is ongoing. Due to problems encountered in the Gas Chromatography ? Mass Spectrometry method,an alternative Liquid Chromatography ? Mass spectrometry method is being explored. Additional sampling has been delayed pending an assessment of the utility of this method.