ATSDR Publishes Final Toxicological Profile for Two Diisocyanates 
The Agency for Toxic Substances and Disease Registry recently published a final toxicological profile for toluene diisocyanate and methylenediphenyl diisocyanate. According to ATSDR, exposure to TDI and MDI can affect respiratory function. Workers involved in the manufacture of polyurethane products or in other industries where diisocyanates are used are at risk for exposure to TDI and MDI. Some workers who are particularly sensitive to the toxicity of these chemicals may become sensitized to them. ATSDR notes that asthma and symptoms of asthma have been observed in sensitized individuals.  OSHA’s current ceiling permissible exposure limit for 2,4-toluene diisocyanate and MDI is 0.02 ppm. This corresponds to 0.14 and 0.20 mg/m3 for 2,4-TDI and MDI, respectively. The agency’s PEL for both diisocyanates is 0.005 ppm as a time-weighted average, which corresponds to 0.035 mg/m3 for 2,4-TDI and 0.05 mg/m3 for MDI. NIOSH’s recommended exposure limit for monomeric 4,4' MDI in workplace air is 0.005 ppm as a time-weighted average. ATSDR toxicological profiles characterize the toxicologic and adverse health effects information for hazardous substances. Each peer-reviewed profile includes a public health statement intended to summarize a substance’s relevant properties in non-technical language. The profiles can also contain health and toxicologic information on the potential for human exposure; analytical methods; regulations, advisories, and guidelines; and information about production, import, use, and disposal.  The ATSDR profile for TDI and MDI is available online. A full list of toxic substances with published profiles can be found on ATSDR's website.
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