Interpreting Occupational Exposure Limits: An Analysis of NIOSH Recommended Exposure Limits by Health Endpoint

Details

• Personal Author:
  Niemeier, R. Todd ; Whittaker C
• Description:
  Occupational exposure limits (OELs) are an essential tool for controlling worker exposures to toxic chemicals. OELs have been developed to protect workers from exposure to carcinogens, chemical irritants, sensitizers, neurotoxicants, and a variety of other toxicities. However, OELs are not all created equal. Many OELs are based on avoidance of chronic health effects, but others are based on acute health impacts. Health-based methods used to determine OEL values have ranged from a determined point of departure from an exposure-response relationship to quantitative risk assessment with extrapolation to a target risk level. In some cases, the OELs are not health-based, but are set based on the analytical limit of quantification or reliable quantitation limit. Still, the OEL (or a specified fraction of the OEL) is perceived as a "safe" level of exposure. In this presentation, thirty NIOSH Recommended Exposure Limits (RELs) are evaluated for the health endpoint basis of the REL, methods used for determining the OEL, target risk levels (where appropriate), and the analytical limit of quantification. The RELs are compared to the results that would be obtained from implementation of the NIOSH Occupational Exposure Banding eTool, and the EPA 8-hour time-weighted average (TWA) Acute Exposure Guideline Levels (AEGL). A description of the risk interpretations from the point of view of the risk assessor is compared with the point of view of the industrial hygienist. For example, the 8-hr TWA REL for ammonia is 25 ppm, with a STEL of 35 ppm. This is based on human observational studies showing respiratory irritation. Tier 1 occupational exposure banding would indicate that ammonia would be classified a band E chemical, corresponding to exposure concentrations of <0.1 ppm, and the AEGL-1 8-hour TWA value is 30 ppm (corresponding to acute health effects in the general population). Interpretation of the RELs, occupational exposure bands and AEGL values for ammonia and 29 other chemicals is discussed. [Description provided by NIOSH]
• Subjects:
  Animals Decision Making Hazardous Substances Occupational Exposure Occupational Health Risk Assessment Risk Factors Safety Toxicology
• Keywords:
  Acute Exposure Ammonia Analytical Methods Animal Studies Chemical Hazards Decision Making Dose Response Exposure Assessment Exposure Limits Guidelines Hazard Banding Hazard Communication Health Effects Humans Industrial Hygienists Occupational Exposure Banding Occupational Exposure Limits OELs Quantitative Analysis Quantitative Risk Assessment Recommended Exposure Limits RELs Risk Assessment Risk Factors Time Weighted Average Exposure Toxic Dose Toxic Effects

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• ISSN:
  1096-6080
• Document Type:
  Text
• Genre:
  Abstract or Summary
• Place as Subject:
  California ; Ohio ; OSHA Region 5 ; OSHA Region 9
• CIO:
  National Institute for Occupational Safety and Health (NIOSH)
• Division:
  DSI - Division of Science Integration
• Topic:
  Workplace Safety & Health
• Location:
  North America
• Volume:
  174
• Issue:
  1
• NIOSHTIC Number:
  nn:20058975
• Citation:
  Toxicologist 2020 Mar; 174(1):298
• CAS Registry Number:
  Ammonia (CAS RN 7664-41-7)
• Federal Fiscal Year:
  2020
• Peer Reviewed:
  False
• Source Full Name:
  The Toxicologist. Society of Toxicology 59th Annual Meeting and ToxExpo, March 15-19, 2020, Anaheim, California
• Collection(s):
  National Institute for Occupational Safety and Health
• Main Document Checksum:
  urn:sha-512:e993004a00f6941eac3085704fe806445f100a0e48364bb5231e96c7d2786c1612e5f65c5aef8f80dad5fbedba68452663464d9d2ba0d6abb9eb3fede521b354
• Download URL:
  https://stacks.cdc.gov/view/cdc/223319/cdc_223319_DS1.pdf
• File Type:
  [PDF - 524.50 KB ]