Top 10 Chemical Exposures
Below are the top 10 most toxic fumes, metals, and gases associated with welding, rank-based on toxicity and health effects according to OSHA, NIOSH, and the International Agency for Research on Cancer (IARC). Most of these chemicals should be listed on SDSs and part of Hazard Communication training.
1. Hexavalent Chromium (Cr(VI))
Hexavalent chromium (Cr(VI)) is a highly toxic form of chromium, recognized as a carcinogen. It can be generated during welding or cutting processes involving chromium-containing alloys, especially stainless steel. It is considered the most dangerous hazardous chemical based on acute toxicity, long-term health effects, and regulatory concern.
Health Effects: Exposure to Cr(VI) can cause cancer and it also targets the respiratory system, kidneys, liver, skin, and eyes.
Risk of Exposure Cr(VI) is very common in general industry, maritime, and construction applications, and that's primarily why the risk of exposure is so high:
- Chromium metal is added to alloy steel to make it harder and corrosion resistant. A major source of worker exposure to Cr(VI) occurs during "hot work" such as welding on stainless steel and other alloy steels containing chromium metal.
- Cr(VI) compounds may be used as pigments in dyes, paints, inks, and plastics. It also may be used as an anticorrosive agent added to paints, primers, and other surface coatings.
- Chromic acid, a Cr(VI) compound, is used to electroplate chromium onto metal parts to provide a decorative or protective coating.
Regulatory Requirements: The OSHA Standards below for Chromium (VI) establish requirements for exposure to Chromium (VI), and set a Permissible Exposure Limit (PEL) of an average of 5 micrograms per cubic meter (µg/m3) over an 8-hour work shift.
Knowledge Check Choose the best answer for the question.
7-6. Which welding process is most likely to produce Hexavalent Chromium Cr(VI)?
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