• Acetylene poses a flammability hazard and must be used, transported, and stored properly to keep workers safe.
• Hexavalent chromium is highly toxic and can damage the eyes, skin, nose, throat, and lungs and cause cancer.
• Cadmium exposure can cause irritation, stomach problems, lung damage, and kidney disease.

Several substances that welders may encounter are regulated individually because of their specific hazards. These include acetylene, hexavalent chromium, and cadmium.

Acetylene

Acetylene is a colorless gas that has many industrial uses, from being a raw material to use in welding. It poses a flammability hazard and must be used, transported, and stored properly.

The Occupational Safety & Health Administration (OSHA) requirements apply to employers who have employees who use or are exposed to acetylene. The specific requirements vary depending on the application.

Relevant citations:

• 1910.102— Acetylene.
• Related regulation: 1910.253 — Oxygen-fuel gas welding and cutting.
• Compressed Gas Association (CGA) Pamphlet G-1-2009.
• National Fire Protection Association (NFPA) 51A-2006 — “Standard for Acetylene Charging Plants.”
• NFPA 51A-2001 — “Standard for Acetylene Charging Plants.”

To comply with requirements and provide a safe workplace, employers must:

• Ensure cylinder safety. Employers must follow the provisions of CGA Pamphlet G-1-2009 for all in-plant transfer, handling, storage, and use of acetylene.
• Store cylinders valve end up, according to OSHA 1910.253.
• Keep piped systems safe. Piped systems installed before Feb. 16, 2006, must comply with Chapter 9 of NFPA 51A-2006. Older systems may instead comply with Chapter 7 of NFPA 51A-2001.
• Ensure that facilities, equipment, structures, and installations used to generate acetylene or charge acetylene cylinders comply with NFPA 51A-2006 or 51A-2001, as above.
• Communicate hazard information through a hazard communication program.
• Ensure cylinders are properly marked.

Hexavalent chromium

Chromium hexavalent (Cr[VI]) compounds, often called hexavalent chromium, may be created during hot work such as welding on stainless steel or melting chromium metal. The high temperatures involved in the process result in oxidation that converts chromium to a hexavalent state.

Hexavalent chromium can pose a serious hazard to workers. Chromium is converted to its hexavalent state, Cr(VI), during the welding process, and Cr(VI) fume is highly toxic and can damage the eyes, skin, nose, throat, and lungs and cause cancer. OSHA regulates worker exposure to Cr(VI) under 1926.1126, which has a permissible exposure limit (PEL) of 5 ?g/m 3 as an eight-hour average.

Cadmium

The Agency for Toxic Substances and Disease Registry estimates that about 300,000 workers in the U.S. face exposure to cadmium each year. Cadmium exposure can threaten workers who perform activities like the following without wearing some type of personal protection:

• Cutting, grinding, or welding on surfaces painted with cadmium-containing paints; or
• Wrecking, demolishing, and salvaging structures where cadmium is present; or
• Transporting, storing, and disposing of cadmium or cadmium-containing materials on site.

OSHA has set the PEL for cadmium in work area air at 5 micrograms per cubic meter of air (5 ?g/m3) for an 8-hour workday.

Cadmium exposure may occur in several ways: