Criteria for a Recommended Standard: Occupational Exposure to Hexavalent Chromium

Summary Statement

This criteria document is derived from the NIOSH evaluation of critical health effects studies of occupational exposure to hexavalent chromium (Cr[VI]) compounds. It provides recommendations for controlling workplace exposures including a revised recommended exposure limit (REL) derived using current quantitative risk assessment methodology on human health effects data. This document supersedes the 1975 Criteria for a Recommended Standard.

Hexavalent chromium compounds include a large group of chemicals with varying chemical properties, uses, and workplace exposures. Their properties include corrosion-resistance, durability, and hardness. Sodium dichromate is the most common chromium chemical from which other Cr(VI) compounds may be produced. Materials containing Cr(VI) include various paint and primer pigments, graphic art supplies, fungicides, corrosion inhibitors, and wood preservatives. Some of the industries in which the largest numbers of workers are exposed to high concentrations of Cr(VI) compounds include electroplating, welding, and painting. An estimated 558,000 U.S. workers are exposed to airborne Cr(VI) compounds in the workplace. Cr(VI) is a well-established occupational carcinogen associated with lung cancer and nasal and sinus cancer. NIOSH considers all Cr(VI) compounds to be occupational carcinogens. NIOSH recommends that airborne exposure to all Cr(VI) compounds be limited to a concentration of 0.2 μg Cr(VI)/m3 for an 8-hr time-weighted average (TWA) exposure, during a 40-hr workweek. The REL is intended to reduce workers’ risk of lung cancer associated with occupational exposure to Cr(VI) compounds over a 45-year working lifetime. It is expected that reducing airborne workplace exposures to Cr(VI) will also reduce the nonmalignant respiratory effects of Cr(VI) compounds, including irritated, ulcerated, or perforated nasal septa and other potential adverse health effects.

Because of the residual risk of lung cancer at the REL, NIOSH further recommends that continued efforts be made to reduce Cr(VI) exposures to below the REL. A hierarchy of controls, including elimination, substitution, engineering controls, administrative controls, and the use of personal protective equipment, should be followed to control workplace exposures.