Agency for Toxic Substances and Disease Registry 
Case Studies in Environmental Medicine (CSEM) 
Chromium Toxicity
What are the Standards and Regulations for Chromium Exposure?

Learning Objectives

Upon completion of this section, you will be able to

• Identify the OSHA permissible exposure limit (PEL) for chromium.
• Identify EPA's maximum contaminant level (MCL) for chromiumin drinking water.

Introduction

The government has developed regulations and guidelines for chromium. These are designed to protect the public from potential adverse health effects.

Workplace Guidelines

OSHA

The Occupational Safety and Health Administration (OSHA) has established an 8-hour time-weighted average (TWA) exposure limit of 5 micrograms of Cr(VI) per cubic meter of air (5 µg/m³). This is a considerable reduction from the previous permissible exposure limit (PEL) of 52 µg/m³ [Federal Register 2006].

OSHA's standard is based upon the best evidence currently available that at the previous PEL for Cr(VI), workers face a significant risk to material impairment of their health. The evidence in the record for this rulemaking indicates that workers exposed to Cr(VI) are at an increased risk of developing lung cancer. The record also indicates that occupational exposure to Cr(VI) may result in asthma and damage to the nasal epithelia and skin. [Federal Register 2006].

The final rule also contains ancillary provisions for worker protection such as

• requirements for exposure determination,
• preferred exposure control methods, including a compliance alternative for a small sector for which the new PEL is infeasible,
• respiratory protection,
• protective clothing and equipment,
• hygiene areas and practices,
• medical surveillance,
• record keeping, and
• start-up dates that include four years for the implementation of engineering controls to meet the PEL [Federal Register 2006].

For Cr(II) and Cr(III) compounds, the PEL is an 8-hour TWA of 500 µg Cr/m³. For chromium metal and for insoluble compounds, the PEL is 1,000 µg Cr/m³[OSHA 2006].

NIOSH

The National Institute for Occupational Safety and Health (NIOSH) has recommended a 10-hour TWA exposure limit for all Cr(VI) compounds of 1 µg Cr(VI)/m³. For chromium metal and Cr (II) and Cr(III) compounds, the recommended exposure limit is 500 µg/m³ as an 10-hour TWA [NIOSH 2005].

On the basis of current evidence, NIOSH considers all Cr(VI) compounds potential occupational carcinogens.

Environmental Guidelines

Air

The U.S. Environmental Protection Agency (EPA) regulates chromium emissions under the Clean Air Act of 1990. EPA uses technology-based standards for categories of industries, rather than numerical emissions standards, to reduce chromium levels in ambient air. These maximum achievable control technology (MACT) standards are based on emissions levels already achieved by the best-performing similar facilities.

Drinking Water

EPA has an enforceable maximum contaminant level of total chromium in drinking water of 100 µg/L (100 ppb) for public water systems [EPA 1999h].

American Conference of Governmental Industrial Hygienists

Air: workplace

10 µg/m³ as Cr

Advisory; TWA* to avoid carcinogenic risk from insoluble Cr(VI) compounds

50 µg/m³ as Cr

TWA for water-soluble Cr(VI) compounds

500 µg/m³ as Cr

TWA for chromium metal and Cr(III) compounds

National Institute for Occupational Safety and Health

Air: workplace

1 µg/m³ as Cr

Advisory; TWA (10-hour) for chromic acid and all Cr(VI) compounds

500 µg/m³ as Cr

Advisory; TWA (10-hour) for chromium metal and Cr(II) and Cr(III) compounds

Occupational Safety and Health Administration

Air: workplace

5 µg/m³ as CrO₃/m³

Regulation; PEL† for chromic acid and chromates, (8-hour TWA)

500 µg/m³ as Cr

1,000 µg/m³ as Cr

PEL for chromium metal and insoluble compounds (8-hour TWA)

Environmental Protection Agency

Air: environment

Not available

Chromium is listed as a hazardous pollutant

Drinking water

100 µg/L

Regulation; current MCL‡ for total chromium

*TWA (time-weighted average): TWA concentration for a normal workday and a 40-hour workweek to which nearly all workers may be repeatedly exposed.

†PEL (permissible exposure limit): highest level of chromium in air, to which a worker may be exposed, averaged over an 8-hour workday.

‡MCL (maximum contaminant level) enforceable level for drinking water.

Key Points

• OSHA has established an 8-hour time-weighted average (TWA) exposure limit of 5 micrograms of Cr(VI) per cubic meter of air (5 µg/m³). This is a considerable reduction from the previous PEL of 52 µg/m³.
• The current EPA maximum contaminant level for chromium in drinking water is 100 µg/L.

Progress Check

To review relevant content, see Table 1 in this section.