Exposure Limits: United States (U.S.)

In the U.S., the federal Occupational Safety and Health Act (OSHAct) of 1970 created the Occupational Safety and Health Administration (OSHA) within the Department of Labor. The stated intent of the OSHAct is to “assure safe and healthful working.” To this end, OSHA has promulgated a variety of health and safety regulations, among them the Air Contaminants Standard, which specifies eight-hour Time Weighted Average Permissible Exposure Limits (PELs) for many substances, including nickel and its compounds. The current PEL for nickel metal and for both water-soluble and -insoluble nickel compounds is 1.0 mg Ni/m3. The PEL for nickel carbonyl is 0.007 mg Ni/m3.

In 1989, OSHA reduced the PEL for soluble nickel compounds to 0.1 mg Ni/m3. However, in July 1992, the U.S. Eleventh Circuit Court of Appeals set aside and remanded the entire Air Contaminants Standard on the ground that OSHA’s generic approach – dealing with over 400 chemicals, including nickel, in a single rule- making – effectively precluded OSHA from making the substance-specific findings of significant risk and the industry-specific findings of technological and economic feasibility that are required by the OSHAct. The effect of the Court of Appeals decision was stayed while OSHA sought review in the Supreme Court. OSHA’s efforts to secure Supreme Court review ended in March 1993, and the PEL for soluble nickel compounds reverted to a level of 1.0 mg Ni/m3, the same as the PEL for nickel metal and insoluble nickel compounds.

In the future, OSHA may seek to reinstate some or all of the PELs that were vacated by the Eleventh Circuit Court of Appeals. If so, the PEL for soluble nickel compounds would be reduced to 0.1 mg Ni/m3. It also is possible that, in the years ahead, OSHA may decide to review nickel and its compounds in a substance-specific proceeding and set a more comprehensive standard for occupational exposure to nickel and individual nickel compounds.

Individual states that have approved occupational health programs may set more stringent requirements than those set by the federal government if they are able to make certain showings. While most states generally follow the federal limits, some individual states which have received authority to implement their own occupational health programs have maintained a PEL of 0.1 mg Ni/m3 for soluble nickel compounds. As mentioned above, some governments have directly based their OELs upon the ACGIH’s TLVs; others. However, others have not adopted the ACGIH TLVs as evidenced by independent decisions reached by countries such as Germany, the U.K., and the U.S.. The ACGIH is a nongovernmental organization of occupational health professionals and technical personnel in government agencies and educational institutions. It publishes an annually updated document on exposure limits called the Threshold Limit Values (TLVs) for Chemical Substances and Physical Agents and Biological Exposure Indices (BEIs). As the ACGIH is not a “true” governmental body, its TLVs are not enforceable standards and employers are not legally obligated to meet the TLVs, unless specifically required to do so by local or national law.

Currently, the TLVs are 1.5 mg Ni/m3 for metallic nickel, 0.2 mg Ni/m3 for water-insoluble forms of inorganic nickel, and 0.1 mg Ni/m3 for water-soluble nickel forms and nickel subsulfide. The TLV for nickel carbonyl is 0.35 mg Ni/m3. These TLVs were adopted in 1998. In addition to new TLVs and carcinogen classifications, the ACGIH stated that the nickel compound TLVs would be based on the Inhalable Particulate Fraction instead of the “Total” Particulate Fraction. In response to comments regarding the differential sampling efficiency of inhalable and ‘total’ aerosol samplers, the ACGIH increases the TLVs that would have resulted for “total” nickel resulting in the final “inhalable” TLVs published in 1998 (Table 9-1).

TABLE 9-1:  LIMIT VALUES AS ESTABLISHED BY MAJOR STANDARD-SETTING BODIES

Country/Body

Status of Standard

Values of Standards1
(mg Ni/m3)

Metallic Nickel

Insoluble Nickel Species

 Soluble Nickel Species

Nickel carbonyl

Argentina

Current

1.5

0.2
0.1 (sulfidic)

0.1

0.35

Austria

Current

0.052

0.052

0.05

0.05 (ml/m3)

Australia

Current

1.0

1.0

0.1

0.12

Belgium

Current

1.0

1.0

0.1

0.12

Brazil

Current

NA8

NA8

NA8

0.28

Canada – Ontario

Current

1.0 16

0.2 16
0.1 (subsulfide) 16 

0.1 16

0.35 16

Canada – Alberta

Current

1.0
[27]

1.0 (sulfide roasting fume) [37

0.1
[0.37]

0.12
[0.367]

Canada – British Columbia

Current

0.05

0.05
0.1 (subsulfide)16

0.05

0.002

Canada – Québec

Current

1.0

1.0

0.1

0.007

Chile

Current

0.8

0.8

0.08

NA8

Denmark

Current

0.05

0.05

0.01

0.007

Finland

Current

1.0

0.1

0.1

0.007
[0.0217]

France

Current

1.0 (VME)5

1.0

0.1

0.12

Germany

Under revision

0. 5 6
[2.07]

0. 5 6
[2.0 7]

0.05 6, 16
[0.2 7]

[0.247]

Greece

NA8

NA8

NA8

NA8

NA8

Italy

Current

1.0

1.0

0.1

0.12

Japan

Under revision

1.0

NS12

NS12

0.007

Netherlands

Current

0.1

NS12

0.1

0.35

New Zealand

Current

1.0

1.0  (sulfide roasting fume and dust)

0.1

0.12

Norway

Current

0.05

0.05

0.05

0.007

Portugal

Current

1.0

NS12

0.1

0.12

South Africa

Current

0.5

0.5
0.1 (subsulfide)

0.1

[0.247]

Spain

Current

1.0

0.2

0.1

0.12

Sweden

Current

0.5

0.1
0.01 (subsulfide)

0.1

0.007

United Kingdom

Current

0.5 (MEL)9,10

0.5 

0.1 (MEL)10

0.24 (OES)7,11

United States

Current13

1.0 14

1.0

1,0

0.007

(USA)  ACGIH TLV15
NON-ENFORCEABLE STANDARD

Current (1997)

1.516

0.216
0.1 (subsulfide)16

0.116

0.35

Current = As of April 2008 
1 8-hour TWA  (Time-Weighted Average) unless otherwise noted. All values refer to ‘total’ nickel unless otherwise noted.
2 This TLV  applies to nickel metal and alloys, nickel sulfide, sulfidic ores, oxidic nickel, and nickel carbonate in inhalable dust, as well as any nickel compound in the form of inhalable droplets.
3 Metallic nickel only.
4 NC = No change.
5 VME = Valeur Moyenne d’Expositiòn. The value of 1 mg/m3 applies to Ni carbonate, dihydroxide, subsulfide, monoxide, sulfide, trioxide and for other chemical forms non-otherwise specified such as ‘insoluble Ni compounds’ and Ni sulfide roasting fume and dust.
6 TRK (Technische Richtkonzentrationen)
7 STEL=15-minutes, short-term standard.
8 NA = Not available.
9 MEL  =  Maximum Exposure Limit.
10 This value is based on “total inhalable” aerosol as measured with the 7-hole sampler (UK HSE, 2000).
11 OES = Occupational Exposure Standard.
12 NS = No Standard.
13 In 1989, OSHA reduced the PEL for soluble nickel compounds to 0.1 mg Ni/m3. However, in July 1992, the U. S. Eleventh Circuit Court of Appeals set aside and remanded the entire Air Contaminants Standard on the ground that OSHA's generic approach dealing with over 400 chemicals, including nickel, in a single rulemaking effectively precluded OSHA from making the substance-specific findings of significant risk and the industry-specific findings of technological and economic feasibility that are required by the Occupational Safety and Health Act. Accordingly, the PEL for soluble nickel compounds reverted to a level of 1.0 mg Ni/m3, the same as the PEL for nickel metal and insoluble nickel compounds. The PEL for soluble nickel compounds may, however, be lower than 1.0 mg Ni/m3 in individual states that have obtained OSHA's approval.
14 PEL  =  Permissible exposure limit.
15 ACGIH = American Conference of Governmental Industrial Hygienists.
16 Based on the inhalable particulate fraction. In response to comments regarding the differential sampling efficiency of inhalable and ‘total’ aerosol samplers, the ACGIH proposed increases to the 1996 proposed TLV values during January, 1997. The new recommendations will be placed on the Notice of Intended Changes during the spring of 1997. The ACGIH has also proposed carcinogen classifications of A5 (Not suspected as a human carcinogen) for metallic nickel, A4 (Not classifiable as a human carcinogen) for soluble nickel, A1 (Confirmed human carcinogen) for insoluble nickel, A1 for nickel subsulfide, and no classification for nickel carbonyl.