OSHA Hazard Information Bulletins
November 30, 1988
| MEMORANDUM FOR: |
REGIONAL ADMINISTRATORS |
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| THRU: |
LEO CAREY
Director
Office of Field Programs |
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| FROM: |
EDWARD J. BAIER
Director
Directorate of Technical Support |
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| SUBJECT: |
Hazard Information Bulletin on Potential
Carcinogenicity of Diesel Exhaust |
The purpose of this bulletin is to alert field personnel to the potential carcinogenicity of whole diesel exhaust and to enumerate the specific gaseous and particulate components that comprise the emission from diesel engines.
Recent animal studies in rats and mice confirm an association between the induction of cancer and exposure to whole diesel exhaust. The lung is the primary site identified with carcinogenic or tumorigenic responses following inhalation
exposure. Limited epidemiologic evidence suggests an association between occupational exposure to diesel engine emissions and lung cancer. The consistency of these toxicologic and epidemiologic findings suggest that a potential
occupational carcinogenic hazard exists in human exposure to diesel exhaust.
NIOSH estimates that approximately 1.35 million workers are occupationally exposed to the combustion products of diesel fuel in approximately 80,000 workplaces in the United States (NIOSH 1983). Workers who are likely to be exposed
to diesel emissions include mine workers, bridge and tunnel workers, railroad workers, loading dock workers, truck drivers, fork-lift drivers, farm workers, and auto, truck, and bus maintenance garage workers.
The emissions from diesel engines consist of both gaseous and particulate fractions. The gaseous constituents include carbon dioxide, carbon monoxide, nitric oxide, nitrogen dioxide, oxides of sulfur, and hydrocarbons (e.g., ethylene,
formaldehyde, methane, benzene, phenol, 1,3-butadiene, acrolein, and polynuclear aromatic hydrocarbons).
Particulates (soot) in diesel exhaust are composed of solid carbon cores that are produced during the combustion process and that tend to form chain or cluster aggregates. As much of 15% to 65% of the mass of particulate emissions
(soot) of diesel engines is made up of organic compounds absorbed onto the surface of the particulates. Among these compounds is a group of compounds known as polynuclear aromatic hydrocarbons( PAHs), several of which are carcinogens
(IARC 1983).
Permissible exposure limits (PELs) established by OSHA and the Mine Safety and Health Administration (MSHA) for some gases typically found in diesel exhaust are listed in Table 1 along with the recommended exposure limits (RELs)
established by NIOSH.
OSHA, MSHA, and NIOSH exposure limits relevant to the particulate fraction of diesel engine emissions are listed in Table 2. Because diesel emission particulates are of respirable size, the presence of diesel equipment contributes
to the total burden of respirable dust present in an occupational environment. Existing limits for occupational exposures to other respirable dust also limit exposure to the particulate fraction of diesel emissions.
Although no specific recommendations are being made from a compliance standpoint, compliance officers should be aware of the various components of diesel exhaust as this knowledge may aid in evaluating a worker's exposures or the
environment in which he or she works.
Please disseminate this bulletin to all Area Offices, State Plan States and Consultation Project Officers.
Reference:
NIOSH Current Intelligence Bulletin 50, Carcinogenic Effects of Exposure to Diesel Exhaust.
| DATE: |
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| MEMORANDUM FOR: |
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| THROUGH: |
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| FROM: |
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| SUBJECT: |
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Table 1. -- Limits for occupational exposure to selected
components of the gaseous fraction of diesel
exhaust; OSHA, MSHA, NIOSH compared
__________________________________________________________________________
MSHA PELs*
Component OSHA PEL Underground
mines
__________________________________________________________________________
Carbon dioxide 5,000 ppm (9,000 mg/m(3)) 5,000ppm (9,000mg/m(3))
(C02) 8-hr TWA^ 8-hr TWA;
30,000 ppm
(54,000 mg/m(3)).
STEL@
__________________________________________________________________________
Carbon monoxide 50 ppm (55 mg/m(3)) 50 ppm (55 mg/m(3))
(CO2) 8-hr TWA 8-hr TWA;
400 ppm (440 mg/m(3))
STEL
__________________________________________________________________________
Formaldehyde 1 ppm, 1 ppm (1.5 mg/m(3)).
8-hr TWA 8-hr TWA;
2 ppm, 2 ppm (3 mg/m(3)).STEL
15-minute STEL
__________________________________________________________________________
Nitrogen dioxide 5 ppm (9 mg/m(3)). 3 ppm (6 mg/m(3)).
(NO2) ceiling 8-hr TWA:
5 ppm (10 mg/m(3))STEL
__________________________________________________________________________
Nitric oxide 25 ppm (30 mg/m(3)). 25 ppm (30 mg/m(3)).
(NO) 8-hr TWA 8-hr TWA
__________________________________________________________________________
Sulfer dioxide 5 ppm (13 mg/m3). 2 ppm (5 mg/m(3)).
(SO2) 8-hr TWA 8-hr TWA;
5 ppm (10 mg/m(3)),STEL
__________________________________________________________________________
Metal and Nonmetal NIOSH REL
mines
__________________________________________________________________________
Carbon Dioxide 5,000 ppm (9,000 mg/m(3)) 10,000 ppm (18,000
(CO2) 8-hr TWA; mg/m(3)). 8-hr TWA;
15,000 ppm (27,000 30,000 ppm (54,000
mg/m(3)) STEL mg/m(3)) 10-min ceiling
__________________________________________________________________________
Carbon Monoxide 50 ppm (55 mg/m(3)) 35 ppm (40 mg/m(3))
8-hr TWA 8-hr TWA
400 ppm (440 mg/m(3)) 200 ppm (230 mg/m(3))
STEL ceiling
(no minimum time)
__________________________________________________________________________
Formaldehyde 2 ppm (3 mg/m(3)) 0.016 ppm (0.020 mg/m(3))
ceiling 8-hr TWA;
0.1 ppm (0.12 mg/m(3))
15-min ceiling
__________________________________________________________________________
Nitrogen 5 ppm (9 mg/m(3)) 1 ppm (1.8 mg/m(3))
Dioxide ceiling 15-min ceiling
(NO(2))
__________________________________________________________________________
Nitric oxide 25 ppm (30 mg/m(3)) 25 ppm (30 mg/m(3))
(NO) 8-hr TWA; 10-hr TWA
37.5 ppm (46 mg/m(3)).
STEL
__________________________________________________________________________
Sulfur dioxide 5 ppm (13 mg/m(3)) 0.5 ppm (1.3 mg/m(3)),
8-hr TWA; 10-hr TWA
20 ppm (52 mg/m(3)),
STEL (5 MIN)
__________________________________________________________________________
* MSHA limits are based on threshold limit values (TLVs) of the American
Conference of Governmental Industrial Hygienists (ACGIH). 1973 TLVs are
used for metal and nonmetal mines. Current TLVs are used for underground
coal mines
^ Time-Weighted average
@ Short-term exposure limit.
Table 2. -- OSHA, MSHA, and NIOSH limits relevant to occupational exposure
to the particulate fraction of diesel exhaust
___________________________________________________________________________
MSHA PELs
Component OSHA PEL Underground Metal & NIOSH REL
coal mines Nonmetal
mines
___________________________________________________________________________
Respirable 5 mg/m(3) 2 mg/m(3) No Limit No REL
dust(*)
___________________________________________________________________________
Respirable 10 mg/m(3) 10 mg/m(3)^ no mg/m(3)@ REL is dust
when specific
content is to quartz
more than
5% of total*
___________________________________________________________________________
Coal tar Not appli- Not Not 0.1 mg/m(3),
pitch cable to considered considered 10-hr TWA
volatiles diesel relevant relevant (cyclo-
(CTPV) emissions. hexane-ext
actables).
___________________________________________________________________________
Polynuclear No PEL No PEL No PEL No REL
aromatic
hydrocarbons
___________________________________________________________________________
FOOTNOTE(*) These limits are not intended for diesel exhaust particulates,
but they would inadvertently limit airborne concentrations because diesel
particulates would be included in respirable dust samples taken where
diesel engines are operating.
^ HRE equivalent concentration.
@ MSHA limits are based on threshold limit values (TLVs) of the American
Conference of Governmental Industrial Hygienists (ACGIH). 1973 TLVs are
used for metal and nonmetal mines.
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