September 1996 |
ToxFAQs™ |
for |
Polycyclic Aromatic Hydrocarbons
(PAHs) |
(Hidrocarburos Aromáticos Policíclicos (HAPs)) |
|
|
This fact sheet answers the most frequently
asked health questions about polycyclic aromatic hydrocarbons
(PAHs). For more information, you may call the ATSDR Information
Center at 1-888-422-8737. This fact sheet is one in a series
of summaries about hazardous substances and their health effects.
This information is important because this substance may harm
you. The effects of exposure to any hazardous substance depend
on the dose, the duration, how you are exposed, personal traits
and habits, and whether other chemicals are present.
|
|
HIGHLIGHTS: Exposure to polycyclic
aromatic hydrocarbons usually occurs by breathing air
contaminated by wild fires or coal tar, or by eating foods
that have been grilled. PAHs have been found in at least
600 of the 1,430 National Priorities List sites identified
by the Environmental Protection Agency (EPA). |
|
|
What
are polycyclic aromatic hydrocarbons (PAHs)? |
Polycyclic aromatic hydrocarbons (PAHs)
are a group of over 100 different chemicals that are formed
during the incomplete burning of coal, oil and gas, garbage,
or other organic substances like tobacco or charbroiled meat.
PAHs are usually found as a mixture containing two or more
of these compounds, such as soot.
Some PAHs are manufactured. These pure
PAHs usually exist as colorless, white, or pale yellow-green
solids. PAHs are found in coal tar, crude oil, creosote, and
roofing tar, but a few are used in medicines or to make dyes,
plastics, and pesticides.
|
back to top |
|
What
happens to polycyclic aromatic hydrocarbons (PAHs) when they
enter the environment? |
- PAHs enter the air mostly as releases from volcanoes,
forest fires, burning coal, and automobile exhaust.
- PAHs can occur in air attached to dust particles.
- Some PAH particles can readily evaporate into the air
from soil or surface waters.
- PAHs can break down by reacting with sunlight and other
chemicals in the air, over a period of days to weeks.
- PAHs enter water through discharges from industrial and
wastewater treatment plants.
- Most PAHs do not dissolve easily in water. They stick
to solid particles and settle to the bottoms of lakes or
rivers.
- Microorganisms can break down PAHs in soil or water after
a period of weeks to months.
- In soils, PAHs are most likely to stick tightly to particles;
certain PAHs move through soil to contaminate underground
water.
- PAH contents of plants and animals may be much higher
than PAH contents of soil or water in which they live.
|
back to top |
|
How
might I be exposed to polycyclic aromatic hydrocarbons (PAHs)? |
- Breathing air containing PAHs in the workplace of coking,
coal-tar, and asphalt production plants; smokehouses; and
municipal trash incineration facilities.
- Breathing air containing PAHs from cigarette smoke, wood
smoke, vehicle exhausts, asphalt roads, or agricultural
burn smoke.
- Coming in contact with air, water, or soil near hazardous
waste sites.
- Eating grilled or charred meats; contaminated cereals,
flour, bread, vegetables, fruits, meats; and processed or
pickled foods.
- Drinking contaminated water or cow's milk.
- Nursing infants of mothers living near hazardous waste
sites may be exposed to PAHs through their mother's milk.
|
back to top |
|
How
can polycyclic aromatic hydrocarbons (PAHs) affect my health? |
Mice that were fed high levels of one
PAH during pregnancy had difficulty reproducing and so did
their offspring. These offspring also had higher rates of
birth defects and lower body weights. It is not known whether
these effects occur in people.
Animal studies have also shown that PAHs
can cause harmful effects on the skin, body fluids, and ability
to fight disease after both short- and long-term exposure.
But these effects have not been seen in people.
|
back to top |
|
How
likely are polycyclic aromatic hydrocarbons (PAHs) to cause
cancer? |
The Department of Health and Human Services
(DHHS) has determined that some PAHs may reasonably be expected
to be carcinogens.
Some people who have breathed or touched
mixtures of PAHs and other chemicals for long periods of time
have developed cancer. Some PAHs have caused cancer in laboratory
animals when they breathed air containing them (lung cancer),
ingested them in food (stomach cancer), or had them applied
to their skin (skin cancer).
|
back to top |
|
Is
there a medical test to show whether I've been exposed to polycyclic
aromatic hydrocarbons (PAHs)? |
In the body, PAHs are changed into chemicals
that can attach to substances within the body. There are special
tests that can detect PAHs attached to these substances in
body tissues or blood. However, these tests cannot tell whether
any health effects will occur or find out the extent or source
of your exposure to the PAHs. The tests aren't usually available
in your doctor's office because special equipment is needed
to conduct them.
|
back to top |
|
Has the federal government made recommendations to protect human health? |
The Occupational Safety and Health Administration
(OSHA) has set a limit of 0.2 milligrams of PAHs per cubic
meter of air (0.2 mg/m³). The OSHA Permissible Exposure
Limit (PEL) for mineral oil mist that contains PAHs is 5 mg/m³
averaged over an 8-hour exposure period.
The National Institute for Occupational
Safety and Health (NIOSH) recommends that the average workplace
air levels for coal tar products not exceed 0.1 mg/m³
for a 10-hour workday, within a 40-hour workweek. There are
other limits for workplace exposure for things that contain
PAHs, such as coal, coal tar, and mineral oil.
|
back to top |
|
Glossary |
Carcinogen: A substance that can cause
cancer.
Ingest: Take food or drink into your
body.
|
back to top |
|
References |
Agency for Toxic Substances and Disease
Registry (ATSDR). 1995. Toxicological Profile for polycyclic aromatic hydrocarbons (PAHs). Atlanta,
GA: U.S. Department of Health and Human Services, Public Health
Service.
|
back to top |
|
Where can I get more information? |
ATSDR can tell you where to find occupational
and environmental health clinics. Their specialists can recognize,
evaluate, and treat illnesses resulting from exposure to hazardous
substances. You can also contact your community or state health
or environmental quality department if you have any more questions
or concerns. For more information, contact:
|
Agency for Toxic Substances and Disease Registry
Division of Toxicology
1600 Clifton Road NE, Mailstop F-32
Atlanta, GA 30333
Phone: 1-888-42-ATSDR (1-888-422-8737)
FAX: (770)-488-4178
Email: ATSDRIC@cdc.gov
|
back to top |
|