As in all things industrial and chemical, safety is of the utmost importance when handling and working around hydraulic fluid. The following summary will serve as a reminder for handling hydraulic fluids appropriately and safely.

It is crucial to know the dangers hydraulic fluids pose, and how those dangers can be avoided and dealt with. Contact with some types of hydraulic fluids can irritate your skin or eyes, and consuming certain types of hydraulic fluids can cause pneumonia, intestinal bleeding, or death in humans. Swallowing or inhaling certain types of hydraulic fluids has caused nerve damage in animals. These substances have been found in at least 10 of the 1,428 National Priorities List sites identified by the Environmental Protection Agency.

Defining hydraulic fluids

The three most common types of hydraulic fluids are mineral oil, organophosphate ester, and polyalphaolefin. Some of the trade names for hydraulic fluids include Durad, Fyrquel, Skydrol, Houghton-Safe, Pydraul, Reofos, Reolube, and Quintolubric. Some hydraulic fluids have a bland, oily smell and others have no smell; some will burn and some will not. Certain hydraulic fluids are produced from crude oil and others are manufactured.

Hydraulic fluids can enter the environment from spills, leaks in machines that use them, or from storage areas and waste sites. If spilled on soil, some of the ingredients in hydraulic fluids will stay on top and others will sink into the groundwater. In water, some hydraulic fluids' ingredients will transfer to the bottom and can stay there for more than a year. Certain chemicals in hydraulic fluids may break down in air, soil, or water, but how much breaks down is not known. Fish may contain some hydraulic fluids if they live in contaminated water.

There are three main ways a person may be exposed to hydraulic fluids, some of which can easily be avoided to those that come with the job:
touching or swallowing hydraulic fluids,
• breathing hydraulic fluids in the air near machines where hydraulic fluids are used, or
• touching contaminated water or soil near hazardous waste sites or industrial manufacturing facilities that use or make hydraulic fluids.

Health concerns

Little is known about how hydraulic fluids can affect your health. Hydraulic fluids are actually mixtures of chemicals. Therefore, some of the effects seen may be caused by additives in the hydraulic fluids.

The effects of breathing air with high levels of hydraulic fluids are not known. Weakness of the hands was seen in a worker who touched a great deal of hydraulic fluids. Rabbits that inhaled very high levels of one type of hydraulic fluid had trouble breathing, congested lungs, and became drowsy. The nervous systems of animals that swallowed or inhaled other hydraulic fluids were affected immediately with tremors, diarrhea, sweating, breathing difficulty, and sometimes several weeks later with weakness of the limbs, or paralysis.

The immediate effects are caused because hydraulic fluids stop the action of certain enzymes, called cholinesterases, in the body. There are no reports of people swallowing or breathing the types of hydraulic fluids that cause these effects. When certain types of hydraulic fluids were put into the eyes of animals or allowed to touch the skin of people or animals for short periods of time, redness and swelling occurred. It is not known whether hydraulic fluids can cause birth defects or reproductive effects.

The Department of Health and Human Services (DHHS), the International Agency for Research on Cancer (IARC), and the EPA have not classified hydraulic fluids as to their carcinogenicity. Hydraulic fluids cannot be measured in the body but certain chemicals in hydraulic fluids can be measured. Some hydraulic fluids stop the activity of cholinesterases in blood and this activity can be measured. However, many other chemicals also cause this effect. This test isn't available at most doctors' offices, but can be done at special laboratories that have the right equipment.

More information

There are no federal government recommendations to protect humans from the health effects of major hydraulic fluids. However, mineral oil, the major chemical ingredient of one type of hydraulic fluid, is part of the petroleum distillate class of chemicals and there are regulations for these chemicals.

The Occupational Safety and Health Administration has set an exposure limit of 2000 mg/m3 petroleum distillates for an 8-hr workday, 40-hr work week. The National Institute for Occupational Safety and Health recommends an exposure limit of 350 mg/m 3 petroleum distillates for a 10-hour workday, 40-hour work week.

Agency for Toxic Substances and Disease Registry (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.

This information was provided by the Agency for Toxic Substances and Disease Registry. For more information, contact the ATSDR, Div. of Toxicology, at (888) 422-8737 or e-mail ATSDRIC@cdc.gov.