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Hydraulic fluids are used for the transmission of power, which is captured when fluid is pushed from one confined place to another through pressurized tanks, pistons, and tubing. Hydraulic fluids also allow machines to use less energy by keeping parts lubricated, transferring heat, and removing impurities.
Some common hydraulic fluids are water, silicone, petroleum oil, synthetic hydrocarbons (such as polyalphaolefins or PAO), and even vegetable oil. If someone is exposed to hydraulic fluid on the skin, a soap and water wash should be all that is needed. Occasionally, some hydraulic fluids can cause skin drying and irritation. Eye exposures tend to resolve with gentle flushing of the eye with water. Doing a gentle eye rinse for 15 minutes with water at a comfortable temperature is recommended. You don't have to hold the eye open! Just let the water run over the eye and try to blink occasionally under the stream of water. Just make sure to do it for the full 15 minutes. Oily substances can leave a film on the eye, making vision temporarily blurry.
Swallowing one of the oily hydraulic fluids, like the synthetic hydrocarbons, is potentially dangerous. These products have a tendency to get into the airway more easily than water-based substances. Remember, your food pipe is right next to your air pipe. If someone coughs hard or vomits after swallowing the hydraulic fluid, they are in danger of aspiration – getting hydraulic fluid into the lungs. If the substance is swallowed and goes to the stomach, diarrhea is usually the only adverse effect.
Some lesser known types of hydraulic fluids are the chlorinated hydrocarbons and phosphate esters. These chemicals share similarities with some pesticides and can have toxicity in humans when swallowed or if enough mist is inhaled. However, just as safer alternatives have become more common for pesticides, hydraulic fluid industries are promoting safer substances as well.
Overall, most hydraulic fluids are not particularly dangerous. However, they are not meant to be touched directly, swallowed, or inhaled. Used hydraulic fluid can contain metal fragments and waste materials collected during the time of use. Even if water is the hydraulic fluid, you would not want to handle it after it has been used due to these possible contaminants. Skin exposure to used hydraulic fluid can be managed by washing your hands with soap and water – but it is best to limit unnecessary exposure to hydraulic fluid.
If someone has been exposed to hydraulic fluid at work or at home, please log on to the webPOISONCONTROL® online tool for guidance or call Poison Control at 1-800-222-1222. Whether you log on or call, expert assistance is available 24 hours a day.
Pela Soto, PharmD, BSHS Pharmacogenomics, BS Microbiology
Certified Specialist in Poison Information