Is Hydraulic Fluid Poisonous?

By London Fog

March 11, 2021


If you own any heavy machinery, be it a car, tractor, or something else, you will know what hydraulic fluids are. They must be changed and replaced periodically to ensure your vehicle operates correctly. 

It is really easy to accidentally spill some of these fluids onto your skin while changing them. What if you have young children that wander past and decide to take a sip of the hydraulic fluid? 

Poison Control states that the ingestion of oil-based hydraulic fluids is potentially dangerous. They can enter your airway with less difficulty than the water-based options which leads to health issues.

If hydraulic fluids are ingested and reach the stomach this is less of a problem as they are destroyed in the acid and generally only result in diarrhea.

Hydraulic fluids are designed to be as non-toxic as possible to prevent problems from occurring. There has been a big move within the industry towards the use and production of safer substances.

That being said, all hydraulic fluids should be treated with caution as many do still contain harmful chemicals. Assume that they are toxic and take all of the necessary safety precautions when you are working with them. 

Appropriate safety precautions to take include tying long hair back, wearing protective goggles, a dust mask, an apron, and gloves to protect your skin. Inhaling toxic fumes from hydraulic fluids can result in damage to your nervous and respiratory systems.

You should only work with hydraulic fluids in open air or rooms with good ventilation systems. Take care to close all containers securely when not in use and be aware of spills and slippery floors.

What does hydraulic fluid do to the skin?

Most hydraulic fluids will not cause a great deal of damage to your skin. If you do get any on 3you, you should not be lax about it and instead, immediately go and wash it off using soap and warm water.

If you work with hydraulic fluids regularly it may be worth investing in a barrier cream. These have been specially designed to protect your skin from the harmful effects of hydraulic fluids.

Some hydraulic fluids can cause irritation to your skin resulting in swelling and redness. This is because the fluids prevent the cholinesterases in the body from working. This can lead to contact dermatitis, eczema, and even skin cancer.

This last one is only likely if you frequently expose your skin to hydraulic fluids. 

If the hydraulic fluid is pressurized then it will likely cause a burn to form on your skin. If it is under any pressure exceeding 100 PSI then the fluid has the potential to penetrate your skin. This is known as hydraulic fluid injection and can be very dangerous.

It is said to feel like a sting but will quickly swell and become painful. If it is not treated promptly, this can lead to your tissue becoming necrotic. This can lead to amputation, or in extreme cases, death. 

If you get hydraulic fluid in your eyes you should immediately find an eye bath or eye washing station. Flush your eye by placing it under a stream of lukewarm water.

Allow the water to run over your eye for at least 15 minutes, blinking occasionally. You may have an oily film residue left on your eye for a few hours, causing your vision to appear blurry. 

Is hydraulic fluid carcinogenic?

The Environmental Protection Agency (EPA), International Agency for Research on Cancer (IARC), and the Department of Health and Human Services (DHHS) have not categorized hydraulic fluids as being carcinogenic. 

While it is not deemed to cause cancer, there are notable adverse side effects from working too closely with hydraulic fluids. This is because one of the main components is mineral oil, which is a petroleum distillate.

These chemicals have strict regulations, which has led to the Occupational Safety and Health Administration setting an exposure limit. This is 2,000 mg / m3 for a 40 hour work week spread over 8 hour working days. 

In 2019 a study was conducted into hydraulic fracturing chemicals. This tested the fluids and water run off from 1,173 different chemicals. In the study, they compared data on many different chemicals from different sources to work out their carcinogenic effects and risks.

This data came from the HF chemical data from the EPA, the agent classification data from the IARC, the Carcinogenic Potency Database (CPDB) from Toxnet, and the Chemical Abstract Service Registry Numbers.

Compiling this data allowed scientists to understand the potential carcinogenic effects of hydraulic fluids. The results showed that when compared to the IARC data 48 chemicals in hydraulic fluids are potentially carcinogenic, including 14 that are definitely carcinogenic.

When compared to the CPDB data on rats and mice, it is suggested that 66 chemicals are possibly carcinogenic. 

Is hydraulic fluid flammable?

We know that when the temperature drops low enough hydraulic fluids can freeze, but can they catch fire if they get hot enough? There are 5 main types of hydraulic fluid – mineral oil, fire-resistant fluid, water and oil emulsions, water-glycol, and phosphate esters. 

Mineral oils are based in petroleum and are flammable in temperatures between 300 to 600 degrees Fahrenheit. 

Water-based hydraulic fluids are inflammable. This is because they contain at least 35% water, and can reach up to 80% concentration. This water cannot catch fire and so neither can the hydraulic fluid. They can cause issues with corrosion though. 

Fire-resistant fluids you would expect to not be flammable, but this is untrue. Under extreme enough temperatures and pressure, they too will ignite. The risk of this happening is greatly reduced. All fluids with the exception of the mineral oil-based ones are considered to be less flammable and hazardous. 

When hydraulic fluids are traveling through the hydraulic systems they are underneath incredible pressure of around 2,000 – 3,000 PSI. This means that if there is a hole anywhere, atomized hydraulic fluids will be allowed to escape.

In this situation, the fluid becomes very flammable and explosive. These dangers have been noted at as low as 250 PSI too.