In the EU, it is estimated that approximately 1 million workers are exposed to mineral oils as used engine oils. Used engine oils are classified as carcinogenic to humans (Group 1) by IARC, which means they are known to cause skin cancer in humans.

The main route of exposure, and to which the main pathologies or adverse effects are related, is the dermal route, which means exposure occurs when the skin is contaminated with used mineral oils. Exposure to this type of oils may cause skin cancer. Inhalation exposure is unlikely.

Where risks occur

Used engine oils can be found in all vehicles or machinery with internal combustion engines, such as cars and mopeds, diesel locomotives, ship engines, aircraft and portable machinery including chainsaws and lawnmowers. It can also be found where waste from the maintenance of such engines is handled, either for processing and disposal or for reuse or recovery. Waste used engine oils are reused as additives in the manufacture of cements and as binders in crumb rubber asphalts for road construction.

Workers most likely to be exposed to waste engine oils are those involved in the maintenance, repair or adjustment of these engines. In particular, the profession of car mechanic or any other equipment with a combustion engine, and operations involving the draining of engine oil or contact with impregnated parts, will be the most at risk.

Other professions at risk from dermal exposure to used engine oils are those related to the recovery, regeneration or recycling of vehicle waste, such as scrapyard workers, waste managers in charge of collecting used engine oils.

More about the substance

Mineral oils that have been used before in internal combustion engines are refined petroleum products with chemical additives that are used to lubricate and cool the moving parts within the engine, as well as to protect metals against corrosion.

PAH (polycyclic aromatic hydrocarbons) are considered to be the cause of carcinogenicity. Unused mineral engine oils have a very low PAH content and are therefore not considered to be carcinogenic; however, during their use in internal combustion engines, changes in their composition occur, mainly due to increased temperatures and the accumulation of unburned fuel residues and combustion products, together with the presence of air.

These changes in the composition lead to a significant increase (among other chemical species) in PAH content, which increases the hazard of using the oils. The PAH content increases with the length of time the oil is used in the engine and also with the number of kilometres the oil is used.
How the symptoms can affect you

When the skin is impregnated with used engine oils, either directly or through contact with stained clothing, irritation and allergic reactions can occur. Effects such as eczema, excess oil on the skin and acne have also been observed. In addition, as mentioned above, dermal exposure to used motor oils has been shown to cause skin cancer, observed in the scrotum. Scrotal cancer is a rare disease, associated only with occupational exposures. It was the first occupational disease to be described and was associated with the chimney sweeping profession.

What you can do

The best solution is to control exposure by elimination or substitution. However, since PAHs originate from burning processes it is not easy to eliminate or substitute this substance. It is therefore essential to enclose the source to reduce dermal exposure, resulting mostly from leakage, splashing or impregnated surfaces.

For the most common engine maintenance tasks, the option of using a closed system is not feasible as human manual intervention by the person carrying out the tasks is required. However, funnel systems to collect the waste oil from a location very close to the outlet, which prevent splashing onto skin, eyes, clothing or nearby surfaces can be installed. Collecting containers for waste oil should be designed to prevent leakage or splashing.

Establish and supervise safe handling procedures, both for the oil itself and for the impregnated parts, including the use of rags for soiled absorbents or papers and suitable containers holding the waste, are of particular importance.

Whenever manual operations are performed that may lead to skin contact with used oil, protective gloves and goggles should be worn, as a general rule and depending on the specific techniques used and as determined by the risk assessment. Gloves should be made of an agent-impermeable material, such as vinyl or nitrile, and cover the entire surface of the hand.
In general, disposable gloves should be disposed off each time the worker removes them. In the case reusable gloves are used, they should be properly washed before removal, to avoid staining hands upon removal and subsequent re-application of the glove to contaminated skin. However, when selecting the most appropriate type of glove, consideration should be given to whether other hazardous products are being handled or whether it is necessary to protect against other hazards such as burns, cuts, punctures, etc.

For maintenance work where the vehicle needs to be lifted to access the underside, goggles are required to protect workers’ eyes from splashes. Face shields could also be used.