2. Lubricant Additive Impacts on Human Health and the Environment

It is estimated that, at present, approximately 50 % of all lubricants sold worldwide end up in the environment via total loss applications, volatility, spills or accidents. More than 95 % of these materials are mineral oil based. In view of their high eco-toxicity and low biodegradability, mineral oil-based lubricants make up a considerable threat to the environment. While, most lubricants and hydraulic fluids based on plant oils are rapidly and completely biodegradable and are of low eco-toxicity; moreover, lubricants based on plant oils display excellent tribological properties and generally have very high viscosity indices and flashpoints. However, in order to compete with mineral-oil-based products, some of their inherent disadvantages must be corrected, such as their sensitivity to hydrolysis and oxidative attack, and their behavior at low temperatures. The chapter also makes effort to characterize the potential human health and environmental hazards of widely used classes of lubricating oil additives and poly-alpha-olefin (PAO) base fluids, and the related toxicity levels.