Silicones

Abstract

Tbe chemical and physical properties of silicones are briefly summarized to provide a basis for assessing their fate and effects in the environment. Roughly one-half of the 400 000 tonnes of silicone produced during 1988 worldwide were believed to have been the potentially environmentally mobile fluids. About one-half of this fluid could conceivably gain entry to aqueous environments, via sludge disposed from Waste Water Treatment Plants, storm water run-off and other sources. Following introduction, the low molecular weight species are either lost to the atmosphere or adsorbed onto sedimenting particles. All of the higher molecular weight PDMS fluids are believed 10 be adsorbed out of the liquid phase, so none of them remain in the water. Sedimented silicones are believed to become permanent, innocuous, inert, minuscule components of the sediments. Since the use of these innocuous silicone fluids is expected to continue to increase, and, although they clearly pose no direct toxic hazards, their fate and elfects in or on the environment will continue to be studied.