PCBs , contaminants from hydraulic fluids

Before the 1960s, products were introduced based on alkyl aryl phosphates that could contain chlorinated aromatic hydrocarbons. Such products have now entirely disappeared from commercial use, and the vast majority of the industrial organophosphate esters are based on triaryl phosphates with no halogenated components (Marino 1992). However, at older waste disposal sites, hydraulic fluid site contaminants could contain chlorinated hydrocarbons. As with the PCBs formerly included as additives in other forms... 

Polychlorinated biphenyls (PCB), are a family of toxic, oily, non-flammable chemicals. They are man-made products and were first commercialised in 1929 (by Monsanto). They were mainly used in electrical equipment (e.g., transformers and capacitors), as heat transfer and hydraulic fluids, and as plasticisers from World War I until recently, mainly due to their exceptional thermal and chemical stabilities. Although their production in the USA was stopped in 1977 (they were banned worldwide), some production still continues, and it is believed that large quantities of PCB may still be present in some old transformer and capacitor systems. PCB are certainly still present in the USA in some electrical equipment and are frequently found at toxic waste sites and in contaminated sediments worldwide. The sealants based on polysulfhide polymers that were used in buildings some 20-40 years ago contained PCB, which has been shown still to exist at alarming levels in some houses in Sweden, [24]. 

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