Supertoxic compounds

Supertoxic compounds are those with LC50 (96h) values <10pg/L (Scott etal. 1987). Fenvalerate is considered supertoxic, as judged by LC50 (96 h) values of <1.0 pg/L for sensitive aquatic organisms, and <10 pg/L for representative aquatic species (Table 20.5). 

Due to the myriad of sources of contamination in polymer recycle, the effect of contamination is difficult to predict and even more difficult to quantify. The plastics recycler may not be aware of the presence of some contamination since it is present in such low amounts. It should be bourn in mind that, despite the possible low levels, some contamination, for example, transformation products of flame retardants are extremely toxic and thus can pose a health risk to operators of the recycling process and end-users of the recycled product. Thus in all forms of recycling, especially pyrolysis and incineration, a careful approach is necessaiy in order to avoid the production of supertoxic compounds. 

Monomethylmercury (MMM) is the most toxico-logically prominent of organic mercury compounds due to its environmental ubiquity and high potential for bioconcentration. Although DMM is less frequently encountered, it exhibits a far more toxic profile. Based on the lethality of only a few drops of the substance, DMM has been classified as a supertoxic chemical. Absorption of 100 pi of the colorless liquid is equivalent to a severely toxic dose of 100-200 mg of mercury per 100 ml of whole blood. Its synthesis, transportation, and use should be minimized and exercised with only extreme care. 

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