Cases chemical cocktail

It is quite clear that traditional risk assessment and risk management approaches are not working sufficiently well in the field of chemicals policy, in particular not in cases of high uncertainty. The traditional approach could hardly deal with the early chemical problems, characterised by evident impacts such as acute effects, and is even less effective in the present situation, with globalised flows of articles that contain hazardous chemicals and the resulting complex chemical cocktail, which may cause diffuse but significant adverse effects on human health and the environment. 

But what about the more volatile organic compounds. Even for these compounds there are differences in the degree to which they are absorbable, and the determining factor is the compound s blood gas partition coefficient. To understand how the blood gas partition coefficient governs absorption, consider a vapor enclosed in a cocktail shaker with a bit of water. After the cocktail is shaken, the vapor can partition either into the water or it can primarily remain in the atmosphere within the shaker. In this case, chemicals that remain in the shaker s atmosphere have low blood gas partition coefficients, whereas chemicals found predominantly in the liquid have high values for the coefficient. These tendencies dramatically influence the capacity for absorption, because low values of the blood gas coefficient are indicative of low rates of absorption, whereas elevated coefficient values predict much higher rates of absorption across the lung epithelium. 

In some cases, the effects of complex environmental mixtures could be accounted for in terms of concentration-additive effects of a few chemicals. In sediments of the German river Spittelwasser, which were contaminated by chemical industries in its vicinity, around 10 chemicals of a cocktail of several hundred compounds were found to explain the toxicity of the complex mixture to different aquatic organisms (Brack et al. 1999). The complex mixture of chemicals contained in motorway runoff proved toxic to a crustacean species (Gammarus pulex). Boxall and Maltby (1997) identified 3 polycyclic aromatic hydrocarbons (PAHs) as the cause of this toxicity. Subsequent laboratory experiments with reconstituted mixtures revealed that the toxicity of motorway runoff could indeed be traced to the combined concentration-additive effects of the 3 PAHs. Svenson et al. (2000) identified 4 fatty acids and 2 monoterpenes to be responsible for the inhibitory effects on the nitrification activity of the bacteria Nitrobacter in wastewater from a plant for drying wood-derived fuel. The toxicity of the synthetic mixture composed of 6 dominant toxicants agreed well with the toxicity of the original sample. 

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