THE PROBLEM OF CHEMICAL RISKS

In sum, if viewed apolitically, the problem of chemical hazards tends not to include considerations of (1) who gains and loses in risk decisions, (2) what logics and forces act on firms making such decisions, and (3) what responsibilities contemporary consumers are increasingly faced with, under the conditions of risk and uncertainty that result. A political approach to the risk ecology of the lawn, which addresses all these issues, seems relevant for understanding the problem. 

The nuts and bolts of animal testing, and the problems of test interpretation and extrapolation of results to human beings, comprise one of the central areas of controversy in the field of chemical risk assessment. They shall be with us, in one form or another, for the remainder of this book. Suffice it to say at this point that animal tests are extensively used to identify the toxic properties of chemicals -in part because animals can be good models for humans and in part because we do not have other good choices - and will continue to be used for that purpose for a long time to come. We shall now begin to show how this is done. 

In the next three chapters we describe some of the many ways chemical exposure can lead to toxic injury and disease, and then enter the final third of the book, devoted to the problem of calculating risks. 

When more than two chemicals are involved, the problem of determining risks becomes increasingly complex. Scientific study of chemical mixtures has been relatively limited because of the sheer number of combinations possible. Even if the exact effects of exposure to mixtures are unknown, reducing exposure is still a good strategy to lower risk. 

Lake District National Park Authority (2002) Habitats of the Lake District , Education Service Factsheet, Lake District National Park Authority, Kendal Light, A. (2003) Urban ecological citizenship , Journal of Social Philosophy, vol 34, no 1, pp44—63 Nilsson, R. (1998) Integrating Sweden into the European Union Problems concerning chemicals control , in R. Bal and W. Halffman (eds) The Politics of Chemical Risk, Kluwer Academic Publishers, Dordrecht, ppl59—171... 

R. Nilsson, Integrating Sweden into the European Union Problems Concerning Chemicals Control, The Politics of Chemical Risk—Scenarios for a Regulatory Future 9, ed. R. Bal and Halffman (Dordrecht, Netherlands Kluwer, 1998), pp. 159-71. 

When designating which ministry is to have primary responsibility for chemicals control, familiarity with legislation of relevance for the management of chemical risks is of importance. Therefore, countries often confer responsibility for chemicals legislation on ministries of the environment or ministries of health. Ministries of the environment (or the like) may be preferable due to the fact that issues of risk assessment and risk management in general, as well as for chemicals, are frequently dealt with in these ministries (air, water and soil pollution, waste problems). Furthermore, modem chemicals control at an international level, in addition to focusing on health problems, focuses very much on environmental risks and environmentally mediated health risks, such as problems with POPs. 

Many very hazardous solvents, such as benzene and carbon tetrachloride, were widely used until the 1970s. The situation was very similar for the use of pesticides. Among the toxic pesticides that were still in wide use 20 years ago were chlorophenols, DDT, lindane, and arsenic salts, all of which are classified as human carcinogens as well as being acutely toxic. Fortunately, use of these kinds of very toxic chemicals is now limited in the industrialized world. However, because the number of chemicals used in various industries continues to increase, the risks of long-term health hazards due to long-term exposure to low concentrations of chemicals continues to be a problem in the workplace. 

It was not nndl the 1950s that detonation flame arresters made of crimped metal ribbon elements were developed and began to be used more freqnendy (Binks 1999). The major impetus for die use of crimped metal ribbon detonation flame arresters in the US was the enactment of clean air legislation (Clean Air Act of 1990) which inadvertently created a safety problem by requiring reductions in volatile organic compound (VOC) emissions. To do this, manifolded vent systems (vapor collection systems) were increasingly installed in many chemical process industry plants which captured VOC vapors and transported them to suitable recovery, recycle, or destruction systems. This emission control requirement has led to the introdnction of ignition risks, for example, from a flare or via spontaneous combustion of an activated carbon adsorber bed. Multiple... 

It thus becomes necessary to preempt the problem by tightly controlling the FW pH, temperature, and residual hardness levels where MU water source contains a high silica level (say, over 20-30 ppm Si02). The location of FW line chemical injection points and the type of chemicals dosed also may influence the risk of silicate sludges and scales developing, and these factors may also need to be considered. 

The most difficult problem of risk evaluation linked to chemicals will be discussed in this Part. This is primarily a medical problem, which therefore comes within the competence of the company medical officer and epidemiologists, but neverthel need not only be dealt with by them. The person in charge of safety control in a place where chemicals are handled also has to tackle this problem. This person will have to take into account the level of toxicity risk of a substance. This will determine the constraint level of the measures to be taken, its favoured means of penetration, which depends on the activity, and its penetration properties specific to the organism. The physical properties of the substance (which will determine the nature of the precautions to be taken) and also the values of toxicity parameters have to be taken into account. He has to check the container labelling and know how to interpret and explain the toxicity instructions on this labelling. 

Additionally, the integration of geographic information system (GIS) with analytical data is an effective procedure in addressing the problem of spatial and temporal variability of the different parameters involved in the environmental fate of chemicals. Based on accurate local estimations, GIS-based models would then also allow deriving realistic and representative spatially averaged regional PECs. Table 4 shows some studies that have used GIS-based methodologies to perform a site-specific risk assessment of PECs in different exposed ecosystems. 

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