ABSTRACT
Slightly more than 100,000 chemicals are produced in such an amount that they threaten or may threaten the environment. They cover a wide range of applications: household chemicals, detergents, cosmetics, medicines, dye stuffs, pesticides, intermediate chemicals, auxiliary chemicals in other industries, additives to a wide range of products, chemicals for water treatment, and so on. They are viewed as mostly indispensable to modern society, resulting in an increase of about 40-fold in the production of chemicals during the last four to five decades. A minor or even sometimes a major proportion of these chemicals reaches the environment through their production, transport, application, or disposal. In addition, the production or use of chemicals may cause more or less unforeseen waste or by-products, for instance, chlorocompounds from the use of chlorine for disinfection. The conflict lies in the fact that humans would like to have the benefits of using chemicals but cannot accept their harmful effects, which raises several urgent questions that we have already mentioned in this book. These questions cannot be answered without at least partial application of models, and we cannot develop models without knowing the most important parameters, at least within some ranges. OECD has made a review of the properties that we should know for all chemicals. We need to know the boiling point and melting point to identify the form in which the chemical (as solid, liquid, or gas) is found in the environment. We must know the distribution of chemicals in the five spheres: hydrosphere, atmosphere, lithosphere, biosphere, and technosphere, as mentioned in Chapter 2; their solubility in water; their lipid/water partition coefficient, denoted by Kow; Henry’s constant; their vapor pressure; their rate of degradation by hydrolysis, photolysis, chemical oxidation, and microbiological processes; and the adsorption equilibrium between water and soil-all as a function of temperature. We need to discover the interactions between living organisms and chemicals, which implies that we should know the biological concentration factor (BCF), that is, the ratio of the concentration in an organism to the concentration in the media, biomagnification (see Chapter 2), uptake rate and excretion rate by
the involved organisms, and where in the organisms the chemicals will be concentrated, not only for one organism but for a wide range of organisms. Table 3.1 gives an overview of the most relevant physical-chemical properties of organic compounds and their interpretation with respect to their behavior in the environment, which should be reflected in their quantification and possibly the developed models. A complete knowledge of all consequences of the use of chemicals may require considerably more knowledge, particularly of the biological effects of chemicals.
