Chemical constituents, risk assessments

In all cases the process of risk assessment of food chemicals has up to now ignored the effect of the other constituents present in that food. The scientific approach to risk (or benefit) assessment has so far demanded a... 

U.S. EPA may list a waste as hazardous for any and all of the above reasons. The majority of listed wastes fall into the toxic waste category. To decide if a waste should be a toxic listed waste, U.S. EPA first determines whether it typically contains harmful chemical constituents. An appendix to RCRA contains a list of chemical compounds or elements that scientific studies have shown to have toxic, carcinogenic, mutagenic, or teratogenic effects on humans or other life forms. If a waste contains chemical constituents found on the appendix list, U.S. EPA then evaluates 11 other factors to determine if the wastestream is likely to pose a threat in the absence of special restrictions on its handling. These additional considerations include a risk assessment and study of past cases of damage caused by the waste. 

The remaining parts of this chapter will provide detailed information about each of these six steps. However, specific strategies for risk assessment and management may need additional elements, depending on the nature of the hazard, the foods in which it may occur and other specific conditions. For example, some additives may also occur as natural constituents in the diet or may be chemically altered when they come into contact with food components. For such substances a unique approach may need to be developed. 

REACH. In 2003 the EU Commission proposed a new chemicals policy -REACH (Registration, Evaluation, and Authorisation of Chemicals). The biocides used in AF products are still registered through the BPD, but the other paint constituents as with all other chemical constituents produced or imported > 1 ton/year on the European market will need to be partly or fully risk assessed under REACH. The legislation is expected to enter into force in 2007 (EU, 2003b). 

Fowles, J. and Dybing, E. (2003) Application of toxicological risk assessment principles to the chemical constituents of cigarette smoke. Tobacco Control, 12(4), 424-30. 

Long-term animal studies of dermal exposure to crude oil can be used to set a no observed adverse effect level (NOAEL) that can be used to predict safe human exposure levels for both dermal and systemic effects. A reference dose of 0.04 mg kg day has been suggested for exposures to crude oil. The individual aliphatic and aromatic fractions of crude oil have also been evaluated for toxicity and sufficient information exists to set references doses for these fractions. An understanding of the exposure to the individual fractions is necessary to use this process. The use of the reference dose for either crude oil as a whole or the individual fractions is preferable to evaluating only the toxic constituents in crude oil. This latter strategy is commonly employed in risk assessment however it ignores the hydrocarbon matrix within which these toxic chemicals are found. This hydrocarbon matrix affects the exposure to... 

Food products contain thousands of compounds — some of nutritive value — nonnutritive components, numerous additives, substances formed during processing, and pesticide residues. Their safety is of utmost importance for human health protection, including cancer risk assessment. In order to evaluate the carcinogenicity of individual food constituents and their mixtures, often of unknown chemical structure, as well as the impact of cooking procedures, short-term reliable and inexpensive tests are necessary. Since cancer risk associated with chemical compounds is thought to stem mainly from their ability to induce mutations, mutagenicity... 

Computerized System for Performing Risk Assessments for Chemical Constituents of Hazardous Waste... 

In addition to size, PM mass and number concentrations, volatility, morphology and chemical composition (e.g. organic, metal, salt content) are critical factors to be considered in the assessment of risk. The evidence regarding the relationship between airborne PM mass exposures (i.e. PM2.5) and patterns of cardiopulmonary morbidity and mortality is quite solid. It is not clear, however, what chemical constituents may be particularly responsible for the observed effects. 

In general, the interactions between xenobiotics and ecosystem constituents are reversible and tend to establish steady states conditioned by the rate-limiting steps. The reversibility applies, of course, only to the interactions at the molecular level, not to the (long-term) impacts on ecosystems. With respect to hazard and risk assessment, parameters regarding the distribution (e.g. bioconcentration and soil sorption), the reactivity (e.g. degradation) and the toxicity (e.g. aquatic species such as fish, crustaceans, algae) are considered. For the description of the chemicals, mostly structurally derived physico-chemical properties are used, among which the most prominent is the 1-octanol/water partition coefficient. The log parameter quanti-... 

A risk assessment for explosivity, oxidising properties and flammability is required unless none of the product s constituents possess such properties, and, in addition, that on the basis of information available the product is unlikely to present dangers of this kind. Due to the type and nature of the studies conducted under the physicochemical data requirements section (see Tables 1 and 2 for a list of the required studies on the active substance and 23 product types to fulfill the BPD), a physico-chemical risk assessment on a particular product is usually qualitative and is based solely on the intrinsic hazards of the constituents. Therefore, the outcome of a physicochemical risk assessment usually relies on the eventual classification of the product for physical and chemical characteristics and this then leads directly to risk management proposals. 

Cefic claims that polymeric materials, reaction intermediates and substances used for R D should not be subject to the REACH evaluation and authorisation process being proposed by the European Commission in its White Paper on future chemicals policy, it is briefly reported. On specific issues, Cefic wants a risk-based approach to chemicals assessment and regulation realistic deadlines for the REACH process and exemption from REACH of finished articles, so that it applies only to substances marketed as substances or as constituents of a preparation. 

Until very recently the risks associated with different types of chemicals such as food additives, pesticides, environmental contaminants and natural constituents of food were assessed and managed separately. However, a particular substance might fall into two or more of these categories and so the opportunity for simultaneous exposure might be overlooked. Furthermore, exposure to a chemical could occur through diet, drinking water, air pollution or dermal absorption. Aggregate exposure assessment aims to take all of the possible sources and routes of exposure into account in a realistic manner and thereby obtain a better overall estimate of risk. Initiatives have been set up in both the... 

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