Toxicity and Environmental Hazard

Although Cr(VI) oxidants are very versatile and efficient, they have one drawback, which becomes especially serious in larger-scale work the toxicity and environmental hazards associated with chromium compounds. The reagents are used in stoichiometric or excess amount and the Cr(III) by-products must be disposed of safely. 

Figure 2.1 shows a typical assessment procedure Ai5 A similar procedure should be applied to ensure that operational, toxic and environmental hazards are identified and assessed in order to specify safe operation. 

On the other hand, though toxicity and environmental hazardousness of most ILs is still to be completely assessed (75), their very low vapor pressure may alleviate the safety restrictions as far as an (xcid cloud event or fiammability risks are concerned. 

The characterisation of health hazards of food contaminants, the assessment of the occurrence of undesirable compounds in food and the estimation of the dietary intake are key issues in the risk assessment. In 2000, the European Commission published a White Paper on Food Safety, which underlined the importance of ensuring the highest possible standards of food safety and proposed a new approach to achieve them. Recently, PFCs have gained increased scientific and socioeconomic interest as emerging environmental contaminants due to the unique combination of persistence, toxicity and environmental prevalence. Risk assessment of the dietary exposure to PFCs, however, is hampered by the lack of sufficient data about the occurrence of these contaminants in food. 

Mahlman M. 1991. Dangerous and cancer-causing properties of products and chemicals in the oil refining and petrochemical industry, part Xll. Human health and environmental hazards. In MA Mehlman, ed.. Advances in Modern Environmental Toxicology, Vol XIX Health and Risks from Exposure to Complex Mixtures and Air Toxic Chemicals, Princeton Scientific Publishing CO, Inc., Princeton, New Jersey, 99-116. 

OECD has published a document on a Harmonised integrated classification system for human health and environmental hazards of chemical substances and mixtures (OECD 2001b). Chapter 2.1 addresses a harmonized system for the classification of chemicals which cause acute toxicity, and Chapter 2.8 addresses the chemicals which cause specific target organ oriented systemic toxicity following a single exposure. 

It is obvious that synthetic pesticides are important in controlling weeds and plant-pathogenic fungi, but in judging the efficacy of a method, it is essential to assess its nontarget toxicity, including health and environmental hazards. The literature abounds with reports that synthetic pesticides affect nontarget plants, their consumers and the environment (2). Thus, plant protection needs... 

Common alcohol oxidation methods employ stoichiometric amounts of toxic and reactive oxidants like Cr03, hypervalent iodine reagents (Dess-Martin) and peracids that pose severe safety and environmental hazards in large-scale industrial reactions. Therefore, a variety of catalytic methods for the oxidation of alcohols to aldehydes, ketones or carboxylic acids have been developed employing hydrogen peroxide or alkyl hydroperoxides as stoichiometric oxygen sources in the presence of catalytic amounts of a metal catalyst. The commonly used catalysts for alcohol oxidation are different MoAV(VI), Mn(II), Cr(VI), Re(Vn), Fe(II) and Ru complexes . A selection of published known alcohol oxidations with different catalysts will be presented here. 

The basic idea of the CLH process is the transfer of responsibility for classification and labeling from industrial companies to authorities on a European Community level. In case of active substances in biocidal or plant protection products, all intrinsic properties including physicochemical properties, human health hazards, and environmental hazards are subject to the harmonization. By contrast, in the case of chemicals which are used in other application fields only some specific hazard classes are considered in the CLH procedure. According to Article 36 of the CLP Regulation, these are respiratory sensitization, carcinogenicity, germ cell mutagenicity, and reproductive toxicity. Consequently, these provisions have... 

Green chemistry utilizes the information that is now available to the scientific community about the toxicity and other hazards posed by certain chemicals. Through a combination of knowledge of the nature of a chemical s hazardous properties with the ability to manipulate the chemical s structure, chemists possess the ability and skill to mitigate the hazard. Selection of a solvent should be based not only on any hazards that the chemical may possess, but also on existing environmental problems that its use may exacerbate. Selection of solvents needs to optimize the utility of the solvating material and minimize its environmental impact. 

Swedish law requires that major retailers make an assessment of potential health and environmental hazards when deciding on which products to stock and sell. As a guide to which chemicals should be avoided, KEMI has published a list of especially hazardous chemicals ( OBS-listan ). The hazard profiles of the KEMI-listed substances differ widely, from decidedly toxic compounds, like arsenic salts and benzene, to practically innocuous substances, such as metallic zinc and many zinc compounds. (Like any other chemical, including table salt, zinc and its compounds should, of course, not be dumped in rivers in large quantities, but they are perfectly safe in most other contexts.)... 

In recent years, many efforts are being made to avoid the problematic effects of solvents and many international and national regulations have been established (see Chapter 19 of Ref. [24]) toxic solvents are being replaced by non-toxic ones and environmentally hazardous solvents by harmless ones. The search for new environmentally benign reaction media is the subject of current research and there are many studies into the use of supercritical fluids and room temperature ionic liquids as such media (see 11 and Section 12.7). 

Finally, a recent study was undertaken to assess the human and environmental hazard of recycled tire crumb as ground covering in playgrounds (Birkholz et al., 2003). Here, the PEEP scale was called upon to estimate hazard associated with aquatic exposure to water-soluble extracts of tire crumbs. Based on an initially-determined PEEP value of 3.2 for projected volumes of tire crumb leachates to the aquatic environment and a documented decrease in toxicity three months after tire crumb cover had been in place, the study concluded that tires recycled in this fashion would not present a significant risk of contamination for either receiving surface or groundwaters. 

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