Toxicity, general environment

The hazards of chemicals are commonly detected in the workplace first, because exposure levels there are higher than in the general environment. In addition, the exposed population is well known, which allows early detection of the association between deleterious health effects and the exposure. The toxic effects of some chemicals, such as mercury compounds and soot, have been known already for centuries. Already at the end of the eighteenth century, small boys who were employed to climb up the inside of chimneys to clean them suffered from a cancer of the scrotum due to exposure to soot. This was the first occupational cancer ever identified. In the viscose industry, exposure to carbon disulfide was already known to cause psychoses among exposed workers during the nineteenth century. As late as the 1970s, vinyl chloride was found to induce angiosarcoma of the liver, a tumor that was practically unknown in ocher instances. ... 

STEVENS URETHANE UK,DEPT.OF TRADE IND. UK,LABORATORY OF THE GOVERNMENT CHEMIST SCIENTIFIC COMMITTEE ON TOXICITY,ECOTOXICITY ENVIRONMENT AMERICAN COUNCIL ON SCIENCE HEALTH EUROPEAN COMMISSION TNO PLASTICS RUBBER RESEARCH INSTITUTE DENMARK EU EUROPEAN COMMUNITY EUROPEAN UNION FRANCE NETHERLANDS SCANDINAVIA UK USA WESTERN EUROPE WESTERN EUROPE-GENERAL... 

KemI (2000). Non-toxic Environment. See www.kemi.se Lohse, Joachim et.al. Substitution of Hazardous Chemicals in Products and Processes, Report compiled for the Directorate General Environment, Nuclear Safety and Civil Protection of the Commission of the European Communities, Contract No. B3-4305/2000/293861/MAR/E1,... 

Phosphorus exists mostly in the phosphate form in the general environment. The levels of phosphorus determined in most environmental samples are reported as total phosphorus and do not distinguish between elemental phosphorus and its compounds. However, elemental phosphorus is far more toxic than other oxidized phosphorus states (oxides and acids of phosphorus). This profile reports the level of elemental phosphorus and not total phosphorus in environmental samples. 

Carbon dioxide is, by far, the most attractive SCF for many reasons It is inexpensive and abundant at high purity (food grade) worldwide and it is nonflammable, non-toxic, and environment friendly moreover, its critical temperature T = 31 °C) permits operations at near-ambient temperature which avoids product alteration and its critical pressure (= 74 bar) leads to acceptable operation pressure, generally between 100 and 350 bar. In fact, supercritical carbon dioxide behaves as a rather weak nonpolar solvent, but its solvent power and polarity can be significantly increased by adding a polar cosolvent that is chosen among alcohols, esters, and ketones. Ethanol is often preferred because it is not hazardous to the environment, not very toxic, and available pure at low cost. Hydro fluorocarbons (HFCs) are very costly and their specific properties rarely justify their use in the replacement of carbon dioxide. 

The solvent and/or formulation should not have undesirable effects on the general environment e.g. persistence, odor or environmental toxicity. 

Age can be a factor in toxicity. Generally, the very young and very old are more susceptible to the toxic effects of chemicals. The biological systems of children are not fuUy developed and these immature systems can leave them more vulnerable to toxicity. Old age brings about breakdowns or weaknesses in mature protective systems. This also relates to the health status of the individual. As we age we develop more chronic health conditions and diseases, such as diabetes, heart conditions, cancer, or arthritis. These conditions weaken and compromise our overall health status, making us more susceptible to exposures to chemical or biological agents in our environment. Diet has also been shown to have an effect on the toxicity of substances in animal studies. 

Nogawa K, Honda R, Kido T, Tsuritani I, Yamada Y, Ishizaki M, Ymaya H (1989) A dose-response analysis of cadmium in the general environment with special reference to total cadmium intake limit. Environ Res 48 7-16 Nomiyama K (1982) Carcinogenicity of cadmium. Jpn J Ind Health 24 13-23 Nordberg GF (1989) Modulation of metal toxicity by metallothionein. Biol Trace Elem Res 21 131-135... 

The effects of pollution can be direct, such as toxic emissions providing a fatal dose of toxicant to fish, animal life, and even human beings. The effects also can be indirect. Toxic materials which are nonbiodegradable, such as waste from the manufacture of insecticides and pesticides, if released to the environment, are absorbed by bacteria and enter the food chain. These compounds can remain in the environment for long periods of time, slowly being concentrated at each stage in the food chain until ultimately they prove fatal, generally to predators at the top of the food chain such as fish or birds. 

Isocyanates. Isocyanates in general are toxic chemicals and require great care in handling. Oral ingestion of substantial quantities of isocyanates can be tolerated by the human body, but acute symptoms may develop from the inhalation of much smaller amounts. The inhalation of isocyanates presents a ha2ard for the people who work with them as weU as the people who Hve in the proximity of an isocyanate plant. Adequate control of exposure is necessary to achieve a safe working environment. The suppHers Material Safety Data Sheets (MSDS) have to be consulted for the most current information on the safe handling of isocyanates. 

Nonmolecular species, including radiant quanta, electrons, holes, and phonons, may interact with the molecular environment. In some cases, the electronic environment (3), in a film for example, may be improved by doping with impurities (4). Contamination by undesirable species must at the same time be limited. In general, depending primarily on temperature, molecular transport occurs in and between phases (5), but it is unlikely that the concentration ratios of molecular species is uniform from one phase to another or that, within one phase, all partial concentrations or their ratios are uniform. Molecular concentrations and species that are anathema in one appHcation may be tolerable or even desirable in another. Toxic and other types of dangerous gases are handled or generated in vacuum systems. Safety procedures have been discussed (6,7). 

Carotenoids have two general characteristics of importance to the food iadustry they are not pH sensitive ia the normal 2—7 range found ia foods, and they are not affected by vitamin C, making them especially important for beverages. They are more expensive than synthetic food dyes and have a limited color range. In their natural environment they are quite stable, but they become more labile when heated or when they are ia solution. Under those conditions, there is a tendency for the trans-double bonds to isomerize to the cis-stmcture with a subsequent loss of color iatensity. The results of controlled tolerance and toxicity tests, usiag pure carotenoids, iadicate that they are perfecdy safe as food colors (132). 

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