Chemical additives environmental concerns

TABLE II. Chemicals of environmental concern and plastic additives with analogous structures... 

Simultaneous exposure of rats to Aroclor 1254 or 1260 and chemicals of environmental concern such as the pesticides mirex, photomirex, and/or kepone in the diet resulted in increased severity of the liver lesions attributed to exposure to chlorinated biphenyls alone (Chu et al. 1980). Induction of hepatic AHH activity by Aroclor 1254 in the diet of lactating rats was increased in an additive manner by simultaneous dietary exposure to polybrominated biphenyls such as Firemaster BP-6 (McCormack et al. 1979). 

The formulation of a carrier depends on four considerations (/) the carrier-active chemical compound (2) the emulsifier (J) special additives and (4) environmental concerns. Additional parameters to be considered in the formulation of a carrier product with satisfactory and repeatable performance arise from the equipment in which the dyeing operation is to be carried out. The choice of equipment is usually dictated by the form in which the fiber substrate is to be processed, eg, loose fiber, staple, continuous or texturized filament, woven or knot fabric, yam on packages or in skeins (see Textiles). 

The negative aspects of chemical additives appear to be getting more and more attention in the public debate. Results linking chemical additives to adverse environmental and human health impacts are being produced. But more results are needed. More economic valuation studies are needed to support analysis as well as impact analysis on parameters such as human fertility, animal reproduction and animal productivity. Of big concern for the authors of this chapter is the need to know more about diffuse exposure from the use of products containing chemical additives. 

Antimony (Sb), 3 41-56, 56. See also Group Ill-Sb system InAsSb alloy InSb photodiode detectors/arrays Lead-antimony alloys Low antimony lead alloys Stib- entries in babbitts, 24 797 catalyst poison, 5 257t chemical reactions, 3 42—44 in coal, 6 718 economic aspects, 3 47-48 effect of micro additions on silicon particles in Al-Si alloys, 2 311-312 effect on copper resistivity, 7 676t environmental concerns, 3 50 gallium compounds with, 12 360 health and safety factors, 3 51 in pewter, 24 798... 

Situated between the solid and gaseous states as the only non-metallic element liquid at ambient temperature, bromine is sandwiched in the periodic table between the ubiquitous chlorine and the rather rare iodine. In terms of production volumes it is neither a bulk commodity chemical like chlorine, nor a speciality chemical like iodine. And commercially, bromine is beset by uncertainty. Until the 1970s, the major market forbromine was in dibromoethane - a co-additive for leaded petrol. The phase-out of lead in petrol could have spelled the collapse of the bromine industry, but alternative bromine markets developed and the industry both rationalised and flourished. However, although world bromine production continues to increase slowly, fresh environmental concerns have emerged and the industry is once more under threat. Details are given. 19 refs. 

Poppy cultivation and opium processing also have consequences for the environment. Waste from morphine extraction can cause environmental damage when dumped by processors. In addition to water pollution from this chemical dumping, other environmental concerns include the deforestation that may occur when clearing land for poppy cultivation, soil erosion, and dangers to wildlife in the area where these chemicals are dumped. 

The four-coordinate sqnare planar iron(n) porphyrins discussed above are not only of great valne in heme protein model chemistry, but also in chemical applications, since they undergo a wealth of ligand addition reactions. For example it has been shown that TPPFe complexes are active catalysts for important carbon transfer reactions in organic chemistry and are found to catalyze the stereoselective cyclopropanation of aUcenes, olefin formation from diazoalkanes, and the efficient and selective olefination of aldehydes and other carbonyl compounds. The active species in these carbon transfer reactions are presumably iron porphyrin carbene complexes. " It was also found that ferrous hemin anchored to Ti02 thin films reduce organic halides, which can pose serious health problems and are of considerable environmental concern because of their prevalence in groundwater. ... 

Surfactants are widely used for a variety of reasons, including surface wetting agents, detergents, emulsifiers, lubricants, gasoline additives, and enhanced oil-recovery agents. The type of surfactants selected for a particular application often depends on the chemical and physical properties required and on economics or other considerations such as environmental concerns. To meet these requirements, a typical surfactant formulation may contain blends of a variety of commercial products, which could include ionic and nonionic ethoxylated surfactants, alkylsulfonates, and alkylaryl-sulfonates, and petroleum sulfonates. 

MRLs are, by definition (Chou et al. 1998), substance-specific and do not include effects attributable to interaction (whether additive, synergistic, or antagonistic) with other chemicals or environmental substances. Their relevance to the mission of ATSDR is to assist public health officials in the identification of chemicals/elements of potential health concern at hazardous waste sites. The ATSDR MRL is not intended to be used in the regulatory or site clean-up process, but is instead intended to serve as a basis of comparison with actual measured levels of environmental exposure. Further, the role of informed biomedical judgment is crucial in the application of any MRL, or the media-specific health guidance values (HGVs) derived from them, in any given exposure scenario (Risher and De Rosa 1997). MRLs for a particular substance are based upon the most sensitive effect/endpoint in that portion of the human population considered to be most susceptible to injury from exposure to that substance. Thus, the... 

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