Auto toxicity

Influence of the chemical composition of fuels on emissions of toxic materials (auto/oil program). 

Health and Safety Factors. Sulfur monochloride is highly toxic and irritating by inhalation, and is corrosive to skin and eyes (156). The OSHA permissible exposure limit is 1 ppm (6 mg/m ). Pulmonary edema may result from inhalation. Because its vapor cannot be tolerated even at low concentrations, its presence serves as a warning factor. Sulfur monochloride is not highly flammable, having flash poiats of 118°C (closed-cup) and 130°C (open-cup) and an auto-ignition temperature of 234°C. 

Caution Most selenium compounds are toxic consequently care should be exercised in handling them. The hydrogen peroxide oxidation of selenides is highly exothermic, acid-catalyzed, and auto-catalytic. The procedure given for adding the hydrogen peroxide solution should be carefully followed. 

The worst hazard scenarios (excessive temperature and pressure rise accompanied by emission of toxic substances) must be worked out based upon calorimetric measurements (e.g. means to reduce hazards by using the inherent safety concept or Differential Scanning Calorimetry, DSC) and protection measures must be considered. If handling hazardous materials is considered too risky, procedures for generation of the hazardous reactants in situ in the reactor might be developed. Micro-reactor technology could also be an option. Completeness of the data on flammability, explosivity, (auto)ignition, static electricity, safe levels of exposure, environmental protection, transportation, etc. must be checked. Incompatibility of materials to be treated in a plant must be determined. 

This is the reaction by which sodium chlorate is manufactured commercially. In the present context, however, the formation of chlorates is generally undesirable since they tend to be explosive and toxic. The reaction given by Equation 26.2 is strongly affected by pH and temperature as well as the hypochlorite ion concentration. As the alkali becomes exhausted, and the system is thus over-chlorinated, the rate of chlorate formation is greatly accelerated as the reaction becomes auto-catalysed by hypo-chlorous acid. The acid is formed by... 

Sometimes CYPs can also produce reactive metabolite species that, instead of undergoing the normal detoxification pathway, can act as irreversible CYP inhibitors, thus causing toxicity. Such reactive metabolites that cause CYP inactivation are called MBI and are described in Chapter 9. Mechanism-based enzyme inhibition is associated with irreversible or quasi-irreversible loss of enzyme function, requiring synthesis of new enzymes before activity is restored. The consequences of MBI could be auto-inhibition of the clearance of the inactivator itself or prolonged inhibition of the clearance of other drugs that are cleared by the same isozyme. There may also be serious immunotoxicological consequences if a reactive intermediate is covalently bound to the enzyme. Therefore, screening of new compounds for MBI is now a standard practice within the pharmaceutical industry. 

PPG Industries has developed a substitute for lead in a coating process used widely in the auto industry. The replacement is yttrium that, though much less studied than lead, is considered orders of magnitude lower in hazard. In addition it was discovered that as yttrium is used in the process it is converted to yttrium oxide that is appears to be non-toxic by ingestion, in stark contrast to lead. As PPG customers implement yttrium overthe next several years, it is projected that the use of approximately one million pounds (some 454 tonnes) of lead will be avoided. 

Auto-flammability Subacute (28-day) toxicity Hydrolysis screening... 

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