Synthetic toxicity

In view of the development in synthetic toxic agents, described in this paper, this phase of the project has become somewhat less important. It was equally essential then, however, that some oil diluent should be available, so that toxicities of oil-soluble, water-insoluble substances could be studied. 

The buildup of greenhouse gases in the atmosphere, and the rupture of the earth s stratospheric ozone shield by chlorofluorocarbons (CFCs), indicate that the human economy has already exceeded the assimilative and regenerative capacities of the biosphere to absorb some human wastes. There is considerable evidence to support this general proposition. Eor example, persistent synthetic toxicants are now measurable from the peaks of the highest mountains to the floors of the deepest oceans and everywhere in between. It is... 

McEvoy " reviewed the legislative framework controlling the use of veterinary medicines and zootechnical feed additives in the EU. From a contamination perspective, problem compounds include sulfonamides, tetracyclines, nitroimidazoles, nitrofurans, ionophore coccidiostats, and nicarbazin. The literature on each of these was reviewed and examples of interventions to minimize contamination were given. Examples of contaminants include naturally occurring and synthetic toxic enviromnental compounds (e.g. mycotoxins and dioxins) that may contaminate feed raw materials. Zootechnical feed additives and veterinary medicines may also contaminate unmedicated feeding stuffs due to carry over during feed production. Contaminated feed can cause deleterious health effects in the animals and, through secondary exposure of consumers to products derived from these animals, may be harmful to people. 

Toxins are present in many forms. There are natural inorganic toxins, natural organic toxins, and, more important in modern life, synthetic toxic compounds. 

Formaldehyde, HCHO, is a primary and necessary constituent of the first five synthetic adhesives in the listing. It is a simple organic chemical first identified during the latter half of the 1800s. Its irritating and toxic odor and preservative properties were known from the time of its early development. It is a ubiquitous chemical, formed naturally in small quantities by every process of incomplete combustion as well as in normal biologic processes. The human body has a natural formaldehyde level of about 3 lg/g, ie, 3 parts per million (ppm) in the blood at all times. 

In general, nonconventional protein foods must be competitive with conventional plant and animal protein sources on the bases of cost delivered to the consumer, nutritional value to humans or animals, functional value in foods, sensory quality, and social and cultural acceptability. Also, requirements of regulatory agencies in different countries for freedom from toxins or toxic residues in single-cell protein products, toxic glycosides in leaf protein products, pathogenic microorganisms, heavy metals and toxins in fish protein concentrates, or inhibitory or toxic peptide components in synthetic peptides must be met before new nonconventional food or feed protein products can be marketed. 

To enable interchangeabiUty of the SNG with natural gas, on a calorific, flame, and toxicity basis, the synthetically produced gas consists of a minimum of 89 vol % methane, a maximum of 0.1% carbon monoxide, and up to 10% hydrogen. The specified minimum acceptable gross heating value is approximately 34.6 MJ/m (930 Btu/fE). 

Oral LD q levels have been deterrnined in the mouse at 470 mg/kg (21) and the guinea pig at 7750 mg/kg (22). Several other studies (23—25) have shown that large quantities of both synthetic and natural glycerol can be adniinistered orally to experimental animals and humans without the appearance of adverse effects. Intravenous adniinistration of solutions containing 5% glycerol to animals and humans has been found to cause no toxic or otherwise undesirable effects (26). 

Vegetable and seed oils as well as some synthetic base stocks present a new class of biodegradable base stocks. These fluids (10) have excellent biodegradation properties as measured by criteria developed by the Environmental Protection Agency (EPA) or Organization of Economic Cooperation and Development (OECD). OECD 301 and EPA 560/6-82-003 measure the biodegradation of lubricants. These tests were developed to measure the degradation of oil, especially two-cycle ok, on waterways. Aquatic toxicity criteria toward fish is also found to be acceptable for this class of fluids as measured by EPA 560/6-82-002 and OECD 203 1-12. 

Other than fuel, the largest volume appHcation for hexane is in extraction of oil from seeds, eg, soybeans, cottonseed, safflower seed, peanuts, rapeseed, etc. Hexane has been found ideal for these appHcations because of its high solvency for oil, low boiling point, and low cost. Its narrow boiling range minimises losses, and its low benzene content minimises toxicity. These same properties also make hexane a desirable solvent and reaction medium in the manufacture of polyolefins, synthetic mbbers, and some pharmaceuticals. The solvent serves as catalyst carrier and, in some systems, assists in molecular weight regulation by precipitation of the polymer as it reaches a certain molecular size. However, most solution polymerization processes are fairly old it is likely that those processes will be replaced by more efficient nonsolvent processes in time. 

Sulfonylureas. The hypoglycemic effect of sulfonylureas was first noted in the early 1940s when several patients died in hypoglycemic coma after testing glyprothia2ole, a synthetic sulfonamide used to treat typhoid. Chemical modifications which enhanced activity and lowered toxicity led to the development of the first-generation sulfonylureas. Carbutamide [339-43-5] the first commercial sulfonylurea, came onto the European... 

Petroleum (qv) products dominate lubricant production with a 98% share of the market for lubricating oils and greases. While lower cost leads to first consideration of these petroleum lubricants, production of various synthetic lubricants covered later has been expanding to take advantage of special properties such as stability at extreme temperatures, chemical inertness, fire resistance, low toxicity, and environmental compatibility. 

Triaryl phosphates are produced by reaction of phosphoms oxychloride with phenoHc compounds at 100—200°C with magnesium or aluminum chloride catalyst. Past use of cresols and xylenols from coal tar or petroleum is replaced for lower toxicity and cost by synthetic phenoHcs, primarily isopropyl phenol, /-butyl phenol, and phenol itself A range of viscosities is achieved by selection and proportioning of the phenols and their isomers used for the starting material. 

To overcome these difficulties, drilling fluids are treated with a variety of mud lubricants available from various suppHers. They are mostly general-purpose, low toxicity, nonfluorescent types that are blends of several anionic or nonionic surfactants and products such as glycols and glycerols, fatty acid esters, synthetic hydrocarbons, and vegetable oil derivatives. Extreme pressure lubricants containing sulfurized or sulfonated derivatives of natural fatty acid products or petroleum-base hydrocarbons can be quite toxic to marine life and are rarely used for environmental reasons. Diesel and mineral oils were once used as lubricants at levels of 3 to 10 vol % but this practice has been curtailed significantly for environmental reasons. 

The compound is an intermediate in several synthetic reactions and recently has found extensive use in experimental toxicity studies in animals. It has been shown to cause methemoglobinemia its metaboHsm in humans has been discussed (189,190). 

Clinical use of lL-1, lL-6, and TNF- a, is limited by associated systemic toxicity. SCF seems better tolerated. It may be possible to develop derivatives of other cytokiaes that are less toxic. The synthetic nonapeptide VQGEESNDK (position 163—171 of human lL-1 P) (see Amino acids ... 

---