Chemical industry nitrosamines

The NO + 03 chemiluminescent reaction [Reactions (1-3)] is utilized in two commercially available GC detectors, the TEA detector, manufactured by Thermal Electric Corporation (Saddle Brook, NJ), and two nitrogen-selective detectors, manufactured by Thermal Electric Corporation and Antek Instruments, respectively. The TEA detector provides a highly sensitive and selective means of analyzing samples for A-nitrosamines, many of which are known carcinogens. These compounds can be found in such diverse matrices as foods, cosmetics, tobacco products, and environmental samples of soil and water. The TEA detector can also be used to quantify nitroaromatics. This class of compounds includes many explosives and various reactive intermediates used in the chemical industry [121]. Several nitroaromatics are known carcinogens, and are found as environmental contaminants. They have been repeatedly identified in organic aerosol particles, formed from the reaction of polycyclic aromatic hydrocarbons with atmospheric nitric acid at the particle surface [122-124], The TEA detector is extremely selective, which aids analyses in complex matrices, but also severely limits the number of potential applications for the detector [125-127],... 

Cyclohexylamine is miscible with water, with which it forms an azeotrope (55.8% H2O) at 96.4°C, making it especially suitable for low pressure steam systems in which it acts as a protective film-former in addition to being a neutralizing amine. Nearly two-thirds of 1989 U.S. production of 5000 —6000 t/yr cyclohexylamine serviced this appHcation (69). Carbon dioxide corrosion is inhibited by deposition of nonwettable film on metal (70). In high pressure systems CHA is chemically more stable than morpholine [110-91-8] (71). A primary amine, CHA does not directiy generate nitrosamine upon nitrite exposure as does morpholine. CHA is used for corrosion inhibitor radiator alcohol solutions, also in paper- and metal-coating industries for moisture and oxidation protection. 

Occupational health and safety in the rubber industry is discussed with reference to UK, US and European legislation. The review covers both natural and synthetic rubber industries. The first section outlines the laws affecting health and safety in the industry and the remainder presents specific health and safety issues of interest to employers and employees. Industrial safety is examined with reference to equipment, fire and explosions, solvents, epidemiology, NR latex allergy, skin irritations and dermatitis, dust and fume control, work-related musculoskeletal disorders, nitrosamines, 1,3-butadiene, and handling of rubber chemicals. 484 refs. 

Air Samples NMOR, NDMA, and NPYR were found during the first NIOSH visit in air samples collected at a tire manufacturing plant in Maryland. One process sample, collected at a feedmill, contained 250 yg/M3 of NMOR, a level several times higher than has been reported for any airborne nitrosamine at any industrial site (1). Maximum concentrations of NDMA and NPYR found in the hot process areas were 4.4 yg/M3 and 3.4 yg/M3, respectively. Over the following 7 months, ventilation improvements and changes in chemical formulation of the rubber resulted in a 200-fold reduction in NMOR levels and elimination or reduction of other nitrosamines at most sites. Results are shown in Figure 2, and Table I. 

Variations in the use pattern of industrial and agricultural chemicals throughout the world preclude standardization by international organizations such as OECD. Despite this fact, common dietary constituents, which are known to influence toxicity are antioxidants, unsaturated fatty acids, and selenium. These must be present in interfering concentrations. The potential impact of several common dietary contaminants on chronic toxicity assessment therefore, necessitates that special attention be given to their presence. In this respect, substances of concern include pesticide residues, chlorinated and polycyclic aromatic hydrocarbons, estrogens, heavy metals, nitrosamines, and mycotoxins. 

Toxicology Abstracts. U.S.A. Cambridge Scientific Abstracts. Monthly. ISSN 0140-5365. Each issue contains approximately 800 abstracts covering the toxic effects of pharmaceuticals, food, agrochemicals, cosmetics, toiletries, household products, industrial chemicals, metals, natural substances, poisons, polycyclic hydrocarbons, nitrosamines, and radiation. Toxicological methods and papers concerned with legislation are also included. 

Attending to the different pathways for the nitrosation of amines and amine derivatives, it is not unexpected for the A-nitrosamines to be found in many different areas of human environment. Nitrosamines and their precursors nitrite and amines, are ubiquitous in the environment. Nitrite can be formed by the nitrification of ammonia or by the denitrification of nitrate by microorganisms. The decomposition of organic materials from plants and animals, industrial (chemical) discharge, and pesticide preparations are primary sources of environmental amines. 

In the rubber industry, chemicals containing amines are used as vulcanization accelerating agents, which may be transformed during the production process (vulcanization) into nitrosamines. Such substances are added to condoms to give the rubber the needed degree of elasticity. 

Nitrosamine-generating chemicals represent an area where suspect materials have been removed from rubber products, even though no governing legislation has yet been drafted. Nitrosamines can be formed when secondary amine accelerators are used to cure rubber. These accelerator changes have a very significant effect on the total rubber industry. 

Two workhorse members of the thiuram class, particularly active in cure rate as well as economical, are TMTD and TMTM (R= methyl, x = 2 and 1, respectively, in 2). Both TMTD and TMTM are stable nitrosamine generators, as they liberate the secondary amine, dimethyl amine, during vulcanization (12,13). Replacements for these rubber chemicals has been a target of considerable technical effort in the rubber industry. Several candidates have emerged, each with its own attributes. None is a direct substitute for either TMTD or TMTM but several have proven... 

Another commonly used sulfur donor is TMTD. However, TMTD can be used in some recipes as a sulfur donor, while in other recipes with sulfur present it functions as an accelerator. Just as with DTDM, the TMTD is also a nitrosamine generator during the curing process, which poses a health hazard to workers if air ventilation is not adequate. Therefore a large effort has been made by the rubber industry to find chemical substitutes that do not emit nitrosamines into the air. 

A survey is made of French and European Union legislation relating to hazardous chemicals in the workplace, and particular attention is paid to regulations concerning exposure to chemicals in the rubber industry. The carcinogenicity of nitrosamines formed during vulcanisation processes is examined, and methods used in their detection are discussed. 2 refs. 

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