Nitrosamines rubber

The largest known htiman exposures to exogenous nltrosamines have been shown to occur in the work place, particularly in the rubber and leather tanning industries. Recent data for amines, nitrosating potential and nitrosamines will be presented in the framework of assessing the extent of the various exposures. 

The complex pattern of human exposure to environmental N-nitroso compounds is summarized. Recent results are given in three areas, where a significant reduction of human exposure has been achieved after elucidation of its causes 1, N-Nitrosodimethylamine in beer. 2, Volatile N-nitrosamines in baby nipples and pacifiers and 3. occupational exposure in the rubber industry. 

A migration test was developed to simulate human exposure patterns. 5 g of rubber material was cut into 1-2 mm stripes and then immersed in 20 ml of standard test solution of artificial saliva (4.2 g NaHC03, 0.2 g K2CO3, 0.5 g NaCl, 0.03 g NaNO, ad 1000 ml with aqua dest.j. After 24 h incubation at 40 C volatile nitrosamines were determined in an aliquot and determined after destination with a standard technique (GC-TEA-method). 

The nitrosamine contamination of rubber products originates from amine-containing accelerators and... 

Migration of N-nitrosamines from nipples and pacifiers after incubation in a standard test with artificial saliva for 24 h at 40 C. Concentrations in ug/kg rubber product (- <1 ppb)... 

Effect of decreasing amounts of accelerators on nitrosamine and nitrosatable amine content in nipple rubber... 

B.G. Willoughby and K.W. Scott, Nitrosamines in Rubber, Rapra Technology Ltd, Shawbury (1997). 

The rate of vulcanisation of a rubber compound is controllable by the choice of accelerator. The range of products offered to the rubber industry has been categorised historically into recognised classes. New developments have resulted in products that improve compound performance and which overcome dermatological problems, and do not generate nitrosamines and other extractable or volatile decomposition products. 

N-Nitroso compounds occur in many operations in the rubber industry. Some nitrosamines (nitrosodiphenylamine, N-N-dinitrosopentamethylenetetramine, polymerized N-nitroso 2,2,4-trimethyl-l,2-dihydroquinoline and N-methyl-N-4-dinitroso aniline) are used as organic accelerators and antioxidants in the production of rubber and often the products are found to be contaminated with such compounds [19]. 

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. 

Consideration is given to the toxicity of nitrosamines formed during rubber vulcanisation in the presence of certain accelerators, the mechanisms by which they are formed, and French, German and European Union regulations relating to nitrosamines in the workplace atmosphere and in rubber products. Methods used in the sampling and analysis of nitrosamines are also described. 6 refs. 

In the area of environmental protection the Japanese tyre firm Toyo is doing more as a tyre producer than the law demands. In this article Wilhelm Hoeppner, responsible for publicity at Toyo Reifen GmbH, explains in an interview how Toyo is involved. It looks at rubber mixtures, the problem of nitrosamines, legal environmental stipulations, economic impact and the future efforts by Toyo. 

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 industiy. The carcinogenicity of nitrosamines formed during vulcanisation processes is examined, and methods used in their detection are discussed. 2 refs. 

French and European Union legislation relating to the control of emissions in the workplace is examined, with particular reference to the rubber processing industry. Air sampling and analytical procedures used in the detection of nitrosamines formed in vulcanisation reactions are reviewed. 2 refs. 

Volatile nitroso compounds were determined in hams processed in elastic rubber nettings by SPE and GC-CLD577. By a similar method A-n i tro sodi ben zy lamine (278b), a semivolatile nitrosamine, was determined in these products by SPE followed by GC interfaced to a nitrosamine-specific TEA-CLD detector the coefficient of variation was 10.6% at the 2.1 ppb level578. The nitrosamines detected in ham most likely originate from the amine precursors in rubber and from the nitrite commonly used in the meat curing process. 

Microconcentrations of carcinogenic IV-nitrosamines were determined in various rubber articles (tubing, stoppers, hoses, seals, etc.) for medical and food uses by extraction followed by HPLC-FLD593. V-Nitrosodi phenyl amine (278c) present in diphenylamine formulations was determined by LC-TEA on a Zorbax CN column594. 

Migration of nitrosamines into consumer products can occur via direct contact of materials such as waxed containers, elastic and rubber etc.81. Morpholine is used extensively as an industrial solvent for wax formulations. The wax formulations are used for coating fruits and vegetables to prevent moisture loss and increase shelf-life of the products. Paper and cardboard packed with morpholine was also found to give rise to NDMA, as these packaging materials were found to be contaminated with NDMA as well. Besides this, rubber products also provided a migratory source for both nitrosamines and nitros-able amine precursors, as trace levels of NDEA and TV-nitrosodibutylamine (NDBA) have been reported in cured meats with amine-based accelerators in the rubber nettings82. 

Three groups of substances are regulated individually, i.e. vinyl chloride monomer in plastics (78/142/EEC), nitrosamines in rubber teats and soothers (93/11/EEC), and bisphenol A diglycidyl ether, bisphenol F diglycidyl ether, and novolac glycidyl ethers in plastics and coatings (2002/16/EC). 

Uses/Sources. Research chemical impurity in herbicides treflan, isopropalin, and triflu-ralin contaminant in wastewater from chemical factories and production of cheese and brandy and other liquors. AT-nitrosamines are frequently produced during rubber processing and may be airborne in the workplace. 

Spiegelhalder, B. and Preussmann, R. (1983). Occupational nitrosamine exposure. 1. Rubber and tyre industry, Carcinogenesis 4,1147. 

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. 

Dangerous materials other than PAHs, such as polychlorinated bi- and ter-phenols, polychlorinated dioxins and polychlorinated hydrofurans were not found in carbon blacks. Nitrosamines could not be detected in carbon black, but they may be formed in rubber compounds, if rubber chemicals containing secondary amines are used. The total amine content of carbon black is less than 0.01 % and the aromatic amine content is therefore less than this. No heavy metal is present in amounts above 0.002 %. Carbon blacks therefore conform to all known regulations that limit these impurities. 

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