Study of the Health Effects of Chromium Rollers Used in Cotton Roller Ginning Industries and Development of an Alternative Ginning Process

摘要

This review paper realizes the hazards of chromium contamination and pollution caused by the use of Chrome Composite Leather-Clad (CCLC) rollers commonly used in cotton roller ginning industries and attempts to eliminate the chromium contamination and pollution during the cotton ginning process. The cotton roller ginning process is the mechanical separation of cotton fibres from their seeds by means of one or more rollers to which fibres adhere while the seeds are impeded and struck off or pulled loose. When the seed-cotton is ginned, due to persistent rubbing of CCLC rollers over the fixed knives, the ginned lint cotton adsorbs about 143 to 1990 mg/kg (ppm) as total chromium of trivalent and hexavalent forms and the cotton products carry with it of about 17 to 250 mg/kg (ppm) of chromium which according to Indian Standards (MOEF-157, 1996) for yarn and fabrics, should not be more than 0.1 mg/kg (ppm). Toxic effects are produced by prolonged contact with airborne or solid or liquid chromium compounds even in small quantities because of their properties viz. carcinogenecity, mutagenecity and corrosiveness. Traces of Cr (VI) are found even in analar grade trivalent compounds and complications do arise due to reduction in nature of these traces that affect the organic tissues of the body. To offset the unsafe chromium contamination and pollution from cotton ginning industries, chrome-free rubberized cotton fabric (RCF) rollers or eco-friendly rollers both for laboratory and commercial studies have been designed, fabricated and experimented on a special-built gin roller experimentation device (GRED) and double roller (DR) gins. These rollers are covered with packing-type roller covering material made from multiple layers of cotton fabric bonded together with a rubber compound. On the basis of the design and development of various rollers with subsequent performance evaluation studies, chrome-free RCF roller has been demonstrated with reference to techno-commercial and eco-friendliness in ginning industries. This pollution-free and chrome-free RCF rollers were found successful in ginning out seed-cotton in an environment friendly way, while maintaining high ginning rate potential, cotton technological parameters of lint, yarn and fabric properties. The ginneries have been tested commercially and found better in all aspects with reference to cotton technological parameters, dye-catching properties, physical and chemical properties. It could be successfully used commercially as an improved alternative in cotton ginning industries for the cleaner environment with benefits to society, industry owners, traders, workers, employees and the Government.