Vinyl Chloride Monomer (VCM) production

VCM hazards

Care has to be taken in handling and storing VCM. Mostly because it is a highly flammable and potentially explosive gas (like the lighter fuel butane). But also because, if breathed in quantity, it is a strong narcotic (like chloroform). In fact, during the 1950’s VCM was trialled as a potential anaesthetic gas for medical applications. However, studies conducted during the 1970s on workers in PVC polymerisation plants revealed that VCM is a carcinogen, and significant exposure over a prolonged period can cause a rare form of cancer, known as angiosarcoma (cancer of liver blood vessels), if there is significant exposure over a prolonged period. Once industry discovered this link, major action was taken to reduce levels of exposure amongst industry personnel.

All manufacturing processes involving the use of VCM today are closed, and all personal exposure is avoided and closely monitored. Workers are regularly tested for even the lowest levels of exposure and there have been no incidences of angiosarcoma related to exposure since the PVC production process was modified. Other than potential flammability on release into the open atmosphere, VCM poses little threat to human health as it quickly dissipates, and degenerates when exposed to normal daylight.

Another threat to human health is the migration of microscopic amounts of residual chemicals from packaging into food. It is highly regulated today, and in part concerns PVC. During polymerisation, virtually all of the VCM is processed into the inert polymer chains that make up the PVC plastic. Nevertheless, it is possible for extremely low levels of residual, unpolymerised VCM to remain in the polymer, and to eventually migrate into food from PVC packaging.However, this only occurs at levels considered entirely harmless by health authorities, and which fall well within European Union regulations.

Regulation concerning VCM migration is based on the tests of independent toxicologists. In 1993 a five-year long Italian study, led by Professor Cesare Maltoni, Director of Bologna's Institute of Oncology, looked at the health effects on rats given mineral water from bottles made of PVC (which contained low levels of VCM) compared with water from glass bottles. There were no noticeable differences concerning the animals' lifespan, weight and general health during the tests and, importantly, no noticeable differences in the development of tumours.