Hazardous chemicals requiring health monitoring
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- Background information on vinyl chloride exposure
- Acute effects
VINYL CHLORIDEBASELINE HEALTH MONITORING BEFORE STARTING WORK IN A VINYL CHLORIDE PROCESS
There are many non-work factors associated with hepatocellular carcinoma, including excessive alcohol consumption and viral hepatitis that the medical practitioner needs to be aware of. The following details about the worker’s medical history will be collected by the medical practitioner:
A physical examination will be conducted only if work and medical history indicates this is necessary, for example if the symptoms of vinyl chloride exposure are present.
In addition to medical history and physical examination, there are a number of test methods that can be used to assess exposure to vinyl chloride. These are:
The registered medical practitioner may choose to conduct these tests to assess the worker’s exposure to vinyl chloride. The medical practitioner should consider testing for viral markers for hepatitis B and hepatitis C after pre-test counselling. Note: There is no specific biological marker for angiosarcoma of the liver (ASL) and hepatocellular carcinoma (HCC) due to vinyl chloride monomer exposure. Background information on vinyl chloride exposureWith the level of potential exposure in vinyl chloride monomer/polyvinyl chloride (VCM/PVC) plants at such a low level these days, it is unlikely workers will develop ASL—only one case has been diagnosed in Australia in 1978—or HCC due to VCM. However, workers should be made aware of the additional risk of developing HCC when they have hepatitis B virus (HBV) or hepatitis C virus (HCV) or when their alcohol consumption is too high. If workers are suffering from active hepatitis, the registered medical practitioner should discuss with the treating gastroenterologist possible exemption from working in duties potentially exposing them to VCM. DURING EXPOSURE TO A VINYL CHLORIDE PROCESS
Medical examinations should occur every two years, with laboratory tests repeated annually where required.
The person conducting a business or undertaking should arrange an appointment with the registered medical practitioner for workers who are excessively exposed to vinyl chloride, are suspected of being excessively exposed to vinyl chloride, or have concerns about vinyl chloride exposure. AT TERMINATION OF WORK IN A VINYL CHLORIDE PROCESS
A final medical examination will be conducted and may include tests used by the registered medical practitioner to assess exposure including:
SUPPLEMENTARY INFORMATION ON VINYL CHLORIDE
Examples of work activities involving vinyl chloride which require special attention when assessing exposure include production of polyvinyl chloride (PVC), in particular during cleaning of autoclaves. Special attention should also be given to acute exposures that may occur in the above vinyl chloride processes.
Vinyl chloride is not known naturally although it has been found in landfill, gas and groundwater as a degradation product of chlorinated hydrocarbons deposited as solvent wastes in landfills. The level of residual vinyl chloride in PVC has been regulated since the late 1970’s in many countries. Since then, release of vinyl chloride monomer from the thermal degradation of PVC is either not detectable or is at very low levels. Vinyl chloride is also present in cigarette smoke. POTENTIAL HEALTH EFFECTS FOLLOWING EXPOSURE TO VINYL CHLORIDE
The primary routes of vinyl chloride entry into the body are through inhalation and ingestion.
Liver – fibrosis, angiosarcoma. CNS – dizziness, ataxia, visual disturbance, coma, death. Irritant – eyes, mucous membranes, respiratory tract. Skin – scleroderma. Circulatory – Raynaud’s syndrome.
CNS: The central nervous system (CNS) is the primary target of vinyl chloride acute toxicity. Vinyl chloride is thought to depress the CNS via a solvent effect on lipids and protein components of neural membranes that interrupts signal transmission. There may be a latent period of hours to days between exposure and symptom onset. Symptoms include euphoria, dizziness, ataxia, fatigue, drowsiness, headache and loss of consciousness. With inhalational exposure, signs and symptoms increase in severity over a range of 8000 to 20 000 ppm in air. Exposure to higher concentrations can cause death. Sub-lethal CNS effects resolve quickly when the victim is removed from further exposure. Respiratory: Vinyl chloride gas inhalation can cause mild respiratory tract irritation, wheezing and chemical bronchitis. These effects are transient and resolve quickly following removal from exposure. Cardiovascular: Vinyl chloride may lower the myocardial threshold to the dysrhythmogenic effects of catecholamines. Dermal, Ocular: Exposure to escaping compressed gas or liquid can cause frostbite injury with redness, blistering, and scaling of the skin and corneal and conjunctival irritation or burns.
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