Vinyl Chloride: Hazards, Uses, And Exposure Sources.pdf

Vinyl chloride, primarily used in manufacturing polyvinyl chloride (PVC) plastic and vinyl products, poses significant health risks. Acute exposure to high levels through inhalation affects the central nervous system, causing dizziness, drowsiness, and headaches. Chronic exposure can lead to liver damage, and it is classified as a Group A human carcinogen due to its link to rare liver cancer, particularly angiosarcoma.

Uses:
- Production of PVC for pipes, wire coatings, packaging, furniture, automotive parts, and historical use as a refrigerant.

Sources and Exposure:
- Ambient air concentrations are low, but exposure occurs from industrial discharges, evaporation from chemical waste storage, and higher levels in new cars due to outgassing from plastic parts.
- Drinking water can be affected by leaching from PVC pipes.
- It is a microbial degradation product of trichloroethylene in groundwater.
- Occupational exposure is common among workers involved in its production, use, transport, storage, and disposal.

Health Effects:

Acute:
- Inhalation of high levels causes CNS effects like dizziness, drowsiness, headaches, and giddiness.
- Mildly irritating to eyes and respiratory tract.
- Extreme exposure can lead to lung and kidney irritation, blood clotting inhibition, cardiac arrhythmias, and loss of consciousness.

Chronic:
- Liver damage from both inhalation and oral exposure.
- "Vinyl chloride disease" in occupationally exposed individuals includes Raynaud's phenomenon, bone changes, joint/muscle pain, and scleroderma-like skin changes.
- CNS and peripheral nervous system symptoms reported in workers.
- Animal studies show effects on liver, kidney, and CNS from chronic exposure.

Reproductive and Developmental:
- Limited case reports suggest potential impact on male sexual performance.
- Epidemiological studies link vinyl chloride exposure during pregnancy to increased birth defects, while others do not support this.
- Animal studies report testicular damage, decreased male fertility, and fetal weight reduction with low-level exposure over 12 months.

Cancer Risk:
- Inhaled vinyl chloride increases the risk of liver cancer (angiosarcoma).
- Animal studies confirm this carcinogenic effect via inhalation.
- Early life exposures are more susceptible to vinyl chloride's carcinogenicity than later ones.
- EPA's unit risk estimate for lifetime exposure is 8.8 × 10^-6 (µg/m³)⁻¹, and the oral cancer slope factor is 1.5 (mg/kg/d)⁻¹.

Physical Properties:
- Colorless gas with a mild, sweet odor.
- Slightly soluble in water, highly flammable.
- Chemical formula: C₂H₃Cl; molecular weight: 62.5 g/mol.
- Half-life in air: few hours.