Cancer Liver Rare ?

The risk of getting liver damage and liver cancer depends on the length of exposure(for how many years he is working in a plastic factory) and your friend's occupation.
Exposure to vinyl chloride generally occur after production, when the finished vinyl chloride is piped to storage or transportation, or during maintenance. Also, exposure can be very high during the process of forming PVC, when vinyl chloride may escape into the air.
Breathing the vinyl chloride for long time period is related with a rare type of liver cancer, angiosarcoma.