If you are using a hazardous substance your employer has to undertake a COSHH risk assessment and must provide you with the information about the hazards, risks and control measures, and instruction and training to use the control measures.
Carcinogens have a varying potential to cause occupational cancer, whether you are at risk depends on the kind of work that you do and whether there are measures in place to prevent exposure to particular carcinogens that might be present in your workplace.
Report the matter to your local HSE office or Local Authority Environmental Health Officer. You can do so anonymously. Further information can be found on the page complaints about workplace health and safety.