Apart from those who intentionally work with micro-organisms in a laboratory type setting, there are many occupations where there will be an element of incidental exposure to micro-organisms as a result of the kind of work that is carried out.
This incidental exposure could be because the hazard, i.e. the micro-organism, is present on or within the materials, substances, animals or people that are being handled. For example, handling waste contaminated with human/animal waste or working with equipment or in an environment that is contaminated e.g. sewers. HSE has prepared guidance on the prevention of such incidental exposure.
Below is a list of occupations where there may be a risk of infection - it's not exhaustive but gives an indication of the range of jobs where biological hazards should be considered. Abattoir workers, acupuncturists, ancillary healthcare workers such as cleaners, porters, animal rescue workers, beauticians, butchers, care workers, chiropodists, cleaners (e.g. public transport, parks, street, public toilets), custodial work e.g. police, prison officers, dentists/dental nurses, ditch clearers, doctors, ear and body piercers, embalmers, emergency service workers, farmers, foresters, grave diggers, grooms, groundsmen, hairdressers, heating and ventilation engineers, kennel/cattery workers, local authority environmental heath services such as pest control, gardeners, park keepers, laundry workers, metalworking, motor vehicle repairers, nurses, plastics injection moulding, plumbers, post mortem technicians, poultry processors, refuse collectors, sewage workers, slurry spreaders, social workers, tattooists, undertakers, veterinary workers, water sports teachers, zookeepers.
For more about two of the key risk occupations: