- A retrospective postal survey of 24 000 medical laboratory workers in England, Wales, and Scotland showed highly variable standards of safety and health care. Pre-employment health screening was offered to two-thirds of employees, the physicians being the least likely to be examined (15%). Scottish laboratories provided better safety control than English and Welsh laboratories, while Public Health Service Laboratories had a better record than National Health Service establishments. Mouth pipetting is still practised in 65% of English and Welsh laboratories, and the use of protective clothing is rarely compulsory. The servicing of safety cabinets is often inadequate. Known and suspected carcinogens are still apparently used in a few laboratories (2-10%). In view of the wide variation in standards among laboratories, urgent consideration should be given to establishing regulations for codes of safe practice rather than relying merely on recommendations as at present.