Parkes v Meridian Ltd  EWHC B1 (QB) 14th Feb 2007.
in an area where the hearing loss to be expected can be regarded as marginal, or minimal, or so small as not to be identifiable in individuals but only in a statistical sense there could in my view be no liability at common law for breach of duty in exposing employees at such levels.
Degree of risk remains a valid test of the standard applied to the duty of care.
If, however, the actual risk at any level was so small that no action was required of them, the fact that there may have been other information current at an earlier time which was inaccurate as to the extent of risk does not help, in my judgment, to establish liability.
This passage clearly sets out the principle that harm to an individual must be identifiable in that individual if an employer is to have a duty to prevent it or, to pay compensation if he fails to prevent it. In our view, this means that where a biological change is only significantly detected in population averages it will not be sufficient to give rise to a duty of care. Guidance that is based on the protection of populations from such biological effects cannot automatically be assumed to have relevance to the common law.