Food label warnings on products in the US are confusing and ineffective, according to an industry researcher in the country.

Of some 179 products bearing a variety of accidental-peanut warnings, University of Nebraska food scientist Steve Taylor found 7% contained enough peanuts to seriously harm allergic people.

US law requires full disclosure on foods intentionally containing highly allergenic ingredients, but accidental-allergy warnings are voluntary and wording varies.

A report in the Journal of Allergy and Clinical Immunology shows more parents of food-allergic children avoid products labelled "may contain peanuts" (88%) than "packaged in a facility that processes peanuts" (64%).

Additionally, the number of people avoiding foods with accidental-allergy warnings is down 12% from 2003, owing to growing numbers of vague warning labels on foods with little allergy risk.

The US Food and Drug Administration will hold consultations this year to determine if mandatory measures are necessary. An estimated 12m Americans have some degree of food allergy.