A quarter of cooked ham sliced in-store and sold to consumers is not satisfactory in terms of hygiene and freshness, according to samples obtained by health officers.
The survey also found 2 per cent of the sliced ham had an unsuitable level of contamination.
The analysis of 923 samples obtained by environmental health officers in retailers such as butcher shops, delicatessens, corner shops and supermarkets also suggests that ham sliced in processing plants and then packaged may often be fresher than ham sliced in-store.
Conducted last year as part of the national microbiology surveillance programme, the analysis shows that almost 25 per cent of the samples were classified as unsatisfactory for aerobic colony count (ACC) - used as an indicator of hygiene and freshness.
Some 2.4 per cent were also classified as unsatisfactory for enterobacteriaceae, an indicator of hygiene and post-process contamination.
Details of the survey are contained in the most recent issue of the Food Safety Authority of Ireland (FSAI) newsletter.
The article notes that a 2003 survey of cooked ham which was sliced and prepacked in processing plants - as opposed to in-store - revealed that 13 per cent of samples were unsatisfactory in terms of ACC.
This indicates that the location of slicing has a significant impact on hygiene and freshness.
Last week the food safety authority revealed that the number of closure orders served increased from 13 to 15 in the first six months of this year.
This included two closure orders served last month. They were on Dublin grocery shop owner Daya Mutombo, of Daya Shop, Killarney Street, Dublin, and one on Eamonn Fitzgerald, of the Claremont Hotel in Lahinch, Co Clare.
The food authority also issued one prohibition order last month on JCS Sales Ltd, trading as Joe Hayes butcher, of Brackernagh, Ballinasloe, Galway.