This comes from the UK's Food Standards Agency:
People over the age of 60 are more likely to take risks with 'use by' dates than younger people, according to new research published today by the Food Standards Agency. The research coincides with the launch of an Agency campaign to focus on this age group during Food Safety Week.
Eating food beyond its 'use by' date increases the risk of food poisoning from the listeria food bug, which can be life-threatening for this age group.
A recent sharp rise in the number of people taken ill with listeria has seen more older people affected. The number of cases rose by 20% in 2007 and has doubled since 2000, this increase occurring predominantly among people over 60.
The research published today shows that less than half of this age group recognise 'use by' dates as an important indicator of whether food is safe or not, and so they could be putting themselves at risk of serious illness.