"These increases could be caused by increasing exposure to environmentalriskfactors such as peanuts and other foods or latex, to an increased susceptibility in the population to these allergens or a combination of these factors, " they wrote.
But it added there appeared to be a link but the vaccine "is likely to have interacted with genetic or environmentalfactors which might raise the risk of narcolepsy, and that other factors may have contributed to the results".
The Institute of Medicine (IOM) has just released a large-scale report reviewing the evidence for the role of certain lifestyle variables and environmentalfactors in breast cancer risk.