The association between a history of waterside vacations and having nevi at age seven was significant only for smaller nevi, and only when vacations during the year prior to examination were excluded.
Factors such as use of hats and sunscreens, eye color, and tanning sensitivity were not predictive of nevi.
The data also indicated that the length of vacations and the total estimated ultraviolet exposure was not a factor in nevus counts -- only the number of vacations appeared to have an effect.
Dr. Crane and colleagues said there may be a threshold effect at work, such that the radiation necessary to induce nevi is received early in a vacation and additional exposure does not increase nevus formation further.
Male gender was also a risk factor for nevi, with a 19% increase in small nevi (95% CI 6% to 33%) relative to girls.
Hispanic ethnicity appeared to be protective, reducing the likelihood of nevi by 35% compared with non-Hispanic whites (95% CI 21% to 47%).
Not surprisingly, a history of sunburn as reported by parents was associated with larger numbers of nevi, as was the presence of facial freckles.
Dr. Crane and colleagues thought it was important that vacations during the year prior to examination did not appear to contribute to nevus formation in the study.
"It suggests a time lag of at least one year for the effects of sun exposure during waterside vacations to result in new nevi," they hypothesized.
Alternatively, they said, perhaps age six to seven is a pivotal period in children's dermal reactions to sun exposure.
"It is plausible that children's melanocytes become less susceptible to the intense sun exposure received on waterside vacations as they age and that after age six the effect of waterside vacations on nevus development becomes undetectable," the researchers said.
Limitations to the study included reliance on parental interviews for data on vacation and sunburn history and other important variables. The study did not collect specific behavioral information related to waterside vacations and only recorded detailed information on the first seven vacations reported.
Also, it did not address children's later development of skin neoplasms.
Back to HCB News
