[Ultraviolet radiation doses in Mexican students].

OBJECTIVE

To determine the ultraviolet radiation dose received by children and adolescents at elementary, middle, or high school.

MATERIAL AND METHODS

A cohort study was conducted in the City of San Luis Potosí between May 2001 and April 2002. The study population consisted of 80 school male and female children, selected at random, aged 6 to 19 years of age. The dose was quantitated during an entire schoolyear by recording the time each student was exposed to sunlight. Ultraviolet radiation was simultaneously monitored with terrestrial radiometry equipment. Holidays and weekends were excluded. Data were analyzed using univariate analysis and comparative analysis by sex and months of exposure. A regression model was fit to explain the dose of solar exposure.

RESULTS

The erythemally weighted UV dose for Mexican schoolchildren averaged 16,456 J/m2/year. Differences by gender were found: 14,264 J/m2/year in females vs. 18,648 J/m2/year in males (Kolmogorov-Smirnov, p = 0.003). No significant differences were found among groups. Significant differences were found among months of exposure (Kruskal-Wallis, p = < 0.0001). Stepwise regression models were fit to find the best model, using generalized linear modeling and the Akaike information criterion, to explain the radiation dose according to month of exposure; the final equation was 587.20 + 438.45(gender)0.16(month)-49.65(month2). The results showed higher radiation doses between March and September.

CONCLUSIONS

A theoretical framework is advanced to formulate policies aimed at protecting children in Mexican schools from solar overexposure. Implementing prevention measures at least during the months of greatest exposure (March to June) is in order since 51% of the annual ultraviolet radiation dose is received in this period. By avoiding exposure 8 minutes daily, the radiation dose could be decreased in 39,495 J/m2, which is the dose accumulated in two years. The English version of this paper is available at:http://www.insp.mx/salud/index.html.