The findings show that, overall, self-reports of sun exposure produce valid measures of UVR exposure among parents, children, and lifeguards who work outdoors. The highest rates of UVR exposure on both weekdays and weekends were found in the lifeguard group, who reported the longest time outdoors in survey and diary measures with high exposure also indicated the dosimeter readings. Compared to the lifeguards, adults and children were more likely to have intermittent exposure compared to the lifeguards who are more likely to have continuous exposure for longer periods.
The agreement between self-reported time outside by diary and the objective measurement of sun exposure by dosimeters are reasonably good, although they are better on weekends than weekdays. The improvement in self-report may be due to less variability in daily activities on weekends. The findings are consistent with previous recommendations that data should be collected over several days due to the variation in habits (12
While parents and children reported similar amounts of sun exposure, the ambient measures from the dosimeters for parents were lower. The difference in sun exposure could be due to parents seeking shade more often while outdoors when children were more likely to be openly exposed while playing the swimming pool and deck areas. This might also explain the parents’ appearing to over-report their UVR exposure on diaries (); they may not have been outside for the entire hour marked as “outside” in their diaries. Also, since in most cases the parents were filling out the diaries for their children, they may not have perceived their own sun exposure to be the same when the children are receiving more. There may be a need to educate the parents to make them more aware of the difference in exposure.
Systematic error was minimal, and was found only for children who were at in the lowest or highest risk tertiles for skin cancer. The self-report measures of children at moderate risk were highly correlated with the dosimeter readings. These findings suggest that perhaps there should be more focus on educating higher-risk children and their parents on the importance of reducing exposure to UVR, as they may not be conscious of the risk.
The study is the largest of its kind to date. Previous studies of this issue have focused on mothers and children less than 12 months of age (12
) and adults aged 40+ who were indoor workers (24
). The associations found here were higher than those found by O’Riordan et al. (12
) and slightly lower than those of Chodick, et al (24
) – though the lifeguard associations were similar. Methodological differences between the studies may explain the differences in associations. In two publications from by Chodick and others (24
), data were collected over a 7-day period, five weekdays and two weekend days, and the agreement on weekdays (between surveys/diaries and diaries/dosimeters) was significantly higher than weekends. Since the subjects in both studies were indoor workers and measures were taken during their work days, there was probably less variability during the five weekdays of data collection than the two weekdays in this study.
Some strengths of this study are the large sample, multiple locations, and a high cooperation rate. The study also includes two types of self-report which offered the possibility for more comparisons.
These findings are the third in a series of reports from the Sun Exposure Protection Habits (SEPH) study. Previous reports focused on the validity of self-reported sunscreen use compared with an objective test of the presence of sunscreen (14
) and the validity of self-reported covering-up sun protection habits (use of hats, shirts and sunglasses) compared to observations (26
). The results for sunscreen use showed good agreement between a swabbing method and diary and survey reports. Agreement between the objective measure of sunscreen use was greater for the diary than for the survey (14
). The observations also had good agreement with the two self-report methods, surveys and diaries. There was fair to moderate agreement between the diaries and observation, which was better than the agreement between surveys and observation (26
Data recorded in diaries and surveys were significantly correlated with dosimeter findings, despite surveys collecting information about usual rather than daily or hourly behavior. Surveys and diaries can be considered as reasonably valid options for assessing sun exposure habits, given the respondent and researcher burden and cost of using dosimeter badges in lieu of self-report. If diaries are used along with surveys to derive a combined assessment of UVR exposure, the validity is likely to be even better. Overall, surveys, which are common, inexpensive, and non-invasive, are an acceptable method of data collection. They are limited by the lack of time specificity, which is an advantage of diaries and polysulfone dosimeters. We recommend that researchers validate UVR exposure measures in a sub-sample with polysulfone film in studies using different methodology and new populations and that diary data should be collected across at least two weekdays and two weekend days. Also, as electronic UVR monitors allowing for real-time data collection become increasingly available (27
), these tools should be incorporated in future studies. These devices would make it possible to measure not only cumulative UVR exposure but actual timing of the exposure, allowing for more fine-tuned assessments and comparisons with self-report.
The present report adds on a new focus on the validity of self-report measures of UVR exposure compared to exposure as assessed with PS dosimeters. This area of research is increasingly important now, as epidemiologic findings emerge showing the possible benefits of UVR exposure in decreasing risks of some cancers, prolonging survival and conferring other possible health benefits (28