Solar ultraviolet and the occupational radiant exposure of Queensland school teachers: A comparative study between teaching classifications and behavior patterns

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Highlights

  • UV exposures of teachers were assessed relative to national standards.

  • A total 23.0% of all teachers exceeded the standard.

  • Highest doses were received by PE teachers and teacher aides.

  • Exposure times of teaching staff corresponded with peak UV periods.

Abstract

Classroom teachers located in Queensland, Australia are exposed to high levels of ambient solar ultraviolet as part of the occupational requirement to provide supervision of children during lunch and break times. We investigated the relationship between periods of outdoor occupational radiant exposure and available ambient solar radiation across different teaching classifications and schools relative to the daily occupational solar ultraviolet radiation (HICNIRP) protection standard of 30 J/m2. Self-reported daily sun exposure habits (n = 480) and personal radiant exposures were monitored using calibrated polysulphone dosimeters (n = 474) in 57 teaching staff from 6 different schools located in tropical north and southern Queensland. Daily radiant exposure patterns among teaching groups were compared to the ambient UV-Index. Personal sun exposures were stratified among teaching classifications, school location, school ownership (government vs non-government), and type (primary vs secondary). Median daily radiant exposures were 15 J/m2 and 5 J/m2 HICNIRP for schools located in northern and southern Queensland respectively. Of the 474 analyzed dosimeter-days, 23.0% were found to exceed the solar radiation protection standard, with the highest prevalence found among physical education teachers (57.4% dosimeter-days), followed by teacher aides (22.6% dosimeter-days) and classroom teachers (18.1% dosimeter-days). In Queensland, peak outdoor exposure times of teaching staff correspond with periods of extreme UV-Index. The daily occupational HICNIRP radiant exposure standard was exceeded in all schools and in all teaching classifications.

Graphical abstract

Personal exposure measurements of solar ultraviolet referenced to national occupational standards for workers in Australian Queensland schools revealed patterns in exposure risk that correlated strongly with supervision duties at meal break times. Exposure risk was considered for different teaching classifications, school locations, and school types during the peak solar irradiance period of the teaching semester.

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Introduction

Limited data on solar ultraviolet radiation (UVR) radiant exposure in predominately indoor occupations highlights that skin cancer and eye disease are rarely considered diseases of occupation [1], yet skin cancer and chronic eye disease such as cataract, and pterygium are a probable consequence of lifetime exposure habits [2], [3], [4], [5]. Research measuring annual and/or lifetime UVR radiant exposure and evaluating the associated risks in workers with predominantly outdoor occupations are common. Such studies include: building and construction workers [6], [7], [8]; Lifeguards [9]; Gardeners [10]; and Physical Education teachers [11], [12]. Consequently, strong evidence is available correlating outdoor occupational radiant exposure with the incidence of non-melanocytic skin cancers. Much effort is required to reduce UVR radiant exposure in these occupations, particularly in tropical and sub-tropical regions which experience high levels of ambient solar radiation.

The intermittent sun exposure hypothesis, which places traditional indoor workers at higher risk, states that cumulative lifetime radiant exposure to solar-UVR, particularly episodes of sunburn, contribute to the risk of cutaneous melanoma in Caucasian populations [13], [14], [15]. Recent research by Kitchener [16] has shown there to be limited evidence of elevated risk of melanoma in Australian Navy personnel compared to the general population. The findings of this research contribute toward a recognized complexity in associating occupational exposure, whether acute, chronic or intermittent with increased melanoma skin cancer risk [17], [18], [19]. The Kitchener [16] study did however associate a higher risk of melanoma for Naval personnel who spent most of their working life out of direct sunlight. That intermittent exposures among workers who spend most of their time indoors cannot be excluded as a risk factor for the development of melanoma, particularly in populations exposed to high ambient levels of UVR [20], [21], [22] makes Classroom teachers an interesting case for studying occupational radiant exposure. The traditional role of a classroom teacher involves supervising children in the playground during meal breaks that generally coincide with periods of peak ambient solar UVR intensity. In Queensland, Australia melanoma rates are among the highest in the world [23], [24], [25]. Personal radiant exposures received as a consequence of the occupational requirement to be outdoors during periods of peak ambient UVR intensity highlight the potential value of collecting baseline information that may be used to advocate behavioral changes aimed at reducing melanoma risk [26], [27], and reduced risk of keratinocyte cancers [28], [29].

Queensland employers are legally obliged to provide a working environment that prevents the injury or illness of workers according to the Work Health and Safety Act [30]. Solar-UVR radiant exposure, received as a consequence of the occupational requirement to provide a duty of care to Queensland school children carries the potential to cause harm to teachers due the high levels of ambient solar radiation in school playgrounds [31], [32], [33]. The responsibility of employers to provide a safe working environment highlighted in recent research shows that an increasing number of successful worker's compensation claims in Australia have been reported for skin damage resulting from radiant exposure to UVR in the workplace [34]. A position statement by the Cancer Council Australia [35], recommends that workplaces have a comprehensive sun protection program incorporating: assessment of UVR exposure risks, implementation of protective control measures, education and training for employees and the development of written policy. Teachers and teacher aides, as employees are bound by the policies of their designated workplaces and are therefore a population group that have the potential to adopt and follow measures aimed at reducing personal solar-UVR radiant exposure. The role teaching staff play in demonstrating sun safe behavior to school children is also recognized as one of several relevant intervention strategies actively encouraged and supported by the National ‘SunSmart Schools’ program which has been credited with reducing skin cancer incidence in Australia since its inception in 1988 [36], [37].

We report objective measurements of the Spring-time occupational radiant exposure of primary school teachers, teacher aides, and secondary school teachers from sites in tropical (Townsville) and sub-tropical (Toowoomba) Queensland separated by 8.2 degrees of latitude. Radiant exposures are referenced relative to the Australian Radiation Protection Standard (ARPS) [38] and the erythemal action spectrum [39]. For studies in which the personal risk of erythema is of concern, the erythemally effective [39] radiant exposure is often cited rather than ARPS, although the later is more relevant in occupational radiant exposure studies. The ARPS specifically weights solar UV radiant exposure to the hazard sensitivity spectrum of the International Commission on Non-Ionizing Radiation Protection [40] for the skin and eye. According to the standard, exposure of the skin to solar radiation must not exceed a weighted daily UV radiant exposure of 30 J/m2. Below this limit, the risk of detectable acute or delayed effects are considered extremely small [41].

Section snippets

Study Location

The northern Australian state of Queensland, located between the latitude of 10oS and 28oS experiences a warm tropical to sub-tropical climate, a high number of sunshine days and extreme solar UV-levels annually from September through to April in the austral spring, summer and autumn seasons. In this research solar UV radiant exposures were monitored at two sites over a wide latitudinal range in 57 workers employed in teaching roles in November toward the end of the 2014 school semester from

Response

A total of 474 dosimeters were returned from the 570 dosimeters distributed to participants (83.2% response rate). Non-return of dosimeters was primarily due to the inclusion of 12 part-time staff (worked < 10 days per fortnight; Table 1), in addition to unscheduled staff absences due to sickness etc., and damage/loss of a small proportion of badges (5 dosimeters).

Distribution of Personal UV Radiant Exposures and Time Spent Outdoors

The median HICNIRP received by all teachers across both locations was 11 J/m2, (IQR: 2–28 J/m2) per day. The measured personal radiant

Discussion

Classroom teachers, as a group have not been studied extensively with reference to ICNIRP radiant exposure limits. Several studies have concluded that radiant exposures received by indoor workers receive between 0 and 4% of the available ambient UVR [50], [51], however these studies do not weight measured radiant exposures specifically to the ICNIRP [40] action spectrum. To ascertain UVR radiant exposure risk in the workplace, internationally recognized radiant exposure safety standards should

Conclusions

The findings of the current study provide baseline information on occupational radiant exposures and behavior patterns of teachers from schools located in a warm, and high ambient UV climate. This information is relevant to teaching staff working in tropical and subtropical locations and may by indicative of radiant exposure patterns likely to be observed by staff working in an increasingly warmer and variable global climate.

A clear strategy that would have a measureable impact on reducing the

Acknowledgments

The authors acknowledge the support of participant school principals and school staff for their valuable contribution to this work. We also thank JCU research assistant, Hilla Cohen for her contribution and data analysis assistance. Travel costs and collaboration between JCU and USQ research staff was supported by a Research Infrastructure Block Grant from JCU, and a Research Incentive Activation Scheme and Research Giants Travel Award from USQ. The authors declare that they have no actual or

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