Accuracy of annual erythema exposure estimation using different numbers of ambient exposure fractions in the human exposure model

BACKGROUND

The aim was to determine the optimum number of ambient exposure fractions required in the human exposure model for accurate computation of annual erythema effective solar exposure.

METHODS

Ambient exposure fractions were determined on a daily basis over a period of a year in the Rockhampton region using ambient exposure measurements and erythema effective solar exposure measurements at selected body sites of Australia post mail delivery personnel (APMDP). Several values of annual erythema effective exposure for the same body sites were computed using different combinations of ambient exposure fractions on a monthly, seasonally and half-yearly basis in the human exposure model and compared with the measured values.

RESULTS

This method enabled a check on the accuracy of annual erythema effective solar exposure estimation using the different combinations of ambient exposure fractions in the human exposure model. In the worst case there was approximately 35% difference between the measured value and the computed value.

CONCLUSION

The best accuracy was obtained with the use of ambient exposure fractions on a monthly basis where most of the estimated values for the different body sites were within 20% of the measured values.

Description of the use of a risk estimation model to assess the increased risk of non-melanoma skin cancer among outdoor workers in Central Queensland, Australia

BACKGROUND

The aim was to use the measured data on annual exposure to ultraviolet (UV) radiation in the risk estimation model to estimate the increase in risk of Non-Melanomic Skin Cancer (NMSC) among outdoor workers compared to indoor workers in Rockhampton (lat. 23 degrees S), Central Queensland, Australia.

METHODS

Results on annual occupational exposure measured on two occupational groups namely Australia Post Mail Delivery Personnel (APMDP) and Physical Education Teachers (PE) using film badge dosimeters was used in the risk estimation model to determine the increase in risk of NMSC with years of outdoor occupational exposure compared to indoor workers. The sensitivity of the model was tested for variations in recreational and childhood exposure of both groups, as well as occupational exposure of indoor workers.

RESULTS

For APMDP the increase in risk for Basal cell carcinoma (BCC) varied from 1.1 to 3.6 for 5-20 years of exposure and for Squamous cell carcinoma (SCC) the risk varied from 1.2 to 5.5 for the same periods of exposure. For the PE teachers the risk for BCC varied from 1.1 to 1.8 and for SCC the range was 1.1-2.3 for similar exposure periods.

CONCLUSION

The increased risk estimates did not show any significant changes for variations in occupational and recreational exposure. A maximum change of 20% was computed for 25% variation in childhood exposure, which was mainly for the APMDP with high occupational exposure levels and more than 10 years of occupational exposure. The increased risk estimates are useful to identify high risk groups at an early age and implement long-term protective measures against NMSC.

Annual occupational exposure to ultraviolet radiation in central Queensland

The purpose of this study was to determine annual occupational exposure to UV radiation by measurement and derive ambient exposure fractions for an entire year that could be applied in the human exposure model. Using polysulphone the daily occupational erythema effective solar ultraviolet radiation exposure at selected body sites of Australia Post mail delivery personnel and physical education teachers were measured over an 18-mo period on a daily basis in the Rockhampton (lat. 23.5 degrees S) region. The daily exposures were summed to estimate an annual exposure for these occupations in this region. For the Australia Post mail delivery personnel, who had very little change to the posture or route during delivery, the annual mean estimates of exposure to erythema effective solar irradiance for the chest, hands, and back were in the range of 192+/-27 kJ m(-2), 388+/-45 kJ m(-2), and 283+/-32 kJ m(-2), respectively. Physical education teachers had varied duties on a day-to-day basis and many changes in their posture and outdoor locations where the exposure occurred. Their annual mean exposure on the vertex (hat), chest, shoulder, thigh, and back were in the range 340+/-71 kJ m(-2), 140+/-28 kJ m(-2), 180+/-40 kJ m(-2), 129+/-24 kJ m(-2), and 212+/-42 kJ m(-2), respectively. The annual exposure range for erythema effective solar irradiance at different body sites during the experimental period was between 120 and 440 kJ m(-2) for the two occupational groups. These exposures greatly exceed the National Health and Medical Research Council occupational standard limit of 30 J m(-2) for daily exposure, which indicates the need for additional protective measures. The ambient exposure was also measured and used to compute ambient exposure fractions for the different body sites over an entire year, which are useful for model calculations on human exposure and assess increase in risk of n on melanoma skin cancer.