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A model of ocular and facial skin exposure to UVB is presented that combines interview histories of work activities, leisure activities, eyeglass wearing, and hat use with field and laboratory measurements of UV radiant exposure. Site-specific exposure is expressed as the product of personal ambient exposure, defined as the ambient exposure while an individual is exposed to sunlight, and factors that describe the ratio of site-specific to personal ambient exposure. Ocular exposure is further corrected by the UV attenuation of typical eyewear. The model was used to compute cumulative and yearly exposures in a population of 838 watermen who work on the Chesapeake Bay and are highly exposed to sunlight. The model was found to be predictive of conditions known to be caused by excessive sun exposure--skin elastosis, climatic droplet keratopathy, and squamous cell carcinoma--and has been useful in several epidemiological studies.

We determined the cumulative exposure of 3 body sites to ultraviolet radiation from sunlight for 126 children observed from 1-3 d during a variety of common recreational activities at a girl scout camp, baseball camp and community baseball field. Median arm exposure to children playing baseball at a camp ranged from 27.6% to 33.2% of the possible ambient exposure. These exposures are similar to adult exposures reported for comparable activities. Median exposure to the arm at the girl scout camp during mixed activities ranged from 9.0% to 26.5% of possible ambient exposure. At the girl scout camp, exposure both within and between activity groups varied substantially and were more variable than the baseball players' exposure. Arm exposure was greater than cheek and forehead exposure for all subject groups, with an arm-to-cheek exposure ratio ranging from 1.7 to 2.3. For organized sports, such as baseball, it may be possible to assign a single exposure estimate for use in epidemiologic studies or risk estimates. However, for less uniform outdoor activities, wide variability in exposure makes it more difficult to predict an individual's exposure.

Childhood exposure to ultraviolet (UV) radiation in sunlight may be an important risk factor for later development of skin diseases. We quantified the UVB radiant exposure on the wrist and face of children performing mixed outdoor activities at a summer camp. Polysulfone film badges were attached directly to the skin for several hours and simultaneously were used to measure ambient UVB levels. The results for the ratio of site-specific exposure to ambient exposure indicate a high degree of intersubject variability, a parity of samples taken in right and left positions, and a significantly higher exposure on the wrist compared with the face. The technique was well accepted by the subjects but some badges could not be read because of loss or damage. Measurement of exposure ratios in additional settings as well as data on childhood activity patterns are needed for an overall assessment of childhood exposure.

Ocular ultraviolet radiation (UVR) exposure was assessed in three occupational groups: fisherman, landscape workers and construction workers. The ratio of ocular exposure to ambient exposure was determined by placing UV-sensitive film (295-320 nm) between the eyes of the subjects and in a nearby open field. The mean ocular exposures varied between 2 and 17% of the ambient exposure on a horizontal surface, depending on whether subjects wore hats, the job performed and the time of year. Wearing a brimmed hat significantly reduced ocular exposure in all groups of subjects. Subjects working over more reflective surfaces had significantly higher ocular exposure. A seasonal effect on the ocular ambient exposure ratio (OAER) was also observed. These results are consistent with measurements of OAER in mannikin and measurements of surface reflectivity in this and previous studies. The results provide parameters which can be used in modeling ocular UVR exposure in epidemiological and clinical studies.

Skin cancer is the most common form of cancer in humans and occurs primarily on sun-exposed areas of the body. In a study of 808 Caucasian Maryland watermen, we examined the prevalence of nonmelanoma skin cancer in relation to age and exposure to solar ultraviolet B (UVB) radiation. For each study subject, the exposure to solar UVB radiation for each year of life after the age of 16 years was calculated. We obtained the data for this analysis by combining a detailed occupational history with laboratory and field measurements. Prevalence of the three major types of nonmelanoma skin neoplasms was analyzed: squamous cell carcinoma (SCC), basal cell carcinoma (BCC), and actinic keratosis (AK). Average annual exposure to UVB radiation was strongly correlated with the prevalence of SCC, but not with the prevalence of BCC or AK. This finding is consistent with dose saturation (plateau in dose-response relationship) for the induction of BCC and AK in humans with high annual exposure to UVB radiation. In addition, two small groups of apparently hypersusceptible individuals were present in the population. One group had SCC despite low annual exposure to UVB radiation, and the other group had multiple skin cancers despite average exposure to UVB radiation.

To investigate the relation of ultraviolet radiation and cataract formation, we undertook an epidemiologic survey of 838 watermen (mean age, 53 years) who worked on Chesapeake Bay. The annual ocular exposure was calculated from the age of 16 for each waterman by combining a detailed occupational history with laboratory and field measurements of sun exposure. Cataracts were graded by ophthalmologic examination for both type and severity. Some degree of cortical cataract was found in 111 of the watermen (13 percent), and some degree of nuclear cataract in 229 (27 percent). Logistic regression analysis showed that high cumulative levels of ultraviolet B exposure significantly increased the risk of cortical cataract (regression coefficient, 0.70; P = 0.04). A doubling of cumulative exposure increased the risk of cortical cataract by a factor of 1.60 (95 percent confidence interval, 1.01 to 2.64). Those whose annual average exposure was in the upper quartile had a risk increased by 3.30 (confidence interval, 0.90 to 9.97) as compared with those in the lowest quartile. Analysis using a serially additive expected-dose model showed that watermen with cortical lens opacities had a 21 percent higher average annual exposure to ultraviolet B (t-test, 2.23; P = 0.03). No association was found between nuclear cataracts and ultraviolet B exposure or between cataracts and ultraviolet A exposure. We conclude that there is an association between exposure to ultraviolet B radiation and cataract formation, which supports the need for ocular protection from ultraviolet B.

As some ultraviolet (UV) radiation is transmitted by the ocular media, there is a growing concern that there may be a possible relationship between long-term exposure to ultraviolet radiation and increased risk of age-related macular degeneration. To address this question, a survey was conducted of 838 Maryland watermen who had well-characterized ocular UV-A and UV-B exposure. Fundus photographs were taken and graded for presence of exudative disease, geographic atrophy, focal hyperpigmentation of the retinal pigment epithelium, and drusen that were large and/or confluent. None of the subjects in these analyses were aphakic. The results suggested that age-related macular degeneration was not associated with cumulative exposure to either UV-A or UV-B. Age and the presence of nuclear opacity were independently associated with an increased risk of macular degeneration. Thus, we found that in phakic subjects, even with high levels of sunlight exposure, there was no evidence of increased risk of age-related macular degeneration associated with UV-B or UV-A exposure.

Several studies have suggested that ultraviolet radiation in sunlight may cause cataracts and other eye disease. We evaluated the effect of prescription eyewear in attenuating ocular exposure to ultraviolet radiation (UVR) in the sunlight portions of the ultraviolet spectrum (295-350 nm). Using natural sunlight as the source, the attenuation was measured with two ultraviolet detectors, one sensitive to only UVB (295-315 nm) and one sensitive to both UVA and UVB (295-350 nm). A random sample of spectacles, spectacle lenses, and contact lenses was examined. The average transmission, as measured with either detector, was highest for soft contact lenses, followed by glass spectacle lenses, untinted hard contact lenses, and plastic spectacle lenses. Measurements performed with mannikins wearing spectacles showed that an average of 6.6 per cent of incident radiation reached the eye even when the lenses were covered with black opaque tape. The amount of exposure was increased substantially when the spectacles were moved 0.6 cm away from the forehead. The results show that the protection against ultraviolet exposure provided by prescription eyewear is highly variable and depends largely on its composition, size, and wearing position.

The association between exposure to UV radiation and corneal disease was investigated in 838 watermen who work on the Chesapeake Bay, Maryland. Individual ocular exposure was calculated by combining a detailed occupational history with laboratory and field measurements. Pterygium was found in 140, climatic droplet keratopathy in 162, and pinguecula in 642. Logistic regression analysis showed that pterygium and climatic droplet keratopathy were significantly associated with a broad band of UV radiation exposure (UV-B, 290 to 320 nm; A1, 320 to 340 nm; and A2, 340 to 400 nm), but the association with pinguecula was weaker. Simple measures such as wearing a hat or spectacles protect the eye and could potentially reduce the amount of pterygium and climatic droplet keratopathy attributable to UV radiation exposure.

Thirty-two pairs of inexpensive sunglasses were examined for their effectiveness in preventing ultraviolet radiation (UVR) from reaching the eyes. The transmission of UVB (290-310 nm) by all of the sunglass lenses was less than 2 per cent. However, in measurements performed with mannikins wearing the sunglasses, up to 14.1 per cent of the incident UVR passed through to the eyes. When the sunglasses were moved 6 mm from the forehead, the per cent reaching the eyes ranged from 3.7 to 44.8 per cent. Although sunglasses are somewhat more effective than untinted prescription eyewear in attenuating ocular exposure, the amount of attenuation is highly variable and depends mainly on their size, shape, and wearing position.