Antoine Milon

Effective exposure to solar UV in building workers: influence of local and individual factors

Excessive exposure to solar UV light is the main cause of skin cancers in humans. UV exposure depends on environmental as well as individual factors related to activity. Although outdoor occupational activities contribute significantly to the individual dose received, data on effective exposure are scarce and limited to a few occupations. A study was undertaken in order to assess effective short-term exposure among building workers and characterize the influence of individual and local factors on exposure. The effective exposure of construction workers in a mountainous area in the southern part of Switzerland was investigated through short-term dosimetry (97 dosimeters). Three altitudes, of about 500, 1500 and 2500 m were considered. Individual measurements over 20 working periods were performed using Spore film dosimeters on five body locations. The postural activity of workers was concomitantly recorded and static UV measurements were also performed. Effective exposure among building workers was high and exceeded occupational recommendations, for all individuals for at least one body location. The mean daily UV dose in plain was 11.9 SED (0.0–31.3 SED), in middle mountain 21.4 SED (6.6–46.8 SED) and in high mountain 28.6 SED (0.0–91.1 SED). Measured doses between workers and anatomical locations exhibited a high variability, stressing the role of local exposure conditions and individual factors. Short-term effective exposure ranged between 0 and 200% of ambient irradiation, indicating the occurrence of intense, subacute exposures. A predictive irradiation model was developed to investigate the role of individual factors. Posture and orientation were found to account for at least 38% of the total variance of relative individual exposure, and were also found to account more than altitude on the total variance of effective daily exposures. Targeted sensitization actions through professional information channels and specific prevention messages are recommended. Altitude outdoor workers should also benefit from preventive medical examination.

Estimating the contribution of occupational solar ultraviolet exposure to skin cancer

Exposure to solar ultraviolet (UV) radiation is the main causative factor for skin cancer. Outdoor workers are at particular risk because they spend long working hours outside, may have little shade available and are bound to take their lunch at their workplace. Despite epidemiological evidence of a doubling in risk of squamous cell carcinoma (SCC) in outdoor workers, the recognition of skin cancer as an occupational disease remains scarce.

A numeric model to simulate solar individual ultraviolet exposure.

Exposure to solar ultraviolet (UV) light is the main causative factor for skin cancer. UV exposure depends on environmental and individual factors. Individual exposure data remain scarce and development of alternative assessment methods is greatly needed. We developed a model simulating human exposure to solar UV. The model predicts the dose and distribution of UV exposure received on the basis of ground irradiation and morphological data. Standard 3D computer graphics techniques were adapted to develop a rendering engine that estimates the solar exposure of a virtual manikin depicted as a triangle mesh surface. The amount of solar energy received by each triangle was calculated, taking into account reflected, direct and diffuse radiation, and shading from other body parts. Dosimetric measurements (n = 54) were conducted in field conditions using a foam manikin as surrogate for an exposed individual. Dosimetric results were compared to the model predictions. The model predicted exposure to solar UV adequately. The symmetric mean absolute percentage error was 13%. Half of the predictions were within 17% range of the measurements. This model provides a tool to assess outdoor occupational and recreational UV exposures, without necessitating time‐consuming individual dosimetry, with numerous potential uses in skin cancer prevention and research.

Anatomical exposure patterns of skin to sunlight: relative contributions of direct, diffuse and reflected ultraviolet radiation

Summary Background  The dose‐response between ultraviolet (UV) exposure patterns and skin cancer occurrence is not fully understood. Sun‐protection messages often focus on acute exposure, implicitly assuming that direct UV radiation is the key contributor to the overall UV exposure. However, little is known about the relative contribution of the direct, diffuse and reflected radiation components.

A general model to predict individual exposure to solar UV by using ambient irradiance data

Excessive exposure to solar ultraviolet (UV) is the main cause of skin cancer. Specific prevention should be further developed to target overexposed or highly vulnerable populations. A better characterisation of anatomical UV exposure patterns is however needed for specific prevention. To develop a regression model for predicting the UV exposure ratio (ER, ratio between the anatomical dose and the corresponding ground level dose) for each body site without requiring individual measurements. A 3D numeric model (SimUVEx) was used to compute ER for various body sites and postures. A multiple fractional polynomial regression analysis was performed to identify predictors of ER. The regression model used simulation data and its performance was tested on an independent data set. Two input variables were sufficient to explain ER: the cosine of the maximal daily solar zenith angle and the fraction of the sky visible from the body site. The regression model was in good agreement with the simulated data ER (R2=0.988). Relative errors up to +20% and −10% were found in daily doses predictions, whereas an average relative error of only 2.4% (−0.03% to 5.4%) was found in yearly dose predictions. The regression model predicts accurately ER and UV doses on the basis of readily available data such as global UV erythemal irradiance measured at ground surface stations or inferred from satellite information. It renders the development of exposure data on a wide temporal and geographical scale possible and opens broad perspectives for epidemiological studies and skin cancer prevention.

Comparison of Indices Proposed as Criteria for Assigning Skin Notation

OBJECTIVES Skin notations are used as a hazard identification tool to flag chemicals associated with a potential risk related to transdermal penetration. The transparency and rigorousness of the skin notation assignment process have recently been questioned. We compared different approaches proposed as criteria for these notations as a starting point for improving and systematizing current practice. METHODS In this study, skin notations, dermal acute lethal dose 50 in mammals (LD(50)s) and two dermal risk indices derived from previously published work were compared using the lists of Swiss maximum allowable concentrations (MACs) and threshold limit values (TLVs) from the American Conference of Governmental Industrial Hygienists (ACGIH). The indices were both based on quantitative structure-activity relationship (QSAR) estimation of transdermal fluxes. One index compared the cumulative dose received through skin given specific exposure surface and duration to that received through lungs following inhalation 8 h at the MAC or TLV. The other index estimated the blood level increase caused by adding skin exposure to the inhalation route at kinetic steady state. Dermal-to-other route ratios of LD(50) were calculated as secondary indices of dermal penetrability. RESULTS The working data set included 364 substances. Depending on the subdataset, agreement between the Swiss and ACGIH skin notations varied between 82 and 87%. Chemicals with a skin notation were more likely to have higher dermal risk indices and lower dermal LD(50) than chemicals without a notation (probabilities between 60 and 70%). The risk indices, based on cumulative dose and kinetic steady state, respectively, appeared proportional up to a constant independent of chemical-specific properties. They agreed well with dermal LD(50)s (Spearman correlation coefficients -0.42 to -0.43). Dermal-to-other routes LD(50) ratios were moderately associated with QSAR-based transdermal fluxes (Spearman correlation coefficients -0.2 to -0.3). CONCLUSIONS The plausible but variable relationship between current skin notations and the different approaches tested confirm the need to improve current skin notations. QSAR-based risk indices and dermal toxicity data might be successfully integrated in a systematic alternative to current skin notations for detecting chemicals associated with potential dermal risk in the workplace.

Occupational UV exposure in French outdoor workers

Objectives: Occupational ultraviolet (UV) exposure was evaluated in a population-based sample in France. Methods: A random survey was conducted in 2012 in individuals aged 25 to 69 years. The median daily standard erythemal UV dose (SED) was estimated from exposure time and place and matched to satellite UV records. Results: A total of 889 individuals were exposed to solar UV with highest doses observed among gardeners (1.19 SED), construction workers (1.13 SED), agricultural workers (0.95 SED), and culture/art/social science workers (0.92 SED). Information and communication technology, industry, and transport workers were highly exposed (>0.70 SED). Significant factors associated with high occupational UV exposure were sex (P < 0.0001), phototype (P = 0.0003), and taking lunch outdoors (P < 0.0001). Conclusions: This study identified not only expected occupations with high UV exposure but also unexpected occupations with high exposures. This could serve as a basis for future prevention.

Health effects of occupational exposure in a dairy food industry, with a specific assessment of exposure to airborne lactic acid bacteria.

Objective: Lactic acid bacteria (LAB) are used in food industries as probiotic agents. The aim of this study is to assess the potential health effects of airborne exposure to a mix of preblend (LAB and carbohydrate) and milk powder in workers. Methods: A medical questionnaire, lung function tests, and immunologic tests were carried out on 50 workers. Occupational exposure to inhalable dust and airborne LAB was measured. Results: Workers not using respiratory masks reported more symptoms of irritation than workers using protection. Workers from areas with higher levels of airborne LAB reported the most health symptoms and the immune responses of workers to LAB was higher than the immune responses of a control population. Conclusions: Measures to reduce exposure to airborne LAB and milk powder in food industries are recommended.

Prediction of anatomical exposure to solar UV: A case study for the head using SimUVEx v2

Excessive exposure to solar ultraviolet (UV) radiation is the main cause of skin cancer. The dose-response between UV exposure and skin cancer occurrence is not yet fully understood since UV exposure is highly heterogeneous and strongly influenced by host and behavioural factors, such as posture, orientation to the sun, skin complexion and clothing. To address this issue, a three-dimensional (3D) numeric model (SimUVEx) has been developed to assess dose and distribution of anatomical UV exposure. The model uses 3D computer graphics techniques to compute UV radiance on the basis of postural information and ambient irradiation data, without necessitating time-consuming individual dosimetry, ensuring a wide potential use in skin cancer prevention and research. With the purpose to improve simulation capabilities in order to obtain more realistic scenarios and quantify effective sun protection strategies, a new version has been released, SimUVEX v2. Among new features, a specific morphology for the most sun-exposed body area, the head, has been added. We selected three different styles of hat (cap, wide-brimmed hat and helmet) to compare scenarios with and without solar protections considering the relative contribution of the direct, diffuse and reflected radiation. It was found that, sites directly covered apart (e.g., forehead and top of the head), hats with a wide brim are necessary in order to provide reasonable protections around facial zones on which non-melanoma skin cancers commonly occur, such as nose and cheeks.

SimUVEx v2: A numeric model to predict anatomical solar ultraviolet exposure

Solar ultraviolet (UV) radiation has a dual effect on human health. Low UV doses promote the photosynthesis of vitamin D and regulate calcium and phosphorus metabolism, while an excessive UV exposure is the main cause of skin cancer, along with eye diseases and premature skin ageing. Nevertheless, the link between UV radiation levels and UV exposure is not fully understood since exposure data are limited and individual anatomical variations in UV doses are significant. For these reasons, a numeric simulation tool (SimUVEx) has been developed and validated in order to predict the dose and distribution of UV exposure received taking into account postural information and ambient irradiation data. SimUVEx is based on 3D graphics techniques usually used to render virtual environments to estimate the exposure of a 3D virtual manikin characterised as a triangular mesh surface. Each triangle receives a certain quantity of solar energy depending on the direct, diffuse and reflected radiation, the body surface orientation to the sun and the shadows from other parts of the body. The goals of the second version of SimUVEx are to move from individual-based to population-based (e.g., Switzerland and, eventually, Europe) exposure assessment, expanding temporal, spatial and morphological simulation capabilities. Outputs from SimUVEx version 2 will allow building exposure scenarios, identifying high-risk situations and producing reference dose ranges for typical outdoor occupational and leisure activities.