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Artificial Sunlight in Industry
856 to the deputation described on p. 874, suggest that he is alive to the difficulties in which many of the profession now find themselves. It would indeed be surprising if he were anything but sympathetic in considering a problem so intimately related to the prosperity of the plan he has placed before Parliament.
reply
Artificial
in Industry charged with the
Sunlight
care of DURING the war those such key personnel as submarine and air crews thought it worth while to use ultraviolet irradiation as an aid to operational fitness. At that time there was little option but to assume that this treatment did good. At least it had some moral effect, in that the men felt that something positive was being done to promote their health and efficiency. A controlled experiment under Service conditions was impracticable, because in those critical days it would have been unfair and unwise to deny any man the possible benefits of treatment which certainly did no harm. Now, however, the Industrial Health Research Board has completed a convincing trial of artificial sunlight as a prophylactic against illness among clerical and industrial workers. The report1 by Dr. DORA COLEBROOK, the board’s investigator, gives a clear-cut answer to the specific question and is also an excellent prototype of the experiments which will become of increasing value in research in social and industrial medicine. Outside the well-defined field of treatment of such diseases as rickets and non-pulmonary tuberculosis, the precise value of ultraviolet light as a tonic " or prophylactic against minor sickness has been the subject of much debate. Views and reports were conflicting, and the experimental methods of the protagonists were open to serious statistical criticism. The subject had engendered a good deal of emotional heat among people interested in industrial welfare, and the existence of personal bias on both sides the need for a watertight experimental in all experiments of this type, the first As design. considerations are the variables involved and their control. Dr. COLEBROOK clearly thought that three factors were of prime importance-the physical action of the ultraviolet rays themselves ; the psychological effects of basking in the rays in the soothing atmosphere of a sun-ray clinic ; and last, but by no means least, the possible effects of chance influences unconnected with irradiation. To control these factors she divided her volunteers into three groups. The first group were regularly exposed to the unscreened lamps (without causing more than a mild erythema). The second group were exposed to the rays of similar lamps which were screened by ordinary glass to exclude the shorter rays ; this group thought they were receiving exactly the same treatment as group 1, so the psychological effects of the lamps were identical in the two groups. The third group, chosen by strictly random selection so as to be as far as practicable like the other two, received no treatment at all. The scope of the experiment was widened by including in the second group a subgroup who received a vitamin-D supplement, and by extending the survey to three types of worker-in office, factory, and mine. As her criteria of benefit from the treatment Dr. COLEBROOK adopted sick-absence, the subjective "
emphasised
.
1. Artificial Sunlight Treatment in Industry. Rep. indust. Hlth Res. Bd, Lond. no. 89. H.M. Stationery Office. Pp. 64. 1s.
of the volunteers themselves, and, in the mines, absence either casual or due to injury.All three groups in each of the fields of study were followed up during the course of treatment and for the. two subsequent months. Parallel records were carefully kept and then analysed statistically. The results were substantially the same in the office, factory, and mining groups. In neither the office nor the factory group was there any significant difference in the average amount of sick-absence among those receiving screened and those receiving unscreened rays-that is, there was no evidence that the shorter rays of the spectrum increase resistance to infection. Further, there was no real difference between the sick-absence in these treated groups and in the group receiving no light treatment at all, so the psychological stimulus of the sun-ray clinic also does not increase resistance. Within the screened group, too, there was no sign that the vitamin supple. ment in any way affected the subject’s liability to ailments. In the colliery, the untreated group had a slightly lower sickness-rate than the treated, but this was probably due to the difficulty of obtaining a satis. factory control group by strict random sampling from the volunteers ; the treated and control groups were therefore not strictly comparable. Next Dr. COLEBROOK analysed the reported duration of common colds in the clerical and factory workers-it was not possible to collect such data among the miners. Again no material difference was observed between the groups fully exposed to the shorter rays and those exposed to the screened lamps. Among the untreated workers colds lasted a shorter time than in the other groups. Here again, however, there was a suggestion that the more efficient recording of sickness among the people actually attending the clinic might have influenced this result. In the colliery it was possible to compare the absence due to sickness and to other causes in all three groups, and this comparison again gave barely appreciable differences. Lastly, the less precisely measurable impressions of the workersthemselves were elicited by interview, " and the proportion of subjects who " felt better" was no higher after a full course of sun-ray therapy than in either the" screened " or untreated groups. To those who hoped that artificial sunlight would prove a useful weapon in the campaign against industrial ill health these results will seem depressing. It is true that some details in the practical conduct of the research are open to criticism-as much is admitted in the report-but from a practical point of view these inevitable imperfections do not detract from the unequivocal nature of the findings. In brief, these findings are that artificial sunlight, used in this particular way in this particular population, has no appreciable effect on health as judged by the criteria adopted in this study. They in no way imply that ultraviolet-ray therapy is useless in other conditions, or when more intensive methods are used. Nor does the finding that this form of " tonic " for industrial workers is of problematical value imply that nothing can be done to raise their resistance to infection and so reduce their sick-absence. There is an urgent need for research conceived and carried out like this example, and like it freed from any commercial bias, into problems even more fundamental to industrial health than the use of artificial sunlight.
impressions
.
reply
Artificial
in Industry charged with the
Sunlight
care of DURING the war those such key personnel as submarine and air crews thought it worth while to use ultraviolet irradiation as an aid to operational fitness. At that time there was little option but to assume that this treatment did good. At least it had some moral effect, in that the men felt that something positive was being done to promote their health and efficiency. A controlled experiment under Service conditions was impracticable, because in those critical days it would have been unfair and unwise to deny any man the possible benefits of treatment which certainly did no harm. Now, however, the Industrial Health Research Board has completed a convincing trial of artificial sunlight as a prophylactic against illness among clerical and industrial workers. The report1 by Dr. DORA COLEBROOK, the board’s investigator, gives a clear-cut answer to the specific question and is also an excellent prototype of the experiments which will become of increasing value in research in social and industrial medicine. Outside the well-defined field of treatment of such diseases as rickets and non-pulmonary tuberculosis, the precise value of ultraviolet light as a tonic " or prophylactic against minor sickness has been the subject of much debate. Views and reports were conflicting, and the experimental methods of the protagonists were open to serious statistical criticism. The subject had engendered a good deal of emotional heat among people interested in industrial welfare, and the existence of personal bias on both sides the need for a watertight experimental in all experiments of this type, the first As design. considerations are the variables involved and their control. Dr. COLEBROOK clearly thought that three factors were of prime importance-the physical action of the ultraviolet rays themselves ; the psychological effects of basking in the rays in the soothing atmosphere of a sun-ray clinic ; and last, but by no means least, the possible effects of chance influences unconnected with irradiation. To control these factors she divided her volunteers into three groups. The first group were regularly exposed to the unscreened lamps (without causing more than a mild erythema). The second group were exposed to the rays of similar lamps which were screened by ordinary glass to exclude the shorter rays ; this group thought they were receiving exactly the same treatment as group 1, so the psychological effects of the lamps were identical in the two groups. The third group, chosen by strictly random selection so as to be as far as practicable like the other two, received no treatment at all. The scope of the experiment was widened by including in the second group a subgroup who received a vitamin-D supplement, and by extending the survey to three types of worker-in office, factory, and mine. As her criteria of benefit from the treatment Dr. COLEBROOK adopted sick-absence, the subjective "
emphasised
.
1. Artificial Sunlight Treatment in Industry. Rep. indust. Hlth Res. Bd, Lond. no. 89. H.M. Stationery Office. Pp. 64. 1s.
of the volunteers themselves, and, in the mines, absence either casual or due to injury.All three groups in each of the fields of study were followed up during the course of treatment and for the. two subsequent months. Parallel records were carefully kept and then analysed statistically. The results were substantially the same in the office, factory, and mining groups. In neither the office nor the factory group was there any significant difference in the average amount of sick-absence among those receiving screened and those receiving unscreened rays-that is, there was no evidence that the shorter rays of the spectrum increase resistance to infection. Further, there was no real difference between the sick-absence in these treated groups and in the group receiving no light treatment at all, so the psychological stimulus of the sun-ray clinic also does not increase resistance. Within the screened group, too, there was no sign that the vitamin supple. ment in any way affected the subject’s liability to ailments. In the colliery, the untreated group had a slightly lower sickness-rate than the treated, but this was probably due to the difficulty of obtaining a satis. factory control group by strict random sampling from the volunteers ; the treated and control groups were therefore not strictly comparable. Next Dr. COLEBROOK analysed the reported duration of common colds in the clerical and factory workers-it was not possible to collect such data among the miners. Again no material difference was observed between the groups fully exposed to the shorter rays and those exposed to the screened lamps. Among the untreated workers colds lasted a shorter time than in the other groups. Here again, however, there was a suggestion that the more efficient recording of sickness among the people actually attending the clinic might have influenced this result. In the colliery it was possible to compare the absence due to sickness and to other causes in all three groups, and this comparison again gave barely appreciable differences. Lastly, the less precisely measurable impressions of the workersthemselves were elicited by interview, " and the proportion of subjects who " felt better" was no higher after a full course of sun-ray therapy than in either the" screened " or untreated groups. To those who hoped that artificial sunlight would prove a useful weapon in the campaign against industrial ill health these results will seem depressing. It is true that some details in the practical conduct of the research are open to criticism-as much is admitted in the report-but from a practical point of view these inevitable imperfections do not detract from the unequivocal nature of the findings. In brief, these findings are that artificial sunlight, used in this particular way in this particular population, has no appreciable effect on health as judged by the criteria adopted in this study. They in no way imply that ultraviolet-ray therapy is useless in other conditions, or when more intensive methods are used. Nor does the finding that this form of " tonic " for industrial workers is of problematical value imply that nothing can be done to raise their resistance to infection and so reduce their sick-absence. There is an urgent need for research conceived and carried out like this example, and like it freed from any commercial bias, into problems even more fundamental to industrial health than the use of artificial sunlight.
impressions
.