Australas J. Dermatol 1992; 33: 1-10
OCCUPATIONAL CONTACT DERMATITIS IN NEW SOUTH WALES ROBERT H . ROSEN AND SUSANNE FREEMAN
Sydney SUMMARY
Five hundred and seventy patients with occupational contact dermatitis (OCD) were seen between 1984 and 1990 at the Skin and Cancer Foundation in Sydney. Data derived from these patients demonstrated that hairdressing, food, construction and the medical industries were the most at risk of OCD. The hairdressing and food industries had a high percentage of apprentices suffering OCD whilst the 35 to 44 year age bracket was most at risk in the construction industry. Allergic contact dermatitis was responsible for 38.2% of cases. The main allergens were chromate, thiuram, epoxy resin, nickel and cobalt. A third (33.9%) of patients were atopic. The average time lost from work was 16 days each year and the calculated yearly cost of OCD in New South Wales was approximately $12 million. Key words: Occupational skin disease, contact dermatitis, workers compensation. National Occupational Health and Safety Commission.' Recently a study of patients with OSD seen in a Perth private dermatological practice over an eight year period was published by Wall and Gebauer.^" The authors provided information on the commonest allergens and the highest risk industries in Western Australia. They also analyzed patient information such as age, sex and history of atopy and concluded that OSD in Western Australia did not differ in any major way from other countries. The aim of our research project was to investigate occupational contact dermatitis in New South Wales and correlate the results with currently availble workers compensation statistics. Therefore the files of the Occupational and Contact Dermatitis Clinic of the Skin and Cancer Foundation from 1984 until 1990 were reviewed and follow-up data was collected from the patient population. Two and half thousand cases were examined and roughly one quarter (570) were determined to be occupationally related. These patients were followed up by means of a series of questionnaires. Follow-up data in regard to outcome and further employment will be examined in another publication.
INTRODUCTION
Occupational skin disease (OSD) is a very common, if not the most common, industrial illness^' The cost of OSD has been estimated at between $222 million and $1 billion annually in the USA.' The true cost could be 10 to 50 times more if an accurate figure of the incidence of occupational contact dermatitis (OCD) could be identified.'" The cost of OSD in Australia has not hitherto been estimated. Contact dermatitis accounts for more than 90% of occupational skin disease." " ' ' Allergic contact dermatitis can be diagnosed by patch testing with the offending allergen whereas irritant contact dermatitis is a diagnosis of exclusion." " Most American and Asian studies have documented allergic contact dermatitis as accounting for about one third of cases.'"" The European literature however claims that allergic contact dermatitis may account for at least fifty percent of all cases.""* Australian statistical data on occupational skin disease has been mostly restricted to compensation statistics'" which were thought to underestimate numbers and to be inadequate by the Robert H. Rosen, MBBS, M.Med. Dermatology Registrar. Susanne Freeman, MBBS, DDM, FACD. Head of Industrial and Contact Dermatitis Clnic, Skin and Cancer Foundation, Sydney. Address for correspondence: Dr Susanne Freeman, Skin and Cancer Foundation, 277 Bourke St, Darlinghurst, NSW 2010.
PATIENTS AND METHOD
The Skin and Cancer Foundation is a tertiary referral centre in Sydney and is affiliated with the University of New South Wales. Patients with 1
ROBERT H . ROSEN AND SUSANNE FREEMAN
FIGURE 1—ACD in a construction worker caused by cement. Positive patch test to chromate and cobalt.
FIGURE 2—ACD in an abbatoir worker caused by rubber boots. Positive patch tests to thiuram chemicals.
2
OCCUPATIONAL CONTACT DERMATITIS IN NEW SOUTH WALES
suspected OSD are referred to its contact and occupational dermatitis clinic, predominantly by dermatologists and occupational health physicians. A three page protocol is completed on each patient including a detailed occupational and non-occupational history, and a physical examination is performed. Patch testing is carried out using the European standard series of allergens as well as series of allergens which are appropriate to the individual's industry or history of exposure. Actual compounds and material with with the patient works are tested, in carefully determined dilutions. Patch testing is carried out using Trolab® allergens on Epitest® strips. These are aluminium chambers on hypoallergenic tape. Readings are then made at 48 hours and 96 hours according to the standards of the International Contact Dermatitis Research Group. The patients are therefore seen on three occasions. After the final reading of the patch test, the patient is informed about the relevance of the results and a report is sent to the referring physician. Five hundred and seventy patients with a work related dermatitis were selected from 2400 patients seen between 1984 and 1990. They were determined to be occupationally related on the basis of a detailed history, physical examination and patch test findings. Their data was entered onto a spreadsheet database for subsequent crosstable analysis. Meanwhile the patients were sent a series of three questionnaires in order to 0.00%
2.00%
4.00%
evaluate their progress (and the prognosis for this disease). The total number of patients returning questionnaires was 337, giving a compliance rate of 59%. RESULTS
The main industries affected by contact dermatitis were (in order) the hairdressing industry, the food industry and the construction and medical industries. Almost one third of all the women in this study worked in the hairdressing industry. They represented a disproportionate 94% of the industry, whilst all the members of the construction industry were men. The food industry was the second most frequently affected by contact dermatitis, and was common to both sexes. It is of interest to observe that the cleaning industry and farm (or agricultural) industries were not well represented in this list of OCD as they are in Sweden or the United States. This may represent a bias of the referral base or may be due to under-reporting by the patients. Figure 3 compares the incidence of contact dermatitis between the industries and figure 4 lists these main industries against their sex composition. In this study allergic contact dermatitis (ACD) was reponsible for 38.2% of the cases and irritant contact dermatitis the remaining 61.8%. The largest group was men suffering from irritant dermatitis (Figure 5).
6.00%
8.00%
10.00%
12.00%
14.00%
Hairdresser Food Construction
1
Medical 1
Printing
1
1
•1
1
Maintenance 1
Laboratory
1
Auto Farm Machinist
—
1
«:5:!S:S!::$!:f:l:vS:a FIGURE 3
Top ten industries with OCD. Percentages refer to the proportion of total number of cases in the study. (See figure 4 also.) 3
ROBERT H . ROSEN AND SUSANNE FREEMAN
Industry Hairdresser Food Construction Medical Printing Maintenance Laboratory Auto Farm Others
TOTAL
Male %of Female %of TOTAL % OF ALL Industry 570 PTS IN Industry STUDY 5 73 78 6.4% 93.6% 13.7% 41 25 66 62.1% 37.9% 11.6% 53 100.0% 0 53 0.0% 9.3% 11 40 51 21.6% 78.4% 8.9% 19 6 25 76.0% 24.0% 4.4% 22 2 24 91.7% 8.3% 4.2% 14 9 23 60.9% 39.1% 4.0% 21 1 22 95.5% 4.5% 3.9% 15 6 21 71.4% 28.6% 3.7% 119 88 207 36.3% 320
56.1%
250
43.9%
570
100.0%
FIGURE 4
Top industries with OCD showing differences between numbers of males and females affected.
Sex Exogenous FEMALE % female Allergic 84 14.7% Irritant 166 29.1% 250 TOTAL 43.9%
MALE 134 186
320
%male 23.5% 32.6% 56.1%
TOTAL 218
352 570
% total 38.2% 61.8% 100.0%
FIGURE 5
Types of contact dermatitis. Percentages refer to the proportion of total number of cases in study. (% female refers to proportion of all female cases in the study, etc.) The allergens most often identified as causing allergic contact dermatitis in this survey were potassium dichromate (18.3%) found in cement as well as many other materials such as paint and leather, thiuram (17%) an antioxidant present in rubber, expoxy resins (17%) found in glues and hardeners, nickel sulphate (12.4%) used in some metal instruments, and cobalt chloride (10.1%) which often accompanies potassium dichromate and nickel. These allergens affected each sex with different frequency. The main allergens affecting women were nickel (25%), and thiuram (17.9%)
whilst men were most often allergic to chromate (26.9%), epoxy resins (24.6%) and thiuram (16.4%). Of the 570 patients studied 56.1% (320) were men and the remaining 43.9% (250) were women. Roughly a third of the population was between the ages of 15 and 24 years old (35.6%). This relates to the high incidence of dermatitis in apprentices. Men were distributed more evenly throughout the age groups. This is because, in addition to younger workers, men in their middle years are
OCCUPATIONAL CONTACT DERMATITIS IN NEW SOUTH WALES
1 5-1920-2425-2930-3435-3940-4445-4950-5455-5960-6465-6970-75 AGE (Years) FIGURE 6
Age/sex study of OCD cases. The prevalence of apprentices is seen by the peak in the 15 to 25 year age group. The second peak in the 35 to 45 year age group represents workers in the construction industry. subject to dermatitis particularly in the develop contact dermatitis is not while they are construction industry. Figure 6 demonstrates apprentices (or new to the industry) but during graphically the concentration of younger workers, middle age, after they have been fully trained and especially women with dermatitis, and the have the greatest financial burden of their lives. It has previously been suggested that individsecondary peak in men aged 35 to 44 years. Apprentices are often expected to perform the uals with atopic dermatitis are more prone to most menial and repetitive tasks. Usually this is developing irritant contact dermatitis than nonin the areas of preparation and cleaning. It would atopies and also less prone to developing allergic not be surprising therefore, if they were at the contact dermatitis. In this survey there were 193 highest risk of dermatitis in some industries. The atopies of whom 132 (almost 70%) suffered main industry affecting the 15 to 24 year age irritant dermatitis and 61 (or 31.5%) suffered group is the hairdressing industry. More than allergic contact dermatitis. This compares to 70% were apprenticess. Indeed 65% of the people 51.6% of non-atopies suffering from irritant affected with occupational dermatitis in this dermatitis and 48.4% suffering from allergic contact dermatitis. This demonstrates the industry were less than 20 years old. Hairdressing is the main industry in which expected polarization of atopies towards irritant young women in the 15 to 24 year age group were contact dermatitis (p-^0.02) which has affected but most young men in this age group implications for pre-employment counselling of were from the food industry. More than 70% of atopies against entering high risk industries. men and women with dermatitis in the food, However, it is also of interest that almost a third of the atopies showed a superimposed ACD. industry were between the ages of 15 and 29. Only about one third of patients with occupaThe peak incidence in the construction industry was observed in the 35 to 44 year age group. In tional dermatitis had applied for workers human terms this means that the likely time compensation (211 people or 37.5%), despite the members of the construction industry will average time lost from work being one month!
ROBERT H . ROSEN AND SUSANNE FREEMAN
Workers Compensation. undefined Yes
m.
Sex Males Females total
180 171 351
3 5 8
137 74 211
total
320 250 570
FIGURE 7
Patients who applied for workers compensation. Note that only about 'A ofpatients with OCD applied for workers compensation (211 patients/37.5%)
0 .60 0 .50 Ratio
w. C./TOTAL GROUP
.40
0 .30 0.20 0.10 0.00
15 to 19
20 to 24
25 to 29
30 to 35 to 34 39
40 to 44
45 to 50 to 54 49
55 to59
60 to 64
Ages FIGURE 8
Relative proportion of WC total group. Note that the smallest proportion of WC claimants were in the apprentice age group (15 to 25 years old) A larger proportion of men applied for workers compensation than women (p-^0.01). About 43% of men and 30% of women applied for compensation (or 24% and 13% of the total number of men and women respectively). This is demonstrated in figure 7. The age group which claimed compensation most often was the 20 to 24 year group. However when compared to the age distribution in the whole study population they were in fact a relatively small proportion of all those affected.
This can be visualized in figure 8. There was in fact a relative lack of application for compensation in the 15 to 29 year groups. These were mostly women and were very often apprentices. The greatest proportion of people applying for compensation is at 35 to 40 years and 45 to 50 years (seen in figure 8 as the two peaks). Indeed a majority of the men in these age divisions had applied for workers compensation. When one considers that the greatest living costs are during the 35 to 60 year bracket (mortgages, child
OCCUPATIONAL CONTACT DERMATITIS IN NEW SOUTH WALES
%of F/U group receiving we 28.5% 25.7% 27.4%
% Successful applications 71.4% MALE 82.9% FEMALE 75.4% TOTAL FIGURE 9
Percentage of workers applying for and receiving WC. Note that at follow up just over 'A of patients with OCD had received WC. However of those who applied V4 were successful. education, househotd expenses), it is not surprising that a large proportion of these people would seek compensation. Perhaps the most important finding is that at follow up only one quarter of patients with OSD had received workers compensation, even though 75% of those who applied for workers compensation were approved (Figure 9). This means that Australian workers with OSD assessed in this study are certainly not overusing "compo", as is often thought. Furthermore occupational contact dermatitis may be four times more prevalent in Australia, than we had previously imagined from workers compensation statistics. In addition there are premium based disincentives for employers to report workers compensation claims. The number of patients successfully followed up was 337 (3 had died of other illness). This represented 59% of the study population. The patients who replied were analysed for bias and no statistically significant bias influencing follow up data was demonstrated, including bias due to age, sex, industry, type of dermatitis or workers compensation. In the average two year period before referral to the Skin and Cancer Foundation, most people had taken up to a month off work to recover from their dermatitis, the average loss of time being 30.9 days. If one were to extrapolate this in terms of the total study population it would mean a total loss of 48.3 years. That is more than 100,000 man hours (if each one worked 8 hours per day, 5 days per week) lost from productivity from only 570 people. After diagnosis almost half the follow up population still required up to one month to convalesce. Roughly 10% of the answering population required more than one year off. The
average convalescent time after diagnosis was 79.3 days. The time lost as a result of OCD can be calculated by adding the 30.9 days (taken on average over two years) before diagnosis and 80 days (taken over the average follow up period of three years) after diagnosis. Therefore 110.2 days were lost over a five year period. This is equivalent to 16 workdays lost per year per patient (working a five day week). This is probably an underestimate as most of the people affected come from industries such as the food, construction and medical industries which often work more than an eight hour day and a five day week. DISCUSSION
Occupational contact dermatitis is the major occupational skin disease and is one of the most common worldwide industrial illnesses.'*" '^ Our study population was 570 people which places it amongst the larger international studies.^' Patients were sent three batteries of questionnaires and the non-responders were telephoned. This achieved a comphance rate of 59%. Most international researchers iri the field of contact dermatitis have used retrospective studies with the assistance of either follow up interviews or questionnaires. The response rates in these studies usually lie between 30% and 50%^' (although Wall s study in Western Australia had a remarkable 96%"). The majority of these were performed in Europe or in the United States of America. The top four industries in which workers were most at risk of developing contact dermatitis were, in order, the hairdressing industry, the food industry, the construction and the medical industries. More than 90% of people in the hair-
ROBERT H . ROSEN AND SUSANNE FREEMAN
The construction industry on the other hand, exclusively affected men in this study and most of them were in their middle working years. Unlike the other major industries affected by this disease, apprentices were not a primary target. Men may work many years in this industry before they develop dermatitis. By the time it occurs they could be working to support a family and a mortgage and they probably could not afford a drop in wages in order to be retrained, even if the high proportion of migrants in this occupation could overcome the language barrier. Financial incentives, including overtime, generally keep these men working despite the appearance of an occupational disease. When they do seek assistance the dermatitis is already well established and it is not surprising therefore that they require more time off work. They lose approximately three times the average work time lost by other industries.
dressing industry were wotnen and more than 70% were apprentices. Similar fignres have been published from other studies.^°^^^' When one considers the length of time the apprentices spend washing, shampooing and colouring hair it is not surprising that they would rate highly as an industry affected by contact dermatitis. In Fregert's ten year study of occupational dermatitis in Sweden he ranked hairdressers just behind the medical and cleaning industries as the commonest industries affecting women.' In all these industries, prolonged exposure to detergents and water would account for large numbers of cases of irritant dermatitis. In a similar way housewives often develop ICD but are not considered by Workcover to have a work related disease and so cannot be tabulated in this study. NIOSH (National Institute of Occupational Safety and Health)" listed the main US industries affected by occupational dermatitis in 1984 as agriculture (farm), manufacturing and construction. In contast, earlier statistical analysis published by Mathias and Morrison from the Annual Survey of Occupational Illnesses' in the US ranked the food industry ahead of construction in the list of top industries with the highest incidence of occupational dermatitis. They rated the health (medical) industry as the industry with the largest number of skin disease cases between 1973 and 1984. The food and construction industries feature more prominently in this New South Wales sample than do agriculture or manufacturing. There may be logistic and financial restrictions which limit the attendance of the agricultural population at clinics in the city, but there is no other occupational dermatology centre which performs patch testing in New South Wales. Therefore the lower frequency of contact dermatitis in this industry is unlikely to be due entirely to referral bias. The food industry is, not surprisingly, a key 'at risk' industry. The high incidence of occupational contact dermatitis amongst food workers has been frequently documented.''^''^' It was the commonest industry in Wall and Gebauer's study in Western Australia" and the fourth commonest industry affected by OSD in the study by Goh in Singapore.' More than 70% of the food industry patients were less than 30 years old and roughly a third were apprentices. This industry was a common source of contact dermatitis for both sexes.
The construction industry is prominently placed in the occupational dermatitis statistics of all the countries reviewed. It was the main industry in the Singapore study of 389 patients by Goh' and the second commonest industry affecting males in Fregert's study of 1752 patients in Sweden." As mentioned above, NIOSH" ranks it as America's third major affected industry and it was fourth overall in Western Australia." ACD constituted 67% of the cases of occupational dermatitis in the construction industry because of the high proportion of chromate sensitive dermatitis in this industry, for which cement is the usual source." Most of the other main industries have a higher proportion of irritant rather than allergic contact dermatitis (38% ACD and 62% ICD). (These statistics were not included in the results section). This disproportionate frequency of chromate allergy has already gained considerable international atten{JQjj2o,2935 ^j^j suggestions on methods of addressing this problem have already been implemented." " The addition of ferrous sulphate to cement in order to reduce the soluble chromate concentration has already been adopted in Europe (Denmark and Sweden)" '* but not yet in Australia. Chromium, however is a ubiquitous allergen. It is present in many industrial processes, as well as in the diet, and of course in cement. Fisher states that it "is more abundant than all other metals".^" Chromate dermatitis tends to become chronic and self perpetuating even after 8
OCCUPATIONAL CONTACT DERMATITIS IN NEW SOUTH WALES
the removal of the worker from the initial work environment.^" The other major causative allergens overall were thiuram (used as an antioxidant in rubber) and epoxy resin. Nickel was the single commonest allergen in women and occured in several industries. Fregert* also found nickel to be the major occupational allergen in females with ACD. However, nickel allergy in women is usually derived from the wearing of earrings or other costume jewellery and its source is probably nonoccupational in most cases. The cost of OCD in New South Wales can be estimated by adding the figures for loss of productivity together with the cash payments to patients from Workcover. We have worked on loss of income as an estimate of loss of productivity. This is in fact an underestimate as an employee's value to an employer should be greater than his wages. In this study 16 working days were lost by each worker annually as a result of occupational contact dermatitis. Using the average weekly wage in NSW of $492.00 (as at August 1990"), the loss of income for 16 days is $1574.40 per employee. Therefore for the 570 patients represented in this study the cost (in lost productivity) would be approximately $900,000. In 1987 Workcover reported that 523 new patients were awarded workers compensation for OCD."" This unfortunately, was the last year that they classified compensation by disease. In round terms this approximates the number of people in our study and so the cost of lost productivity would probably have been a similar $900,000. As previously stated, the estimated cost to NSW is the sum of the lost productivity and workers compensation payments. The most recent figures of Workcover payments was in 1989 when they paid approximately $40.5 million for all occupational diseases."""""" According to Workcover 6% of occupational diseases are due to OSD.^"" Thus OSD would have cost approximately $2.4 million. OCD accounts for 90% of O S D " ' " ^ and therefore cost about $2.2 million annually. If one adds this figure to the $900,000 figure for the lost wages (reflecting lost productivity) the resultant total loss to the community is an estimated $3.1 million. In this survey only about one quarter of the study population actually received workers compensation. It would therefore be fair to say that the incidence of occupational contact derma-
titis was four times the Workcover figure or at least 2100 people annually. Similarly the cost would have been more than $12 million annually. When one considers that this figure is based on only the most persistent cases of dermatitis and conservative calculations, then the estimate of $12 million annually in NSW must be an understatement. Many people probably suffer a milder form of dermatitis, see a local doctor, take only a few days from work and hence are not patch tested or recorded in workers compensation statistics.'" The additional cost of these milder cases would naturally magnify the potential cost of this disease many times. In conclusion, contact dermatitis is an important occupational disease costing NSW and Australia far more than had been previously thought. Of course the cost to the individual in terms of personal distress and frustration is extremely high, although this cannot be measured in absolute terms. ACKNOWLEDGEMENTS
This research was carried out with the assistance of a Worksafe Australia grant, and formed the basis of Dr Rosen's Master of Medicine degree at Sydney University. The authors also wish to thank the Australasian College of Dermatologists (Ewan MurrayWill/F.H. Florance prize), Schering-Plough, Roche Australia and Lederle for financial support in preparing this work for publication. We also thank Dr Elizabeth Gow for the files on her patients seen at the Westmead branch of the Skin and Cancer Foundation and Profession Berry of the Department of Public Health, University of Sydney for assistance with statistical analysis. REFERENCES ' Emmett E. The skin and occupational disease. Arch Environ health 1984; 39: 144-149. ' Prevalence, morbidity and cost of dermatological disease (Edit). J Invest Dermatol 1979; 75: 395-401. ' National Strategy for the Prevention of Occupational Skin Disorders. Worksafe Australia Publication. Dec 1988; p6. ' Nethercott J, Gallant C. Disability due to occupational contact dermatitis. Occup Med 1986; 1: 199-203. ' Keil J, Shmunes E. The epidemiology of work-related skin disease in South Carolina. Arch Dermatol 1983; 119: 650-654. ' Fregert S. Occupational dermatitis in a 10 year material. Contact Dermatitis 1975; 1: 96-107. ' Goh C, Soh S. Occupational dermatoses in Singapore. Contact Dermatitis 1984; U: 288-293.
ROBERT H . ROSEN AND SUSANNE FREEMAN Workers Compensation Statistics for New South Wales. Year ended 30 June 1987. State Compensation Board Publicaton: booklet: 1988. Mathias CG, Morrison J. Oecupational skin disease. United States. Arch Dermatol 1988; 124: 1519-1524. Tciylor J. Occupational Disease Statistics. Arch Dermatot 1988; 144: 1557-1558. The National Institute for Occupational Safety and Health. Prevention of Oecupational Skin Disorders. Am J Contact Dermatitis 1990; 1: 55-64. Occupational Disease Statistics Unit. Division of Labour Statistics and Research. Occupational Skin Disease in California, San Francisco. Department of Industrial Relations 1982. Mathias T. Contact dermatitis and workers' compensation: Criteria for establishing occupational causation and aggravation. J Am Acad Dermatol 1989; 20: 842-848. Adams RM. Contact dermatitis due to irritation and allergic sensitization. In Adams RM (ed) Oecupational Skin Disease, 1st Edition, Grune & Straton: 1983; Chi: 1-26. Epstein WL. Allergic Contact Dermatitis. In Fitzpatriek TB (ed): Dermatology in General Medicine, 3rd Edition, McGraw-Hill Book Company: 1987; Chll7: 1373-1384. Fregert S, Hjorth N, Magnusson B et al. Epidemiology of Contact Dermatitis. Trans St John's Hosp Derm Soc 1969; 55: 17-35. Wilkinson D, Budden M, Hambly E. A 10-year review of an industrial dermatitis clinic. Contact Dermatitis 1980; 6: 11-17. Kanerva L, Estlander T, Jolanki R. Occupational skin disease in Finland. Int Arch Occup Environ Health 1988; 60: 89-94. Workers Compensation Statistics for 1987-88 and 1988-89. Workcover Authority Publication: booklet: 1990. Wall M, Gebauer K. Occupational skin disease in Western Australia. Contact Dermatitis 1991; 24: 101-109. Hogan D, Dannaker J, Maibach HI. The prognosis of contact dermatitis. J Am Acad Dermatol 1990; 23: 300-307. Nethercott J, McPherson M, Choi B, et al. Contact dermatitis in hairdressers. Contact Dermatitis 1986; 14: 73-79, Matsunaga K, Hosokawa K, Suzuki M, et al. Occupational allergic contact dermatitis in beauticians. Contact Dermatitis 1988; 18: 94-96. Cronin E. Dermatitis of the hands in caterers. Contact Dermatitis 1987; 17: 265-269.
10
Hansen K, Petersen H. Protein contact dermatitis in slaughterhouse workers. Contact Dermatitis 1989; 21: 221-224. Nethercott J, Holness D. Occupational dermatitis in food handlers and bakers. J Am Acad Dermatol 1989; 21: 485-490. Hjorth N, Roed-Petersen J. Occupational protein contact dermatitis in food handlers. Contact Dermatitisz 1976; 2: 28-42. Fisher AA. Contact dermatitis due to food additives. Cutis 1975; 16: 383-388. Burrows D. Chromium and the skin. Br J Dermatol 1978; 99: 587. Fisher AA. Chromate dermatitis and cement burns. In: Fisher AA (ed). Contact Dermatitis. Lea & Febiger. 3rd Edition: Ch42: 762-772. Varigos G, Dunt D. Occupational dermatitis. An epidemiologieal study in the rubber and cement industries. Contact Dermatitis 1981; 7: 105-110. Hunziker N, Musso E. A propos de I'eczema au ciment. Dermatologica 1960; 121: 204-212. Seidenari S, Danese P, Di Nardo A, et al. Contact sensitization among ceramics workers. Contact Dermatitis 1990; 22: 45-49. Goh C. Epidemiology of contact allergy in Singapore. Int J Dermatol 1988; 27: 308-311. Fisher AA. Chromates: Prime cause of industrial allergic contact dermatitis. Cutis 1983; 32: 24-29. Fregert S, Gruvberger B. Factors decreasing the content of water soluble chromate in cement. Acta Derm Venerol 1973; 53: 225-228. Fregert S, Gruvberger B, Sandahl E. Reduction of chromate in cement by iron sulfate. Contact Dermatitis 1979; 5: 39-42. Kanerva L, Estlander T, Jolanki R. Occupational skin disease in Finland. Int Arch Occup Environ Health 1988; 60: 89-94. Australian Bureau of Statistics Publication. Catalogue number: 6302.0; TSble 1; Average weekly earnings, NSW August 1990. Workers Compensation Statistics for New South Wales. Year ended 30 June 1987. State Compensation Board Publication: booklet: 1988. Plotnick H. Analysis of 250 consecutively evaluated cases of workers' disability claims for dermatits. Arch Dermatol 1990; 126: 782-786.
OCCUPATIONAL CONTACT DERMATITIS IN NEW SOUTH WALES ROBERT H . ROSEN AND SUSANNE FREEMAN
Sydney SUMMARY
Five hundred and seventy patients with occupational contact dermatitis (OCD) were seen between 1984 and 1990 at the Skin and Cancer Foundation in Sydney. Data derived from these patients demonstrated that hairdressing, food, construction and the medical industries were the most at risk of OCD. The hairdressing and food industries had a high percentage of apprentices suffering OCD whilst the 35 to 44 year age bracket was most at risk in the construction industry. Allergic contact dermatitis was responsible for 38.2% of cases. The main allergens were chromate, thiuram, epoxy resin, nickel and cobalt. A third (33.9%) of patients were atopic. The average time lost from work was 16 days each year and the calculated yearly cost of OCD in New South Wales was approximately $12 million. Key words: Occupational skin disease, contact dermatitis, workers compensation. National Occupational Health and Safety Commission.' Recently a study of patients with OSD seen in a Perth private dermatological practice over an eight year period was published by Wall and Gebauer.^" The authors provided information on the commonest allergens and the highest risk industries in Western Australia. They also analyzed patient information such as age, sex and history of atopy and concluded that OSD in Western Australia did not differ in any major way from other countries. The aim of our research project was to investigate occupational contact dermatitis in New South Wales and correlate the results with currently availble workers compensation statistics. Therefore the files of the Occupational and Contact Dermatitis Clinic of the Skin and Cancer Foundation from 1984 until 1990 were reviewed and follow-up data was collected from the patient population. Two and half thousand cases were examined and roughly one quarter (570) were determined to be occupationally related. These patients were followed up by means of a series of questionnaires. Follow-up data in regard to outcome and further employment will be examined in another publication.
INTRODUCTION
Occupational skin disease (OSD) is a very common, if not the most common, industrial illness^' The cost of OSD has been estimated at between $222 million and $1 billion annually in the USA.' The true cost could be 10 to 50 times more if an accurate figure of the incidence of occupational contact dermatitis (OCD) could be identified.'" The cost of OSD in Australia has not hitherto been estimated. Contact dermatitis accounts for more than 90% of occupational skin disease." " ' ' Allergic contact dermatitis can be diagnosed by patch testing with the offending allergen whereas irritant contact dermatitis is a diagnosis of exclusion." " Most American and Asian studies have documented allergic contact dermatitis as accounting for about one third of cases.'"" The European literature however claims that allergic contact dermatitis may account for at least fifty percent of all cases.""* Australian statistical data on occupational skin disease has been mostly restricted to compensation statistics'" which were thought to underestimate numbers and to be inadequate by the Robert H. Rosen, MBBS, M.Med. Dermatology Registrar. Susanne Freeman, MBBS, DDM, FACD. Head of Industrial and Contact Dermatitis Clnic, Skin and Cancer Foundation, Sydney. Address for correspondence: Dr Susanne Freeman, Skin and Cancer Foundation, 277 Bourke St, Darlinghurst, NSW 2010.
PATIENTS AND METHOD
The Skin and Cancer Foundation is a tertiary referral centre in Sydney and is affiliated with the University of New South Wales. Patients with 1
ROBERT H . ROSEN AND SUSANNE FREEMAN
FIGURE 1—ACD in a construction worker caused by cement. Positive patch test to chromate and cobalt.
FIGURE 2—ACD in an abbatoir worker caused by rubber boots. Positive patch tests to thiuram chemicals.
2
OCCUPATIONAL CONTACT DERMATITIS IN NEW SOUTH WALES
suspected OSD are referred to its contact and occupational dermatitis clinic, predominantly by dermatologists and occupational health physicians. A three page protocol is completed on each patient including a detailed occupational and non-occupational history, and a physical examination is performed. Patch testing is carried out using the European standard series of allergens as well as series of allergens which are appropriate to the individual's industry or history of exposure. Actual compounds and material with with the patient works are tested, in carefully determined dilutions. Patch testing is carried out using Trolab® allergens on Epitest® strips. These are aluminium chambers on hypoallergenic tape. Readings are then made at 48 hours and 96 hours according to the standards of the International Contact Dermatitis Research Group. The patients are therefore seen on three occasions. After the final reading of the patch test, the patient is informed about the relevance of the results and a report is sent to the referring physician. Five hundred and seventy patients with a work related dermatitis were selected from 2400 patients seen between 1984 and 1990. They were determined to be occupationally related on the basis of a detailed history, physical examination and patch test findings. Their data was entered onto a spreadsheet database for subsequent crosstable analysis. Meanwhile the patients were sent a series of three questionnaires in order to 0.00%
2.00%
4.00%
evaluate their progress (and the prognosis for this disease). The total number of patients returning questionnaires was 337, giving a compliance rate of 59%. RESULTS
The main industries affected by contact dermatitis were (in order) the hairdressing industry, the food industry and the construction and medical industries. Almost one third of all the women in this study worked in the hairdressing industry. They represented a disproportionate 94% of the industry, whilst all the members of the construction industry were men. The food industry was the second most frequently affected by contact dermatitis, and was common to both sexes. It is of interest to observe that the cleaning industry and farm (or agricultural) industries were not well represented in this list of OCD as they are in Sweden or the United States. This may represent a bias of the referral base or may be due to under-reporting by the patients. Figure 3 compares the incidence of contact dermatitis between the industries and figure 4 lists these main industries against their sex composition. In this study allergic contact dermatitis (ACD) was reponsible for 38.2% of the cases and irritant contact dermatitis the remaining 61.8%. The largest group was men suffering from irritant dermatitis (Figure 5).
6.00%
8.00%
10.00%
12.00%
14.00%
Hairdresser Food Construction
1
Medical 1
Printing
1
1
•1
1
Maintenance 1
Laboratory
1
Auto Farm Machinist
—
1
«:5:!S:S!::$!:f:l:vS:a FIGURE 3
Top ten industries with OCD. Percentages refer to the proportion of total number of cases in the study. (See figure 4 also.) 3
ROBERT H . ROSEN AND SUSANNE FREEMAN
Industry Hairdresser Food Construction Medical Printing Maintenance Laboratory Auto Farm Others
TOTAL
Male %of Female %of TOTAL % OF ALL Industry 570 PTS IN Industry STUDY 5 73 78 6.4% 93.6% 13.7% 41 25 66 62.1% 37.9% 11.6% 53 100.0% 0 53 0.0% 9.3% 11 40 51 21.6% 78.4% 8.9% 19 6 25 76.0% 24.0% 4.4% 22 2 24 91.7% 8.3% 4.2% 14 9 23 60.9% 39.1% 4.0% 21 1 22 95.5% 4.5% 3.9% 15 6 21 71.4% 28.6% 3.7% 119 88 207 36.3% 320
56.1%
250
43.9%
570
100.0%
FIGURE 4
Top industries with OCD showing differences between numbers of males and females affected.
Sex Exogenous FEMALE % female Allergic 84 14.7% Irritant 166 29.1% 250 TOTAL 43.9%
MALE 134 186
320
%male 23.5% 32.6% 56.1%
TOTAL 218
352 570
% total 38.2% 61.8% 100.0%
FIGURE 5
Types of contact dermatitis. Percentages refer to the proportion of total number of cases in study. (% female refers to proportion of all female cases in the study, etc.) The allergens most often identified as causing allergic contact dermatitis in this survey were potassium dichromate (18.3%) found in cement as well as many other materials such as paint and leather, thiuram (17%) an antioxidant present in rubber, expoxy resins (17%) found in glues and hardeners, nickel sulphate (12.4%) used in some metal instruments, and cobalt chloride (10.1%) which often accompanies potassium dichromate and nickel. These allergens affected each sex with different frequency. The main allergens affecting women were nickel (25%), and thiuram (17.9%)
whilst men were most often allergic to chromate (26.9%), epoxy resins (24.6%) and thiuram (16.4%). Of the 570 patients studied 56.1% (320) were men and the remaining 43.9% (250) were women. Roughly a third of the population was between the ages of 15 and 24 years old (35.6%). This relates to the high incidence of dermatitis in apprentices. Men were distributed more evenly throughout the age groups. This is because, in addition to younger workers, men in their middle years are
OCCUPATIONAL CONTACT DERMATITIS IN NEW SOUTH WALES
1 5-1920-2425-2930-3435-3940-4445-4950-5455-5960-6465-6970-75 AGE (Years) FIGURE 6
Age/sex study of OCD cases. The prevalence of apprentices is seen by the peak in the 15 to 25 year age group. The second peak in the 35 to 45 year age group represents workers in the construction industry. subject to dermatitis particularly in the develop contact dermatitis is not while they are construction industry. Figure 6 demonstrates apprentices (or new to the industry) but during graphically the concentration of younger workers, middle age, after they have been fully trained and especially women with dermatitis, and the have the greatest financial burden of their lives. It has previously been suggested that individsecondary peak in men aged 35 to 44 years. Apprentices are often expected to perform the uals with atopic dermatitis are more prone to most menial and repetitive tasks. Usually this is developing irritant contact dermatitis than nonin the areas of preparation and cleaning. It would atopies and also less prone to developing allergic not be surprising therefore, if they were at the contact dermatitis. In this survey there were 193 highest risk of dermatitis in some industries. The atopies of whom 132 (almost 70%) suffered main industry affecting the 15 to 24 year age irritant dermatitis and 61 (or 31.5%) suffered group is the hairdressing industry. More than allergic contact dermatitis. This compares to 70% were apprenticess. Indeed 65% of the people 51.6% of non-atopies suffering from irritant affected with occupational dermatitis in this dermatitis and 48.4% suffering from allergic contact dermatitis. This demonstrates the industry were less than 20 years old. Hairdressing is the main industry in which expected polarization of atopies towards irritant young women in the 15 to 24 year age group were contact dermatitis (p-^0.02) which has affected but most young men in this age group implications for pre-employment counselling of were from the food industry. More than 70% of atopies against entering high risk industries. men and women with dermatitis in the food, However, it is also of interest that almost a third of the atopies showed a superimposed ACD. industry were between the ages of 15 and 29. Only about one third of patients with occupaThe peak incidence in the construction industry was observed in the 35 to 44 year age group. In tional dermatitis had applied for workers human terms this means that the likely time compensation (211 people or 37.5%), despite the members of the construction industry will average time lost from work being one month!
ROBERT H . ROSEN AND SUSANNE FREEMAN
Workers Compensation. undefined Yes
m.
Sex Males Females total
180 171 351
3 5 8
137 74 211
total
320 250 570
FIGURE 7
Patients who applied for workers compensation. Note that only about 'A ofpatients with OCD applied for workers compensation (211 patients/37.5%)
0 .60 0 .50 Ratio
w. C./TOTAL GROUP
.40
0 .30 0.20 0.10 0.00
15 to 19
20 to 24
25 to 29
30 to 35 to 34 39
40 to 44
45 to 50 to 54 49
55 to59
60 to 64
Ages FIGURE 8
Relative proportion of WC total group. Note that the smallest proportion of WC claimants were in the apprentice age group (15 to 25 years old) A larger proportion of men applied for workers compensation than women (p-^0.01). About 43% of men and 30% of women applied for compensation (or 24% and 13% of the total number of men and women respectively). This is demonstrated in figure 7. The age group which claimed compensation most often was the 20 to 24 year group. However when compared to the age distribution in the whole study population they were in fact a relatively small proportion of all those affected.
This can be visualized in figure 8. There was in fact a relative lack of application for compensation in the 15 to 29 year groups. These were mostly women and were very often apprentices. The greatest proportion of people applying for compensation is at 35 to 40 years and 45 to 50 years (seen in figure 8 as the two peaks). Indeed a majority of the men in these age divisions had applied for workers compensation. When one considers that the greatest living costs are during the 35 to 60 year bracket (mortgages, child
OCCUPATIONAL CONTACT DERMATITIS IN NEW SOUTH WALES
%of F/U group receiving we 28.5% 25.7% 27.4%
% Successful applications 71.4% MALE 82.9% FEMALE 75.4% TOTAL FIGURE 9
Percentage of workers applying for and receiving WC. Note that at follow up just over 'A of patients with OCD had received WC. However of those who applied V4 were successful. education, househotd expenses), it is not surprising that a large proportion of these people would seek compensation. Perhaps the most important finding is that at follow up only one quarter of patients with OSD had received workers compensation, even though 75% of those who applied for workers compensation were approved (Figure 9). This means that Australian workers with OSD assessed in this study are certainly not overusing "compo", as is often thought. Furthermore occupational contact dermatitis may be four times more prevalent in Australia, than we had previously imagined from workers compensation statistics. In addition there are premium based disincentives for employers to report workers compensation claims. The number of patients successfully followed up was 337 (3 had died of other illness). This represented 59% of the study population. The patients who replied were analysed for bias and no statistically significant bias influencing follow up data was demonstrated, including bias due to age, sex, industry, type of dermatitis or workers compensation. In the average two year period before referral to the Skin and Cancer Foundation, most people had taken up to a month off work to recover from their dermatitis, the average loss of time being 30.9 days. If one were to extrapolate this in terms of the total study population it would mean a total loss of 48.3 years. That is more than 100,000 man hours (if each one worked 8 hours per day, 5 days per week) lost from productivity from only 570 people. After diagnosis almost half the follow up population still required up to one month to convalesce. Roughly 10% of the answering population required more than one year off. The
average convalescent time after diagnosis was 79.3 days. The time lost as a result of OCD can be calculated by adding the 30.9 days (taken on average over two years) before diagnosis and 80 days (taken over the average follow up period of three years) after diagnosis. Therefore 110.2 days were lost over a five year period. This is equivalent to 16 workdays lost per year per patient (working a five day week). This is probably an underestimate as most of the people affected come from industries such as the food, construction and medical industries which often work more than an eight hour day and a five day week. DISCUSSION
Occupational contact dermatitis is the major occupational skin disease and is one of the most common worldwide industrial illnesses.'*" '^ Our study population was 570 people which places it amongst the larger international studies.^' Patients were sent three batteries of questionnaires and the non-responders were telephoned. This achieved a comphance rate of 59%. Most international researchers iri the field of contact dermatitis have used retrospective studies with the assistance of either follow up interviews or questionnaires. The response rates in these studies usually lie between 30% and 50%^' (although Wall s study in Western Australia had a remarkable 96%"). The majority of these were performed in Europe or in the United States of America. The top four industries in which workers were most at risk of developing contact dermatitis were, in order, the hairdressing industry, the food industry, the construction and the medical industries. More than 90% of people in the hair-
ROBERT H . ROSEN AND SUSANNE FREEMAN
The construction industry on the other hand, exclusively affected men in this study and most of them were in their middle working years. Unlike the other major industries affected by this disease, apprentices were not a primary target. Men may work many years in this industry before they develop dermatitis. By the time it occurs they could be working to support a family and a mortgage and they probably could not afford a drop in wages in order to be retrained, even if the high proportion of migrants in this occupation could overcome the language barrier. Financial incentives, including overtime, generally keep these men working despite the appearance of an occupational disease. When they do seek assistance the dermatitis is already well established and it is not surprising therefore that they require more time off work. They lose approximately three times the average work time lost by other industries.
dressing industry were wotnen and more than 70% were apprentices. Similar fignres have been published from other studies.^°^^^' When one considers the length of time the apprentices spend washing, shampooing and colouring hair it is not surprising that they would rate highly as an industry affected by contact dermatitis. In Fregert's ten year study of occupational dermatitis in Sweden he ranked hairdressers just behind the medical and cleaning industries as the commonest industries affecting women.' In all these industries, prolonged exposure to detergents and water would account for large numbers of cases of irritant dermatitis. In a similar way housewives often develop ICD but are not considered by Workcover to have a work related disease and so cannot be tabulated in this study. NIOSH (National Institute of Occupational Safety and Health)" listed the main US industries affected by occupational dermatitis in 1984 as agriculture (farm), manufacturing and construction. In contast, earlier statistical analysis published by Mathias and Morrison from the Annual Survey of Occupational Illnesses' in the US ranked the food industry ahead of construction in the list of top industries with the highest incidence of occupational dermatitis. They rated the health (medical) industry as the industry with the largest number of skin disease cases between 1973 and 1984. The food and construction industries feature more prominently in this New South Wales sample than do agriculture or manufacturing. There may be logistic and financial restrictions which limit the attendance of the agricultural population at clinics in the city, but there is no other occupational dermatology centre which performs patch testing in New South Wales. Therefore the lower frequency of contact dermatitis in this industry is unlikely to be due entirely to referral bias. The food industry is, not surprisingly, a key 'at risk' industry. The high incidence of occupational contact dermatitis amongst food workers has been frequently documented.''^''^' It was the commonest industry in Wall and Gebauer's study in Western Australia" and the fourth commonest industry affected by OSD in the study by Goh in Singapore.' More than 70% of the food industry patients were less than 30 years old and roughly a third were apprentices. This industry was a common source of contact dermatitis for both sexes.
The construction industry is prominently placed in the occupational dermatitis statistics of all the countries reviewed. It was the main industry in the Singapore study of 389 patients by Goh' and the second commonest industry affecting males in Fregert's study of 1752 patients in Sweden." As mentioned above, NIOSH" ranks it as America's third major affected industry and it was fourth overall in Western Australia." ACD constituted 67% of the cases of occupational dermatitis in the construction industry because of the high proportion of chromate sensitive dermatitis in this industry, for which cement is the usual source." Most of the other main industries have a higher proportion of irritant rather than allergic contact dermatitis (38% ACD and 62% ICD). (These statistics were not included in the results section). This disproportionate frequency of chromate allergy has already gained considerable international atten{JQjj2o,2935 ^j^j suggestions on methods of addressing this problem have already been implemented." " The addition of ferrous sulphate to cement in order to reduce the soluble chromate concentration has already been adopted in Europe (Denmark and Sweden)" '* but not yet in Australia. Chromium, however is a ubiquitous allergen. It is present in many industrial processes, as well as in the diet, and of course in cement. Fisher states that it "is more abundant than all other metals".^" Chromate dermatitis tends to become chronic and self perpetuating even after 8
OCCUPATIONAL CONTACT DERMATITIS IN NEW SOUTH WALES
the removal of the worker from the initial work environment.^" The other major causative allergens overall were thiuram (used as an antioxidant in rubber) and epoxy resin. Nickel was the single commonest allergen in women and occured in several industries. Fregert* also found nickel to be the major occupational allergen in females with ACD. However, nickel allergy in women is usually derived from the wearing of earrings or other costume jewellery and its source is probably nonoccupational in most cases. The cost of OCD in New South Wales can be estimated by adding the figures for loss of productivity together with the cash payments to patients from Workcover. We have worked on loss of income as an estimate of loss of productivity. This is in fact an underestimate as an employee's value to an employer should be greater than his wages. In this study 16 working days were lost by each worker annually as a result of occupational contact dermatitis. Using the average weekly wage in NSW of $492.00 (as at August 1990"), the loss of income for 16 days is $1574.40 per employee. Therefore for the 570 patients represented in this study the cost (in lost productivity) would be approximately $900,000. In 1987 Workcover reported that 523 new patients were awarded workers compensation for OCD."" This unfortunately, was the last year that they classified compensation by disease. In round terms this approximates the number of people in our study and so the cost of lost productivity would probably have been a similar $900,000. As previously stated, the estimated cost to NSW is the sum of the lost productivity and workers compensation payments. The most recent figures of Workcover payments was in 1989 when they paid approximately $40.5 million for all occupational diseases."""""" According to Workcover 6% of occupational diseases are due to OSD.^"" Thus OSD would have cost approximately $2.4 million. OCD accounts for 90% of O S D " ' " ^ and therefore cost about $2.2 million annually. If one adds this figure to the $900,000 figure for the lost wages (reflecting lost productivity) the resultant total loss to the community is an estimated $3.1 million. In this survey only about one quarter of the study population actually received workers compensation. It would therefore be fair to say that the incidence of occupational contact derma-
titis was four times the Workcover figure or at least 2100 people annually. Similarly the cost would have been more than $12 million annually. When one considers that this figure is based on only the most persistent cases of dermatitis and conservative calculations, then the estimate of $12 million annually in NSW must be an understatement. Many people probably suffer a milder form of dermatitis, see a local doctor, take only a few days from work and hence are not patch tested or recorded in workers compensation statistics.'" The additional cost of these milder cases would naturally magnify the potential cost of this disease many times. In conclusion, contact dermatitis is an important occupational disease costing NSW and Australia far more than had been previously thought. Of course the cost to the individual in terms of personal distress and frustration is extremely high, although this cannot be measured in absolute terms. ACKNOWLEDGEMENTS
This research was carried out with the assistance of a Worksafe Australia grant, and formed the basis of Dr Rosen's Master of Medicine degree at Sydney University. The authors also wish to thank the Australasian College of Dermatologists (Ewan MurrayWill/F.H. Florance prize), Schering-Plough, Roche Australia and Lederle for financial support in preparing this work for publication. We also thank Dr Elizabeth Gow for the files on her patients seen at the Westmead branch of the Skin and Cancer Foundation and Profession Berry of the Department of Public Health, University of Sydney for assistance with statistical analysis. REFERENCES ' Emmett E. The skin and occupational disease. Arch Environ health 1984; 39: 144-149. ' Prevalence, morbidity and cost of dermatological disease (Edit). J Invest Dermatol 1979; 75: 395-401. ' National Strategy for the Prevention of Occupational Skin Disorders. Worksafe Australia Publication. Dec 1988; p6. ' Nethercott J, Gallant C. Disability due to occupational contact dermatitis. Occup Med 1986; 1: 199-203. ' Keil J, Shmunes E. The epidemiology of work-related skin disease in South Carolina. Arch Dermatol 1983; 119: 650-654. ' Fregert S. Occupational dermatitis in a 10 year material. Contact Dermatitis 1975; 1: 96-107. ' Goh C, Soh S. Occupational dermatoses in Singapore. Contact Dermatitis 1984; U: 288-293.
ROBERT H . ROSEN AND SUSANNE FREEMAN Workers Compensation Statistics for New South Wales. Year ended 30 June 1987. State Compensation Board Publicaton: booklet: 1988. Mathias CG, Morrison J. Oecupational skin disease. United States. Arch Dermatol 1988; 124: 1519-1524. Tciylor J. Occupational Disease Statistics. Arch Dermatot 1988; 144: 1557-1558. The National Institute for Occupational Safety and Health. Prevention of Oecupational Skin Disorders. Am J Contact Dermatitis 1990; 1: 55-64. Occupational Disease Statistics Unit. Division of Labour Statistics and Research. Occupational Skin Disease in California, San Francisco. Department of Industrial Relations 1982. Mathias T. Contact dermatitis and workers' compensation: Criteria for establishing occupational causation and aggravation. J Am Acad Dermatol 1989; 20: 842-848. Adams RM. Contact dermatitis due to irritation and allergic sensitization. In Adams RM (ed) Oecupational Skin Disease, 1st Edition, Grune & Straton: 1983; Chi: 1-26. Epstein WL. Allergic Contact Dermatitis. In Fitzpatriek TB (ed): Dermatology in General Medicine, 3rd Edition, McGraw-Hill Book Company: 1987; Chll7: 1373-1384. Fregert S, Hjorth N, Magnusson B et al. Epidemiology of Contact Dermatitis. Trans St John's Hosp Derm Soc 1969; 55: 17-35. Wilkinson D, Budden M, Hambly E. A 10-year review of an industrial dermatitis clinic. Contact Dermatitis 1980; 6: 11-17. Kanerva L, Estlander T, Jolanki R. Occupational skin disease in Finland. Int Arch Occup Environ Health 1988; 60: 89-94. Workers Compensation Statistics for 1987-88 and 1988-89. Workcover Authority Publication: booklet: 1990. Wall M, Gebauer K. Occupational skin disease in Western Australia. Contact Dermatitis 1991; 24: 101-109. Hogan D, Dannaker J, Maibach HI. The prognosis of contact dermatitis. J Am Acad Dermatol 1990; 23: 300-307. Nethercott J, McPherson M, Choi B, et al. Contact dermatitis in hairdressers. Contact Dermatitis 1986; 14: 73-79, Matsunaga K, Hosokawa K, Suzuki M, et al. Occupational allergic contact dermatitis in beauticians. Contact Dermatitis 1988; 18: 94-96. Cronin E. Dermatitis of the hands in caterers. Contact Dermatitis 1987; 17: 265-269.
10
Hansen K, Petersen H. Protein contact dermatitis in slaughterhouse workers. Contact Dermatitis 1989; 21: 221-224. Nethercott J, Holness D. Occupational dermatitis in food handlers and bakers. J Am Acad Dermatol 1989; 21: 485-490. Hjorth N, Roed-Petersen J. Occupational protein contact dermatitis in food handlers. Contact Dermatitisz 1976; 2: 28-42. Fisher AA. Contact dermatitis due to food additives. Cutis 1975; 16: 383-388. Burrows D. Chromium and the skin. Br J Dermatol 1978; 99: 587. Fisher AA. Chromate dermatitis and cement burns. In: Fisher AA (ed). Contact Dermatitis. Lea & Febiger. 3rd Edition: Ch42: 762-772. Varigos G, Dunt D. Occupational dermatitis. An epidemiologieal study in the rubber and cement industries. Contact Dermatitis 1981; 7: 105-110. Hunziker N, Musso E. A propos de I'eczema au ciment. Dermatologica 1960; 121: 204-212. Seidenari S, Danese P, Di Nardo A, et al. Contact sensitization among ceramics workers. Contact Dermatitis 1990; 22: 45-49. Goh C. Epidemiology of contact allergy in Singapore. Int J Dermatol 1988; 27: 308-311. Fisher AA. Chromates: Prime cause of industrial allergic contact dermatitis. Cutis 1983; 32: 24-29. Fregert S, Gruvberger B. Factors decreasing the content of water soluble chromate in cement. Acta Derm Venerol 1973; 53: 225-228. Fregert S, Gruvberger B, Sandahl E. Reduction of chromate in cement by iron sulfate. Contact Dermatitis 1979; 5: 39-42. Kanerva L, Estlander T, Jolanki R. Occupational skin disease in Finland. Int Arch Occup Environ Health 1988; 60: 89-94. Australian Bureau of Statistics Publication. Catalogue number: 6302.0; TSble 1; Average weekly earnings, NSW August 1990. Workers Compensation Statistics for New South Wales. Year ended 30 June 1987. State Compensation Board Publication: booklet: 1988. Plotnick H. Analysis of 250 consecutively evaluated cases of workers' disability claims for dermatits. Arch Dermatol 1990; 126: 782-786.
