|Year : 2016 | Volume
| Issue : 2 | Page : 103-108
Civil construction work: The unseen contributor to the occupational and global disease burden
R Sitalakshmi1, P Saikumar1, P Jeyachandran2, Manoharan3, Thangavel4, Jayakar Thomas3
1 Department of Physiology, Sree Balaji Medical College and Hospital, Bharath University, Chennai, India
2 Chief Medical Officer and Occupational Health Consultant, Renault Nissan Automobile Industry, Chennai, India
3 Department of Dermatology, Sree Balaji Medical College and Hospital, Bharath University, Chennai, India
4 Department of Environmental Health Engineering, Sri Ramachandra Medical College and Research Institute, Sri Ramachandra University, Chennai, India
|Date of Web Publication||4-Jan-2017|
Department of Physiology, Sree Balaji Medical College and Hospital, Chromepet, Bharath University, Chennai - 600 044
Source of Support: None, Conflict of Interest: None
Background: Construction industry is the second largest employment giving industry in India with many semi-skilled or unskilled workers taking up the occupation for livelihood without any training and proper guidance. Aim: To evaluate the pathogenic association of cement exposure to occupational contact dermatoses as evidenced by immune markers and to correlate their pulmonary functions with years of exposure to cement. Setting and Design: This was a cross-sectional study conducted among randomly selected cement workers. Methods and material: Evaluation of socioeconomic status (SES) and years of exposure of cement workers was done using a questionnaire. Clinical examination of skin lesions and strip patch test with application of potassium dichromate on unexposed skin was performed. Results were interpreted after 48 hours. Absolute eosinophil count (AEC) and IgE levels measured, and spirometric evaluation was performed. Statistical Analysis: Analysis of variance and Pearson's correlation test were used for data analysis. P < 0.05 was considered to be statistically significant. Results: Clinically, skin lesions were noticed in 51%, elevated AEC in 47%, and raised Anti IgE in 73%. Two participants developed positive reactions to the skin strip patch test. Duration of exposure to cement and SES were compared with clinical skin lesions. Spirometry result was normal in 81%, obstruction in 8%, restriction in 10%, and mixed pattern in 1%. Forced expiratory volume at 1.0 second, forced expiratory flow (25-75%), and (PEFR) Peak Expiratory Flow Rate were markedly reduced with years of exposure. Workers who had greater skin lesions and with increase in exposure had increased AEC and IgE levels, although statistically not significant. Conclusions: Exposure to cement and poor SES is strongly correlated to increased prevalence of skin lesions and reduced pulmonary functions.
Keywords: AEC, cement exposure, IgE antibodies, occupational contact dermatoses, PFT, socioeconomic status
|How to cite this article:|
Sitalakshmi R, Saikumar P, Jeyachandran P, Manoharan, Thangavel, Thomas J. Civil construction work: The unseen contributor to the occupational and global disease burden. Indian J Occup Environ Med 2016;20:103-8
|How to cite this URL:|
Sitalakshmi R, Saikumar P, Jeyachandran P, Manoharan, Thangavel, Thomas J. Civil construction work: The unseen contributor to the occupational and global disease burden. Indian J Occup Environ Med [serial online] 2016 [cited 2020 Jan 27];20:103-8. Available from: http://www.ijoem.com/text.asp?2016/20/2/103/197542
| Introduction|| |
The construction industry in India is large and complex with more than 20 million laborers. Occupational contact dermatosis (OCD) due to cement exposure  is the leading cause of OCD worldwide, both in developed as well as developing countries. With increasing construction activities, contractual workers are exposed for long hours to chemical irritants in cement due to lack of personal protective equipment. Symptoms of OCD can vary from mild forms of dermatitis ,, to severe ulcerative burns. ,, Inhalation of cement dust along with environmental pollutants irritate the bronchial tree, and particulate matter less than 2 μ in size get deposited along the alveolar walls causing prominent lung volume changes, which can be measured using spirometry. Other complications of these workers include noise-induced hearing loss, , musculoskeletal disorders, , and even pneumoconiosis. 
To improve the workers' health, International Labour Organisation has legalized the Workers Health Surveillance programme (WHS) insisting on technical and ethical guidelines for workers' health surveillance worldwide.  WHS advocates periodic monitoring of the workers' health in relation to their occupation, introduction of preventive measures, and if needed, improvement of their working health conditions. Health and safety institute in Amsterdam invites construction workers under the WHS scheme once in every 2 to 4 years to monitor their health and provide safety measures. Similar protection and compensation is well practiced in the developed countries worldwide.
In India, the construction industry gives employment opportunities to millions of men, women, and even children in the lower socioeconomic strata. It is the second largest economy boosting industry.  Job in civil construction work is laborious involving intense physical activity and exposure to various allergens including hexavalent chromium with minimal protective gadgets. The wages are minimum and paid on daily/weekly basis. In addition, in India, due to poor safety in work place, more number of semi-skilled and unskilled laborers are at high risk of getting injured, which could be fatal at times. In spite of work place safety and health policies, practical implementation of the laws and provision of effective compensation for such accidents is very minimal.
Health hazards among construction workers have been reported by several authors worldwide, however, very few studies have been conducted in the Indian subcontinent. Literature search showed studies from North India highlighting OCD. In 2009, Sarma et al.  reported point prevalence of dermatitis in 93.75% in exposed areas and 62.5% in covered areas, and proved that chromate is the most important allergen. Such alarming prevalence of OCD in West Bengal is just the tip of the iceberg. Smilee et al.  from Karnataka showed that pulmonary functions in construction workers were reduced when compared with controls; this reduction being the greatest in workers exposed for more than 10 years. Lacuna of data in Chennai (south India) prompted us to initiate this study.
We aimed to evaluate the pathogenic association of cement exposure to occupational dermatitis as evidenced by immune markers and to assess pulmonary functions.
| Materials And Methods|| |
The study was carried out in various construction sites of Chennai where contractual workers were exposed to cement over a 1-year period. The participants were randomly selected 69 men and 15 women between 25 and 60 years of age. Workers using topical or oral steroids, pregnant and lactating women, H/O abdominal surgery within 3-6 months, and H/O recent respiratory infection were excluded from our study. Written consent was obtained from the contractual workers after our Institutional Ethical Committee team approved the study. This study is in accordance with the standards of Helsinki Declaration of 1975.
Structured, validated questionnaire to elicit socioeconomic status, exposure to cement, clinical examination of skin lesions, and strip patch test were filled by our dermatologist ,, for hexavalent chromium. The allergens were mixed with a nonallergic material (base) and placed in direct contact with the skin, usually on the upper back, after stripping off the skin several times by using a 3M tape, within small aluminium discs, and left in situ for 48 hours. The participants were instructed not to wash the area or remove the tapes. After 48 hours, the patches were removed and an initial reading was taken 1 hour later followed by the final reading. Reaction was scored as per the International Contact Dermatitis Research Group guidelines.
Pulmonary function test (PFT) was performed using Helios 401 spirometer (Recorders & Medicare Systems Pvt. Ltd. Haryana, India. Manufacturers of Helios 401 Spirometer (Automated)) as per the (ATS) American Thoracic Society protocol. Blood samples were collected for IgE estimation by enzyme linked immunosorbent assay technique and absolute eosinophil count (AEC) in the laboratory of Sree Balaji Medical College and Hospital, Bharath University, Chennai. The data was analyzed by using the Statistical Package for the Social Sciences software, and the results was tabulated using P < 0.05 as statistically significant. Pearson's correlation and analysis of variance tests were performed.
| Results|| |
We surveyed 69 male and 15 female cement workers. Most of them were migrants from various parts of South and North India and were employed on contractual basis. Their working hours were long from 9 AM till 7 PM, usually with a 1-hour lunch break. Workers were stratified into varying socioeconomic classes using Uday Pareekh's scales;  they were distributed as follows: 2 in higher middle class, 6 in middle class, 33 in lower middle, and 43 in lower class.
Spirometry was found to be normal in 81%, showed obstruction in 8%, restriction in 10%, and mixed pattern in 1% out of 77 workers. Lung volume reduction was more pronounced in elderly workers (older than 35 years) with more years of exposure to cement seen in forced volume vital capacity (FVC) and forced expiratory volume in 1.0 second (FEV 1 ); although the results were not statistically significant, as shown in Graph 1. Based only on years of exposure, it was found except FVC other parameters decreased, more so FEV 1 , forced expiratory flow (FEF) 25-75%, and PEFR indicating smaller airway obstruction and reduced compliance, which is a hallmark of restrictive airway disease in the near future, as shown in [Table 1].
|Table 1: Pulmonary function tests with years of exposure of study population |
Click here to view
In our study, we found that, protective gears namely gloves, boots, and head gears were regularly used by 16 workers, occasionally by 33 workers, and never by 35 workers. No other protective measures were taken by the workers.
Fifty-one percent of the workers had positive skin lesions, as evident in Graph 2, which were classified by our dermatologist. Thirteen workers had mixed lesions, 8 had lichenification, 1 had fissures in palms and soles, and 4 had dryness with positive H/O pruritis. The most common sites were those exposed to cement, especially the palm and the dorsum of the hands followed by the feet and legs. Seventy-six out of 84 workers underwent strip patch test - 3 were not willing, 2 did not cooperate, and 3 workers removed patch before 48 hours. After 48 hours, 2 male workers showed a positive response. Their AEC, IgE, and years of exposure are presented in [Table 2].
IgE antibodies were positive in 73% of the workers and 41.7% of workers had raised AEC levels. AEC levels were high in 18 workers (400-1000), moderately high in 11 workers (1000-2000), and extremely high in 6 workers (>2000). These workers were also found to have greater skin lesions, and with increase in the number of years of exposure, they had increased AEC and IgE levels; although statistically not significant. Lung volumes decreased with increase in AEC and IgE values, being significantly greater in FEF 25-75% and PEFR.
| Discussion|| |
Awareness of occupational hygiene is dated back to 1700 AD when Bernardo Ramarzzini, considered as "father of industrial medicine," published a book titled "Diseases of workmen." Since then, many people have published their work on the health hazards of occupational workers. Most authors have written about shortage of manpower, especially in rapidly developing countries, being compensated by bringing in unskilled laborers from less developed parts of the country. These workers learn the job as they go along without any proper training and personal protective equipment that result in chronic ill health in the long run. The Indian construction industry is no exemption to this and workers have lesser protection and greater morbidity.
Most of the participants in our study were migrants from various parts of South and North India and were multilinguistic. They had minimal formal education and took up masonry as unskilled or semi-skilled workers for their livelihood. 92.9% of our workers were overworking and underpaid in accordance with the National Commission for Enterprises in Unorganised Sector (NCEUS).  They were temporary contractual workers with many going back to their native place for a short span of time, not exceeding 2-3 weeks, for other jobs such as agriculture, carpentry, or weaving when they had no work at the construction sites. The workers stayed in kutcha houses with poor sanitary facilities near construction sites where they were constantly exposed to cement dust and exhaust from automobiles and kitchen vents.
Pulmonary function and years of exposure and age
Lung volume reduction is more pronounced in elderly workers with more exposure, as evidenced by reduced FEV 1 and FVC seen in this study, although not statistically significant. Workers more than 35 years of age had a greater reduction in pulmonary function than young workers, which can be physiologically accepted. There was a statistically significant reduction in FEF 25-75% and PEFR whereas FEV 1 , FVC, and FEV 1 /FVC were reduced, although the results were not significant probably because the workers were asymptomatic at the time of spirometry. Seventy-seven workers underwent PFT, and in the rest it was abandoned due to recent H/O respiratory infection and poor efforts. Smokers with greater exposure had larger reduction in lung volumes, as expected. These results were interpreted by an occupational pulmonary physician.
Reduced FEV 1 /FVC could not be explained by increasing age, BMI, years of smoking, and probably increasing years of cement exposure alone, as shown earlier by Al- Neaimi et al.  In 8% of workers found to have obstruction in our study, decline in FEV 1 /FVC was not affected by increasing age (mean age: 32.5 years) and years of exposure (mean exposure: 5.5 years) in contradiction to Saric et al.  In 10% of the workers with restriction in our study, increase in age (mean age: 37.75 years) and years of exposure (mean exposure: 9.15 years) had significantly reduced FVC values. Fell et al.  showed no dose response-related reduction in PFT, which is in contrast to our study and other similar studies. , A study from Jordan by Abudhaise  proved that age significantly affected mean FEV 1 /FVC values.
Smilee et al.,  in their study population of 61 construction workers, showed that, with increase in years of exposure, the mean PFT values decreased significantly, especially, in workers exposed to 6-10 years and more than 10 years. Mean PFT values in workers of our study was much less in the same exposure categories, especially those pertaining to smaller airways and PEFR, signifying poor efforts.
Though we have not compared lung functions with age and sex-matched control groups, few earlier studies ,,, have reported no significant difference in mean PFT in exposed and control groups, which could probably be explained by factors such as individual workers' susceptibility, concentration of cement dust and its accepted permissible levels, and physical factors that control the movement of the mucociliary tract movement.
Cement workers and allergenic indices
Literature shows elevated blood parameters of IgG, IgM, and IgE as well as liver enzymes , and positive patch test, , proving skin hypersensitivity to hexavalent chromium. Hexavalent chromium is a well-known toxin to many vital organs, especially the liver, kidney, and lungs. Inflammatory products, i.e., IL-4 and 6 and formation of free radicals have been postulated to cause DNA damage , and possible mutations. Increase in IgE levels in cement workers have been reported in Nigeria by Ogunbileje et al. , in 2010 and 2011, respectively. Johansson from Ethopia and Barbie , reported raised IgE levels which were two standard deviations above the normal values in atopic than those in nonatopic individuals. Elevated IgE levels are seen in 73% of the patients and many also have associated dermatological changes and decreased lung functions.
Cement workers and occupational contact dermatoses
Cement is a mixture of various oxides which include silica oxide, magnesium oxide, and calcium oxide. With the addition of water, the alkaline mixture with a pH of approximately 9, becomes toxic to individuals who are sensitive and come in direct contact with cement. Chromium concentration is approximately 2 mg/gm of cement (much higher than the minimum amount to cause hypersensitivity). In tropical countries, where the climate is hot, with increased sweating inside gloves with minimal water seepage the incidence of contact dermatitis is high. Even brief periods of exposure are enough to cause changes in sensitive individuals.
Type IV delayed hypersensitivity reactions form the major pathological basis of contact dermatitis in our study, as evidenced by elevated IgE antibodies in 73% of workers. Workers with positive skin lesions had raised IgE levels and AEC, which was not statistically significant with years of exposure explaining the results of the strip patch test.
Our study results show that 51% of the workers had skin lesions which include mixed pattern in 13, lichenification in 8, dryness and pruritis in 4, and fissure in 1 worker, especially over the exposed parts of the dorsum of the hand, metacarpophalangeal, and interphalangeal joints. These workers also had positive symptoms of itching as well as repeated episodes of dryness of the skin. Previous studies have shown presence of skin lesions ranging from mild dermatitis by Wang and Athavale et al. , to severe burns by Machovcova et al. and Mehta et al., , respectively. The response shown by workers is variable as their skin sensitivity is also highly variable, as shown in [Table 3], comparing our study with other national and international studies. Indian (Adsul et al 35 and Shah et al 36 ) and international studies (Nielsen et al 37 and Shelnett et al 38 ), over a period of many years have shown increase in the percentage of skin problems among the workers with increase in years of exposure but not substantiated their studies with patch test results.
|Table 3: National and international studies and their results of skin lesions and patch tests in cement workers |
Click here to view
From the abovementioned table, it is evident that the workers are exposed to varying degrees of skin problems even in recent years, as proved by Jayakrishnan et al.  . International studies show very high percentage of skin lesions; Wang et al.  reported 25% incidence of dermatoses in Taiwan; another European study reported an incidence of 5%. Many international and national scenarios are very disappointing and immediately call for safety regulations that need to be implemented effectively.
Patch test is the gold standard test for allergic contact dermatitis as shown by JL Nelson in 2010.  Strip patch test is proven to be more efficient than normal patch test, hence, strip patch test was done and found to be positive in only 2 workers in our study. Reaction is scored as per the International Contact Dermatitis Research Group guidelines. Duration of patch test exposure and development of reaction is critical, especially in tropical countries such as India where workers sweat heavily, are exposed to UV rays, have tanned skin, improper contact of allergen and the skin due to physical activity, , which could result in a negative patch test reaction. Workers were instructed to avoid physical work for 2 days after the patch application. Considering their poor wages, it was difficult to motivate other suspected workers for retesting for allergens other than potassium dichromate or repeat the test and take the readings after 72 hours and 96 hours. The reported that the most important reason for nonreproducibility of patch test are the common methodological pitfalls during routine patch testing.
| Conclusions|| |
Our study that included a combination of clinical examination, dermatological evaluation, and hematological indices with spirometry has thrown light on the present health hazards of contractual cement workers in Chennai, South India. Minimal use of protective gears in unsafe working conditions increase allergenic conditions in them. We recommend usage of chromium less than 2 parts per million of cement, protective thiuram-mix free gloves and masks, addition of ferrous sulphate to cement, and regular safety audits and review of safety procedures complying with occupational and safety laws. The study results clearly emphasize that workers should not be exploited due to poor socioeconomic conditions and ignorance calling for better implementation of occupational health schemes in developing countries.
Sample size was small and threshold limit value and total cement dust levels were not measured. The contractual workers were exposed to cement intermittently. When they had no construction work, they went back to their villages and resumed some other occupation, namely, agriculture/pottery/weaving for brief periods not more than 3-4 weeks for their livelihood.
We sincerely thank all the workers who participated enthusiastically in our study. We also thank the management, faculty of Physiology and Dermatology departments of Sree Balaji Medical College and Hospital, Chennai, India for their continuous support and encouragement.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
| References|| |
Bock M, Schmidt A, Bruckner T, Diepgen TL.
Occupational skin disease in the construction industry. Br J Dermatol 2003;149:1165-71.
Wang BJ, Wu JD, Sheu SC, Shih TS, Chang HY, Guo YL, et al
. Occupational hand dermatitis among cement workers in Taiwan. J Formos Med Assoc 2011;110:775-9.
Athavale P, Shum KW, Chen Y, Agius R, Cherry N, Gawkrodger DJ. Occupational dermatitis related to chromium and cobalt: Experience of dermatologists (EPIDERM) and occupational physicians (OPRA) in the U.K. over an 11-year period (1993-2004). Br J Dermatol 2007;157:518-22.
Sarma N. Occupational allergic contact dermatitis among construction workers in India. Indian J Dermatol 2009;54:137-41.
Machovcova A. Caustic ulcers caused by cement Aqua: Report of a case. Ind Health 2010;48:215-6.
Mehta RK, Handfield Jones S, Bracegirdle J, Hall PN. Contact dermatitis and chemical burns. Clin Exp Dermatol 2002;27:347-8.
Spoo J, Elsner P. Cement burns: A review 1960-2000. Contact Dermatitis 2001;45:68-71.
Leensen MC, Van Duivenbooden JC, Dreschler WA. A retrospective analysis of noise induced hearing loss in the Dutch construction industry. Int Arch Occup Environ Health 2011;84:577-90.
Edelson J, Neitzel R, Meischke H, Daniell W, Sheppard L, Stover B, et al
. Predictors of hearing protection use in construction workers. Ann Occup Hyg 2009;53:605-15.
Bosch man JS, Van der Molen HF, Sluiter JK, Frings-Dresen MH. Musculo-skeletal disorders among construction workers: A one-year follow -up study. BMC Musculo Skelet Disord 2012;13:196.
Engholm G, Holstrom E. Dose-response associations between musculoskeletal disorder and physical and psychosocial factors among construction workers. Scand J Work Environ Health 2005;31:57-67.
Suarthene E, Moons KG, Heedrick D, Meijer E. A simple diagnostic model for ruling out pneumoconiosis among construction workers. Occup Environ Med 2007;64:595-601.
Jayakrishnan T, Thomas B, Rao B, George B. Occupational health problems in construction workers in India. Int J Med Pub Health 2013;3:225-9.
SmileeJohncy S, Ajay KT, Dhanya KG, Prabhu RN, Vivian ST. Dust exposure and lung function impairment in construction workers. J Physiol Biomed Sci 2011;24:9-13.
Dickel H, Kamphowe J, Geier J, Altmeyer P, Kuss O. Strip patch test vs. conventional patch test: Investigation of dose-dependent test sensitivities in nickel- and chromium-sensitive subjects. J Eur Acad Dermatol Venereol 2009;23:1018-25.
Dickel H, Kreft B, Kuss O, Worm M, Soost S, Brasch J, et al
. Increased sensitivity of patch testing by standardized tape stripping beforehand: A multicentre diagnostic accuracy study. Contact Dermatitis 2010;62:294-302.
Hessam S, Altmeyer P, Dickel H. Add-on diagnostic tool for allergic contact dermatitis: The strip patch test. G Ital Dermatol Venereol 2012;147:103-9.
Holyachi S, Santhosh A. Socioeconomic status scale-An update. Ann Community Health 2013;1:24-7.
NCEUS. Summary and Recommendation; Skill formation and employment assurance in the unorganized sector; 2009. p. 72-84.
Al-Neaimi YI, Gomes J, Lloyd OL. Respiratory illnesses and ventilatory function among workers at a cement factory in a rapidly developing country. Occup Med 2001:51:367-73.
Saric M, Kalacic I, Holetic A. Follow up of ventilatory lung function in a group of cement workers. Br J Ind Med 1976;33:18-24.
Fell AK, Thomassen TR, Kristensen P, Egeland T, Kongerud J. Respiratory symptoms and ventilator function in workers exposed to Portland cement dust. J Occup Med 2003;45:1008-14.
AbuDhaise BA, Rabi AZ, al Zwairy MA, el Hader AF, el Qaderi S. Pulmonary manifestations in cement workers in Jordan. Int J Occup Med Environ Health 1997;10:417-28.
Rasmussen FV, Borchsenius L, Holstein B, Sølvsteen P. Lung function and long term exposure to cement dust. Scand J Respir Dis 1977;58:252-64.
Abrons HL, Petersen MR, Sanderson WT, Engelberg AL, Harber P. Symptoms, ventilatory functions and environmental exposures in Portland cement workers. Br J Ind Med 1998;45:368-75.
Arndt V, Brenner H, Rothenbacher D, Zschenderlein B, Fraisse E, Fliedner TM. Elevated liver enzyme activity in construction workers: prevalence and impact on early retirement and all-cause mortality. Int Arch Occup Environ Health. 1998;71:405-12.
Khalil S, Shouman AE, El SH, Moussa EM. Chromium induced contact dermatitis and indices for diagnosis. J Egypt Public Health Assoc 1999;74:485-50.
Aadly AA. Oxidative stress and disease. An update. Res J Immunol 2010;3:129-45.
Kohen R, Nyska A. Oxidation of biological system. Oxidative stress phenomena, antioxidants, redox reactions and methods for their quantification. Toxicol Pathol 2002;30:620-50.
Ogunbileje JO, Akinosun OM, Anetor JI, Akinduti PA, Ejilude O, Nwobi NL, et al
. Effects of different cement factory sections products on Immunoglobulin levels and some biochemical parameters in Nigeria cement factory workers. N Y Sci J 2010;3:102-6.
Ogunbileje JO, Akinosun OM. Biochemical and haematological profile in Nigerian cement factory workers. Res J Environ Toxicol 2011;5:133-40.
Johansson SG, Melbin T, Vahlquist G. Immunoglobulin levels in Ethiopian preschool children with special reference to high concentration of immunoglobulin E (IgND). Lancet 1968;1:1118-21.
Barbee RA, Halonen M, Lebowitz M, Burrows B. Distribution of IgE in a community population sample: Correlations with age, sex, allergen, skin test reactivity. J allergy Clin Immunol 1981;68:106-11.
Adsul BB, Laas PS, Howal PV, Chaturvedi RM. Health problems amongst migrant construction workers. Indian J Occup Environ Med 2011;15:29-32.
Shah KR, Tiwari RR. Occupational skin problem in construction workers. Indian J Dermatol 2010;55:348-51.
Nielsen NH, Menne T. Allergic contact sensitization in an unselected Danish population. The Glostrup Allergy study, Denmark. Acta Derm Venereol 1992;72:456-60.
Shelnutt SR, Goad P, Belsito DV. Dermatological toxicity of hexavalent chromium. Crit Rev Toxicol 2007;37:375-87.
Jenny L. Nelson, Christen M. Mowad. Allergic Contact Dermatitis: Patch Testing Beyond the TRUE Test. J Clin Aesthet Dermatol 2010;3:36-41.
Cheng Lily S, Alikhan Ali, Maibach, Howard I. Compilation of International standards for Patch testing methodology and allergens. Dermatitis 2009;20:257-60.
Ale S, Maibach H. Reproducibility of patch test results: A concurrent right- versus-left study using T.R.U.E test. Contact Dermatitis 2004;50:304-12.
[Table 1], [Table 2], [Table 3]