Contact Dermatitis and Exposure to N, N-dimethylformamide
K. Asanati*, J. GH-Sanati
Dept of Occupational Medicine, Polyacryl Iran Corporation (PIC), Isfahan, Iran
Objective
We conducted this investigation in order to evaluate the relationship between contact dermatitis and exposure to the solvent N,N-dimethylformamide (DMF). We also assessed DMF absorption in the workers with contact dermatitis.
Methods
In a factory producing synthetic fibres, International Classification of Diseases, Ninth Revision (ICD-9), codes were noted for workers during their periodic check ups. Skin diseases were documented by an occupational medicine consultant or a dermatologist. In order to monitor DMF levels, urine samples were taken at the end of the working hours and urinary N-methylformamide (NMF) was used as an indicator. Both ICD codes and biological monitoring results were recorded in the Occupational Health Register. Data for this study were taken from this register (March, 1990 to March, 2002). In the first step, we conducted a retrospective (historical) cohort study among 3140 employees who served in the factory during the period under investigation (March, 1990 to March, 2002), and also had no codes of skin disorders in the starting point of the investigation (1990). Logistic regression analysis was performed to compare dermatitis between exposed cases and non-exposed controls. In the second step, a case-control investigation was set up in the exposed population. The 8 dermatitis-coded exposed workers were matched with a group of 18 exposed controls. None of the controls have any code of skin disorders. Matching criteria were the working area and the employment period, with a maximum difference of one year being allowed on the employment period. The mean age of cases and controls were 46 and 47.2 respectively (P > 0.05). The mean exposure period was 24.5 years (range, 21-26). Moreover, for each exposed worker, the average of urinary NMF measurements was determined and categorized as Low if 0-10, Middle if 10-20 and High if >20 mg/g creatinine.
Results
Of 3140 employees, 64 had associated contact dermatitis codes. Of 247 occupationally exposed workers, 8 were coded as contact dermatitis. In order to assess the association between contact dermatitis and DMF exposure, odds ratio (OR) and 95% confidence interval (CI) were computed by means of logistic regression (OR: 1.66, 95% CI: 0.78, 3.53). For analyzing the obtained data in the second step of the study, firstly, we used the Kolmogorov-Smirnov test to check the normality of urinary NMF data. No significant difference was observed between mean urinary values of dermatitis and normal skin workers (17.8 vs. 13.5 mg/g creatinine; P > 0.05). However, logistic regression revealed an association between high urinary NMF and contact dermatitis (OR = 2.4).
Conclusions
DMF absorption might be more in dermatitis-workers compared to normal skin-employees. In authors' view, protective clothing could play an important role in reducing DMF absorption to an acceptable level in workers with dermatitis. Further investigations in order to evaluate the effect of protective clothing in DMF exposed workers are highly recommended.
Content last modified: 21 May 2005
