Compensatability and contact dermatitis in the canning industry.

If reports from the Workmen's Compensation Commissioner are compared with international figures, dermatitis in South African industry appears to be underestimated. Compensation for occupational dermatitis in South Africa relies on the presence of a positive patch test. A prevalence study at a canning factory in the western Cape showed high rates of dermatoses. No association could be shown between dermatitis, intertrigo or chronic paronychia and patch-test positivity. It is argued that patch-test positivity is purely coincidental to the dermatoses and that patch testing has little role to play where the majority of occupational dermatoses are irritant in nature. Reform of the system of compensation for occupational skin disorders is urgently needed and should be integrated in workplace-based preventive and curative programmes.

Dermatoses--an occupational hazard in the canning industry.

Despite the recognition that occupational dermatitis is extremely common, few data exist on the prevalence of skin disorders in South African industry. A cross-sectional prevalence study among 686 female workers in a canning factory in the western Cape showed high rates of dermatoses--in particular, chronic paronychia, intertrigo and dermatitis of the hands. A statistically significant association was found between exposure to 'wet work' in the industry and the prevalence of chronic paronychia and intertrigo. Age was also found to be associated with these dermatoses, irrespective of duration of service. The prevalence of dermatitis of the hands was increased among high-exposure workers, but not significantly. Dermatoses are an important occupational hazard in the canning industry, and there is a need for improved preventive measures.

Dermatoses in the canning industry--the roles of glove use and non-occupational exposures.

Primary prevention is the mainstay of management of occupational dermatoses. Despite the high rates of dermatoses found in a study of 686 female workers in a canning factory in March 1990, use of protective gloves was extremely low, even though there was evidence that they prevented acute paronychia and intertrigo. Reasons associated with low glove use were unavailability, discomfort and workers' failure to perceive a protective role for gloves. Difficulties with replacement of damaged gloves were an important cause of unavailability. Domestic and other non-occupational exposure at the workplace appeared to be unimportant in the development of dermatoses. Important preventive interventions are possible in the industry to reduce the rates of dermatoses among the workforce.

Enhanced weal and flare response to histamine in chronic idiopathic urticaria.

Weal and flare histamine dose-responses were measured in 30 normal subjects and 15 patients with chronic idiopathic urticaria. The log dose-response curves were shifted to the left corresponding to an increase in histamine potency of 2.5 for weal and 3.1 for flare. An enhanced response to histamine may be important in chronic idiopathic urticaria and comparison of potency of antihistamines in different subjects may be unreliable where initial weal response is abnormal.

Response of scalp psoriasis to oral ketoconazole.

A randomised double-blind placebo-controlled study showed improvement of scalp psoriasis with oral ketoconazole, although the study had to be stopped before completion because of the possibility of drug toxicity. The common appearance of psoriasis in the scalp and certain other sites may be due to pityrosporal colonisation that also causes seborrhoeic dermatitis and dandruff.

A comparison of astemizole and chlorpheniramine in dermographic urticaria.

The effects of the H I receptor antagonists astemizole and chlorpheniramine on dermographism were compared in a double-blind study in sixteen patients. Both drugs resulted in a parallel and significant depression of the dermographic force-response curve and an elevation of the weal-force threshold, but the changes were greater in the patients receiving astemizole (a maximal potency shift of 74% for astemizole and 37% for chlorpheniramine). Subjective itch (10 cm line) and frequency of dermographic episodes were also reduced more by astemizole than by chlorpheniramine. The effect of astemizole was greater at 4 weeks than at 2 weeks, whereas the effect of chlorpheniramine had decreased at 4 weeks. The effect of astemizole but not chlorpheniramine was still apparent 4 weeks after treatment had been stopped. Since the degree of residual dermographism was comparable despite great differences in histamine weal inhibition a vasoactive mechanism in addition to that mediated by histamine must be involved in dermographic urticaria.

Minimal effect of complete H1 receptor blockade on urticaria pigmentosa.

The effect of complete H1 receptor blockade on urticaria pigmentosa was studied in 6 patients. Astemizole 10 mg tds was given for 6 weeks to achieve complete H1 receptor blockade and the response measured by change in force-weal response measurements using two different forces on a dermographic stylus and measuring response as weal diameter. Weal and flare reactions to 8 micrograms histamine were completely abolished by the astemizole but dermographic weal-force responses were reduced only by 12-15% indicating that histamine acting at the H1 receptor plays only a small part in the wealing of urticaria pigmentosa.

The effect of terfenadine on dermographic wealing.

A double-blind comparison of terfenadine with placebo showed a reduction in potency of measured dermographic force-response of 67%, which is similar to that for inhibition of histamine weals by terfenadine. This and the parallel displacement of the force-response curves indicates that histamine is the main cause of dermographic wealing. Dermographic threshold and itch change together and appear to be the main determinant of the patients' subjective response. Dermographism relapsed towards its pre-treatment state during the 3 days after treatment was stopped. There was a small decrease in effect after administration of 60 mg b.d. for 47-84 days and a further small increase in response when the dose was increased to 120 mg t.d.s., but neither change was significant. None of the patients had a sedative response to the drug and terfenadine should prove useful in the treatment of wealing disorders.