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Key messages What is already known about this subject?
3-(Bromomethyl)-2-chloro-4-(methylsulfonyl)-benzoic acid (BCMBA) has not previously been identified as a respiratory sensitiser.
What are the new findings?
Six cases of occupational asthma, rhinitis and/or contact urticaria caused by BCMBA were confirmed with challenge tests.
A survey in a chemical factory showed an 8% sensitisation rate to BCMBA among all exposed workers and 25% among production workers with the estimated highest exposure levels.
How might this impact on policy or clinical practice in the foreseeable future?
Careful control of exposure is needed to protect workers.
Introduction
Several low molecular weight (LMW) agents are known to cause occupational asthma via immunological mechanisms. 1 The mechanisms are mainly IgE-independent, but specific IgE antibodies to some agents have been detected. IgE-mediated occupational asthma commonly occurs with occupational rhinitis and contact urticaria. 2 3 New LMW agents are occasionally identified as causal agents of sensitiser-induced occupational asthma. 4 The respiratory sensitisation potency of these agents is seldom identified in animal or in vitro tests before their industrial usage, resulting in the fact that new sensitisers are often first described in clinical case reports. 5 Specific inhalation challenge is the most definitive method of identifying these agents. 6
3-(Bromomethyl)-2-chloro-4-(methylsulfonyl)-benzoic acid (BCMBA) ( figure 1 ) is an LMW agent used as an intermediate product in the manufacture of another chemical. The end product of the process was a plant-protective agent. Two index patients with positive skin prick tests (SPTs) with respiratory and skin symptoms to BCMBA were examined at the Finnish Institute of Occupational Health (FIOH) during 2014. Both patients worked in a chemical factory in which BCMBA powder has periodically been produced since 2009. We subsequently visited the factory and investigated the exposed factory workforce as well as a subset of unexposed workers so as to identify additional cases. We determined the exposure levels and evaluated a possible dose-response relationship related to the BCMBA exposure. We report the results of the outbreak investigations and clinical findings of two index cases and four additional cases with occupational disease due to BCMBA exposure confirmed with challenge tests.
Methods
Outbreak investigations
Outbreak investigations were carried out in 2015 in collaboration with industrial safety personnel and factory occupational healthcare personnel. They comprised exposure assessment and...