Cobalt-associated asthma investigated
MedWire News: The risk for asthma caused by occupational exposure to cobalt increases with increasing levels of exposure, and respiratory symptoms may persist after exposure has ceased, Finnish study results show.
Due to the rarity of cobalt-associated asthma, few studies have investigated the nature of the condition.
To address this, Riitta Sauni (Finnish Institute of Occupational Health, Tampere) and team studied the occupational health care register from the Kokkola cobalt plant in Finland for the period 1967–2003. All diagnoses of asthma associated with cobalt exposure were confirmed in clinical examinations with specific inhalation challenge tests performed at the Finnish Institute of Occupational Health in Helsinki.
The researchers identified a total of 22 individuals diagnosed with cobalt-associated asthma over the study period. Of these only four were atopic.
The incidence of cobalt-associated asthma was highest in departments of the plant in which exposure levels were highest. Furthermore, all individuals diagnosed with asthma caused by exposure to the element worked in areas of the plant where irritant gases were also present.
The results of challenge tests showed that 16% were immediate, 61% were delayed, and 19% were dual reactions
In the 14 individuals who underwent examinations 6 months after changing jobs or retiring, bronchial hyper-responsiveness had increased in four patients, remained at the same level in seven patients, and had fallen in the just one patient.
Sauni and team conclude in the journal Occupational Medicine: “Current evidence indicates that as the mean exposure levels to inhaled cobalt increase, the risk of occupational asthma induced by cobalt also increases, and the irritating gases seem to contribute to the risk.
“Although exposure to the causative agent ceases, the symptoms and bronchial hyper-reactivity may continue.”
They add: “An early diagnosis and cessation of exposure are important when occupational asthma induced by cobalt exposure is suspected.”
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By Mark Cowen