Wednesday, 4 September 2013

Occupational Exposure to Compost and Risk of Contracting ABPA

Recent research has examined the health of a group of workers that collect and sort garden waste. These workers are exposed to high numbers of Aspergillus in their normal daily routine and previous research has limited conclusions to allergic illness in some workers, occasionally identifying cases of Allergic Bronchopulmonary Aspergillosis (ABPA).

Quoting from the original paper:
To date, there have been very few reports of illness in these workers. In a cross sectional study of 218 compost workers in Germany, there was increased job turnover, eye and upper airway irritation, chronic bronchitis, two cases of extrinsic allergic alveolitis (EAA) due to Aspergillus fumigatus and decreased lung function compared with controls. There is one case report of allergic bronchopulmonary aspergillosis (ABPA), EAA and asthma in a garbage collector in Germany; one report of ABPA in a soy sauce maker in Japan who used Aspergillus oryzae in the fermenting process and one suspected case of ABPA in a vegetable compost worker in Belgium. Two cases of EAA after spreading damp bark chippings, one of which was fatal, have been reported from Denmark.

This new paper identified two cases of ABPA in a group of 38 workers.  The prevalence of ABPA in the general population is thought to be 1 in 1000 - 1 in 3000 (Denning 2012) so frequency of 1 in 19 in this group of workers is very significant. A larger study is now required to confirm these results but perhaps precautionary measures need to be taken from now on. The authors suggest:

Until the results of large epidemiological studies of garden waste collectors and industrial compost workers are known, the few case reports of ABPA and EAA due to Aspergillus sp would indicate that workers with asthma who are sensitized to A. fumigatus or who have cystic fibrosis, bronchiectasis or are immunosuppressed should not work with garden waste or compost, unless their exposure to airborne fungi can be controlled. 
Whether asthmatics who are SPT positive or specific IgE positive to A. fumigatus will go on to develop ABPA is unknown, but they should be made aware of the
theoretical risk.
Annual health surveillance by way of a respiratory questionnaire and skin prick testing is also recommended for these workers. Other cases of ABPA or EAA in garden waste and compost workers should be sought and reported, until such time that the results of a national study of UK compost workers are known.

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