Milk Powder Production: Is A New Occupational Disease Emerging?

Main Category: Respiratory / Asthma
Also Included In: Pediatrics / Children's Health
Article Date: 25 Mar 2008 - 4:00 PST

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Occupational exposure to milk powder inhalation increases the risk of respiratory complaints, including wheezing, breathlessness and nasal symptoms, and reduces lung function. So reveals an original study undertaken in a Thai baby milk factory by a British team, due to be published in the forthcoming issue of the European Respiratory Journal (ERJ), the peer-reviewed publication of the European Respiratory Society (ERS). Exposed workers need to be monitored to ensure timely identification of such hypersensitivity to milk powder, the authors recommend.

It is already known that oral consumption of milk powder can lead to  the development of an allergy in children intolerant to cow's milk  proteins. The potential risks of inhaling milk powder have, however,  never been studied specifically. This led Maritta Jaakkola and her  team (Institute of Occupational and Environmental Medicine,  University of Birmingham, United Kingdom) to focus on the issue and  analyse the effects of occupational exposure to milk powder via the  airways.

The study, undertaken jointly with Thailand's Mahidol University,  covered 167 workers in a Thai baby milk factory. They included 130  workers involved directly in product manufacture and packaging, 22  responsible for adding vitamins to the milk and 15 quality  controllers. By way of a control group, 76 office workers employed in  this factory or in other Thai plants were also included in the study. A total of 142 men and 101 women were recruited, aged between 18 and  60 years.

All of the participants were asked to complete a health questionnaire  on respiratory, nasal, eye and skin symptoms experienced in the past  twelve months. These data were complemented by systematic spirometric  tests.

Twice as many symptoms as the control group

Jaakkola and her team conclude that the workers exposed to the milk  powder suffer a significant increase in wheezing, breathlessness and  various nasal symptoms (blocked or runny nose, itching of the nasal  passages and sneezing) as compared to the control subjects. Indeed, the levels of wheezing and breathlessness (24% and 33%  respectively) were twice those of the control group (12% and 16%). After adjustment for other variables, such as smoking, the relative  risk for those two symptoms remains high (1.74 and 2.20), the ERJ  article's authors explain. Admittedly, the latter figures were no  longer statistically significant, but the increased risk of nasal  symptoms (2.3) remained statistically significant, even after  readjustment.

In addition, the exposed workers were apparently twice as likely to  have suffered from asthma. It was also found that the workers responsible for adding vitamins  complained of eye and skin symptoms twice as frequently as the other  employees.

Allergy more probable than irritation

The respiratory function tests recorded a significant reduction in  forced expiratory volume in one second (FEV1) among milk powder- exposed workers who complained of respiratory symptoms. Jaakkola and her team believe that the symptoms observed are much  more typical of a hypersensitivity reaction than a simple irritation.  They point to the low levels of particles (mainly milk powder)  measured in the air within the factory. Even in the packaging areas,  where particle levels were higher, they remained far below the  permitted concentration for respirable dust.

"Milk powder contains milk proteins including casein, alpha- lactalbumin and beta-lactoglobulin, compounds with a high molecular  weight which typically induce hypersensitivity reactions," the  authors explain in their ERJ article. They admit, however, that the  debate remains a speculative one, since immunoglobulin E antibodies  were not measured in the subjects.

"It would be important to provide careful monitoring of respiratory  symptoms and respiratory function tests for workers in milk powder  factories, even where air quality checks are satisfactory," Jaakkola  concludes.

Along similar lines, she believes that respiratory tests could be of  benefit to bakers and nannies, who may also suffer occupational  exposure to milk powder. A number of cases of occupational asthma  have already been recorded in these occupational groups.

"Respiratory effects of occupational exposures in a milk powder factory"

The European Respiratory Journal is the peer-reviewed scientific publication of the European Respiratory Society (more than 8,000 specialists in lung diseases and respiratory medicine in Europe, the United States and Australia).

http://erj.ersjournals.com