Respirable Dust

In 1999 the American Conference of Governmental Industrial Hygienists assigned, for the first time, a threshold limit value (TLV) for flour dust. In response, in 2000 the North American Millers’ Association, the American Bakers Association and the Canadian National Millers Association engaged Sandler Occupational Medicine Associates, Inc. (SOMA) to evaluate the TLV documentation.

That evaluation included a review of the scientific references and data used in support of the TLV.  An independent review and analysis of more than 60 studies published in the scientific literature, including studies referenced in the ACGIH document, was undertaken to assess study methodologies and outcomes as they relate to a flour dust TLV.

Scientific data on flour exposure and flour workers has continued to accumulate. To evaluate the new data, and in the context of inclusion of flour dust in proposed occupational health regulations for allergens or allergy-producing substances, an updated analysis of the flour dust literature was performed in 2009.

The original 2000 analysis observed that the majority of symptom and allergy data on flour workers indicated that occupational allergy is not the primary cause of symptoms in flour workers.  In the context of the proposed regulation of flour worker symptoms as occupational allergy, it was deemed important to update the previous analysis with the relevant literature on flour exposure and flour worker symptoms and flour allergy, which had accumulated since 2000.

This detailed analysis of the new scientific literature pertaining to flour workers included 25 published studies that were relevant to the subject matter of the update. The new results reconfirm several key observations from the 2000 analysis. These observations have important implications for potential exposure standard setting and health surveillance programs for flour workers, particularly in the context of flour allergy. These key observations are as follows:

• Most flour workers who report symptoms, including those specifically reported by workers as work-related, do not have allergy to flour or its components based upon results of objective testing.
• Many flour workers who show flour allergy based on testing have no history of symptoms corresponding with allergy.
• The relationships between flour dust concentrations and health outcomes in flour workers show significant variability and non-linear patterns, with absence of confirmation of threshold exposure levels for specific outcomes including occupational allergy.
• The long-term health impacts of different exposure limits and administrative practices as components of potential flour worker health surveillance programs have not been identified in the existing literature.

To receive a copy of the SOMA study, please contact Jim Bair.

Prepared by Jim Bair, [email protected], 202.484.2200, ext. 14

Last updated February 28, 2011