11/09/2012

Experiences from Occupational Exposure Limits Set on Aerosols Containing Allergenic Proteins

Occupational exposure limits (OELs) together with determined airborne exposures
are used in risk assessment based managements of occupational exposures to
prevent occupational diseases. In most countries, OELs have only been set for
few protein-containing aerosols causing IgE-mediated allergies. They comprise
aerosols of flour dust, grain dust, wood dust, natural rubber latex, and the
subtilisins, which are proteolytic enzymes. These aerosols show dose-dependent
effects and levels have been established, where nearly all workers may be
exposed without adverse health effects, which are required for setting OELs.
Our aim is to analyse prerequisites for setting OELs for the allergenic
protein-containing aerosols. Opposite to the key effect of toxicological
reactions, two thresholds, one for the sensitization phase and one for
elicitation of IgE-mediated symptoms in sensitized individuals, are used in the
OEL settings. For example, this was the case for flour dust, where OELs were
based on dust levels due to linearity between flour dust and its allergen
levels. The critical effects for flour and grain dust OELs were different,
which indicates that conclusion by analogy (read-across) must be scientifically
well founded. Except for subtilisins, no OEL have been set for other industrial
enzymes, where many of which are high volume chemicals. For several of these,
OELs have been proposed in the scientific literature during the last two
decades. It is apparent that the scientific methodology is available for
setting OELs for proteins and protein-containing aerosols where the critical
effect is IgE sensitization and IgE-mediated airway diseases.

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AplusA-online.de - Source: The Annals of Occupational Hygiene