Evaluation of exposure-response relationships for health effects of microbial bioaerosols - A systematic review.
Studies suggest adverse health effects following exposure to bioaerosols in the environment and in particular at workplaces. However, there is still a lack of health-related exposure limits based on toxicological or epidemiological studies from environmental health or from the working environment. The aim of this study was to derive health-based exposure limits for bioaerosols that can protect the general population as group "at risk" via environmental exposure using analysis of peer-reviewed studies related to occupational medicine, indoor air and environmental health. The derivation of exposure limits should be conducted by the members of a bioaerosol expert panel according to established toxicological criteria. A systematic review was performed in Medline (PubMed) including studies containing both data on exposure measurements and observed health outcomes. In addition, literature recommended by the experts was considered. A comprehensive search strategy was generated and resulted in a total of n=1569 studies in combination with the literature recommendations. Subsequently, abstracts were screened using defined exclusion criteria yielding a final number of n=44 studies. A standardized extraction sheet was used to combine data on health effects and exposure to different bioaerosols. After full-text screening and extraction according to the defined exclusion criteria n=20 studies were selected all related to occupational exposures comprising the working areas wood processing, farming, waste processing and others. These studies were analyzed in collaboration with the bioaerosol expert network in terms of suitability for derivation of health-related exposure limits. The bioaerosol expert network concluded that none of the analyzed studies provided suitable dose-response relationships for derivation of exposure limits. The main reasons were: (1) lack of studies with valid dose-response data; (2) diversity of employed measuring methods for microorganisms and bioaerosol-emitting facilities; (3) heterogeneity of health effects; (4) insufficient exposure assessment. However, several indicator parameters and exposure concentrations could be identified for different bioaerosol-emitting facilities. Nevertheless, health-related exposure limits are urgently needed especially in approval procedures of facilities like composting plants or livestock farms emitting bioaerosols in the neighbourhood of residents. In the regulatory toxicology framework, it is common to use animal experimental studies for derivation of general exposure limits if appropriate environmental epidemiological studies on harmful substances are lacking. This might be another possibility to obtain health-related exposure limits for specific bioaerosol parameters. Furthermore, we recommend to use suitable measurable outcome parameters related to bioaerosols; to measure bioaerosols according to a protocol representative for exposure pattern and duration at the particular work place; to develop standardized detection methods for indicator parameters; to combine different detection methods to compensate for the limitations of each method; to apply new analysis methods to identify the real risk potential.
Bavarian Health and Food Safety Authority, Occupational and Environmental Health, Epidemiology, Munich, Germany. Electronic address: sandra.walser@lgl.bayern.de.
Sandra M
SM
Walser
Bavarian Health and Food Safety Authority, Occupational and Environmental Health, Epidemiology, Munich, Germany.
Doris G
DG
Gerstner
Bavarian Health and Food Safety Authority, Occupational and Environmental Health, Epidemiology, Munich, Germany.
Bernhard
B
Brenner
Institute for Prevention and Occupational Medicine of the German Social Accident Insurance, Institute of the Ruhr-University Bochum (IPA), Germany.
Jürgen
J
Bünger
Institute for Hygiene and Environmental Medicine, Justus-Liebig-Universität Giessen, Germany.
Thomas
T
Eikmann
Bavarian Health and Food Safety Authority, Occupational and Environmental Health, Epidemiology, Munich, Germany.
Barbara
B
Janssen
Bavarian Health and Food Safety Authority, Occupational and Environmental Health, Epidemiology, Munich, Germany.
Stefanie
S
Kolb
Institute for Occupational Safety and Health of the German Social Accident Insurance (IFA), Unit Biological Agents, Sankt Augustin, Germany.
Annette
A
Kolk
Institute and Outpatient Clinic for Occupational and Environmental Medicine, Ludwig-Maximilians-University Munich, Germany.
Dennis
D
Nowak
Institute for Prevention and Occupational Medicine of the German Social Accident Insurance, Institute of the Ruhr-University Bochum (IPA), Germany.
Monika
M
Raulf
Hamburg Ministry of Health and Consumer Protection, Hamburg, Germany.
Helmut
H
Sagunski
LfU - Bavarian Environment Agency, Division 21, Augsburg, Germany.
Nadja
N
Sedlmaier
Governmental Institute of Public Health of Lower Saxony, Hannover, Germany.
Roland
R
Suchenwirth
Health Department of the City of Cologne, Department of Infectious and Environmental Hygiene, Germany.
Gerhard
G
Wiesmüller
Governmental Institute of Public Health of Lower Saxony, Hannover, Germany.
Klaus-Michael
KM
Wollin
State Institute for the Environment, Measurement and Nature Conservation Baden-Wuerttemberg (LUBW), Karlsruhe, Germany.
Irene
I
Tesseraux
Bavarian Health and Food Safety Authority, Occupational and Environmental Health, Epidemiology, Munich, Germany.
Caroline E W
CE
Herr
D000336:Aerosols; D000391:Air Microbiology; D000395:Air Pollutants, Occupational / Q000009:adverse effects* / Q000032:analysis; D000397:Air Pollution / Q000009:adverse effects* / Q000032:analysis; D006262:Health; D006801:Humans; D016273:Occupational Exposure / Q000009:adverse effects* / Q000032:analysis
D000336:Aerosols; D000395:Air Pollutants, Occupational
Bioaerosol; Dose–response; Exposure; Health; Microorganisms; Review