biological agents: need for occupational exposure limits (oels) and feasibility of oel setting rafal...
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Biological agents: Biological agents: Need for Need for
Occupational Exposure Limits (OELs) Occupational Exposure Limits (OELs) and feasibility of OEL settingand feasibility of OEL setting
Rafal Górny
Department of BiohazardsDepartment of Biohazards Institute of Occupational Medicine and Environmental Health
WHO Collaborating CentreSosnowiec
Poland
Biological agents Biological agents (BA) (BA) – is it a problem?– is it a problem?
Epidemiological studies: in world scale a few hundred million people are exposed to BA
Putting non-occupational indoor environment aside, exposure to BA is registered for 148 specialist work professional groups in 22 main branches of industry
Important issue for occupational medicine and public health
Adverse health effects: allergic reactions, infections, toxic reactions, and nonspecific symptoms
Biological agents at workBiological agents at work
bioaerosols - airborne transport of biological particles
penetration of biological agents through the skin, mucous membrane or with a bite of bloodsucker arthropoda
less frequently through the alimentary tract (such way is rather atypical for occupational infections)
Conditio sine qua non of proper hygienic regime of occupational settings and health comfort is correct control
of worker exposure and control of crucial parameters determining contamination of work environment by BA
Necessary needsNecessary needs
Elaboration of widely accepted guidelines, standards or limit values enabling proper interpretation of environmental situations or measurement results, at least
Evaluation criteriaEvaluation criteriaChemical/physical hazards Biohazards
The higher concentration/intensity,
the longer time of exposure
the more severe health outcome
(body damage, occupational disease)
Unproportionality of human body answer to risk factor
Lack of standards/limit valuesLack of standards/limit values
dose-response relationship is still indeterminate and controversial in many aspects
it is not possible to identify individual species of microorganisms or other specific BA responsible for health effects (except some common allergies attributed to specific agents or exposure)
susceptibility as an individual feature of each organism
source data regarding environmental/occupational concentrations of biological agents are still insufficient
lack of standardization of sampling methods (lack of standard samplers) and experimental procedures (lack of commonly approved criteria for assessing exposure to biological agents)
Status quo anteStatus quo ante
Standards or limit values, if established, base on clinical picture of disease caused by biological agent, taking into account only presence of the reliable factor in some element of the studied environment (qualitative approach)
Status praesensStatus praesens
Nevertheless, quantitative standards, reference or limit values do exist to facilitate interpretation of measurement data
Strategy of hygienic standard elaborationStrategy of hygienic standard elaboration
ENVIRONMENT
DWELLINGS OCCUPATIONAL ENVIRONMENT
INDOOR OUTDOOR
INDUSTRIAL NONINDUSTRIAL
AIR SURFACES
1.
2.
Quantitative standards/limit valuesQuantitative standards/limit values
ARBITRARY RELATIVE/COMPARATIVEConcentration of biological agent, which is acceptable or non-acceptable
Usually for total microbial flora, their groups or certain species
Proposed by individual investigators, expert groups or as a result of cross-sectional/large-scale research study
Not related to the specific health outcome (do not precise dose-response relationship)
Often equal or close to the detection level of particular analytical method
Usually based on simultaneously measured concentration of biological agent in indoor and outdoor environments
If indoor/outdoor relationship is below 1, it shows that hygienic conditions of indoor environment is good or acceptable
Identification of indoor sources of biological agent(s)
Suitable for qualitative or frequency of appearance comparisons
To ensure the reliability of bioaerosol measurement methods and their proper interpretation, in the first place, it is necessary to unify the methodology, i.e., to recommend the use of proper methods.
The active air sampling (e.g., volumetric methods) should allow the measurement of a concentration of microorganisms and describe their taxonomical origin.
Sampling method as immanent component Sampling method as immanent component of proposed standard/limit valueof proposed standard/limit value
Various technological and lifestyle recommendations and guidance allow to control the work environment contaminated with biological agents using a few different methods (e.g., „Recommended limits for microbiological monitoring of clean areas for sterile processing” according to the EU’s Good Manufacturing Practice (GMP) guideline)
History of standards for History of standards for BA BA Type of premises,
biological agentLimit value proposal, author(s), year of
publication
Dwellings
Bacteria and fungi (CFU/l)Bacteria (#/liter)Total microorganisms (CFU/m3)
600 - Carnelley et al. (1887)50 - Bujwid (1894)1,8103 - Bourdillon et al. (1941)
Occupational premises
Total microorganisms (CFU/m3)4,3105 - Donham et al. (1988)5104 - Erman et al. (1989) 5103-1104 - Malmros et al. (1992)
Gram-negative bacteria (CFU/m3)1103 - Clark (1985)2104 - Buyanov et al. (1990)1103 - Malmros et al. (1992)
Fungi (CFU/m3) 1107 - Clark (1985)
Endotoxins (µg/m3)
0,1 - Clark (1985)0,1-0,2 - Rylander (1987)0,1-0,2 - Malmros et al. (1992)0,005 - DECOS (1998)0,025 - Laitinen et al. (1999)
Quantitative standard/limit value examplesQuantitative standard/limit value examplesCULTURABLE OR VIABLE EVALUATION STANDARDS FOR HOME & COMMERICAL BUIDLINGS Governmental Bodies
1. Brazil 2. Canadian Mortgage and Housing Company (CMHC) 3. Commission of European Communities 4. Czech Republic 5. Finland 6. Netherlands and Research Institute 7. New York City Department of Health (NYCDH) 8. Nordic Council 9. Poland10. World Health Organization (WHO) Trade Associations Indoor Air Quality Standard11. American Conference of Governmental Industrial Hygienists
Trade Associations12. American Industrial Hygiene Association13. Indoor Air Quality Association (AIHA)14. International Society of Indoor Air Quality and Climate (IAQA)
TOTAL SPORE EVALUATION STANDARDS GOVERNMENTAL BODIES15. Russian Federation Standard16. Texas Department of Health Trade Associations (TDH) 17. American Academy of Allergy, Asthma & Immunology18. American College of Occupational and Environmental Medicine
CULTURABLE OR VIABLE SPORE LIMITS FOR MEDICAL DEVICE & PHARMACEUTICAL CLEAM ROOMS Governmental Bodies
19. European Union Clean Room Standard20. U. S. Pharmacopoeia clean room standard
Quantitative standard/limit value examplesQuantitative standard/limit value examples
Functional Grouping of Mold and Bacteria Standards
A. Permissible or Acceptable Exposure Levels
B. Action Levels (Warranting Investigation)
C. Ceiling Limit or IDLH Levels (Immediately dangerous to life and health)
D. Clearance Levels Exposure Guidelines (Post Remediation)
E. The Inside Versus Outside Concentration Rank Order Guidelines
F. Ceiling Limits for Hospitals & Other Susceptible Occupant Environments
G. Bacteria Standards
H. Application of the Standards - The Issue of Open Windows
Quantitative standard/limit value examplesQuantitative standard/limit value examplesTotal bacteria: 1,0103 ÷ 7,0103 CFU/m3 for dwellings and non-
occupational indoor environment as well as ≤7,5102 ÷ 1,0107 CFU/m3 for occupational environment (in all these indoor spaces no safe level for pathogens (0 CFU/m3)
Gram-neg. bacteria: 1,0103 ÷ 2,0104 CFU/m3 for occupational environment
Endotoxins: 0,005 ÷ 0,2 µg/m3 for occupational environment
Total fungi: 1,0101 ÷ 1,0104 CFU/m3 for dwellings and non-occupational indoor environment as well as <1,0102 ÷ 1,0107 CFU/m3 for occupational environment (in all these indoor spaces no safe level for pathogens (0 CFU/m3)
Subtilisins: 0,06 µg/m3 for occupational environment
House dust allergens: mite Der p I: 2,0 ÷ <15,0 µg/gcat Fel d I: <1,0104 ng/gdog Can f I: <1,0105 ng/g
Special environments, i.e., hospital premises and clean areas forsterile processing: 1,0100 ÷ 4,0103 CFU/m3 and <1,0100 ÷ 1,0103 CFU/m3
Clean areas for sterile processing: the microbial quality of the air is accompanied by the control of a quality of the surfaces. The proposed limits are as follows:
<1,0100 ÷ 4,0102 CFU/24 cm2, if concentration is related to
the surface (usually equal to the surface of Petri dish), <1,0100 ÷ 2,0101 CFU/glow, if the certain quality of the
worker hands is required, or 3,23105 CFU/m2, if microorganisms sediment on the surface
within 1 week or up to 106 CFU/g of dust, if the concentration is related to the
amount of settled dust
Quantitative standard/limit value examplesQuantitative standard/limit value examples
Directive 2000/54/EC of the European Parliament and of the Council of 18 September 2000 on the protection of workers from risks related to exposure to biological agents at work.
20002000
Qualitative approachQualitative approach
Defines employers’ obligations in terms of the protection of workers against risks to their health and safety, including the prevention of such risks, arising or likely to arise from exposure to biological agents at work
Annex III – Community classification (the list of classified BA)
European standards (EN) – Workplace atmospheres: 13098: Guidelines for measurement of airborne micro-organisms and endotoxin
14031: Determination of airborne endotoxins
14042: Guide for the application and use of procedures for the assessment of exposure to
chemical and biological agents
14583: Volumetric bioaerosol sampling devices – requirements and test methods
German standards (VDI) – Measurements of airborne microorganisms and viruses in ambient air
4252: Active sampling of bioaerosols
4253: Culture based method for the determination of the concentrations of moulds in the air
4255: Bioaerosols and biological agents - Source of emissions and control measures - Overview
„„Life after... Directive 2000/54/EC”Life after... Directive 2000/54/EC”
No way of interpretation of quantitative No way of interpretation of quantitative results is givenresults is given
20042004
Establishment of
Biological Agents Expert GroupBiological Agents Expert Group
as a part of the Interdepartmental Commission for Maximum Admissible Concentrations and Intensities for Agents Harmful to Health in the
Working EnvironmentCentral Institute for Labor Protection - NRI
Warsaw, Poland
Biological Agents Expert GroupBiological Agents Expert Group
Scientific approachScientific approach
If a solid link between the concentration of investigated parameters and resulting adverse health effect cannot be effectively established,
then, based on the biological agent concentration measurements, the reference values should
enable evaluation of the quality of the environment, as well as determination of “what is typical and acceptable” and “what is atypical or
not acceptable” for a specific type of setting
*) For respirable fraction the proposed limits should be twice as low, i.e., 50000 CFU/m3 for total mesophilic bacteria, 10000 CFU/m3 for both Gram- negative bacteria and thermophilic actinomycetes, and 25000 CFU/m3 for fungi
Polish proposals for OEL and PSLV/RLV for bioaerosols (volumetric methods)
Microbial agent
Limit value
Industrial settings polluted with organic dust
Public service and residential buildings
Mesophilic bacteria 100.000 CFU/m3 * 5.000 CFU/m3
Gram-negative bacteria 20.000 CFU/m3 * 200 CFU/m3
Thermophilic actinomycetes 20.000 CFU/m3 * 200 CFU/m3
Fungi 50.000 CFU/m3 * 5.000 CFU/m3
BA from the risk group 3 & 4 0 CFU/m3 0 CFU/m3
Bacterial endotoxin 200 ng/m3 (2.000 EU/m3) * 5 ng/m3 (50 EU/m3 )
Decision making when standards/limit Decision making when standards/limit values are not availablevalues are not available
Understanding of the nature of phenomenon and adequate measurement of biological agent (usually in the air)
Understanding and defining of health effects as a result of such exposure
Elaboration of the real hypothesis, which should be tested