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