Biologically Derived Airborne Biologically Derived Airborne Contaminants:Contaminants:

Bioaerosols and TLVs Bioaerosols and TLVs®®

Kenneth F. Martinez, MSEE, CIHChair, ACGIH® Bioaerosols Committee

NIOSH

AgricultureIndoor Environments

Biotechnology Health Care

Where ?Where ?

MicroorganismsMicroorganisms

• Obligate parasites (must have a living host)– viruses– bacteria– rickettsia

• Facultative saprophytes (will utilize dead organic material)– fungi– bacteria

Size Ranges of Size Ranges of MicroorganismsMicroorganisms

FungalSpore

Escherichia coli

PolioVirus

RabiesVirus

1 µm

Mechanisms for Mechanisms for Microbial DispersalMicrobial Dispersal

Linear DistancesLinear DistancesVery Short Medium Long

Motility Sewage Wind

Gliding Motion Ground Water Animal Vectors

Eroding Soil Water Currents

Inanimate Objects

Microbiological Microbiological ConcernsConcerns

• Infections

• Immunologic Reactions

• Toxic Effects

Infectious DiseaseInfectious Disease

• Pathogenicity• Virulence• Relationship between virulence (V), numbers

of pathogens or dosage (D), and resistant state of the host (RS)

• Colonization• Invasiveness

Infectious Disease =V * D

RS

Infectious DiseaseInfectious DiseaseTerminologyTerminology

• Portal of entry• Exposure vs. infection• Clinical vs. subclinical or asymptomatic

infection• Carrier state• Opportunistic infection• Human pathogen vs. virulence• Immunosuppression

Infectious DiseaseInfectious DiseasePathwaysPathways

• Respiratory

• Oral (via ingestion)

• Contact

• Penetration

• Vectors (via insect bite)

Allergic DiseaseAllergic Disease

• Allergic rhinitis

• Allergic asthma

• Allergic bronchopulmonary aspergillosis

• Extrinsic allergic alveolitis (hypersensitivity pneumonitis)

U.S. Disease U.S. Disease PrevalencePrevalence

• 1 of 5 Americans suffer from allergic disease

• Indoor allergens responsible for significant share

• Environmental control reduces disease severity0% 10% 20% 30%

HP

ABPA

AllergicDermititis

Asthma

Sinistitis

AllergicRhinitis

Prevalence

Source: NHLBI, 1991

Allergen Exposure

Dust MitesMolds

Animal DanderPollen

Allergenic Chemicals

Other Exposures

Viruses

Air Pollution

Tobacco Smoke

Genetic

Predisposition

or Susceptibility

Immunologic

Sensitization

Allergic Disease

Mild Moderate Severe

(Death)

Source: Pope AM, et al., eds., 1993

Important MycotoxinsImportant MycotoxinsFungal Species Toxin

Aspergillus

Aspergillus parasiticus Aflatoxin

Aspergillus flavus

Aspergillus versicolor Sterigmatocystin

Aspergillus terreus Patulin

Citrinin

Fusarium

Fusarium moniliforme Zearalenone

Fusarium spp. Tricothecenes

Penicillium

Penicillium viridicatum Ochratoxin

Penicillium spp. Citrinin

Patulin

Stachybotrys

Stachybotrys chartarum (atra) Tricothecenes

Where Are We?Where Are We?

Outdoors2%

In Transit5%

Indoors93%

Classification of Classification of Occupant ComplaintsOccupant Complaints

• Sick Building Syndrome

• Building-Related Disease

• Occupant Discomfort

Sick Building SyndromeSick Building SyndromeNon-specific SymptomsNon-specific Symptoms

• Headache• Eye, nose, throat irritation• Sneezing• Fatigue and lethargy• Skin irritation• Dizziness and nausea• Cough• Chest tightness

Building-Related Building-Related DiseaseDisease

• Known etiologies

• Related to identifiable exposure

Legionnaires DiseasePontiac FeverHumidifier Fever

Hypersensitivity PneumonitisAnthrax

Why Not Scientifically Why Not Scientifically Supportable?Supportable?

• Not a single entity

• Human responses cover wide range

• No single sampling method exists

• No exposure/response relationships exist

Total Culturable or Countable Bioaerosols

Why Not Scientifically Why Not Scientifically Supportable?Supportable?

• Data are derived from indicators rather than actual effector agents

• Concentrations vary widely

• Low statistical power in cause-effect relationship studies

Specific Culturable or Countable Bioaerosols- other than infectious

Why Not Scientifically Why Not Scientifically Supportable?Supportable?

• Dose-response data limited to a few agents• Air sampling limited to research• Administrative and engineering controls

remain the primary defenses

Infectious Culturable or Countable Bioaerosols

Why Not Scientifically Why Not Scientifically Supportable?Supportable?

• Some dose-response relationship data available– Experimental studies– Epidemiologic surveys

• Assay methods improving

• May be appropriate in the future

Assayable biological contaminants

Questions?Questions?

• Pat Breysse

• Lisa Brosseau

• Larry Lowry

• Tom Bernard

• Ken Martinez