Understand and differentiate between terminologies related to health surveillance (HS), medical surveillance (MS), biological monitoring (BM) and biological effect monitoring (BEM).
Determine the legislative requirement for HS, MS, BM and BEM.
Identify the OSH professional involved in the work and source of references for HS, MS, BM and BEM
Effects on Health
Hazard intensity and exposure rate affects health.
Amount absorbed is influenced by hazard intensity and exposure time.
Exposure concentration also play a part to have effects on health.
What is Biological Monitoring?
Measurement of a substance or its metabolite in biological material.
Provides a quantitative estimate of uptake into the body by all routes of exposures.
Why Conduct Biological Monitoring?
To ensure that current or past exposure of worker is not harmful to his/her health.
Detecting potential excessive exposure before overt adverse health effects occur.
Types of Biological Monitoring
Biological Monitoring of Exposure
Biological Monitoring of Effective Dose
Biological Effects Monitoring
Biological Monitoring of Susceptibility
Biological Monitoring of Exposures
Estimate internal dose of a chemical exposure.
Internal dose = Amount recently absorbed + Amount stored in the whole body + Amount bound to critical sites of action.
Advantage: Assessment of all routes hence provides more accurate assessment of health risk than atmospheric monitoring.
Knowledge Required for Biological Monitoring of Exposures
Toxicokinetics of the chemical:
Understanding of absorption, distribution and elimination of chemical
Toxicodynamics of the chemical:
Understand early adverse effects and pathogenic mechanism
Relationship between external exposure, internal dose and adverse health effects
Biological Monitoring of Effective Dose
Carboxyhemoglobin (exposure to carbon monoxide)
Protein and DNA addicts (exposure to reactive substances in DNA or target tissues)
Biological Effects Monitoring
Biological monitoring of non-adverse reversible effects - early biochemical changes which are reversible and non-adverse biomarkers of exposure:
Inhibition of delta-amino laevulinic acid dehydratase by lead
Inhibition of pseudocholinesterase by organophosphates
Reversible non adverse effects or early detection of health impairment:
Urinary excretion of α1 and β2 microglobulins due to lead, cadmium, mercury
Indicate pathological damage:
Liver dysfunction (transaminases), kidney dysfunction (albumin in urine)
Biological Monitoring of Susceptibility
Biomarker of susceptibility – indicator of inherent or acquired ability of organism to respond to challenge of exposure to specific substance
e.g. ability to acetylate amines – genetically determined and varies with ethnic origin – slow/rapid acetylators
genetically based low level of anti-trypsin – increased risk of emphysema
Approaches in Biomonitoring
Specific methods:
Direct measurement - unchanged chemicals or metabolites
e.g. urinary measurement of mercury, mandelic acid (styrene), muconic acid (benzene)
Non-specific methods:
Non-specific indicators of exposure
e.g. diazopositive metabolites in urine (aromatic amines), thioethers in urine (mutagens and carcinogens)
How Test is Being Developed?
Fate of pollutant and compound to be determined
Biological material to be analyzed
Time of sampling and duration urine sample to be collected
Storage and preservation of specimens
Methods of analysis and units of measurement
Frequency of testing
Use in establishing biological limits
Criteria for Selecting Tests for Biological Monitoring
Parameter must be sufficiently specific
Parameter must have adequate sensitivity
Analytical and biological variability of test must be acceptable
Test should provide little to no discomfort to subject
Selection must take into account ability of tests to evaluate health risks
When to Collect Biological Sample?
< work shift
work shift
> work shift
Beginning of workweek
End of workweek
Depends on half life of chemical
< 2 hours Not appropriate
2-10 hours End of work shift or Next morning
10-100 hours End of shift at end of week
>100 hours Any time
Biomonitoring Action Levels
The reference values at or below which the adverse health effects do not appear in most workers who are exposed to the chemicals.
Biological Exposure Indices (BEIs) - ACGIH
Occupational Exposure Limit Based on Biological Monitoring (OEL-B) – Japan
Roadblocks for Application/Commercialization of Biomarkers (Steven Rosen)
Analytical, diagnostic and etiological validity of new markers need to be established.
Recognized disease end points need to be more clearly associated with the biomarkers.
Standardized criteria for quantitative measurement of markers must be established.
Predictive values of biomarkers must be determined by population studies.
Health Effects Monitoring
Asbestos, Silica
Medical, occupational and smoking history
Physical examination
Chest X-Ray (PA view)
Pulmonary Function Testing
OSH (Noise Exposure) Regulations 2019
Audiometric testing: 0.5, 1, 2, 3, 4, 6 and 8 kHz
Current Issues - Challenges
Carcinogens – safe level?
Mixtures and interactions
Biomarkers of effect – irreversibility
Data gaps – human + ethical issues – Animal?
Conclusion
Biological, biological effects and health effects monitoring are the various components of a good medical surveillance program.
How effects of exposures to hazards are assessed and monitored depends on the type of the hazard and its effects.