1. Accident Prevention Manual for Business & Industry:
Engineering & Technology
13th edition
National Safety Council
Compiled by
Dr. S.D. Allen Iske, Associate Professor
University of Central Missouri

2. OCCUPATIONAL MEDICAL SURVEILLANCE
CHAPTER 9
OCCUPATIONAL MEDICAL SURVEILLANCE

3. What is Occupational Surveillance?
Epidemiological surveillance is the systematic collection and analysis of health data for planning, implementing, and evaluating public health programs
The ultimate goal of surveillance is prevention of illness or injury.
Focus is on monitoring the health of working populations and the exposure to hazards in the workplace.

4. The Four Components of an Occupational Surveillance System
Gathering information on adverse health events and exposure circumstances
Distill and analyze the data
Disseminating data to interested parties
Intervening on the basis of the evidence provided by the data to alter the factors that produced the hazards and adverse health outcomes

5. Occupational Surveillance
How can occupational surveillance be applied?
Working populations as well as individuals workers
Federal, state, and local officials may use the results to monitor and set policy to mitigate workplace risk.
In individual workplaces, employers may use surveillance to establish and monitor prevention programs specific to processes and conditions.

6. Combined Effects of Exposure
OSHA has medical screening requirements for certain chemical exposures and working populations.
Hazardous waste workers, noise-exposed workers, those who wear respiratory protection
Healthcare professionals generally consider the effects of a chemical independently, but exposure to a single chemical rarely occurs.
Many chemical exposures occur as part of a hazardous mixture.
As chemicals or substances combine in the body the potential for injury or disease increases significantly.

7. Combined Effects of Exposure (Cont.)
OSHA permissible exposure levels (PELs) and ACGIH threshold limit values (TLVs) were developed under the assumption that workers are exposed to one chemical at a time.
To determine overexposure for a mixture:
Add concentrations of substances as a fraction of their respective TLV
If the total exceeds one, an overexposure has been detected
This is known as the mixture rule published by ACGIH.
The underlying assumption is that “combined” chemicals act on the same end-organ.

8. Combined Effects of Exposure (Cont.)
Example:
If an employee is exposed to air that contains 400 ppm of acetone (TLV, 750 ppm), 150 ppm of sec-butyl acetate (TLV 200 ppm) and 100 ppm of methyl ethyl ketone (TLV 200 ppm) during an 8-hour workday, has the exposure exceeded the threshold limit?   
The formula for additive effects is:
C1 + C2 + C3 + … = 1
T1 + T2 + T3 +…
Where C = the observed atmospheric concentration, and T = the corresponding TLV. If the sum of the fractions is greater than 1, then the TLV has been exceeded.
= = 1.78

9. Surveillance of Working Populations
Data collection systems for occupational surveillance:
What illness and injuries are occurring (occupational sentinels)
Why they are occurring (workplace conditions)
How they are occurring (mechanism of injury)
Where they are occurring (industry type, economic sector, establishment size)
When they are occurring (day of the week, time of day, seasonal variations, changes over time)

10. Occupational Surveillance Data Sources

11. What: Occupational Sentinel Health Events
An occupational sentinel health event is a disease, disability, or untimely death which is occupationally related and whose occurrence may:
provide the impetus for epidemiologic or industrial hygiene studies
serve as a warning signal that materials substitution, engineering control, personal protection, or medical care may be required
It is useful for managers, healthcare workers, and public health personnel to review health data for individuals or populations to look for patterns that may be related to occupational exposure.

12. Why/How: Occupational Sentinel Exposures
Hazard surveillance and remediation is a more effective approach to prevention of illness and injury.
Characterization of chemical, physical, biological, biomechanical, and psychosocial hazards associated with work is essential to protect workers from harm.
Hazards may be evaluated on an industry-wide scale or in an individual company.
In addition to exposure hazards that lead to illness, injury mechanisms may be coded in certain health surveillance systems to that mechanisms and circumstances of injury may be determined.

13. Where: Economic Sector, Industry Type, Job Titles
The Standard Industrial Classification (SIC) codes are used in most workers’ compensation reporting systems.
The North American Industrial Classification System is being used more frequently today.
It breaks down industry and job tasks more finely.
Gives a clearer picture of the work tasks leading to injury.

14. When: Day, Date, Time of Injury
Systems that record information on when an injury occurred may give clues to reasons for certain types of injuries and provide a focus for preventive activities.
Example: Outdoor construction and agricultural work take place during warmer seasons, and injuries in those sectors are more likely to occur in the summer.
The time of day that injuries occur can give clues about the impact of shiftwork on workplace health and safety.

15. Types of Surveillance Systems
Active—An agency selects a sample of workplaces, surveys the workplaces, analyzes the data, and extrapolates the results to the U.S. industry as a whole.
OSHA 300 logs and National Health Interview Survey
Passive—Data that are collected for purposes other than occupational surveillance may be used to inform understanding of occupational illness and injury.
Clinics and hospital records, emergency room visits, and workers’ compensation reports

16. Occupational Medical Screening
Screening—performance of medical testing for the purpose of detecting organ dysfunction or disease before an employee would seek medical care
The main goal of screening is to benefit the individual worker.
May provide surveillance information on populations and identify sentinel cases
OSHA has screening requirements for employees exposed to specific hazards.
Medical screening programs require a systematic approach to data collection and require an understanding of many disciplines in order to be accurate informative and preventive.

17. Occupational Medical Screening OSHA Requirements

18. Occupational Medical Screening OSHA Requirements (Cont.)

19. Occupational Medical Screening
Prevention
Optimally, the workplace should be monitored for hazardous conditions on an ongoing basis.
Industrial hygiene hierarchy of controls
It is most effective to implement engineering controls or substitute hazardous agents with less hazardous agents.
Removing hazards before exposure occurs is an example of primary prevention.
Medical surveillance can be used for primary prevention if it entails detecting hazardous agents in the tissues of workers before irreversible clinical effects occur.
Example: An employee exposed to lead has elevated blood levels, but he is removed from work before he becomes ill.

20. Occupational Medical Screening (Cont.)
Prevention (cont.)
Clinical testing may be done for secondary prevention as well:
Example: Workers exposed to solvents, detection of abnormal elevations in liver enzymes in the blood stream, signaling adverse effect of solvents on the liver
Tertiary prevention is undertaken when an irreversible injury or illness has occurred
Goal is to limit damage
Example: An individual who developed asthma as a result of an occupational exposure can be removed from the exposure and treated to prevent exacerbations and limit disease progression.

21. Model for Prevention of Occupational Diseases

22. Occupational Medical Screening (Cont.)
Biomarkers
Biological markers are substances, structures, or processes than can be measured in human tissues that may predict disease.
Biomarkers of exposure measure internal dose.
Blood lead level is one of more than 100 such laboratory tests.
Biomarkers may also be used to determine susceptibility to disease.
DNA tests, immunological response, or specific gene sequences associated with certain diseases

23. Occupational Medical Screening (Cont.)
Biological monitoring limitations
difficulty correlating a health risk with exposure once the exposure information is known
short biological half-lives of some substances
ineffective monitoring for surface active agents
interference of tobacco, alcohol, and other agents with some test results
measurement that may reflect multiple exposure sources (air, food, water, soil, and skin contact), preventing accurate determination of occupational exposure

24. Occupational Medical Screening (Cont.)
Ethical and legal issues
Markers of susceptibility involving genetic screening in the worksite provoked serious debate over who has a right to the information and for what purpose.
Concerns: potential for discrimination against workers on the basis of racial or cultural characteristics and acquired or inherited genetic susceptibility
Central legal issues address the rights of those monitored and the use of monitoring as a primary control strategy.
Before companies approve the use of biomarkers in health surveillance, they must carefully consider how they will handle and communicate personal health data beyond the physician-patient relationship.
Occupational medical surveillance raises difficult issues related to labor-management relations, labor law, and discrimination.

25. Medical Screening Programs
13 steps to design and conduct a screening program
Assess the hazards: evaluate routes of absorption and exposure levels, quantitatively or qualitatively
Identify target organ toxicity: review toxicology literature
Select tests: those which detect disease at an early stage to limit or prevent disease/injury
Develop action criteria: plan for how to interpret data and act on results
Standardize the testing process: a quality-control protocol and standardization of testing to ensure reliability and comparability
Perform the test: informed consent should be obtained from workers and results kept confidential
Interpret the results: utilize predetermined action criteria

26. Medical Screening Programs (Cont.)
Confirm results: abnormal tests should be confirmed by performing a second test before rendering a decision about removal from work.
Determine work fitness: appropriate tests should be used before recommending removal from the job; retention of salary and benefits may be of concern
Notify workers: notification of results of screening tests should be delivered to the worker promptly and in strict confidence, with an interpretation by a health professional
Diagnostic evaluation: abnormal results should result in a sound, medical evaluation
Evaluate and control exposure: if an occupational health sentinel is detected, the work environment should be evaluated and hazardous exposures controlled
Record keeping: medical records should contain all testing results, interpretation, and copies of employee/employer notification