1. IH Toxicology
Subpart Z
29 CFR 1910

2. Industrial Hygiene Anticipation Recognition Evaluation Control
of environmental factors that can cause sickness or disease

3. Hygienist Activities
On which function does an IH* spend the most time? *industrial hygienist
Evaluation
Which most Difficult?
Anticipation
Which should spend most time?
Control

4. Control Methods

5. Control at the Source Chemical substitution Redesign the process
Isolate the process
Enclose the process
Mechanize

6. Control of the Path Local exhaust ventilation General ventilation
Housekeeping
Work methods (wetting down, etc.)

7. Control at the Worker Respirators and other PPE
Administrative controls
Enclose the worker
Hygiene facilities and practices

8. Hierarchy of Control Control the source Control the path
Control the exposure at the worker

9. Hierarchy of Control Engineering Administration
Personal protective equipment (PPE)

10. Types of Illnesses - Time
Acute - a disease that develops quickly after exposure
Chronic - a disease that develops long after exposure
Latency Period - the time between the first exposure and the development of disease

11. Routes of Exposure Breathe the chemical – inhalation
Swallow the chemical – ingestion
Absorb through skin - skin absorption
In all cases, chemicals can travel
through the body.

12. Important Body Organs Lungs Kidney Blood Forming Reproductive
Nervous System Liver
brain
nerves

13. Forms of Chemicals Particles
Dust - formed by Grinding /breaking - large particles
Smoke - formed by burning - large particles
Fume - formed by heating - small particles

14. Forms of Chemicals Gasses Gas - at room temperature
Vapor - heat to turn to gas ---
Droplets - agitating a liquid

15. What is Dose?
Concentration & Time

16. Chemical Interaction Additive Effects 2 + 2 = 4
Synergistic Effects = 9
Potentiation Effects = 8
Antagonistic Effects = 5

17. Signs of Exposure Dust, Mist, Smoke in the air
Accumulation of dust or oils
Unusual Smells
Unusual Tastes
Burning in the eyes
Nose throat irritation
Feel better during vacation

18. Contributory Factors to Toxicity
Dose
Absorption
Rate of Transformation
Excretion Rate
Human Factors
Route of Entry

19. Measuring Particles Concentration Weight of substance in volume of air
Weight in milligrams - mg
Volume in cubic meters m3
mg/m3 = milligrams per cubic meter

20. Measuring Gasses or Vapors
Volume concentration of gas in air
Parts per million
Parts of gas in million parts of air
Cups in a million cups
Quarts in a million quarts
Similar to per cent, which is actually parts per hundred

21. OSHA PEL’s PEL = Permissible Exposure Limit
The concentration of a chemical a worker can be exposed to . . .
8 hours per day
working lifetime
without experiencing health problems

22. Kinds of PEL’s TWA = Time Weighted Average Levels vary over a day
OK for chemicals causing chronic disease

23. TWA Example #1

24. TWA Example #2

25. Ceiling

26. Ceiling PEL Concentrations can never exceed Indicated by OSHA as “C”
Appropriate for chemicals causing acute disease
If can’t measure instantaneously, take 15 minute (worst case) sample

27. STEL

28. STEL STEL = Short term exposure limit
Period of time shown in standard where PEL can be exceeded
Still an absolute maximum that can not be exceeded (a ceiling)
Must still meet the TWA

29. Skin Notation If OSHA says “skin,” then can’t have any skin contact
Appropriate where there is [a possibility of] skin absorption

30. How Do We Get These PEL’s?
Concensus standards ACGIH, 1968
ANSI
New standards attempted to upgrade not successful

31. Other Sources of Standards
ACGIH - TLV’s
NIOSH - REL’s
Company standards

32. Table Z-1 Based on 1968 ACGIH Lists chemical name
CAS (identifying) number
PEL (Time Weighted Average)
Skin (if applies)
Ceiling (if applies)

33. 11/10/1999 - OSHA policy regarding PEL adjustments for extend work shifts
As stated in a previous memorandum dated November 8, 1996:
Compliance officers can choose one of two approaches for employees who work extended work shifts beyond 8-hours. The choice taken will depend on the nature of the hazardous chemical.

34. PEL Adjustments
The first approach is to sample what the compliance officer believes to be the worst continuous 8-hour work period of the entire extended work shift.

35. PEL Adjustments
The second approach is to collect multiple samples over the entire work shift. Sampling is done such that multiple personal samples are collected during the first 8-hour work period and additional samples are collected for the extended work shift. Unless a compliance officer is dealing with lead, the PEL in this approach is calculated based upon the worst 8-hours of exposure during the entire work shift.

36. Table Z-2 Based on ANSI standards Lists chemical name CAS number TWA
Acceptable ceiling
Peak
Duration

37. (b) - Table Z-2
"Acceptable ceiling concentrations." An employee's exposure to a substance listed in Table Z-2 shall not exceed at any time during an 8-hour shift the ceiling concentration limit given for the substance except for:
A time period, and up to a concentration not exceeding the maximum duration and concentration allowed in the column under "acceptable maximum peak above the acceptable ceiling concentration for an 8-hour shift"

38. (b) - Table Z-2
Peak
The substances listed can have limits expressed as:
8-hour TWAs
Ceilings
Peaks
If a substance has both ceiling and peak limits, the peak is the level never to be exceeded
Employee exposure level exceeding the ceiling but under the peak are required to comply with the margin notes provided in the table

39. (b) - Table Z-2
Example:
During 8-hour work shift, an employee may be exposed to Substance A (with a 10 ppm TWA, 25 ppm ceiling, and 50 ppm peak) above 25 ppm (but never above 50 ppm) only for a maximum period of 10 minutes.
Such exposure must be compensated by exposures to concentrations less than 10 ppm so that the cumulative exposure for the entire 8-hour work shift does not exceed a weighted average of 10 ppm.

40. Table Z-3 Mineral Dusts silica and silicates graphite coal dust
Inert or nuisance dusts
(particulates not otherwise classified)
Respirable: < 10 microns
separated with cyclone

41. Substance Specific Standards
31 specific chemicals
asbestos
benzene
coal tar pitch volatiles
lead
formaldehyde
arsenic

42. Substance Specific Requirements
Air monitoring
Control of exposure
Work practices
Respiratory protection
Medical surveillance
medical removal (lead)
Record keeping
Worker training

43. Air Monitoring: Who, What, Where?
Worst case sampling
Representative sampling
Personal vs. area sampling
What conditions can affect sampling results?

44. Chemical Properties Flashpoint Vapor Density Vapor Pressure
Specific Gravity
Evaporation Rate

45. Air Monitoring
Pump
Tube
Collection device
Direct reading

46. Air Monitoring
Calibrate pump with collection device before and after each sample
Sample minimum of one hour less than full shift (for OSHA compliance)

47. Napthalene Exposures
15 ppm for 6 hours
5 ppm for 2 hours

48. Compute TWA 15 ppm x 6 hours = 90 ppm hrs 5 ppm x 2 hour = 10 ppm hrs
____________________________
100 ppm hrs ÷ 8 hours = 13.8 ppm

49. Less Than Full Shift Sample?
15 ppm x 7 hours = 105 ppm hrs
? ppm x 1 hour = ??? ppm

50. Confidence Limits
C / PEL = Y
LCL = y - SAE
UCL = y + SAE

51. Confidence Limits LEAD 54 / 50 = 1.08 1.08 - .12 = .96
= 1.2

52. Beware the PEL If above the PEL are you definitely getting sick?
If you’re below the PEL are you definitely safe?
Why or why not?

53. Any Questions?
Thank You.