IH Toxicology Subpart Z 29 CFR 1910
Industrial Hygiene • Anticipation • Recognition • Evaluation • Control • of environmental factors that can cause sickness or disease
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
Control at the Source • Chemical substitution • Redesign the process • Isolate the process • Enclose the process • Mechanize
Control of the Path • Local exhaust ventilation • General ventilation • Housekeeping • Work methods (wetting down, etc.)
Control at the Worker • Respirators and other PPE • Administrative controls • Enclose the worker • Hygiene facilities and practices
Hierarchy of Control • Control the source • Control the path • Control the exposure at the worker
Hierarchy of Control • Engineering • Administration • Personal protective equipment (PPE)
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
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.
Important Body Organs Lungs Kidney Blood Forming Reproductive Nervous System Liver • brain • nerves
Forms of Chemicals Particles • Dust - formed by Grinding /breaking - large particles • Smoke - formed by burning - large particles • Fume - formed by heating - small particles
Forms of Chemicals Gasses • Gas - at room temperature • Vapor - heat to turn to gas --- • Droplets - agitating a liquid
What is Dose? • Concentration & Time
Chemical Interaction • Additive Effects 2 + 2 = 4 • Synergistic Effects 2 + 3 = 9 • Potentiation Effects 2 + 0 = 8 • Antagonistic Effects 4 + 6 = 5
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
Contributory Factors to Toxicity • Dose • Absorption • Rate of Transformation • Excretion Rate • Human Factors • Route of Entry
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
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
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
Kinds of PEL’s • TWA = Time Weighted Average • Levels vary over a day • OK for chemicals causing chronic disease
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
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
Skin Notation • If OSHA says “skin,” then can’t have any skin contact • Appropriate where there is [a possibility of] skin absorption
How Do We Get These PEL’s? • Concensus standards ACGIH, 1968 • ANSI • New standards attempted to upgrade not successful
Other Sources of Standards • ACGIH - TLV’s • NIOSH - REL’s • Company standards
Table Z-1 • Based on 1968 ACGIH • Lists chemical name • CAS (identifying) number • PEL (Time Weighted Average) • Skin (if applies) • Ceiling (if applies)
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.
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.
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.
Table Z-2 • Based on ANSI standards • Lists chemical name • CAS number • TWA • Acceptable ceiling • Peak • Duration
1910.1000(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"
Peak 1910.1000(b) - Table Z-2 • 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
1910.1000(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.
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
Substance Specific Standards 31 specific chemicals • asbestos • benzene • coal tar pitch volatiles • lead • formaldehyde • arsenic
Substance Specific Requirements • Air monitoring • Control of exposure • Work practices • Respiratory protection • Medical surveillance • medical removal (lead) • Record keeping • Worker training
Air Monitoring: Who, What, Where? • Worst case sampling • Representative sampling • Personal vs. area sampling • What conditions can affect sampling results?
Chemical Properties • Flashpoint • Vapor Density • Vapor Pressure • Specific Gravity • Evaporation Rate
Air Monitoring • Pump • Tube • Collection device • Direct reading
Air Monitoring • Calibrate pump with collection device before and after each sample • Sample minimum of one hour less than full shift (for OSHA compliance)
Napthalene Exposures 15 ppm for 6 hours 5 ppm for 2 hours
Compute TWA 15 ppm x 6 hours = 90 ppm hrs 5 ppm x 2 hour = 10 ppm hrs 8 hours 100 ppm hrs ____________________________ 100 ppm hrs ÷ 8 hours = 13.8 ppm
Less Than Full Shift Sample? 15 ppm x 7 hours = 105 ppm hrs ? ppm x 1 hour = ??? ppm
Confidence Limits • C / PEL = Y • LCL = y - SAE • UCL = y + SAE