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 Methods

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

TWA Example #1

TWA Example #2

Ceiling

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 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"

1910.1000(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

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 ____________________________ 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

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

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?

Any Questions? Thank You.