ACGIH ® TLVs ® for Physical Agents Committee Update Vice-Chair: Thomas Bernard University of South Florida College of Public Health

TLV ® Physical Agents Committee Process for Hazardous Agent Selection and Decision Making

Mission To foster, solicit, collect and evaluate data on potential health hazards of exposures to physical agents. When appropriate, recommend ACGIH ® Threshold Limit Values ® for physical agents.

2002 PAC Harry Mahar Maurice Bitran Thomas Bernard Gerald Coles Anthony Cullen Daniel Johnson John Leonowich William Murray Bhawani Pathak Robert Patterson Thomas Tenforde Carla Treadwell Consultants: Thomas Adams Thomas Armstrong Gregory Lotz Martin Mainster Gary Myers

Overview Physical Agents Process –Committee Activities –TLV ® Development Future –Format –Agents

Disclaimer The opinions expressed here are those of the author and not of his employer, the Physical Agents Committee or the ACGIH ® Worldwide.

Physical Agents It’s the Movement of Energy

Risk of Health Effects What is the nature of the energy? How much energy? What is the interaction with tissue?

Nature of Energy Electric and Magnetic Fields Photons Kinetic Energy –Pressure –Vibration –Mechanical Heat

Amount of Energy Total Amount of Energy Absorbed –What does it take to raise water temperature? Rate of Absorption (Power or Intensity) –How fast does the temperature rise? Normalized to Surface Area (e.g., mJ/cm 2, mW/cm 2 )

Interactions Electric and Magnetic Fields –Induce Currents –Align Molecules –Vibrate Molecular Bonds Photons –Vibrate Molecular Bonds –Disrupt Molecular Bonds

More Interactions Mechanical Disruption of Tissue –Pressure –Vibration –Force Applications Loss of Tissue Function –Thermal: Gain or Loss of Heat

Bernard Watt-O-Meter Power Limits for Various Exposures [mW/cm 2 ] Electric and Magnetic Fields170,000 Radiofrequency/Microwave1.0 Infrared Light10 Blue Light Ultraviolet Light Ionizing Radiation Noise Heat Stress30 {Not Accepted, or Considered Acceptable, by Any Authority}

Exposure Energy Distribution in the Immediate Environment The distribution is usually described as Power or Intensity (directly or through a surrogate) versus Frequency or Wavelength in Bands

Exposure Threshold Total Energy –Ability to Absorb Energy Rate of Energy (Power or Intensity) –Ability to Dissipate Absorbed Energy In a Band Integrated Over All Bands

Process Committee Activities Development of TLVs ®

Representation Usually one or two members with an expertise for a particular agent (e.g., a small portion of the electromagnetic spectrum) Small committee to maintain a working and collegial group. We meet as a whole. Leverage with outside experts

Updating TLVs ® PAC meets with outside experts Members bring recommendations to the PAC for discussion Consideration of actions taken by national and international committees or agencies

New TLVs ® Quintessential Example: Hand Activity Formed a cadre of consultants Convened a conference Developed recommendation and Documentation Presented to PAC and discussed PAC voted after internal deliberations

Future Format Agents

Format TLV ® Book –Use of Flow Charts –Evolving (see Heat Stress and RF/MW) Training Documentation –Expanded and Focused (see HAL and Lifting) –Health Effects and Exposure Indices –Guidance (see Heat Stress)

Form Physical agents have their own history and character with respect to measurement and exposure assessment There is an underlying similarity among the physical agents that may be introduced

Example Set Radiofrequency / Microwave Radiation Optical Radiation (IR, Visible and UV) Vibration (Hand-Arm and Whole Body) Noise

Energy Distribution Energy Bands

Energy Limits Within Bands Energy Limit Bands E min

Limits by Band Is the limit exceeded within one or more bands? Energy Bands PDExp Lmt

Sensitivity Curve Sensitivity = Energy Limit / E min Sensitivity Bands

Hazard Function Filter Multiplier Bands Hazard Function = 1.0 / Sensitivity

Effective Exposure Energy Bands EDE-eff Effective Exposure = Energy Distribution x Hazard Function

Total Energy Multiplying –Energy Limits by Band –Hazard Function by Band and Integrating (Summing) Yields a Constant Value: A Total Energy Limit

Limit by Total Energy Total Energy –In One Band –Under the Effective Energy Curve Compared to Total Energy Limit

In Summary TLVs ® –Limit Power (Ability to Dissipate) –Limit Total Energy (Ability to Absorb) Limit by –Band –Total

Agents Under Review Lasers Vibration Cold Stress HAL Lifting WMSDs Wide-Band RF Altitude Impulse Noise ELF H-Fields

Scheduled Break Take a minute to stretch!