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U.S. Department of Health and Human Services

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FY 2000 Radiation Safety


Radiation safety continues to be a significant concern for the Center. To help CDRH address this topic in FY 2000, OST maintained its calibration facilities for both laser and microwave measurements. In addition, OST continued to investigate the deleterious effects of UV radiation on the skin and retinal hazards from ophthalmic instruments. This program provided laboratory data and consultation aimed at the revision of the CDRH Sunlamp Performance Standard, the CDRH Laser Performance Standard, the CDER Sunscreen Monograph, and the development of ISO standards on Ophthalmic Instruments and various aspects of laser safety. In addition, the program provided laboratory measurements and calibrations of light meters and laser measurement instrumentation for field enforcement of FDA performance standards. It also provided product evaluations on laser pointers, laser range finders, and night vision instruments, and contributed to center-wide working groups on radiological health reengineering.

Ophthalmic Instruments – Fundus Cameras 
Key words: fundus cameras, ophthalmic standards

OST initiated work to study the potential optical radiation hazards associated with the use of fundus cameras to obtain photographs of the retina. OST instrumentation was assembled to measure the integrated spectral radiance of the light emitted from the pulsed Xenon sources used in these devices. Preliminary data showed relatively little ultraviolet and infrared radiation emissions from the device tested. More testing is planned for FY 2001. These independent data will be used to develop major amendments to the ISO 15004 Ophthalmic Instruments Standard.

Ultrasonic Characterization of Skin Following Ultraviolet Light Exposures
Key words: photodamage, dermis, Minimal Erythema Dose (MED), high-frequency ultrasound imaging

The incidence of skin cancer is increasing in the U.S. and is attributed to the cumulative damage from repeated sunburns induced by the ultraviolet (UV) component of sunlight. While the link between cancer and sunlight is strong, the ability to predict any given individual’s susceptibility to UV-induced skin damage is very limited. This study is a component of on-going work involving OST researchers to try to reduce that predictive uncertainty. CDRH laboratories have used high-frequency (20MHz) ultrasound imaging to measure changes in skin structure after exposure to UV radiation. Scientists took M measurements from exposed and non-exposed areas of skin following a graduated series of known UV exposures. Ultrasound images were obtained immediately after exposure and at several time points during the healing interval. Initial data analysis found changes in both the dermal thickness and ultrasound attenuation properties of the skin. These results are promising but warrant further study.

This work is part of a CDRH effort to find new approaches for evaluating the safety and efficacy of UV-emitting products regulated by FDA.

Laser Field Compliance Program 
Key words: lasers, calibrations, product testing, technical support

OST continues to participate in the Center's laser field compliance program. The OST Laser Calibration Laboratory maintains equipment for conducting high precision optical measurements that provide validity to measurements taken in compliance testing programs nationwide. Periodic inter-comparisons are conducted with the National Institute of Standards and Technology (NIST), and in-house quality assurance procedures are followed. During CY 2000, inter-comparisons were conducted with NIST at several laser wavelengths: 632.8 nm, 488 nm, 514 nm, and 1,064 nm. OST also planned and hosted laboratory instruction sessions for FDA field inspectors and personnel from the Office of Compliance. Several pulsed laser pointers and range finders were evaluated in FY 2000 to confirm the manufacturer's classification of the products.

Microwave Oven Leakage Instrument Calibration
Key words: microwave ovens, instrument calibrations, precision, leakage, radiation

More then 30 microwave leakage survey instruments were calibrated in OST’s Electrophysics Branch Precision Anechoic Chamber prior to moving the calibration facility and instrumentation to a new OST laboratory building. This work is done in support of the microwave oven performance standard that limits leakage from these consumer and industrial radiation-emitting products. OST began converting an existing shielded room in the new OST building into an anechoic calibration chamber for precision microwave instrument calibration. The chamber design and instrument positioning equipment were designed and specified in a contract that was awarded to construct the anechoic chamber.

Laser Performance Standard 
Key words: lasers, standards, harmonization

OST participated in the Center's effort to amend the FDA performance standard for laser products to bring it into closer harmonization with the international standard issued by the International Electrotechnical Commission (IEC) [IEC 60825-1]. OST also participates in voluntary standards activities by serving on the ANSI Z136.4 (laser measurements) committee. In the international arena, OST is participating on the ISO TC172/SC9 subcommittee, where work continues on modifying the ISO standards for determining the laser resistance of the shafts of tracheal tubes, laser resistance of surgical drapes, and patient protective covers. OST also hosted a meeting of the U.S. members of the project group.

Sunlamp Performance Standard
Key words: sunlamps, standards, harmonization

OST is participating in an effort to revise the FDA Performance Standard for Sunlamp Products to harmonize with the International Electrotechnical Commission (IEC) 335-2-27 Standard, which includes criteria for skin exposure to ultraviolet radiation. The IEC intends to incorporate a maximum timer limit for sunlamp products, similar to the current FDA requirement. The current FDA requirement is being modified so that the value of MED, which the timer limit is based on, is increased to a value more consistent with recent scientific data. OST performed laboratory measurements to provide independent data to justify changing the MED value. In addition, OST worked with the Winchester Engineering and Analytical Center (WEAC) to analyze spectral transmittance data of protective eyewear for ocular hazards in order to develop new transmittance limits that protect the eye while undergoing sunlamp exposures.

CDER Sunscreen Monograph
Key words: sunscreens, standards, ultraviolet radiation

FDA/CDER is preparing to modify the current Sunscreen Testing Monograph to include provisions for UVA protection. OST performed in vitro testing of the UVA absorbance of several types of commercially available sunscreen products. The results of this testing provided independent data to demonstrate that currently used in vitro test methods lead to large variability in predicted product performance, mostly due to the fact that the substrate used in the testing does not mimic human skin. As a result of these findings, FDA is reconsidering requirements for in vivo testing of UVA transmission of sunscreen products.