Semen Quality and Hormone Levels Among Radiofrequency Heater Operators Barbara Grajewski, PhD Clinton Cox, PhD Steven M. Schrader, PhD William E. Murray, MS Richard M. Edwards, BS Terry W. Turner, BS James M. Smith, PhD Sam S. Shekar, MD Donald P. Evenson, PhD Stephen D. Simon, PhD David L. Conover, PhD Approximately 9,000,000 US workers are occupationally exposed to radiofrequency (RF) radiation; over 250,000 operate RF dielectric heaters. Our purpose was to determine whether male RF heater operators experience increased adverse reproductive effects reflected in reduced semen quality or altered hormone levels. We measured incident RF heater radiation exposures and RF-induced foot currents at four companies. For 12 male heater operators and a comparison group of 34 RF-unexposed men, we measured 33 parameters of semen quality and four serum hormones. Despite wide variation in individual exposure levels, near field strengths and induced foot currents did not exceed current standard levels and guidelines. We observed minor semen quality and hormonal differences between the groups, including a slightly higher mean follicle-stimulating hormone level for exposed operators (7.6 vs 5.8 mIU/mL). Further occupational studies of RF-exposed men may be warranted. (J Occup Environ Med. 2000; 42:993–1005) R adiofrequency (RF) radiation refers to nonionizing electromagnetic en- ergy in the frequency range 30 kilo- hertz to 300 gigahertz. Sources in- clude radar, radio, television, satellite communications, microwave ovens, medical diathermy devices, and industrial heaters and welders. Approximately 9,000,000 US work- ers may be occupationally exposed to RF radiation. 1 RF sealers and dielectric heaters are used to heat, dry, emboss, melt, seal, or cure materials that are poor electrical conductors (dielectric). Applications include the manufac- ture of plastic and wood products and the embossing and drying of textile, paper, plastic, and leather products. These products are usually processed by placing the dielectric material between two parallel, metal- lic plates and applying high voltage between the plates. The applied volt- age oscillates at a high frequency (3 to 100 megahertz [mHz]) and pro- duces RF electromagnetic energy be- tween the plates. As hydraulic or pneumatic pressure is applied to the dielectric material between the me- tallic plates, RF energy is used to process the material. Although most of the RF energy generated is ab- sorbed by the material being pro- cessed, some energy is radiated into the environment, where it can be absorbed by the operator and nearby workers. Electromagnetic energy has both an electric (E) and a magnetic (H) component. Because worker expo- sures from industrial dielectric heat- ers usually occur in the near-field (within one wavelength of the From the National Institute for Occupational Safety and Health, Centers for Disease Control and Prevention (Dr Grajewski, Dr Cox, Dr Schrader, Mr Murray, Mr Edwards, Mr Turner, Dr Smith, Dr Simon, Dr Conover); Environmental Health and Safety, Stanford University (Dr Cox); National Center for Environmental Health, Centers for Disease Control (Dr Smith); Health Resources Services Administration, Department of Field Operations, Rockville, Md. (Dr Shekar); Olson Biochemistry Laboratories, South Dakota State University (Dr Evenson); and Children’s Mercy Hospital, Kansas City, Mo. (Dr Simon). The use of company or trade names in this article is for identification only and does not imply endorsement by the National Institute for Occupational Safety and Health. Address correspondence to: Barbara Grajewski, PhD, National Institute for Occupational Safety and Health, Centers for Disease Control and Prevention, Mail Stop R-44, 4676 Columbia Parkway, Cincinnati, OH 45226. JOEM • Volume 42, Number 10, October 2000 993