Health hazard evaluation report: HETA-2002-0347-2910, Ocean Bank, Miami, Florida.
On July 7,2002, the National Institute for Occupational Safety and Health (NIOSH) received a request for a health hazard evaluation (HHE) at the Ocean Bank in Miami, Florida. The requesters were a bank manager and an employee who requested an evaluation of magnetic field exposures in the office spaces throughout the bank. Health concerns included dizziness, foot swelling, and cancer. On August 15, 2Q02, a NIOSH investigator conducted a site visit at Ocean Bank and conducted a source characterization of the extremely low frequency (ELF) magnetic fields throughout the bank. Over 100 area measurements were collected with particular emphasis on the vacated Branch Management office because this area was identified as having elevated magnetic field levels from previous surveys. The area exposures measured outside the vacated office ranged between 0.4 and 125 milligauss (mG). The area exposures measured inside the vacated office ranged between 16 and 1,424 mG. Personal exposure meters were placed on five volunteer bank employees. Each employee wore these instruments for a period ranging between 2 hours, 15 minutes and 7 hours, 44 minutes; their average magnetic field exposures ranged from 2.3 to 15.8 mG. Neither the Occupational Safety and Health Administration (OSHA) nor NIOSH have exposure criteria in the ELF range (1 to 300 Hz). The American Conference of Governmental Industrial Hygienists (ACGIH) has published frequency-dependent Threshold Limit Values (TLV's); the TLV for the 60 Hz magnetic fields coming into the bank should not exceed 10,000 mG. The health and safety basis for this TLV@ addresses only acute high-level magnetic field exposures that induce magnetophophenes in the visual system and produce induced currents in the body. Research has been conducted over the past decade to determine if slightly elevated magnetic field exposures (greater than 2 mG) pose a health threat. The National Institute of Environmental Health Sciences (NIEHS) recently published a report that addressed this question. The NIEHS report concludes"... the probability that EMF exposure is truly a health hazard is currently small. The weak epidemiological associations and lack of any laboratory support for these associations provide only marginal scientific support that exposure to this agent is causing any degree of harm." However, the report also states that EMF exposures "cannot be recognized as entirely safe" and that efforts to encourage reductions in exposure should continue. Magnetic field exposures were above those typically encountered in an office environment, but were below the ACGIH TLV of 10,000 mG. The magnetic field exposure potential was directly related to the length of time spent near the vacated Branch Management office, which is situated above the electric vault. On the day of the evaluation, the area measurements were in general agreement with previous surveys conducted by Florida Power and Light (FP&L) and two independent engineers hired by the building owners. Recommendations were made to install magnetic shielding on the floor of the bank, increase the distance from the high magnetic field area by relocating employees, reduce the time workers spend in and near the high exposure areas, and request FP&L to rewire the vault to reduce magnetic field emissions.