title: Background Noise Contributes to Organic Solvent Induced Brain Dysfunction.
abstract: Occupational exposure to complex blends of organic solvents is believed to alter brain functions among workers. However, work environments that contain organic solvents are also polluted with background noise which raises the issue of whether or not the noise contributed to brain alterations. The purpose of the current study was to determine whether or not repeated exposure to low intensity noise with and without exposure to a complex blend of organic solvents would alter brain activity. Female Fischer344 rats served as subjects in these experiments. Asynchronous volume conductance between the midbrain and cortex was evaluated with a slow vertex recording technique. Subtoxic solvent exposure, by itself, had no statistically significant effects. However, background noise significantly suppressed brain activity and this suppression was exacerbated with solvent exposure. Furthermore, combined exposure produced significantly slow neurotransmission. These abnormal neurophysiologic findings occurred in the absence of hearing loss and detectable damage to sensory cells. The observations from the current experiment raise concern for all occupations where workers are repeatedly exposed to background noise or noise combined with organic solvents. Noise levels and solvent concentrations that are currently considered safe may not actually be safe and existing safety regulations have failed to recognize the neurotoxic potential of combined exposures.
authors.affiliation: Cell & Molecular Pathology Laboratory, Communication Sciences and Disorders, Northern Arizona University, Flagstaff, AZ, USA; Loma Linda VA Medical Center, Loma Linda, CA, USA; Head & Neck Surgery, Loma Linda University Medical Center, Loma Linda, CA, USA.
authors.forename: O'neil W
authors.initials: OW
authors.lastname: Guthrie
authors.affiliation: Naval Medical Research Unit and Molecular Bioeffects, Wright-Patterson Air Force Base, Dayton, OH, USA.
authors.forename: Brian A
authors.initials: BA
authors.lastname: Wong
authors.affiliation: Naval Medical Research Unit and Molecular Bioeffects, Wright-Patterson Air Force Base, Dayton, OH, USA.
authors.forename: Shawn M
authors.initials: SM
authors.lastname: McInturf
authors.affiliation: Naval Medical Research Unit and Molecular Bioeffects, Wright-Patterson Air Force Base, Dayton, OH, USA.
authors.forename: James E
authors.initials: JE
authors.lastname: Reboulet
authors.affiliation: Naval Medical Research Unit and Molecular Bioeffects, Wright-Patterson Air Force Base, Dayton, OH, USA.
authors.forename: Pedro A
authors.initials: PA
authors.lastname: Ortiz
authors.affiliation: Naval Medical Research Unit and Molecular Bioeffects, Wright-Patterson Air Force Base, Dayton, OH, USA.
authors.forename: David R
authors.initials: DR
authors.lastname: Mattie
mesh_terms: D000818:Animals; D001921:Brain / Q000187:drug effects*; D016057:Evoked Potentials, Auditory, Brain Stem / Q000187:drug effects; D005260:Female; D006838:Hydrocarbons / Q000633:toxicity*; D009622:Noise; D016273:Occupational Exposure; D051381:Rats; D011916:Rats, Inbred F344; D012997:Solvents / Q000633:toxicity*; D009435:Synaptic Transmission / Q000187:drug effects
chemical_list: D006838:Hydrocarbons; C098607:JP8 aviation fuel; D012997:Solvents