No abstract

Epidemiological data indicate that increased small positive air ionization due to changing weather conditions is associated with increases in industrial and automobile accidents, suicide, and crime as well as depression, irritability, and interference with central nervous system (CNS) function. Laboratory research is less consistent, with several studies reporting no effects on mood or performance indicative of CNS disturbance. We have designed an experiment that begins to resolve these contradictory data by examining individual differences in response to small positive air ions. Analysis of these data indicates that whereas mood changes were present for most subjects when exposed to positive ions, assessment of individual differences in susceptibility was essential for detecting effects on performance and physiological activation. For most subjects, mood changes induced by ion exposure were characterized by increased tension and irritability. For susceptible (ion-sensitive) subjects, skin conductance measures showed depressed activation and reaction time increased during exposure to ions. For non-sensitive subjects, skin conductance measures revealed increased activation, with no effects of ions on reaction time.

Electric power transmission lines have become objects of public controversy. Hypotheses have linked neurobehavioral effects to the electric and magnetic fields that these lines produce. The authors conducted a telephone interview survey in November 1987 to assess the prevalence of depressive symptoms and headache in relation to proximity of residence to an alternating-current transmission line in the United States. Proximity to the line, defined as residing on a property abutting the right-of-way or being able to see the towers from one's house or yard, was positively associated with a measure of depressive symptoms. The association was not explained by demographic variables associated with depression or by attitudes about power lines or other environmental issues. The estimated prevalence odds ratio was 2.8 (95% confidence interval (CI) 1.6-5.1). The estimate did not change appreciably when the definitions of depressive symptoms or of proximity to the line were altered. Nonmigraine headaches had a weaker association with proximity to the line (odds ratio = 1.5, 95% CI 0.76-2.8), and self-reported migraine headaches exhibited no association (odds ratio = 0.99, 95% CI 0.29-3.4). Additional studies of psychological and behavioral measures should be conducted in relation to electric and magnetic fields, with a strong emphasis on improved exposure assessment.

Exposure to electrically charged gas molecules (air ions) has been reported to influence physiological and behavioral functions in animals and humans although there is controversy as to whether these findings are valid. A popular hypothesis concerning the reported effects of air ions is that alterations in serotonin (5HT) metabolism, particularly in the brain, are involved. We measured the concentration and turnover of 5HT in rats exposed to 5.0 X 10(5) ions/cm3 for up to 66 hours. Contrary to previous reports of other investigators, we were unable to demonstrate any effect of exposure to air ions or associated DC electric fields on the concentration or turnover of 5HT in rats under carefully controlled and characterized exposure conditions.

Exposure to air ions has been reported to influence serotonin (5HT), although critical reviews of these studies and previous measurements in our laboratory of the concentration, release, and utilization of brain 5HT indicate that neither the data nor the interpretations of the data are particularly convincing. Measurements of other possibly relevant neurotransmitter systems--norepinephrine (NE) and dopamine (DA)--were made in brain regions selected because of their importance in the modulation of brain functions relating to motivation, arousal, endocrine function, and motor activity, all responses that have been reported to be influenced by air ion exposure. Results indicate that exposure of male Holtzman rats to high concentrations (5.0 X 10(5)/cm3) of positive or negative air ions or to DC electric fields (3.0 kV/m) for periods up to 66 h failed to affect the concentration of NE or DA significantly in any of the brain regions.