The same is true of the concern about increased miscarriage rates. Chernoff
et al (Toxicology. 1992. 74:91-126) reviewed animal studies and came to no
conclusion. Shaw and Croen (Environ Health Perspectives. 1993. 101(suppl
4): 107-119) reviewed the human studies and also came to no conclusion.
What I found interesting were the few studies on depression and suicide.
The earliest report was by Reichmanis et al (Physiol Chem Physics. 1979.
11:395-403) in which suicide deaths in England were plotted along with the
location of electric transmission lines, and there was a positive
association with this measure of EMF exposure. In a series of studies,
Perry et al (Public Health. 1989. 103:177-180; Public Health. 1988.
102:11-18; Health Physics. 1981. 41:267-277) found that people living closer
to power cables had higher rates of depressive illness or suicide; Dowson et
al (The Practioner. 1988. 232:435-436) did a similar study with similar results.
The most recent studies give conflicting results. Poole et al (Am J
Epidemiol. 1993. 137:318-330) conducted a telephone survey of residents and
divided them into "near" and "far" groups based on proximity to power lines.
A significant positive association was found between depressive symptoms
and being near a power line. In contrast, McMahan et al (Am J Epidemiol.
1994. 139:58-63) made measurements of magnetic fields in study participants'
homes, and found no significant association between depressive symptomology
and proximity to power lines.
The proposed biological mechanism is based on the neuro-endocrine function
of the pineal gland. Wilson (Bioelectromagnetics. 1988. 9:195-205) provides
the best summary. In the wee hours of the morning the pineal gland kicks in
on melatonin production, and animal studies have found that EMF exposure can
reduce melatonin production, as has an interesting study of humans using
electric blankets. It is believed that a low-melatonin syndrome may disrupt
not only circadium rhythms, but may interfere with the serotonin and
catecholamine balance that is believed to be important in causing clinical
depression.
I found this interesting, but I must note that the big problem with all of
these studies is measuring exposure to EMF. Proximity to power lines is a
very crude measure, and doesn't take into account length of residence,
workplace exposures, or differences in home wiring. It would be expensive
to design a more accurate study, and time-consuming, too.