"We live in a society exquisitely dependent on science and
technology, in which hardly anyone knows anything about science and
technology." The words of Carl Sagan, the American astronomer
famous for popularizing science, describe well the global situation
with regard to electromagnetic radiation. Daily we are immersed in
the electromagnetic fields (EMFs) that provide so many conveniences
in our lives: computer monitors, power lines, mobile phones. But
they may well also be providing us with serious, even lethal,
health problems.
During the past 30 years, about 25,000 essays on the biological
and medical effects of EMFs have been published. Although it is
widely felt that research in this area is far from sufficient, we
have in fact accumulated more data than in many other traditional
subjects, including some branches of chemistry.
In 1982, Samuel Milham conducted a study in the US state of
Washington on the effects of large electrical and magnetic fields
on workers. Milham, an occupational health physician, wrote in the
New England Journal of Medicine that he found more
leukemia-related deaths in men whose work brought them in contact
with electrical and magnetic fields, such as employees of utility
companies.
More recently, the Institute of Cure and Prevention of
Occupational Disease of Hunan Province completed a study on the
effects of radiation on technicians who have close contact with
large EMFs. The comparison group was office workers exposed only to
low-level EMFs in far smaller fields.
The results show that technicians suffered insomnia, heart
palpitations or hair loss at far higher rates than the other group.
Their cardiogram abnormity rate was 37.8 percent, compared with
16.1 percent in the comparison group.
The technicians also suffered poorer eyesight, probably due to
the heat effects of microwave. Since human eye is filled with
liquid that can easily absorb microwave radiation, their
temperature may become elevated with exposure to EMFs. It is
believed that this may solidify proteins, causing the eye's lens to
develop "microwave cataracts."
In addition, more than 64 studies in the United States and
Europe have linked chronic exposure to magnetic fields, such as
those from power lines and computer monitors, to unusually high
incidences of cancer, leukemia, and tumors. EMFs are linked to
headaches, cataracts, heart problems, stress, fatigue, nausea,
insomnia, Alzheimer's disease, chest pain, and significantly higher
than expected rates of leukemia. Animal experiments have shown
higher rates of birth defects and miscarriages.
Many Chinese ask the question, "Are we safe?" TV and radio
transmission towers, power lines and mobile phone base stations
cast shadows over virtually every corner in big cities such as Beijing,
Shanghai
and Guangzhou. Although evidence is incomplete and inconsistent, it
is clear that there is a correlation of some sort between
microwaves and health.
Exposure to high-level EMFs has been shown to be harmful, but
there is no definite answer concerning moderate levels.
Laboratory studies on humans exposed to moderate EMFs have
showed no observable changes in blood pressure, body temperature,
sleep, appetite or physical functions. Other studies have found no
mood and behavior changes in human subjects.
But according to environmental supervision data, one percent of
China's mobile phone base stations exceed the environmental
management standard for EMF density (8μW/cm2 ), and some top the
national standard of 40μW/ cm2 . For instance, among the 3,000 base
stations in the Beijing area owned by China Mobile and China
Unicom, six exceed the standard; of the 5,000 base stations in Liaoning
Province, the number rises to 10.
"China has stricter microwave standards than developed countries
like the United States. However, the density of EMFs in Chinese
cities is higher than that in other countries. Microwave radiation
in developed countries is much lower than the set standard," said
Cao Zhaojin, an electromagnetic radiation expert from the
Environment Supervision Institute of the Academy of Preventive
Medical Science.
"According to current research, it is hard to distinguish
between harmful and non-harmful radiation. A low radiation level
does not mean it is safe. That is why developed countries demand
radiation in public places must be much lower than the
standard."
Obviously China's big cities are actually teetering on the rim
of a radiation hazard.
The issue of mobile phones as a source of danger has been hotly
debated.
Mobile phones use microwaves to transmit signals. The emission
power is between 0.25 and 2 W (the old standard being 3 to 5 W).
But because mobile phones are operated in such close proximity
to?-- actually in contact with?-- the body of the user,
the radiation is great.
Cao noted that both Chinese and foreign experts have measured
electromagnetic density around mobile phone antennas. In most
cases, the figure varies from 10 to several hundred μW/ cm2 . When
a phone is in use, that figure can reach as high as 1,000 μW/ cm2
.
If a user uses a 900 MHz phone, the temperature of his ear and
adjacent skin will rise significantly, as much as 2.5 degrees
Celsius. Heat under the level of the skin may affect brain activity
and the neural system.?
Studies on cat, rat, and chick brain cells show that
low-frequency electromagnetic radiation interacts with brain
activity and could cause a host of negative symptoms, from
heightened stress and depression, slowed reaction and learning
disabilities to miscarriages, fetal deformities and cancer.
In 1996, the World Health Organization (WHO) established the
International Electromagnetic Fields (EMF) Project to address the
health issues associated with exposure to EMFs. A comprehensive
report is expected to be complete between 2005 and 2006.
The WHO's International Agency for Research on Cancer (IARC) has
recently concluded the first step in WHO's health risk assessment
process by classifying EMFs. This year, IARC expects to have
adequate data to complete its assessment.
(China.org.cn by Li Liangdu, July 6, 2004 )?