Experts divided over maximum mercury levels in human blood
Experts divided over maximum mercury levels in human blood
Dewi Santoso and Sari P. Setiogi, Jakarta
The health scare in Pantai Buyat village in Minahasa, North
Sulawesi, has raised the issue of mercury contamination, a topic
over which experts differ when discussing safe levels in the
human body.
According to the director of the University of Indonesia's
Center for Environmental Safety and Risk Assessment, Budiawan,
what is considered a safe level of mercury in the human body
depends on a person's ability to tolerate the element.
"When talking about mercury, there is not a normal or abnormal
level as it can vary in humans, depending on their lifestyles and
diet," Budiawan told The Jakarta Post on Friday.
However, he said mercury was a foreign element that did not
naturally exist in the human body and could be considered
poisonous.
"But there is always the possibility that a person can be
exposed to it (mercury), especially when a person is working in
the metal industry," he said.
For such high-risk people, he said the American Conference on
Government Industrial Hygiene had set the maximum standard for
the total mercury level in the blood at 15 microns per liter
(u/L).
"Thus, if we want to use common sense, the level of mercury in
the average people's blood should be less than 15 u/L," Budiawan
said.
He said that normally when the mercury level was higher than
this, a person developed various symptoms, including nausea,
massive weight loss and irritability, followed by nervous system-
related problem or tremors.
Budiawan's explanation differed slightly from one given by
Amin Soebandrio, an assistant deputy minister for medical and
health sciences at the Office of the State Minister for Research
and Technology.
According to Amin, the maximum safe level of mercury in human
blood is 20 u/L. Anything higher could lead to health defects
affecting the nervous and sensory systems.
"A study by the International Institute for Minamata Disease
in Japan revealed that symptoms of contamination might show in
people with mercury levels above 30 u/L," he told the Post.
The institute recommends that anyone with mercury levels of
some 28 u/L go immediately to the health authorities.
To get a more accurate reading of mercury levels in the human
body, according to Amin, a test on hair samples is required.
"The mercury level in the blood is very much affected by what
someone has eaten within the last 30 hours. That means that if a
person just ate contaminated fish, then the mercury level in his
blood might be extremely high," he said.
Amin said that in victims of Minamata disease in Japan, the
mercury levels obtained from their hair samples reached 7,000
u/L.
Minamata disease is a neurological disorder caused by
methylmercury poisoning. It is known as the first major
environmental disaster in Japan caused by humans.
Although mercury is the main cause of the disease, Amin said
not all types of mercury contaminated the human body.
"There are three kinds of mercury: elemental, organic and
inorganic mercury," he said.
Elemental mercury is the familiar liquid used in thermometers
and barometers. "This type of mercury cannot be absorbed by the
skin. Even if it is swallowed, it will only pass through the
intestines," Amin said.
The dangerous types of mercury are the organic and inorganic
types, he said.
According to the United States Agency for Toxic Substances and
Disease Registry (ATSDR), organic mercury is formed when mercury
combines with carbon.
Inorganic mercury is formed when the element combines with
chlorine, sulfur and oxygen. This type of mercury can be found in
industrial waste.
As dangerous as mercury is, there are also other hazardous
elements that have been found in Buyat Bay: Cyanide and arsenic,
both of which can cause death.
Amin said cyanide might be present in the water due to
discharges from gold and silver and mining industries.
As for arsenic, it can be found in wood preservatives,
pesticides, lead-acid battery from automobiles, rat poison and
ant poison.
Arsenic has been recognized as a human poison since ancient
times. Large oral doses of above 60,000 u/L can produce death,
according to the ATSDR.
However, there is some evidence that small amounts of arsenic
in a normal diet (10-50 u/L) may be beneficial for health.