'No safe dose for radiation exposure'

By Karen Galarpe, abs-cbnNEWS.com

Posted at Apr 06 2011 04:38 PM | Updated as of Apr 07 2011 05:38 AM

MANILA, Philippines - Contrary to claims that radiation will not pose harm at certain levels, a toxicology expert said there is no such thing as "safe dose."

"There is no safe dose for radiation exposure. In fact even the International Commission on Radiation Protection (ICRP) admits that," said Dr. Romeo Quijano, professor of the Department of Pharmacology and Toxicology at the University of the Philippines-Manila.

Dr. Romeo Quijano

"Even the ICRP recognizes that exposure below limits is not safe," he added, and quoted an ICRP report saying: "The permissible doses can therefore be expected to produce effects [illnesses] that could be detectable only by statistical methods applied to large groups."

Quijano, president of the Pesticide Action Network of the Philippines, made the statements on Wednesday at the Senate inquiry on possible radiation threats to the country as a result of the stricken Fukushima nuclear power plant in Japan. The hearing was conducted by Sen. Pia Cayetano, chair of the Senate committee on health and demography.

Quijano pointed out that there is significant leak from a reactor of the Fukushima plant, resulting in significant amounts of radioactivity released in the environment.

The radiation level at the plant has already reached 400 mSv per hour, at which level, said Quijano, "puwede ka ng magkaroon ng acute radiation injury."

Quijano earlier said radiation from Japan may reach the Philippines, and it already has.

The Philippine Nuclear Research Institute (PNRI) then said the radiation level in the country reached 100 to 115 nano-sieverts per hour, and there is no cause for alarm.

The normal radiation level in Metro Manila is 85-115 nano-sieverts per hour, said Dr. Alumanda dela Rosa, PNRI director, at the Senate inquiry on Wednesday.

Quijano raised concerns that a core meltdown in the Fukushima plant "could lead to a very large release of radioactivity to the environment," citing analyses made by concerned scientists.

He pointed out the presence of mixed-oxide (MOX) fuel, a mixture of plutonium and uranium oxides, which is about 6% of the core of unit 3 of the Fukushima plant. "May na-detect na na plutonium sa labas ng reactor. Ibig sabihin nag-leak," Quijano said.

"The adverse effects would be greater in terms of the number of deaths and cancer," he added.

Radiation exposure limits

Quijano told the committee that the ICRP has in the past set standards of radiation exposure limits:

  • less than 2 millirems (20 microSv) in any one hour from external radiation sources in any restricted area;
  • less than 100 millirems (1 mSv) in a calendar year from both external and internal sources of radiation in unrestricted and controlled areas; and,
  • occupational limit is 50 mSv a year and 0.5 rem or 5 mSV for the entire gestation period.

But he said ICRP set these standards "not based on worker and public health criteria, but on value judgments with respect to the acceptability of risk estimates for what it sees as benefits of the activities. The decision makers were either users of ionizing radiation in their employment or are government regulators primarily from countries with nuclear weapons programs."

Quijano cited scientific studies supporting his claim that there is no safe radiation level.

One such study he cited was conducted in 1970 by Dr. Thomas Mancuso, professor of occupational health at the University of Pittsburgh, who found a link between radiation and cancer.

"He found a definite relationship between low levels of radiation and the development of certain types of cancer among workers in the nuclear power industry. The cancers were occurring at well below the official limits of radiation exposure. The official limit for them was 50 mSv a year. This study revealed that radiation as low as 10 mSV a year have been found to have increased incidence of cancer," Quijano explained.