Radioactive iodine in tap water has been found in Tokyo and other places west and south of the Fukushima Dai-ichi nuclear plant, the Ministry of Education, Culture, Sports, Science and Technology said in a published report. Foods affected include milk and spinach, so far.
The amount of radioactive iodine found in Japan is below their national allowable limits. However, radioactive iodine when found in food and water, can be more harmful to babies and children than to adults. Because the thyroid gland of a child is smaller than that of an adult, the child’s thyroid gland will receive a higher radiation dose than the adult exposed to the same amount of iodine. This can cause cancer of the gland. Since the effects of radiation are cumulative, over time the skin, lung, and reproductive organs can be affected.
Consuming small doses of radiation can cause cancer in humans by damaging the DNA molecule. Ingesting radioactive material is more damaging than getting it on skin because externally, it is able to be washed off the body. What is ingested stays in the body and gets into the bones and causes bone cancer and gene mutations.
According to the U.S. Environmental Protection Agency, any living tissue in the body can be damaged by ionizing radiation. The body attempts to repair the damage, but sometimes the damage can’t be repaired or it’s too severe or widespread to be repaired. Also, mistakes made in the natural repair process can lead to cancerous cells.
The body may fail to repair gene mutations or even creates mutations during repair. The mutations can be teratogenic or genetic. Teratogenic mutations are caused by fetal exposure to radioactive toxins in the womb, affecting only the fetus who was exposed. Genetic mutations are passed through the birth line.
When expectant mothers are exposed to radiation, the babies may be born with smaller head or brain size, hydrocephalus (water on the brain) poorly formed eyes, abnormally slow growth, and mental retardation. Fetuses are most sensitive between about eight to 15 weeks after conception. They are less sensitive between six and 25 weeks old. If the mother or child had gene mutations due to exposure, genetic mutations can happen to the child’s children.
An EPA chart on radiation sickness says exposure of five to 10 rem results in changes in blood chemistry; 50 rem results in nausea within hours. Radiation exposure of 55 rem results in fatigue within hours, 70 rem vomiting within hours and 75 rem hair loss within two to three weeks. Exposure of 90 rem results in diarrhea within weeks; 100 rem results in hemorrhage and exposure of 400 rem, possible death within two months. Destruction of intestinal lining internal bleeding and death occurs within one to two weeks with radiation exposure to 1,000 rem. Exposure of 2,000 rem results in damage to central nervous system and loss of consciousness. Death can come within minutes or a few hours to days.
The relationship between how much radiation exposure can cause mental retardation is unknown. However, scientists estimate that if 1,000 fetuses that were between eight and fifteen weeks old were exposed to one rem, four fetuses would become mentally retarded. If the fetuses were between 16 and 25 weeks old, it is estimated that one of them would be mentally retarded.
Genetic effects are those that can be passed from parent to child. Health physicists estimate fifty severe hereditary effects will occur in a group of one million live-born children whose parents were both exposed to one rem. About 120 severe hereditary effects would occur in all descendants.
Short-term, high-level exposure is referred to as acute exposure. Health effects from acute exposure to radiation usually appear quickly, like burns and radiation sickness. It can cause premature aging and death. If the dose is fatal, death usually occurs within two months. The symptoms of radiation sickness include nausea, weakness, hair loss, skin burns or low organ function.
Health physicists suggest limiting exposure to about 100 rem per year from all sources. Exceptions are occupational, medical or accidental exposures. This is far below the exposure levels that cause acute health effects.
U.S. Environmental Protection Agency
Department of Physics, University of Illinois at Urban Champagne
Agency for Toxic Substances and Disease Registry, Centers for Disease Control