Toxic Pollution 157
150 mrem/year. Radiographic and radioscopic testing also cause significant
loads, equal on average to 70 mrem/year in the United States, bringing total
basic load up to approximately 220 mrem/year.
Humans’ basic loads of ionising radiations from natural and artificial
sources are certainly the cause of a percentage of cancers and genetic abnormalities; of particular interest, however, is a quantitative estimation of the
effects caused by doses of radiation exceeding the basic load. Such estimates have resulted from many experimental studies on animals as well as
studies of survivors of Hiroshima and Nagasaki, or of non-cancer patients
treated with radiation, or special occupational groups such as workers in
uranium mines or children whose mothers had x-rays during pregnancy.
The conclusion of the studies is that even small doses of radiation above
the basic load cause additional cases of cancer and genetic abnormalities.
The so-called linear hypothesis is generally accepted, according to which
most of the above-described cases are dose-dependent: that is, if a dose of
0.10 rem causes n cases in a population, then a dose of 1 rem will cause 10n
cases in the same population.
Regarding the long-term effects of small doses, scientific opinions are
divided as concerns the existence of a threshold dose, that is, a maximum
dose under which radioactive radiation has no harmful effects. However,
the prevailing view is that there is no such maximum value, and therefore
there is probably no safe threshold. This means that a small increase in
absorbed radiation will bring about a corresponding increase in the cases
observed: that is, even very small doses may in the long term cause additional cancers and genetic abnormalities. It has been estimated that in a
population of 1,000,000 people a dose of 100 mrem causes 7–30 deaths
from cancer, and that the same dose administered to successive generations will result in 6–100 cases of severe genetic abnormalities per million children. These figures are very low in comparison with the “natural”
cases of cancer and genetic abnormalities, but they refer to additional cases,
i.e. additional lives lost due to radioactive radiation.
150 mrem/year. Radiographic and radioscopic testing also cause significant
loads, equal on average to 70 mrem/year in the United States, bringing total
basic load up to approximately 220 mrem/year.
Humans’ basic loads of ionising radiations from natural and artificial
sources are certainly the cause of a percentage of cancers and genetic abnormalities; of particular interest, however, is a quantitative estimation of the
effects caused by doses of radiation exceeding the basic load. Such estimates have resulted from many experimental studies on animals as well as
studies of survivors of Hiroshima and Nagasaki, or of non-cancer patients
treated with radiation, or special occupational groups such as workers in
uranium mines or children whose mothers had x-rays during pregnancy.
The conclusion of the studies is that even small doses of radiation above
the basic load cause additional cases of cancer and genetic abnormalities.
The so-called linear hypothesis is generally accepted, according to which
most of the above-described cases are dose-dependent: that is, if a dose of
0.10 rem causes n cases in a population, then a dose of 1 rem will cause 10n
cases in the same population.
Regarding the long-term effects of small doses, scientific opinions are
divided as concerns the existence of a threshold dose, that is, a maximum
dose under which radioactive radiation has no harmful effects. However,
the prevailing view is that there is no such maximum value, and therefore
there is probably no safe threshold. This means that a small increase in
absorbed radiation will bring about a corresponding increase in the cases
observed: that is, even very small doses may in the long term cause additional cancers and genetic abnormalities. It has been estimated that in a
population of 1,000,000 people a dose of 100 mrem causes 7–30 deaths
from cancer, and that the same dose administered to successive generations will result in 6–100 cases of severe genetic abnormalities per million children. These figures are very low in comparison with the “natural”
cases of cancer and genetic abnormalities, but they refer to additional cases,
i.e. additional lives lost due to radioactive radiation.