The article discusses the impact of atmospheric nuclear tests on the environment and human health, with a specific focus on the radioactive contamination from the isotope Iodine-131 (131I) and its potential link to thyroid cancer.

According to the US National Cancer Institute, during the Cold War in the mid-1940s through early 1960s, the US government conducted about 100 nuclear weapons tests in the atmosphere at a test site in Nevada, more than 100 in the Pacific, and one—the first ever—in New Mexico. The radioactive substances released by these tests are known as “fallout.” They were carried thousands of miles away from the test site by winds. As a result, people living in the United States at the time of the testing were exposed to varying levels of radiation.

Among the numerous radioactive substances released in fallout, there has been a great deal of concern about and study of one radioactive form of iodine–called iodine-131, or I-131. I-131 collects in the thyroid gland. People exposed to I-131, especially during childhood, may have an increased risk of thyroid disease, including thyroid cancer

Radioactive Contamination

The article highlights that nuclear tests released radioactive materials into the atmosphere. One of these materials is the isotope Iodine-131 (131I). This isotope can get integrated into the CO2 in the atmosphere, reach the marine environment through ocean-atmosphere gas exchange, or enter the biosphere through photosynthesis.

Impact on Human Health

One of the significant health impacts of this radioactive contamination is an increase in thyroid cancer, especially in areas heavily affected by the radioactive contamination. The article uses the United States as a case study.

Thyroid Doses

The article mentions that certain states in the US, such as Idaho, Montana, Utah, Colorado, and South Dakota, experienced the highest average per capita cumulative thyroid doses due to 131I contamination. This dose was significantly higher than the dose from natural sources of radiation.

Thyroid Cancer Incidence

There has been a noticeable increase in thyroid cancer incidence in the past decades, especially among females in states like Utah, Idaho, Wyoming, and Iowa. While there’s a connection between the thyroid dose from 131I and the increase in thyroid cancer, other factors, like therapeutic radiation treatments, also play a role.

Global Context

On a global scale, other events like the Chernobyl accident might have contributed to the rise in thyroid cancer incidence. However, the article emphasizes that the risk from 131I is currently much lower, and only specific groups of people (like children up to 10 years old during the time of the nuclear tests) are at a higher risk.

Thyroid Cancer Rates

In Utah, the thyroid cancer rate among females increased from 10 per 100,000 in 1990 to 29.4 per 100,000 in 2009. Similarly, in Idaho, it rose from 8.5 per 100,000 in 1999 to 26.1 per 100,000 in 2010.

Thyroid Doses

States like Idaho, Montana, Utah, Colorado, and South Dakota had thyroid doses over 90 mGy due to 131I contamination, which is significantly higher than doses from natural radiation sources.

Conclusion

The article concludes that while there’s a clear link between 131I contamination from nuclear tests and the rise in thyroid cancer, especially in certain US states, other factors like therapeutic radiation treatments also play a significant role. The risk from 131I is currently lower, but specific groups, especially those exposed as children during the nuclear tests, remain at a higher risk.