Radiation is defined as

Radiation is defined as, “the emission of energy as electromagnetic waves or as moving subatomic particles, especially high-energy particles that cause ionization” (“Radiation”, n.d., entry 1). “Certain types of radiation can produce damage to cellular DNA that may lead to cancer” (Cohen & Hull, 2015). Three types of radiation are: alpha, beta, and gamma rays. Alpha radiation can be inhaled or swallowed and has the potential to stay in the body. Beta radiation, like alpha radiation, can be inhaled or swallowed; however, it has smaller particles that can go through the skin causing nuclear burns. Gamma radiation, unlike alpha and beta, is highly penetrating and causes damage immediately. Whereas, alpha and beta have long term effects. “High levels of radioactive iodine were released from the Chernobyl reactor in the early days after the accident” (Ionizing Radiation, 2017). “The nature of the radiation released was dependent on the physical and chemical properties of the radioactive elements in the core. Particularly dangerous were the highly radioactive fission products, those with high nuclear decay rates that accumulate in the food chain, such as the isotopes of iodine, caesium and strontium. Iodine-131 and caesium-137 are responsible for most of the radiation exposure received by people” (Radiation Levels, 2013, The release of radiation).
The purpose of the article, “Fallout from the Chernobyl accident and overall cancer incidence in Finland”, is to inform readers on a study of “whether incidence of all cancer sites combined was associated with the radiation exposure due to fallout from the Chernobyl accident in Finland, with an emphasis on the first decade after the accident to assess the suggested ‘promotion effect’.Overall cancer incidence was found to be 10-20% higher in the population with the highest radiation exposure in Central Sweden compared to the lowest exposure areas within 5 years after the accident. This increase in cancer incidence after a short latency was interpreted by the authors as a cancer promoting effect of low-dose radiation” (Kurttio et al., 2013, p. 585). Data used for the study was based on age, sex, residential history, and house type of the Finnish population. “No confidentiality issues arose, as no individual data were used in the analyses and the units of observation were too large for identifying individuals” (Kurttio et al., 2013, p. 589).
The majority of radiation exposure received was during the first post-Chernobyl year. Data was based on 250m x 250m map grid squares covering the whole of Finland and the Finnish population with a stable residence (those who had lived in the same address during the first year). Residence analysis was limited to single family houses due to the assumption that people inhabiting them received higher external radiation doses than people living in apartments because of the substantially lower shielding of the building. Single family houses have a shielding factor of 0.37. However, it was estimated that people stayed indoors 80% of a day, raising the shielding factor to 0.50. The study included people of any age who occupied the same address from May 1986 through April 1987. The quality of data on address locations in Finland is high.
A pre-Chernobyl cohort and a study cohort were formed to compare cancer incidence. “The pre-Chernobyl cohort including persons who lived in the grid squares containing only single-family houses at the end of 1980 with the follow up from the beginning of 1981 until the end of 1985” (Kurttio et al., 2013, p. 586). Cancer incidence for the pre-Chernobyl cohort was used as a baseline. The study cohort also “included persons of all ages who lived in the same address in a grid square including only single-family houses from May 1986 through April 1987.” Both cohorts were divided into age groups by sex, 0-59 and 60+ years, younger and older. “The elevated cancer incidence by calendar time reflects mainly the ageing of the cohorts” (Kurttio et al., 2013, p. 590).
“Finland was divided into four exposure areas based on the estimated effective radiation dose due to external exposure from the Chernobyl accident fallout during the first year after the accident” (Kurttio et al., 2013, p. 586).