Fallout from the Chernobyl accident and overall cancer incidence in Finland

Impact of Disasters on Older Adult Cancer Outcomes: A Scoping Review

PURPOSE

There is an urgent need to address the growing global cancer burden in the context of complex disaster events, which both disrupt access to oncology care and facilitate carcinogenic exposures. Older adults (65 years and older) are a growing population with multifaceted care needs, making them especially vulnerable to disasters. The objective of this scoping review is to characterize the state of the literature concerning older adult cancer-related outcomes and oncologic care after a disaster event.

METHODS

A search was conducted in PubMed and Web of Science. Following Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines for scoping reviews, articles were extracted and screened for inclusion. Eligible articles were summarized using descriptive and thematic analyses.

RESULTS

Thirty-five studies met all criteria for full-text review. The majority focused on technological disasters (60%, n = 21), followed by climate-amplified disasters (28.6%, n = 10) and geophysical disasters (11.4%, n = 4). Thematic analysis classified the current evidence into three major categories: (1) studies concerned with carcinogenic exposure and cancer incidence related to the disaster event, (2) studies examining changes in access to cancer care and cancer treatment disruptions as a result of the disaster event, and (3) studies exploring the psychosocial experiences of patients with cancer affected by a disaster event. Few studies focused on older adults specifically, and most of the current evidence focuses on disasters in the United States or Japan.

CONCLUSION

Older adult cancer outcomes after a disaster event are understudied. Current evidence suggests that disasters worsen cancer-related outcomes among older adults by disrupting continuity of care and access to timely treatment. There is a need for prospective longitudinal studies following older adult populations postdisaster and studies focused on disasters in low- and middle-income country contexts.

Cancer Incidence of Finnish Sami in the Light of Exposure to Radioactive Fallout

This article summarizes the results of studies on the exposure of the Finnish Sami people to radioactive fallout and the estimations of the related cancer risk. We also discuss the lifestyle, genetic origin and diet of this population. The Sami people are an indigenous people who live in the northern part of Scandinavia and Finland. The review is based on the available scientific literature of Finnish Sami. The traditional Sami diet, high in animal products, persists in Sami groups still involved in reindeer-herding, but others have adopted the typical diet of western cultures. Studies have consistently shown an overall reduced cancer risk among the Finnish Sami people, except for stomach cancer among the Skolt Sami. Common cancers among the Finnish main population, such as prostate, breast and skin cancer are especially rare among the Finnish Sami. The incidence of cancer among the Finnish Sami are mostly similar to those of the Swedish and Norwegian Sami. To conclude, we observed no effect of radioactive pollution on cancer incidence. The lifestyles and environments of the Sami are changing, and their cancer mortality rate today is similar to that of the majority of the Finnish and western population.

Long-Term Consequences of the Chernobyl Radioactive Fallout: An Exploration of the Aggregate Data

Policy Points Policymakers should invest more on researching the long-term health effects of low-ionizing radiation exposure, as we are far from reaching a consensus on a topic that is of enormous importance for public health and safety. Public policies such as those limiting the import of contaminated food from areas hit by a radioactive disaster or those regulating the resident population's access to such areas should follow a precautionary approach. Neoplasm diagnosis and medical care should be designed in order to take into account the possible role of long-term, low-dose radiation exposure. Health care policies should provide effective screening and prevention strategies with a specific focus on the regions that were hit most severely by the Chernobyl nuclear fallout. Health care expenditure should be targeted, taking into account the geographical dispersion of the fallout in order to attenuate its possible effect on neoplasm incidence.

CONTEXT

This study investigates the association between the radioactive ¹³⁷ Cesium fallout originated by the 1986 Chernobyl nuclear accident and dispersed over Western Europe, as a result of a combination of radioactive cloud passage days and rainy days over a 10-day period, and long-term health patterns and related costs. Since the half-life of ¹³⁷ Cesium is 30.17 years, part of the radioactivity in the affected regions is still present today, and it is usually still detected in the food chain, although at lower concentration levels.

METHODS

We match longitudinal data on neoplasm incidence over the time span 2000-2013 in a number of European regions not immediately adjacent to Chernobyl with the randomly distributed levels of cesium deposition after the nuclear disaster in order to assess whether we can detect an association with the long-term health effects on the European population through a random effects model.

FINDINGS

Considering 3 levels of fallout deposition-low, medium, and high-hospital discharges after treatment for neoplasms are, respectively, 0.36, 0.44, and 0.98 discharges over 100 inhabitants higher compared to regions with no fallout, with the population average being around 1.7 hospital discharges by neoplasms over 100 inhabitants. We checked the robustness of our findings to a number of tests including a placebo simulation and different model specifications.

CONCLUSIONS

Radioactive fallout is positively associated with a higher incidence of hospital discharges after treatment for neoplasms almost 30 years after its release, with larger effects in regions where the radioactivity was more intense. Our estimates are comparable to the findings of the largest-scale study on the long-term health effects of continuous low levels of radiation exposure among workers in the nuclear industry and suggest that more research is needed on this topic, given its enormous importance for public health and safety.

Total cancer incidence in relation to 137Cs fallout in the most contaminated counties in Sweden after the Chernobyl nuclear power plant accident: a register-based study

OBJECTIVES

To determine the total cancer incidence in relation to a 5-year exposure to caesium-137 (¹³⁷Cs) from the 1986 Chernobyl nuclear power plant accident.

METHODS

A closed cohort was defined as all individuals living in the three most contaminated counties in mid-Sweden in 1986. Fallout of ¹³⁷Cs was retrieved as a digital map from the Geological Survey of Sweden, demographic data from Statistics Sweden, and cancer diagnosis from the National Board of Health and Welfare. Individuals were assigned an annual ¹³⁷Cs exposure based on their place of residence (1986-1990), from which 5-year cumulative ¹³⁷Cs exposures were calculated, accounting for the physical decay of ¹³⁷Cs and changing residencies. HRs were adjusted for age, sex, rural/non-rural residence and pre-Chernobyl total cancer incidence.

RESULTS

The 734 537 people identified were categorised by exposure: the first quartile was low exposure (0.0-45.4 kBq/m²), the second and third quartiles were intermediate exposure (45.41-118.8 kBq/m²), and the fourth quartile was the highest exposure (118.81-564.71 kBq/m²). Between 1991 and 2010, 82 495 cancer cases were registered in the 3 counties. Adjusted HRs (95% CI) were 1.03 (1.01 to 1.05) for intermediate exposure and 1.05 (1.03 to 1.07) for the highest exposure compared to the reference exposure.

CONCLUSIONS

We found a small overall exposure-response pattern of the total cancer incidence related to ¹³⁷Cs after adjustment for age, sex, rural residence and pre-Chernobyl cancer incidence.

Follow-up studies on genome damage in children after Chernobyl nuclear power plant accident

As children are more susceptible to ionizing radiation than adults, each nuclear accident demands special attention and care of this vulnerable population. The Chernobyl nuclear disaster occurred in a region populated with a large number of children, but despite all efforts and expertise of nuclear specialists, it was not possible to avoid casualties. As vast regions of Ukraine, Belarus and Russia were exposed to doses of ionizing radiation, which are known to be related with different diseases, shortly after the accident medical surveillance was launched, which also included analysis of genome damage. Child population affected by internal and external radiation consisted of subjects exposed prenatally, postnatally (both evacuated and non-evacuated), born by irradiated fathers who worked as liquidators, and parents exposed environmentally. In all groups of children during the last 30 years who were exposed to doses which were significantly higher than that recommended for general population of 1 mSv per year, increased genome damage was detected. Increased genome damage includes statistically higher frequency of dicentric and ring chromosomes, chromated and chromosome breaks, acentric fragments, translocations, and micronuclei. The presence of rogue cells confirmed internal contamination. Genome instability and radiosensitivity in children was detected both in evacuated and continuously exposed children. Today the population exposed to ionizing radiation in 1986 is in reproductive period of life and follow-up of this population and their offspring is of great importance. This review aims to give insight in results of studies, which reported genome damage in children in journals without language restrictions.

Cancer incidence in northern Sweden before and after the Chernobyl nuclear power plant accident

Sweden received about 5 % of the total release of (137)Cs from the Chernobyl nuclear power plant accident in 1986. The distribution of the fallout mainly affected northern Sweden, where some parts of the population could have received an estimated annual effective dose of 1-2 mSv per year. It is disputed whether an increased incidence of cancer can be detected in epidemiological studies after the Chernobyl nuclear power plant accident outside the former Union of Soviet Socialist Republics. In the present paper, a possible exposure-response pattern between deposition of (137)Cs and cancer incidence after the Chernobyl nuclear power plant accident was investigated in the nine northernmost counties of Sweden (2.2 million inhabitants in 1986). The activity of (137)Cs from the fallout maps at 1986 was used as a proxy for the received dose of ionizing radiation. Diagnoses of cancer (ICD-7 code 140-209) from 1980 to 2009 were received from the Swedish Cancer Registry (273,222 cases). Age-adjusted incidence rate ratios, stratified by gender, were calculated with Poisson regression in two closed cohorts of the population in the nine counties 1980 and 1986, respectively. The follow-up periods were 1980-1985 and 1986-2009, respectively. The average surface-weighted deposition of (137)Cs at three geographical levels; county (n = 9), municipality (n = 95) and parish level (n = 612) was applied for the two cohorts to study the pre- and the post-Chernobyl periods separately. To analyze time trends, the age-standardized total cancer incidence was calculated for the general Swedish population and the population in the nine counties. Joinpoint regression was used to compare the average annual percent change in the general population and the study population within each gender. No obvious exposure-response pattern was seen in the age-adjusted total cancer incidence rate ratios. A spurious association between fallout and cancer incidence was present, where areas with the lowest incidence of cancer before the accident coincidentally had the lowest fallout of (137)Cs. Increasing the geographical resolution of exposure from nine county averages to 612 parish averages resulted in a two to three times higher value of variance in the regression model. There was a secular trend with an increase in age-standardized incidence of cancer in both genders from 1980 to 2009, but significant only in females. This trend was stronger and statistically significant for both genders in the general Swedish population compared to the nine counties. In conclusion, using both high quality cancer registry data and high resolution exposure maps of (137)Cs deposition, it was not possible to distinguish an effect of (137)Cs on cancer incidence after the Chernobyl nuclear power plant accident in Sweden.