137 Cesium Exposure and Spirometry Measures in Ukrainian Children Affected by the Chernobyl Nuclear Incident

Autor: Lawrence C. Mohr, Timothy A. Mousseau, Vitaliy Vdovenko, Stepanova Yi, Igor Kolpakov, Wilfried Karmaus, David G. Hoel, Maryna V. Naboka, Erik R. Svendsen
Rok vydání: 2010
Předmět:
Zdroj: Environmental Health Perspectives
ISSN: 1552-9924
0091-6765
Popis: The long-term health and environmental consequences of the Chernobyl catastrophe are not yet fully reported despite 23 years of research (Moller and Mousseau 2006; Zakharov and Krysanov 1996). There is considerable disagreement among government agencies, health professionals, and scientists over the long-term effects of radiologic contaminants (Mousseau et al. 2005; Zakharov and Krysanov 1996), and the official position of the United Nations (UN) [Balanov 2005; International Atomic Energy Association (IAEA) 2005, 2006; World Health Organization (WHO) 2006] has been generally interpreted to suggest that the consequences to human health are much lower than expected (Anspaugh 2007; Geras’kin et al. 2008; Yablokov 2009a), although the authors of the UN reports concluded that “given the lack of statistical power based upon the estimated doses and confounding variables from causes other than radiation exposure, studies of the causes of mortality of the general population or evacuees from highly contaminated zones are unlikely to provide useful scientific information on radiation effects” (WHO 2006). This position essentially negates any possibility of conducting useful epidemiologic studies without having individual-based dose measurements, which is a near impossibility for the populations most affected by Chernobyl fallout. Similarly, the parklike appearance of the 2044.4-km2 Chernobyl exclusion zone, with some animals appearing to be increasing in numbers, suggests an ecosystem on the rebound, and the UN position (IAEA 2006) has been that there is little evidence to suggest significant large and persistent effects of contamination on the biota of the zone. However, the UN reports, and interpretations of it in the popular and scientific press, have generated an optimism that may be based on too few studies published in English, conducted too soon after the event to be conclusive. A growing number of reports in the literature suggest measurable effects for both human and animal populations. Recently, a thorough literature review was published on this subject (Yablokov 2009a, 2009b; Yablokov and Nesterenko 2009; Yablokov et al. 2009a, 2009b). A prudent approach to this problem should involve rigorous scientific explorations of all available information. Several β- and γ-emitting radionuclides were released from the Chernobyl nuclear reactor, including 131iodine, and 137cesium (137Cs). 131Iodine has a half-life of 8 days, and 137Cs, 30 years. Most of the acute health effects from the Chernobyl incident have been compared with 131iodine exposures, whereas 137Cs has been the radioisotope of greatest concern for persistent exposures in the affected communities. In many rural villages across the Ukraine and Belarus, people are routinely exposed to 137Cs through their diet of locally grown food that bioaccumulates 137Cs and use of drinking water derived from shallow, open wells (Nesterenko et al. 2009a; Yablokov et al. 2009a, 2009b). In addition, forest fires and agricultural activities in the contaminated regions of Ukraine and Belarus also release radionuclides to the atmosphere as aerosols or attached to dust particles, which are then widely transported (Konoplia et al. 1992) and are potentially inhaled in adjacent regions. Recent summaries of Belarusian and Ukrainian reporting agencies suggest that ingestion is a significant source of exposure for large segments of these populations (Nesterenko et al. 2009a, 2009b; Yablokov and Nesterenko 2009). The short-term effects on the lung and pulmonary system after acute high-dose exposure to radiation are relatively well known, and long-term effects are occasionally reported (Abid et al. 2001; Coggle et al. 1986; Yablokov 2009b). However, comparatively little research has assessed the long-term health effects of persistent 137Cs or other radioisotope exposures on the lung and pulmonary system (Yablokov 2009b). There is increasing evidence that long-term exposure to radioisotopes such as 137Cs is associated with modulation of the immune system (Yablokov 2009b). Such modulation of immune function may lead to recurrent infection, and the most commonly reported long-term effect on the pulmonary system from persistent exposure to 137Cs or other radioisotopes is increased pulmonary infection (Yablokov 2009b). Detrimental functional effects of recurrent pulmonary infection during childhood lung development have been suggested (Gern et al. 2005). However, we are unaware of any study reported in English that has documented deficits in lung function or increased bronchial reactivity in children associated with chronic exposure to 137Cs or other radioisotopes. We studied the association of average soil 137Cs levels in a community with pulmonary function and reactivity measures of children living in this community to test the hypothesis that prolonged exposure to 137Cs during childhood development reduces lung function and increases airway reactivity. To test this hypothesis, we conducted an epidemiologic study using a “natural experiment” design that took advantage of the highly heterogeneous nature of contaminant deposition during the Chernobyl radiologic incident. Because of variation in wind direction and rainfall during the nuclear fire that burned for 10 days starting 26 April 1986, and variation in local soil types, contaminant levels can vary by two orders of magnitude between villages within a small region. This provides a unique opportunity to conduct relatively controlled comparisons among groups of individuals who share most elements of their living and socioeconomic conditions but who have been chronically exposed to widely different levels of contaminants. We used a prospective longitudinal cohort study design with data from a population of children under annual medical surveillance who were currently exposed to 137Cs through their drinking water and diet of locally grown food in the Narodichesky region of Ukraine, a region adjacent to an evacuated region heavily contaminated by radioactive fallout from the 1986 Chernobyl radiologic incident.
Databáze: OpenAIRE
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