Evidence from the Chernobyl Nuclear Accident: the Effect on Health, Education, and Labor Market Outcomes in Belarus Maksim Yemelyanau1 Aliaksandr Amialchuk2 Mir M. Ali3 Abstract The Chernobyl nuclear accident of 1986 had deleterious health consequences for the population of Belarus, especially for those who were children at the time of the disaster. Using the 20032008 waves of the Belarusian Household Survey of Income and Expenditure (BHSIE), we estimate the effect of radiation exposure on the health, education, and labor market outcomes among cohorts and areas affected by the accident, utilizing the nuclear accident as a natural experiment. We find that young individuals who came from the most contaminated areas had worse health, were less likely to hold university degrees, were less likely to be employed, and had lower wages compared to those who were older at the time of the accident and who came from less contaminated areas. JEL-code: I18 I20 Q53 J24 Keywords: Chernobyl, Belarus, health, education, wage, employment. The authors would like to thank Christopher Jepsen, Štěpán Jurajda, Randall K. Filer, Mykhaylo Salnykov, Kateryna Bornukova, Lauren Heller and the participants of the seminar at BEROC for their valuable comments. The views expressed here are those of the authors and do not necessarily reflect the views of the Food & Drug Administration. 1 CERGE-EI, P.O. Box 882, Politických vězňů 7, Prague, 111 21, Czech Republic. Tel.: (420) 224 005 205; Fax: (+420) 224 211 374, e-mail: [email protected] 2 Department of Economics, University of Toledo, Toledo, OH 43606-3390, USA, phone: (419) 530-5147, fax: (419) 530-7844, e-mail: [email protected] 3 Department of Economics, University of Toledo & Office of Regulations, Policy and Social Science, Food & Drug Administration, College Park, MD 20740, USA, phone: (301) 436-1784, fax: (301) 4362637, e-mail: [email protected] 1. Introduction In less than twenty years of its modern history, the Republic of Belarus experienced several major external shocks that had serious impacts on its economy. In addition to the current world economic crisis, the Russian crisis of 1998, and the collapse of the Soviet Union in 1991, the Chernobyl disaster, which happened even before Belarus regained its independence, affected—and continues to affect—the Belarusian economy. Twenty-five years later, there is an ongoing debate on the socio-economic consequences of this radioactive catastrophe.4 The goal of this paper is to investigate its long-term impact on health, education, and labor market outcomes in Belarus. On April 26, 1986, reactor number four at the Chernobyl nuclear plant in Ukraine exploded. A series of subsequent explosions and the resulting fire sent clouds of highly radioactive particles into the atmosphere and resulted in radioactive fallout over an extensive geographical area. Large areas of Belarus, northern Ukraine, and parts of the Russian Federation were contaminated, and radioactive clouds later reached Scandinavia and western Europe. According to various estimates, 60-70 percent of all radioactive substances fell on Belarus, and almost a quarter of its territory was affected (Reiners et al., 2008). While the medical and physical consequences of the Chernobyl accident have been widely documented in the literature, the long-term socioeconomic consequences of the accident have, with a few exceptions, received little attention (Almond et al., 2009; Lehmann and Wadsworth, 2009). Because many countries increasingly rely on nuclear power as a source of energy and because the radioactive waste storage continues to expand and age, it is important to understand the socioeconomic consequences of potential radiation accidents, including explosions and radiation leaks. The recent Fukushima Daiichi nuclear plant crisis in Japan and the Three Mile Island accident in the US in 1979 also highlight the need to understand more completely the consequences of nuclear 4 See, for example, the discussion of the safety of using the contaminated land for agriculture in Belarus: http://lenta.ru/articles/2010/07/22/chernobyl/, accessed on 05.25.2011. 2 radiation exposure. Investigating the consequences of these nuclear accidents will help illuminate their total cost, which goes beyond high energy prices, nuclear waste disposal, and global warming concerns to include the large amounts of state resources required to deal with long-term health and socioeconomic consequences. Comprehensive knowledge about the relationships between radiation exposure and public health and socioeconomic outcomes will allow states to formulate more efficient policies for effective response to such accidents and to clarify the direct and indirect costs of such accidents. Using data from a nationally representative sample of the population in Belarus, this paper addresses the relationship between exposure during childhood to radiation from the Chernobyl accident and subsequent health, education, and labor market outcomes. We treat radiation exposure as an exogenous shock because the radiation fallout from Chernobyl was distributed randomly, conditional upon the distance to the reactor, the prevailing wind patterns, the rainfall levels and the local topography (Lehmann and Wadsworth, 2009). We examine the relationship between the extent of irradiation in the region of residence of individuals who were between one and seven years old at the time of the accident, and their health, education, and labor market outcomes seventeen and more years later. We use differences in radiation dosage by region and by age at exposure, using a difference-in-differences estimation approach, in order to identify the effect of the accident on the outcomes of interest. We also account for a range of confounding factors and address the issue of endogenous migration. Our results indicate that individuals who lived in the affected regions and those who were young at the time of the Chernobyl accident had worse health, were less likely to hold university degrees, were less likely to be employed, and had lower wages compared to those who were older at the time of the accident and who came from the less contaminated regions. We also find that the negative effects were concentrated among males. To the best of our knowledge, this is the first study to quantify the impact of the Chernobyl disaster on the socioeconomic outcomes in Belarus, the country most affected by the accident. 3 The rest of the paper is structured as follows: section 2 summarizes the literature on radiation-induced health effects, section 3 describes the health implications of the Chernobyl accident for Belarus, section 4 describes the data, section 5 discusses our methods and identification strategy, section 6 presents the results, and section 7 offers a concluding discussion. 2. Literature review Social scientists have long recognized a significant correlation between health and socioeconomic outcomes like education, wages, and employment. In particular, the link between poor health experienced during childhood and poor education and socioeconomic outcomes in adulthood has been widely documented in the literature (Case et al., 2002 and 2005). However, understanding the long-term consequences of a negative health shock has presented serious challenges in empirical work because of the endogeneity concerns that arise from omitted variables and measurement errors in health measures. In other words, unobservable factors that lead to both poor health and poor economic performance result in a downward bias of the estimates. While the majority of extant empirical studies report only correlational relationships between health and socioeconomic outcomes (see literature surveys in Grossman and Kaestner, 1997; Strauss and Thomas, 1998), a growing body of literature has attempted to establish a causal link between poor health and socioeconomic outcomes. Empirical research that has attempted to estimate this causal relationship has, utilizing a variety of approaches, generally found evidence of a negative impact of poor health on educational and economic outcomes. For example, Kremer and Miguel (2004) used a randomized assignment of a deworming treatment in primary schools in Kenya and found a significant reduction in school absenteeism but no gains in academic performance after the treatment. Bleakley (2007) used the differential timing of different birth cohorts’ exposure to a large-scale intervention against hookworm in children in the American South circa 1910 and found improvements in health, income, and schooling as a result of the treatment. Maccini and Yang 4 (2009) used geographical variations in rainfall around the time of the birth of Indonesian adults and found that higher levels of rainfall in women’s early years had positive effects on their adult socioeconomic status, with the benefits mediated by higher education attainment. Fletcher and Lehrer (2008) used differences in genetic inheritance among children in the same family and found a significant impact of poor mental health on academic achievement. Several recent studies have used environmental shocks to determine the effect of health on socioeconomic status. Almond (2006) exploited the 1918 influenza pandemic to find that cohorts in utero during the pandemic had reduced educational attainment, lower income, and lower socioeconomic status later in life. Meng and Qian (2006) used regional variation in famine intensity in China to find that childhood exposure to famine had significant adverse effects on adult health and work capacity. In the context of the literature that relies on natural experiments, the Chernobyl accident can be viewed as an exogenous environmental shock to health whose influence varies according to the extent of irradiation. Almond et al. (2009), arguing that young children and those in utero appeared to be more vulnerable to radiation, used variation in radiation across Swedish regions to compare the performance of those in utero to the performance of those born before and after 1986. They found that the cohort in utero during the accident had worse educational outcomes. However, the doses of radiation received by the affected cohorts in Sweden were significantly lower than those received by comparable cohorts in Belarus. Lehmann and Wadsworth (2009) used Ukrainian data to find a positive association between radiation dosage in local areas and the individual’s perception of poor health status, but only a weak association between the level of radiation and labor market performance measures. In this paper, we argue that the radioactive fallout from the Chernobyl accident produced disparities in health by age at exposure and by region of residence. The radioactive contamination was higher in Belarus than in any other country because of the predominantly northwestward winds at the time of the accident. The most heavily contaminated areas in Belarus were located in 5 the Gomel region, followed by the Mogilev and Brest regions and Minsk city. However, certain parts of the country, notably the Vitebsk region and most of the Grodno and Minsk regions, suffered very little (Figure 1). In addition, the effect of radiation was age-specific: children aged 0-4 years were especially vulnerable to radiation because of their higher rates of absorption of radioactive iodine.5 2. Health implications of Chernobyl in Belarus 2.1. Thyroid malignancies One of the principal radioactive elements released during the Chernobyl accident was radioactive iodine-131 (¹³¹I), which was significant for the first few months after the accident. The thyroid gland accumulates iodine from the blood stream as part of its normal metabolism. Iodine-131 was incorporated in the thyroid glands of the vast majority of Belarus’ inhabitants through inhalation and ingestion of food, especially milk, containing high levels of ¹³¹I, causing internal irradiation. Even though the entire population of the Republic of Belarus was exposed to radioactive ¹³¹I in 1986, the thyroid doses varied widely based on age, level to which the ground was contaminated with ¹³¹I, and milk consumption rate. Individual thyroid doses of ¹³¹I reached 50 Gy,6 with average doses in contaminated areas between 0.03 Gy and a few Gy, depending on the region where people lived and on their age. Among those exposed, children and adolescents received maximal doses, primarily from drinking milk from cows that ate contaminated grass 5 Lehmann and Wadsworth (2009) also looked at the differences in irradiation by age at exposure. However, their analysis looked at the differences at much older ages, and their treatment group was comprised of children under age 13 at the time of the Chernobyl accident. 6 Because many organs and tissues were exposed by the Chernobyl accident, the concept of effective dose, which characterizes the overall health risk that is due to any combination of radiation, has been commonly used. The effective dose accounts for both absorbed energy and type of radiation and for susceptibility of various organs and tissues to developing a severe radiation-induced cancer or genetic effect. For gamma radiation, the unit of effective dose is the sievert (Sy). (One Gy corresponds to one Sv.) One Sy is a comparatively large dose, so the millisievert or mSv (one one-thousandth of a Sv) is commonly used to describe normal exposures. Annual natural background doses of humans worldwide were estimated to average 2.4 mSv, with a typical range of 1–10 mSv (IAEA 2005). 6 immediately after the accident7 (Bespalchuk et al., 2007; Farahati et al., 2000; Reiners et al., 2008; IAEA, 2005; Balonov, 2007; WHO, 2006; Lehmann and Wadsworth, 2009). Childhood thyroid cancer caused by radioactive iodine was one of the main manifestations of the health impacts of the accident since the thyroid gland is one of the organs most susceptible to cancer from radiation. Children have been found to be the most vulnerable population, and a substantial increase in thyroid cancer among those exposed as children was recorded after the accident (IAEA, 2005). Thyroid cancer in children occurs rarely in most countries, but Belarus is an exception (Bespalchuk et al., 2007). A strong age-dependent risk for thyroid cancer was previously observed in the Japanese population after the atomic bomb explosions, with the highest risk in the group of children below the age of ten. After the Chernobyl accident, children from Belarus who lived in highly exposed regions received mean thyroid doses by radioactive fallout approximately twice as high as did the survivors of the atomic bomb explosions in Japan (Reiners et al., 2008). The literature suggests little doubt that the Chernobyl accident was responsible for the abnormal increase in thyroid cancer in the affected areas. According to Bespalchuk et al. (2007), three major factors are indicative of the radiogenic nature of the thyroid cancer. The first is the high prevalence of the disease; before the Chernobyl accident, the incidence of thyroid cancer was very low in both children and adults. The second factor is geographical; the majority of children and adolescents diagnosed for thyroid carcinoma lived in the Gomel region and the southeastern parts of the Brest region. The third factor is the correlation between level of radiation dosage in a region and the number of registered cancer cases. Farahati et al. (2000) found in a cohort of 483 patients that younger age at the time of the Chernobyl accident was associated with greater cancer complications: compared with patients who were 6.1-8 years old at the time of the accident, patients who were younger than 2 years old had significantly more 7 The rural population of Belarus consumed locally produced milk, and the urban population consumed milk from the numerous local milk factories that used primarily local milk for their production (Kruk 2004). 7 cancer complications. The rapid cellular growth that occurs in children under age two in all likelihood facilitated quicker and broader development of the cancer (Farahati et al., 2000). By 2008 radiation was linked to approximately five thousand cases of thyroid cancer in children and adolescents, with the highest incidence in the group of those who were 0-4 years old in 1986 (Balonov, 2007; Reiners et al., 2008). In addition to cancer among the most heavily irradiated individuals, exposure to Chernobyl's radioactive iodine caused a large majority of the exposed children to have more antithyroid antibodies than other children, which may cause later development of hypothyroidism8 (Pacini et al., 1998). Ostroumova et al. (2009) found a significant relationship between the prevalence of hypothyroidism and individual ¹³¹I thyroid doses from the Chernobyl accident. In several studies conducted in Belarus and Ukraine, a significant increase in the rates of juvenile hypothyroidism was reported in children who lived in radionuclide-contaminated areas compared with children from uncontaminated areas (Goldsmith et al., 1999; Quastel et al., 1997; Vykhovanets et al., 1997). 2.2. Other health effects of Chernobyl While thyroid cancer is the most demonstrable health impact of Chernobyl, a number of other illnesses, including lung diseases, digestive and blood disorders, birth defects, fertility problems, and immune deficiencies, are more prevalent in the radiation-affected areas than in other areas (UNDP, 2002). Acute Radiation Syndrome was the most immediate effect of irradiation from the release of radioactive particles, which primarily consisted of isotopes of uranium and plutonium (the most toxic), iodine-131, strontium-90 and cesium-137. However, Acute Radiation Syndrome affected relatively few people, limited primarily to those who directly participated in the liquidation of the effects of the disaster on the power plant itself. 8 Hypothyroidism is the result of an underactive thyroid gland that cannot make enough thyroid hormone to keep the body running normally. When thyroid hormone levels are too low, the body's cells cannot get enough thyroid hormone, and the body's processes start slowing down. As the metabolism slows, the patient tires easily, becomes forgetful and depressed, and gains weight (Source: American Thyroid Association, http://www.thyroid.org/patients/patient_brochures/childhood.html, accessed on 05.25.2011). 8 Apart from the dramatic increase in thyroid cancer among those exposed at a young age, there is no clearly demonstrated increase in the population of Belarus of solid cancers or leukemia from radiation. Several studies have cited a notable increase in psychological problems among the affected population, compounded by insufficient communication about the effects of radiation and by the social disruption and economic depression that followed the break-up of the Soviet Union (see review in Lehmann and Wadsworth, 2009). Some studies have cited "Chernobyl AIDS," which is characterized by weakened immune system and susceptibility to cardiac conditions and common infections. There have also been reports of the effects of Chernobyl on mental health, manifested in anxiety, depression, and reduced cognitive function from prenatal radiation in the high fallout areas of Ukraine, Belarus, and Russia (Nyahu et al., 1998; Kolominsky et al., 1999; Loganovskaja and Loganovsky, 1999; Almond et al., 2009). 3. Data Our empirical analysis is based on the 2003-2008 waves of the Belarusian Household Survey of Income and Expenditure (BHSIE), called the Belarusian Household Budget Survey (BHBS) in the literature. BHSIE, which was first fielded in 1995, incorporates interviews with a random sample of approximately five thousand households every year. BHSIE is the most reliable and comprehensive source of micro-data in Belarus. In addition to demographic and labor force variables, it contains information on self-assessed health status, hospitalizations, and medical visits. Our sample consists of individuals who were born before the Chernobyl accident. Because we do not observe the exact month of birth and cannot distinguish between the individuals born in 1986 before and after April 26, we restrict the latest year of birth to 1985. In addition, we restrict our analysis to individuals who were under age sixteen in 1991. There had been a major break-up in the labor markets in 1991 because of the collapse of the Soviet Union, so restricting the age in this way allows us to compare individuals who faced similar labor market 9 conditions.9 We use two age cohorts: individuals born in 1983, 1984, and 1985 (the treatment cohort) and those born in 1979, 1980, and 1981 (the control cohort). Those in the treatment cohort were age 18-25 in 2003-2008, and those in the control cohort were age 22-29 in 20032008. Our sample consists of 6,504 individuals in six years of data (2003-2008), although data for some of our variables for some individuals is missing (see Table 1). Information on current employment is available for 5,392 individuals, and information on wages is available for 4,443 individuals. Because the first half of the 1980s was a time of high birth rates in Belarus, the treatment cohort represents 52 percent of the data, versus 48 percent for the control cohort. The geographic identifier available in the data refers to six regions (corresponding to “oblast” in Russian) and the capital city of Minsk. Among the six regions and the city of Minsk, the most affected region was the Gomel region, the less affected were the Mogilev and Brest regions and Minsk city, and the least affected were the Grodno, Vitebsk, and Minsk (excluding Minsk city) regions. The average thyroid dose received by the residents of Gomel region (0.3-0.35 Gy), the most affected area, was over thirty times the dose in the least affected regions (Hrodno, Minsk, and Vitebsk). The average thyroid dose in the less affected areas (the Mogilev and Brest regions and Minsk city) was approximately six times the dose in the least affected regions (see Figure 3). Sixteen percent of our sample came from the most radiation-contaminated region,48 percent came from the less contaminated areas, and the remaining 36 percent came from the least contaminated areas. 4. Methods Our empirical strategy is based on observed geographic and age differences in the amount of irradiation received. Children and adolescents in the Gomel region received the 9 This choice assumes that entry into the labor market entry starts at age 16. While most people at this age are continuing their secondary education, some choose to join the labor force. 10 greatest amount of radiation, followed by those in the less affected area (the Brest and Mogilev regions and Minsk city), while those who lived in the Vitebsk, Grodno, and Minsk regions received relatively mild doses (Figures 2 and 3). Children under the age of four at the time of exposure were especially affected by the radiation. We estimate the following empirical model: yijt 1 (Youngerijt Most_affected ijt ) 2 (Youngerijt Less_affected ijt ) 3 Youngerijt 4 Most_affected ijt 5 Less_affected ijt X ijt ijt , where yijt is the outcome of interest of an individual i living in region j and observed in year t . Among the health, educational, and labor market outcomes that we consider, the variable “medical visits” refers to the number of an individual’s reported medical visits in the last three months. The variable “hospitalized” is a dummy variable that equals one if the individual reported being hospitalized in the last twelve months and zero otherwise. The variable “not good health” is a dummy variable that equals one if the individual rated his/her health as “not very good” or “bad” and zero otherwise. The variable "university diploma" is a dummy variable that equals one if the individual has any diploma of higher education and above and zero otherwise. The variable “employed” is a dummy variable equal to one if the individual reported being currently employed and zero otherwise. The variable “log wages” refers to the natural logarithm of the current wages at the individual’s main job. Youngerijt is a dummy variable equal to one if an individual was one, two, or three years old in 1986 (the treatment cohort) and equal to zero if an individual was five, six, or seven years old in 1986 (the control cohort). This dummy variable captures any fixed differences in the outcome between the two cohorts, as well as general economy-wide time trends that drive changes between the cohorts. Our geographic indicators are based on the region of current residence. Most_affected ijt is a dummy variable indicating the most contaminated Gomel region. Less_affected ijt is a dummy variable indicating the less contaminated areas (the Mogilev and Brest regions and Minsk city). These geographical variables control for any fixed differences 11 between the affected and non-affected regions. X ijt is a vector of demographic and socioeconomic controls including age (in years) and its square, a rural/urban dummy, a dummy for living in a big city (>100,000 residents), and a dummy for male. In addition, we have information on how long the family lived in the current home. We constructed two dummy variables, one indicating whether the family moved in 1986 and the other indicating whether the family moved at any time after 1986. In the absence of data on the region of birth, these dummy variables are intended to control for the possibility that the families that migrated on or after 1986 may have different characteristics from the families that migrated before the accident or that did not migrate. Finally, year dummies are included to control for the general economy-wide trends. Our empirical model seeks to identify the coefficients 1 and 2 on interaction variables Youngerijt Most_affected ijt and Youngerijt Less_affectedijt , respectively. We hypothesize that both of these coefficients are negative and that 1 2 . In other words, people who were younger at the time of the accident and who lived in the more contaminated areas had worse health, education, and labor market outcomes, and the effect increased in magnitude with the extent of area-level contamination. 5. Results Main results Table 1 reports descriptive statistics for the sample used in our analysis. As a first step in our analysis, we plotted all of our outcome variables by area of exposure to radiation (most affected, less affected, least affected) and by age at the time of the accident. Our research design is based on the assumption that younger children (especially those age four and below at the time of the Chernobyl accident) who lived in the more contaminated regions experienced worse outcomes. Accordingly, for the negative outcomes (number of medical visits, being hospitalized, not good health), we expect to see that individuals who were younger and who were from the 12 more contaminated areas experienced disproportionately more of these outcomes than individuals who were older and from the more contaminated areas. On the other hand, for the positive outcomes (having a university degree, being currently employed, monthly wage), we expect to see that younger individuals from the more contaminated areas experienced disproportionately less of these outcomes compared to older individuals from the more contaminated areas. In other words, we expect a more flat (steep) age profile in the more contaminated areas relative to the less contaminated areas for the negative (positive) outcomes. Conforming to our expectations, the left-hand panel of Figure 4 suggests that the number of medical visits, being hospitalized and reports of not being in good health all follow a flatter age profile for the more contaminated areas relative to the less contaminated areas, while having a university degree and a monthly wage follow a steeper age profile for the more contaminated areas. We estimate our empirical specification using a linear regression for all of our outcome variables except for the number of medical visits. Linear regression provides the best linear approximation to the Condition Expectation Function even if the latter is non-linear (Angrist and Pischke, 2009, p. 38).10 We estimated a negative binomial regression for the count variable “medical visits” and presented the incidence rate ratios (exponentiated coefficients). The hypothesized mechanism for the effect of radiation on education and labor market outcomes is via the effect on health. Therefore, we start our multivariate analysis by exploring the impact of radiation exposure on three self-reported health outcomes (Table 2). The number of medical visits for individuals who were exposed to radiation in the most contaminated region increased by 1.112 visits, and these individuals had a 7 percentage points higher chance of not being in good health. While we do not find differences in the effect of radiation on the number of medical visits between the less exposed regions and the least exposed areas, we do find that 10 We also estimated probit regressions for the binary variables “hospitalized,” “not good health,” “university,” and “employed” and obtained similar results. In order to address endogenous selection into employment, we estimated the wage equation using the Heckman (1979) selection model, where the selection equation included the “not good health” dummy variable in addition to all of the main regression equation variables. 13 individuals in the less contaminated regions have a 9 percentage points higher chance of not being in good health. While the probability of not being in good health is slightly higher among those living in the less exposed areas, compared to the most exposed region, the difference is not statistically significant. We do not find that the probability of being hospitalized is affected by the amount of radiation exposure, which may be due to the non-critical nature of the malignancies caused by the radiation in most people and the possibility that cancer patients are hospitalized at the time of the survey and so are unable to respond. Chernobyl’s lack of effect on the probability of hospitalization is in line with the corresponding finding in Almond et al. (2009). However, the radiation doses received by the treated group in that study were an order of magnitude smaller than the doses received by individuals in the most contaminated areas of Belarus. On the other hand, our findings of the negative effect of radiation on the other health measures are in accordance with Lehmann and Wadsworth (2009), who found a significantly positive association between a self-reported measure of poor health and residence in contaminated areas in 1986 for all adults living in Ukraine in 2003 and 2004. 11 There is evidence of a negative effect of radiation on education in the most contaminated region, which reduces the probability of having a college degree by 2.5 percentage points. While a negative effect of radiation is also present in the less contaminated areas, this effect does not attain statistical significance at the conventional levels. We also find a negative effect of radiation on the labor market outcomes, as shown in the last two columns of Table 2. 12 The probability of being currently employed reduces by 4.1 percentage points in the most exposed region. While 11 There is also a significant association between the dummy variable “influenced by Chernobyl” (=1 if a person reported being seriously or partially influenced by Chernobyl and zero otherwise) and all health measures in the years 1999-2002 (results not shown). This association gives further support to the hypothesis that the reported health problems were related to Chernobyl. Unfortunately, the survey does not elaborate on exactly how the person was influenced by Chernobyl, and this variable is not available in BHSIE after 2002. 12 Education variables were not included in the wage regression because they constitute “bad controls,” since they are “outcome variables in the notional experiment at hand” (Angrist and Pischke, 2009). In our case, since all of the individuals are under age 30 and many are still enrolled in secondary education or college, including education variables as controls could introduce selection bias. Furthermore, we are interested in the reduced effect of Chernobyl on earnings, including the part of this effect that works through education. 14 individuals living in the less contaminated regions have 5.7 percentage points reduction in employment probability, this effect is only marginally statistically significant (at the 10% level). We also observe a negative effect of radiation on wages for those living in the most contaminated region since there is a 5.5 percent reduction in the current wage at the main job for these individuals. The 2.9 percent reduction in wages for individuals living in the less contaminated regions is not statistically significant. The coefficients on the indicators “moved in 1986” and “moved after 1986” were insignificant in all regressions, supporting the hypothesis that migration is not an important predictor of our outcomes and that migration from the contaminated regions is unlikely to bias our results. Among the other regressors, the male dummy is the only highly statistically significant predictor of every outcome in our analysis, which could in part reflect the different labor market experiences of males and females. The industrial composition of employment in Belarus is very gender-specific, with males dominating the manufacturing and construction industries and females dominating healthcare, education, and service industries. Furthermore, the gender wage gap, which has been persistently high, more than doubled in Belarus between 1996 and 2004 (Pastore and Verashchagina, 2007). We explore the differences in the effect of radiation on health, education, and labor market outcomes by gender in Table 3. The estimates reveal some differences by gender in the negative effects of radiation on the outcomes. For example, the incidence rate of medical visits is higher in the most contaminated areas only for males, but both males and females have a higher probability of not being in good health in both the most and the less contaminated areas (the differences in the effects are not statistically significant between the genders in each type of area). Both males and females in the most contaminated region have a lower probability of having a university degree, with the effect being more pronounced among females. The largest differences in the effect of radiation are found in the labor market outcomes. While males are almost 6 percentage points less likely to be currently employed in the most contaminated region, the 15 corresponding effect among females is only 2 percentage points (the latter effect is only marginally statistically significant). The negative effect of radiation on wage appears to be present only among males in the most contaminated region, who suffer almost 10 percent reduction in their wages. Robustness of the results If different regions experienced pre-existing trends in the socio-economic development across age cohorts, our interaction variables would pick up these trends, and our results would reflect these trends rather than the effect of the Chernobyl accident. Even though Belarus has a relatively homogenous population, some regions may be historically less developed than others. We test for the possibility that differential trends drive our results using a falsification test where we obtained the main results using two unaffected groups: those who were five, six, or seven years old in 1986 (the pseudo-treatment group) vs. those who were nine, ten, and eleven years old in 1986 (another control group) (Table A1). Estimates on the interaction variables are not statistically significant except for the estimates for the outcome “not good health” and “employed,” which are significant only at the 5 percent level and have an unexpected sign. This result supports the validity of our identification strategy based on comparisons across age cohorts and regions. There is also a possibility of endogenous migration in response to the Chernobyl accident. If migrants had different characteristics than those of non-migrants, then the estimated coefficients on the interaction terms would pick up the effect of selective migration, thus biasing the effect of radiation on the outcomes. However, migration in the USSR, especially in the rural areas, was difficult because of the institution of “propiska,” which required individuals to be registered at their address of residence. In addition, there was a lack of public safety information on the adverse health effects of radiation after the accident.13 In an attempt to evaluate the 13 Notably, a May 1st parade was held as usual in Kiev, right after the catastrophe on April 26, 1986, only 90 km (about 56 miles) away from the burning power plant. Medvedev (1990) documented the lack of 16 influence of selective migration on our results, we used the 1999 Belarus Census data, which has information on migration, and compared the characteristics of migrants from their areas of birth with different levels of irradiation (Table A2). We did not find that migrants from the most contaminated region or from the less contaminated areas who moved after 1986 were systematically different from migrants from the least contaminated regions or from individuals who migrated before 1986 in terms of such characteristics as attainment of a university degree, being currently employed, having a professional occupation, having a white collar occupation, being married, and number of children. We also examined whether the population size of the regions changed in response to the disaster, but as Figure A1 shows, there is no evidence that the population of the most contaminated Gomel region declined in the decade from 1979 to 1989, which ends three years after the accident. In fact, it increased by a greater percentage than in any other region during this decade. The bottom panel of Figure A1, which plots population sizes by the areas that differed in their levels of contamination, reveals no evidence that the population trends after 1986 were related to the area-level contamination. 6. Conclusion The Chernobyl nuclear accident of 1986 had deleterious health consequences for the population of Belarus, especially for children under four years of age at the time of the disaster. This paper utilizes the natural experiment generated by this nuclear accident, which produced sizable increases in radiation levels in many areas of Belarus. Using the 2003-2008 waves of BHSIE, we estimate the effect of radiation on health, education and labor market outcomes by relying on differences in the amount of irradiation across age cohorts and across areas of Belarus. We find that children who were younger at the time of the accident and who came from the most information and slow response after the catastrophe, pointing out, for example, that “the population of Pripyat was not warned about the accident, nor were the civil defense headquarters informed. Since the civil defense staff had no information about the situation, they took no measures. As a result, the usual rhythm of life on Saturday proceeded …. The evacuation began only 36 hours later and was conducted according to a newly worked-out plan.” 17 contaminated Gomel region have significantly more medical visits, have a higher probability of not being in good health, and have a lower probability of having a university degree. They are also less successful in the labor market, where they have a lower probability of being employed and earn a lower wage. In addition, we find some evidence that the effect of radiation is not restricted to the most contaminated region: Younger children who lived in the less contaminated areas have a significantly higher incidence of not being in good health than those who lived in the least contaminated regions. Separate analysis by gender reveals that a higher incidence of medical visits resulting from radiation exposure is present only for males, who also appear to have lower rates of employment and to earn a lower wage than males from the least irradiated areas. Taken together, our results support the hypothesis that the effect of radiation on education and labor market outcomes can be attributed to the effect of radiation on health. There are several potential caveats to our analysis. First, a potential problem with the self-reported health measures is that individuals tend to assess their health by comparison to those in their immediate surroundings (e.g., parents, siblings, and friends). Therefore, children who come from affected families are likely to answer that their health is not bad by comparison. Furthermore, while reported poor health status may be due to the real impacts of exposure, it may also be a self-fulfilling prophecy since those who were exposed expect to have their health suffer and may become highly sensitive to any health issue. Our results on health measures are also consistent with the alternative hypothesis of psychological effect and parental stress, which may affect younger children more than older ones (Lehmann and Wadsworth, 2009). The current analysis does not consider the possibility of differential effects on child mortality by level of exposure, which would introduce “survivor bias” in our estimates. One example of such an effect occurs when wealthier people live farther from the plant so their children are more likely to survive. In addition, higher mortality among the affected population would tend to bias our estimates toward zero. However, according to the literature (Bespalchuk et al., 2007; Farahati et al., 2000; Balonov, 2007; Reiners et al., 2008), only a small fraction of the 18 population has developed thyroid cancer (only about five thousand cancer cases for a population of about 10 million by 2008), and very few of these patients have died. Most other affected people develop intermediate stages of thyroid disease, which do not significantly impact mortality rates but show up only in higher morbidity rates. Another caveat to our analysis is that parents and the government may have invested more resources in health and education in the more affected areas in order to offset the effect of irradiation (Almond et al., 2009).14 If unaccounted for, these investments would tend to bias the estimated effect of irradiation toward zero. Finally, while it is not possible to determine individuals’ place of birth and residence during childhood using the BHSIE data in order to address the issue of endogenous migration directly, the dataset does provide a unique opportunity to look at various health and socio-economic measures in the country that suffered most from the Chernobyl accident. 14 The government of Belarus created special privileges for applicants to secondary professional and higher educational institutions who were from the contaminated regions. For example, Law #9-3 of January 6, 2009, “on social protection of citizens who suffered from the Chernobyl and other radioactive disasters” (article 18 clause 7, article 21 clause 1.3, article 22 clause 1.3, article 23 clause 1.2) provides that people who participated in the liquidation of the consequences of the Chernobyl accident or who lived in the contaminated regions are entitled to preferential rights to obtain secondary, specialized, or higher education. 19 References Almond, D. (2006). "Is the 1918 Influenza Pandemic Over? Long-Term Effects of In Utero Influenza Exposure in the Post-1940 U.S. Population". Journal of Political Economy, 2006, Vol. 114, No. 4, pp. 672--712. Almond, D., Edlund, L., & Palme, M. (2009). "Chernobyl's Subclinical Legacy: Prenatal Exposure to Radioactive Fallout and School Outcomes in Sweden". Quarterly Journal of Economics, Vol. 124, No. 4, pp. 1729--1772. Angrist, J.D., & Pischke, J.-S. (2009). 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(2007) When Does Transition Increase the Gender Wage Gap? An Application to Belarus. IZA Discussion Paper No. 2796. Quastel, M.R., Goldsmith, J.R., Mirkin, L., Poljak, S., Barki, Y., Levy, J., & Gorodischer, R. (1997). "Thyroid-stimulating hormone levels in children from Chernobyl". Environmental Health Perspectives, Vol. 105, Suppl. 6, pp. 1497--1498. Reiners, C., Demidchik, Y.E., Drozd, V.M., & Biko, J. (2008). "Thyroid cancer in infants and adolescents after Chernobyl". Minerva Endocrinologica, Vol. 33, No. 4, pp. 381--395. Remennick, L.I. (2002). "Immigrants from Chernobyl-affected areas in Israel: the link between health and social adjustment". Social Science & Medicine, Vol. 54, No. 2 (Jan. 2002), pp. 309--317. Strauss, J., & Thomas, D. (1998). "Health, Nutrition, and Economic Development". Journal of Economic Literature, Vol. 36, No. 2, pp. 766--817. 21 UNDP (2002). "The Human Consequences of the Chernobyl Nuclear Accident: A Strategy for Recovery". A Report Commissioned by UNDP and UNICEF with the support of OCHA and WHO, 25 Jan. 2002. Vykhovanets, E.V., Chernyshov, V.P., Slukvin, I.I., Antipkin, Y.G., Vasyuk, A.N., Klimenko, H.F., & Strauss, K.W. (1997). "¹³¹I dose-dependent thyroid autoimmune disorders in children living around Chernobyl". Clinical Immunology and Immunopathology, Vol. 84, No 3, pp. 251--259. WHO (2006). "Health effects of the Chernobyl accident and special health care programmes". WHO, Geneva, ISBN 978 92 4 159417 2. 22 Table 1. Descriptive statistics. Variable N Mean SD Min Max Young Most affected Less affected YoungXMost affected YoungXLess affected 6504 6504 6504 6504 6504 0.52 0.16 0.48 0.08 0.25 0.5 0.36 0.5 0.27 0.44 0 0 0 0 0 1 1 1 1 1 Year Male Age Age square Year born Rural Big city Moved in 1986 Moved after 1986 6504 6504 6504 6504 6504 6504 6504 6504 6504 2005.51 0.49 23.43 556.36 1982.09 0.21 0.56 0.07 0.54 1.72 0.5 2.76 129.64 2.15 0.41 0.5 0.26 0.5 2003 0 18 324 1979 0 0 0 0 2008 1 29 841 1985 1 1 1 1 Number of medical visits Hospitalized Not good health University degree Currently employed Monthly wage in 2008$ 6504 6504 6504 6504 5392 4443 0.67 0.09 0.47 0.14 0.84 175.3 1.35 0.28 0.5 0.35 0.37 138.63 0 0 0 0 0 0 20 1 1 1 1 1391.43 Note: Authors’ calculations based on the BHBS. The estimates were adjusted using the BHBS sampling weights. 23 Table 2. The effect of radiation on health, education, and labor market outcomes. Medical visits Hospitalized Not good health University Employed Log Wages YoungXMost affected 1.112*** (0.039) -0.002 (0.004) 0.070** (0.024) -0.025*** (0.006) -0.041*** (0.003) -0.055*** (0.014) YoungXLess affected 1.036 (0.068) -0.006 (0.007) 0.092** (0.026) -0.107 (0.061) -0.057* (0.028) -0.029 (0.029) Young 1.049 (0.145) -0.001 (0.012) -0.037 (0.034) 0.033 (0.050) 0.053** (0.016) 0.128* (0.074) Most affected 1.236 (0.163) 0.013 (0.013) 0.107 (0.063) 0.033** (0.013) 0.006 (0.013) -0.056 (0.081) Less affected 1.188 (0.150) 0.002 (0.015) 0.082 (0.062) 0.090 (0.053) 0.015 (0.022) 0.046 (0.143) Age 0.768 (0.125) 0.002 (0.022) -0.058 (0.032) -0.028 (0.015) -0.092 (0.048) 0.930*** (0.122) Age square 1.006 (0.004) -0.000 (0.000) 0.001 (0.001) 0.001** (0.000) 0.002** (0.001) -0.017*** (0.003) Rural 0.801*** (0.049) -0.006 (0.009) -0.017 (0.037) -0.051** (0.015) -0.019 (0.011) -0.299*** (0.071) Big city 1.191* (0.123) -0.013 (0.011) 0.041 (0.050) 0.065*** (0.016) -0.008 (0.015) 0.100 (0.079) Male 0.576*** (0.023) -0.055*** (0.010) -0.043*** (0.011) -0.045*** (0.009) 0.030*** (0.007) 0.407*** (0.028) Moved in 1986 1.159 (0.120) -0.011 (0.019) -0.002 (0.020) -0.014 (0.013) 0.016 (0.031) -0.002 (0.132) Moved after 1986 1.069 (0.080) 0.006 (0.010) -0.012 (0.013) 0.012 (0.012) 0.029 (0.017) 0.101 (0.063) Observations R-squared Pseudo R-squared 6504 6504 0.012 6504 0.031 6504 0.157 5392 0.039 4443 0.193 0.011 Note: Authors’ calculations based on the BHBS. Significance levels: * p < 0.1, ** p < 0.05, *** p < 0.01. Standard errors in parentheses are adjusted for arbitrary heteroskedasticity and clustered by region. The estimates were adjusted using the BHBS sampling weights. Incidence rate ratios from negative binomial regression are reported for the outcome “Medical visits”, OLS coefficients are reported for the other outcomes. Estimates for the outcome “Log Wages” were obtained from the Heckman (1979) selection 24 model. Actual number of non-missing wage observations is shown. Year dummy variables are included in all regressions. See the text for the definition of all the variables. Table 3. The effect of radiation on health, education, and labor market outcomes by gender. Medical visits Hospitalized Not good health University Employed Log Wages YoungXMost affected 1.272*** (0.082) -0.011* (0.005) 0.045*** (0.009) -0.010** (0.004) -0.059*** (0.003) -0.096*** (0.019) YoungXLess affected 0.950 (0.089) -0.012 (0.009) 0.074*** (0.012) -0.076 (0.064) -0.085* (0.035) -0.040 (0.032) Observations 3174 3174 3174 3174 2644 2339 YoungXMost affected 1.014 (0.055) 0.006 (0.012) 0.097** (0.039) -0.033*** (0.009) -0.021* (0.009) -0.002 (0.050) YoungXLess affected 1.094 (0.085) 0.001 (0.021) 0.108* (0.045) -0.135* (0.058) -0.029 (0.029) -0.012 (0.061) Observations 3330 3330 3330 3330 2748 2104 A. Estimates for males B. Estimates for females Note: Authors’ calculations based on the BHBS. Significance levels: * p < 0.1, ** p < 0.05, *** p < 0.01. Only main coefficients are displayed. However, all models also include all of the variables from Table 3 and year dummies. Standard errors in parentheses are adjusted for arbitrary heteroskedasticity and clustered by region. The estimates were adjusted using the BHBS sampling weights. Incidence rate ratios from negative binomial regression are reported for the outcome “Medical visits”, OLS coefficients are reported for the other outcomes. Estimates for the outcome “Log Wages” were obtained from the Heckman (1979) selection model. Actual number of non-missing wage observations is shown. See the text for the definition of all the variables. 25 Figure 1. Degree of radioactive contamination and number of post-Chernobyl thyroid cancer cases in children and adolescents in the regions of Belarus. Source: Pacini et al. (1998). Note: The numbers in the figure refer to the number of thyroid carcinoma cases registered in each region of Belarus between May 1986 and December 1995 among individuals aged less than 21 years old. These numbers represent 97.7% of all thyroid carcinoma cases. The percentages of cancer cases in each region in the total number of cancer cases are indicated in parentheses. Figure 2. Estimated average thyroid doses for the age group 0–18 years in districts of Belarus. Source: Kruk et al. (2004), Figure 13. Note: The estimates are derived from a radioecological model based on cesium-137 local area depositions during the Chernobyl accident, the rainfall data for different regions of Belarus, and the iodine-131/cesium137 ratio in the deposit at the start of the grazing period in Belarus in April/May 1986. 26 Figure 3. Estimated average thyroid doses for the age group 0–18 years in all Belarus regions and in the cities of Gomel and Minsk. Source: Kruk et al. (2004), Figure 14. Note: The estimates are derived from a radioecological model based on cesium-137 local area depositions during the Chernobyl accident, the rainfall data for different regions of Belarus, and the iodine-131/cesium137 ratio in the deposit at the start of the grazing period in Belarus in April/May 1986. 27 Figure 4. Trends in the outcomes across single-year age in 1986, by area of exposure to radiation. Average percent with university degree 0 .5 .1 University degree .2 .3 Number of medical visits .6 .7 .8 .9 1 .4 Average number of medical visits 0 1 2 3 4 5 6 Most affected 7 8 9 Age in 1986 10 11 Less affected 12 13 14 15 0 1 2 Least affected 3 4 5 6 Most affected 10 11 12 Less affected 13 14 15 Least affected Average probability of being employed .06 .6 .08 Hospitalized .1 .12 Currently employed .7 .8 .14 .9 .16 Average probability of being hospitalized 7 8 9 Age in 1986 0 1 2 3 4 5 6 Most affected 7 8 9 Age in 1986 10 11 Less affected 12 13 14 15 0 1 2 Least affected 3 4 5 6 Most affected 10 11 12 Less affected 13 14 15 Least affected Average monthly wage in USD (base year 2000) .3 100 Not good health .4 .5 Monthly wage in 2008$ 150 200 .6 250 Average probability of not being in good health 7 8 9 Age in 1986 0 1 2 3 4 Most affected 5 6 7 8 9 Age in 1986 Less affected 10 11 12 13 14 15 Least affected 0 1 2 3 4 Most affected 5 6 7 8 9 Age in 1986 10 11 12 Less affected Note: Authors’ calculations based on the BHBS. “Most affected” area includes Gomel region; “Less affected” area includes Brest, Mogilev regions and Minsk city; and “Least affected” area includes Vitebsk, Grodno, and Minsk regions. 28 13 14 Least affected 15 Appendix Table A1. Falsification test of the effect of radiation using two older age groups. Medical visits Hospitalized Not good health University Employed Log Wages YoungXMost affected 0.835 (0.131) -0.005 (0.022) -0.073** (0.037) 0.028 (0.030) 0.024 (0.025) -0.075 (0.069) YoungXLess affected 1.188 (0.142) 0.004 (0.016) -0.036 (0.028) 0.015 (0.024) 0.038** (0.019) -0.010 (0.065) Observations R-squared Pseudo R-squared 6263 6263 0.015 6263 0.030 6263 0.079 6036 0.009 4891 0.166 0.012 Note: Significance levels: * p < 0.1, ** p < 0.05, *** p < 0.01. Only main coefficients are displayed. However, all models also include all of the variables from Table 3 and year dummies. Standard errors in parentheses are adjusted for arbitrary heteroskedasticity and clustered by region. The estimates were adjusted using the BHBS sampling weights. Incidence rate ratios from negative binomial regression are reported for the outcome “Medical visits”, OLS coefficients are reported for the other outcomes. Estimates for the outcome “Log Wages” were obtained from the Heckman (1979) selection model. Actual number of non-missing wage observations is shown. Year dummy variables are included in all regressions. See the text for the definition of all the variables. Table A2. Differences in the outcomes of migrants between affected and unaffected regions. Born in Gomel and out-migrated from Gomel after 1986 Born in Brest, Mogilev, or Minsk city and out-migrated after 1986 Observations R-squared University degree Employed Professional occupation White collar occupation Married Number of children -0.045 0.006 -0.007 -0.001 0.033 -0.029 (0.027) (0.031) (0.030) (0.001) (0.023) (0.071) -0.029 -0.082* -0.029 -0.002 -0.055 -0.225** (0.019) (0.037) (0.027) (0.001) (0.029) (0.085) 63572 0.010 63572 0.006 63572 0.006 63572 0.001 63572 0.018 36329 0.005 Note: Authors’ calculations based on the Belarusian Population Census of 1999. Significance levels: * p < 0.1, ** p < 0.05, *** p < 0.01. Standard errors in parentheses are adjusted for arbitrary heteroskedasticity and clustered by region. The estimates are obtained from linear regressions, where other regressors include dummies “Born in Gomel and out-migrated from Gomel”, “Born in Brest, Mogilev, or Minsk and outmigrated” and “Migrated after 1986”. Estimation sample includes only individuals who out-migrated from their region of birth. Question about the number of children was only asked to females. 29 Figure A1. Population trends by region and by area of exposure to radiation, 1969-2009. Note: Data for 1969-1999 is taken from the Statistical Yearbook of the Republic of Belarus, ed. 2002. Data for 2009 is taken from the National Statistical Committee of the Republic of Belarus web-site http://belstat.gov.by/homep/en/main.html, accessed on 05.25.2011. The vertical dashed line marks year 1986. 30
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