Thursday, October 23, 2014

Female Thyroid Cancer Rates near Nuclear Power Plants

I think this is my third post about the risk of living near nuclear power plants. Previous two posts on this topic are:
(1) Exposure to Radiation Causes Birth Defects or Abnormal Sex Ratios http://j.mp/Dangerous_Nuclear
(2) Infant Cancer Rates near Nuclear Power Plants http://j.mp/Infants_vs_NPPs

Now, let's go back to female thyroid cancer. The study I am citing here is two years old. But I think the results could explain the peculiar increase in thyroid cancer incidents in South Korea. According to the study:

In South Korea,
Thyroid cancer incidence in women in the exposed and Control-1 was as high as 2.5 and 1.8 times, respectively, than in Control-2 cohort. And the trend in risk was statistically significant (p for trend = 0.03).” (Ahn et al., 2012)
Note:
a. Exposed: the group living within a 5 km radius from the Nuclear Power Plants
b. Control-1: the inter-mediate proximity (5-30 km radius) group
c. Control-2: the far-distance (more than 30 km) group

It is NOT 2.5% or 1.8%, BUT 2.5 times and 1.8 times! If a woman is living within a 5 km radius from a nuclear power plant, she has 150% more possibility of getting thyroid cancer.

Thyroid cancer incidence among Korean females are definitely a serious concern. Let's see Table 1. Although the annual percentage change of overall cancer incidence was 5.4% over 1999-2011, that of thyroid cancer was unbelievably high 23.3%. If we are aware of the above study, researchers must find one of main causes of high thyroid cancer increase rate from the female patients' proximity to nuclear power plants.

Table 1. Trends in cancer incidence rates in females from 1999 to 2011 in Korea
Unit: Age-standardized incidence rate per 100,000
Site/Type1999200020012002200320042005200620072008200920102011APC
All sites61.1157.4169.0174.6184.3193.4207.816.4232.0249.0263.0273.6286.25.4%
Bladder1.61.61.71.71.81.71.71.61.71.61.61.51.5-0.8%
Brain and CNS2.62.52.52.42.52.62.82.72.92.72.62.72.40.3%
Breast20.920.924.727.227.829.332.033.335.637.138.740.443.86.3%
Cervix uteri16.315.115.814.814.213.112.412.211.111.510.610.810.1-4.0%
Colon and rectum16.416.417.918.820.521.523.024.124.525.126.326.026.44.5%
Corpus uteri2.82.63.03.33.83.73.94.04.24.75.15.15.36.1%
Esophagus0.60.60.60.50.60.50.40.50.50.50.40.40.4-2.6%
Gallbladder5.35.55.75.85.85.96.05.55.65.55.85.45.5-0.1%
Hodgkin lymphoma0.10.20.20.20.20.20.20.30.30.30.30.30.46.3%
Kidney1.71.81.92.02.12.22.52.72.83.03.23.03.46.0%
Larynx0.40.30.30.30.30.30.30.20.20.20.20.20.2-7.6%
Leukemia3.93.84.14.04.14.14.04.44.24.34.24.14.50.9%
Lip, oral cavity, and pharynx1.62.41.71.71.71.91.91.81.91.91.82.22.11.2%
Liver12.311.812.211.811.511.311.411.111.110.710.610.310.3-1.5%
Lung12.412.512.312.612.413.013.514.013.914.214.114.615.11.7%
Multiple myeloma0.80.80.90.81.01.01.21.11.21.21.21.31.13.9%
Non-Hodgkin lymphoma3.43.23.43.53.94.14.44.44.44.75.15.15.54.5%
Ovary5.04.84.85.05.15.25.45.45.95.65.45.85.71.6%
Pancreas4.04.04.04.24.54.54.74.74.84.94.95.05.12.2%
Stomach26.725.226.226.325.924.726.825.124.825.125.725.225.1-0.4%
Thyroid10.410.113.216.221.829.535.343.355.669.480.688.696.823.3%
Other and ill-defined11.811.511.811.512.813.113.914.114.814.914.815.515.73.0%
Source: Ahn et al. (2012)
Notes:
APC = annual percentage change (age-standardized)
CNS = central nervous system

Although there is no statistically significant evidence about overall cancer incident rate and proximity to nuclear power plants, I suspect that presence of nuclear power plants could be a clue how to explain Korea's skyrocketing cancer mortality, as manifested in the figure below. While the average OECD countries showed 15% decline in cancer mortality rates during the past two decades, South Korea showed 6% increase. It was the 2nd highest increase rate in the OECD.

According to an IAEA data, South Korea has the most number of nuclear reactors per unit land area (Table 2). Korean people have more chance of finding themselves living near a nuclear power plants than any other country in the world. South Korea might urgently need a comprehensive re-examination of the relationship between people's proximity to nuclear power plants and other kinds of cancer.

Maybe some people will ask a question,
"Why Belgium, the No. 2 country in terms of the reactor density per area in the world (Table 2), showed a decreasing cancer mortality rates in the figure below?"
I don't know. However, at least as for thyroid cancer, the country must be worried. In a recent study (Bollaerts et al., 2014), Belgian people living in the vicinity (20 km radius) of 3 nuclear sites (out of total 5 sites studied) have shown to have 15-47% more chance of getting thyroid cancer than the people living outside the radius. If the study has taken accounted for sex-specific incidence rates, female thyroid cancer rates might have been higher, I suspect.




Table 2. Reactors in operation, in long term shutdown, or under construction (as of December 31, 2013)
CountryReactors
in operation or
long term shutdown
Reactors
under
construction
TotalLand areaReactors per
land area
No. of unitsN. of unitsN. of unitskm2No. of units/
1000 km2
Korea, South2352897,1000.2884
Belgium7
730,2800.2312
Taiwan62836,1910.2210
Japan49251364,5000.1399
Switzerland5
540,0000.1250
Slovak Republic42648,0910.1248
France58159547,6600.1077
Czech Republic6
677,2400.0777
United Kingdom16
16241,9300.0661
Slovenia1
120,1400.0497
Hungary4
490,5300.0442
Armenia1
128,4800.0351
Netherlands1
133,7300.0296
Ukraine15217579,3200.0293
Germany9
9348,5700.0258
Sweden10
10410,3400.0244
United Arab Emirates02283,6000.0239
Bulgaria2
2108,5600.0184
Finland415303,9000.0165
Spain8
8498,8000.0160
United States10051059,147,4200.0115
India216272,973,1900.0091
Romania2
2230,0500.0087
Pakistan325770,8800.0065
China2029499,327,4900.0053
Belarus011202,9000.0049
World43672508129,710,3790.0039
Russia33104316,376,8700.0026
Canada19
199,093,5100.0021
South Africa2
21,213,0900.0016
Argentina21327366900.0011
Mexico2
21,943,9500.0010
Iran1
11,628,5500.0006
Brazil2138,459,4200.0004
Sources:
a. nuclear reactors: International Atomic Energy Agency (2014)
b. land area: The World Bank (2014)


References:

Ahn, Y.-O. et al. (2012). Cancer Risk in Adult Residents near Nuclear Power Plants in Korea - A Cohort Study of 1992-2010. Journal of Korean Medical Science, 27(9), 999-1008. [Full-text at http://dx.doi.org/10.3346/jkms.2012.27.9.999]

Bollaerts, K. et al. (2014). Thyroid cancer incidence in the vicinity of nuclear sites in Belgium, 2000–2008. Thyroid, 24(5), 906-917. [Full-text at http://dx.doi.org/10.1089/thy.2013.0227]

International Atomic Energy Agency. (2014). Nuclear Power Reactors in the World: 2014 Edition. Vienna, Austria: International Atomic Energy Agency. [Full-text at http://j.mp/NPRs_2014]

Jung, K.-W. et al. (2014). Cancer Statistics in Korea: Incidence, Mortality, Survival, and Prevalence in 2011. Cancer Research and Treatment, 46(2), 109-123. [Full-text at http://dx.doi.org/10.4143/crt.2014.46.2.109]

OECD. (2013). Health at a Glance 2013: OECD Indicators. Paris, France: OECD Publishing. [Full-text at http://dx.doi.org/10.1787/health_glance-2013-en]

The World Bank. (2014). World Development Indicators 2014. Washington, DC: The World Bank. [Data at http://j.mp/WDI_Data]

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