Data from: Uranium and Radium in groundwater and incidence of colorectal cancer in Georgia counties, USA: An ecologic study

Published Oct 10, 2024 on Dryad. https://doi.org/10.5061/dryad.b5mkkwhnz

Data files

Oct 10, 2024 version files 147.67 KB

Georgia_County_Data_July_2024_Deidentified.xlsx
143.28 KB
README.md
4.38 KB

Abstract

Colorectal cancer (CRC) is the third most commonly occurring cancer in the United States, with higher incidence rates among Black populations. Groundwater concentrations of natural radionuclides uranium and radium have seldom been investigated in relation to CRC despite their known carcinogenicity. We investigate spatial patterns of CRC by race, and in relation to groundwater concentrations of uranium and radium, testing the hypothesis that uranium and radium in groundwater might differentially contribute to incident CRC in Black and White populations in counties of Georgia, USA. Black populations showed higher incidence of CRC than White populations; the median incident rate difference was 9.23 cases per 100,000 (95% CI: 2.14, 19.40). Spatial cluster analysis showed high incidence clusters of CRC in similar regions for Black and White populations. Linear regression indicated there are, on average, 1-2 additional cases of colorectal cancer in counties with higher levels of radium in their groundwater, irrespective of race. Uranium was not associated with CRC. This ecologic study suggests that radium in groundwater may be linked with increased incidence of CRC, although it did not explain higher CRC incidence rates in Black populations. Further studies are needed to verify this association given the inherent limitations in the ecologic study design and the crude exposure assessment.

https://doi.org/10.5061/dryad.b5mkkwhnz

Description of the data and file structure

Datasets publicly available online and supplied by the Georgia Cancer Registry were accessed for colorectal cancer incidence rates in Georgia, 1999-2008 (http://cancer-rates.info/ga/). Incident cases by sex and race were downloaded along with age-adjusted population for each sex and race group, using the year 2000 as the standard. Data were organized into nine different groupings: all cases; all males; all females; all Black individuals; all White individuals; White males; White females; Black males; and Black females.

Drinking water uranium and radium concentrations at the county level were reported by US Geological Survey (USGS) in 2003 [12]. Uranium concentrations were categorized in two ways: as above or below 27 pCi/L which is equivalent to the maximum contaminant limit (MCL) in drinking water set by the US Environmental Protection Agency (EPA); and above or below 270 pCi/L, a value 10 times the MCL. The combined radium 226 and 228 isotopes were categorized as above or below 5 pCi/L, the USEPA drinking water MCL. Counties were coded based on the presence of at least one sample that exceeds pre-defined cutoff values. There were 628 uranium analytical results, including 192 resulting in concentrations higher than 27 pCi/L and 7 counties with at least one sample of uranium concentration higher than 270 pCi/L [12]. Of the 955 total results of combined radium-226 and 228, 476 had concentrations greater than 5 pCi/L [12].

Covariates at the county-level were also downloaded from year 2000 US census data [13] These include: median household income (HHI); and rural or urban classification [14]. We also were able to download county risk factor rankings from countyhealthrankings.org; earliest data available were from 2010. Each county receives a score based on many factors including smoking, obesity, alcohol use, physical activity, community resources, access to care, among others; 2 counties were missing data. As a sensitivity analysis, we also adjusted for this county risk factor ranking.

Files and variables

File: Georgia_County_Data_July_2024.xlsx

Description:

Variables

B=black; W=white; M=male; F=female
Missing data are identified by a blank space, or by a “.”
Rural/Urban (1=rural; 2=urban)
uranium and radium data 1=yes; 2=no): Uranium > 27 picocuries per liter; Uranium > 270 picocuries per liter; Combined Radium-226/Radium-228 > 5 picocuries per liter
covariates on “health outcomes” and “health factors” (Z-score and rank are provided)
colorectal cancer incidence data for total population (All), Black population (All B), White population (All W), Male population (All M), Female population (All F), Black male population (BM), White male population (WM), Black female population (BF), and White female population (WF): variables for each grouping are – population at risk, cases, crude rate, age-adjusted rate, 95% confidence interval (of age-adjusted rate), age-adjusted population.

Code/software

Microsoft Excel can be used to view the data file.

Data were derived from the following sources:

http://cancer-rates.info/ga/
Ref 12. Albertson, P.N. (2003) Naturally occurring radionuclides in Georgia water supplies: Implications for community water systems. In: Hatcher, K.J., Ed., Proceedings of the 2003 Georgia Water Resources Conference, Athens, Georgia.
Ref 13. United States Census, 2024. Profile of Selected Economic Characteristics: 2000, DP3 https://data.census.gov/table/DECENNIALDPSF32000.DP3?q=2000%20georgia%20county%20median%20household%20income&g=040XX00US13$0500000. Accessed July 15, 2024.
Ref 14. Georgia Department of Community Health, 2021 Georgia Rural Counties Map, https://dch.georgia.gov/divisionsoffices/state-office-rural-health/sorh-maps-georgia. Accessed July 15th, 2024.