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Investigation of cyanobacterial blooms as an environmental risk factor for various cancer types

Gorham, Tyler James
http://rave.ohiolink.edu/etdc/view?acc_num=osu1494055981679989

Abstract Details

2017, Doctor of Philosophy, Ohio State University, Public Health.
Freshwater cyanobacterial blooms are on the rise globally and many species within these blooms are capable of producing cyanotoxins. Microcystin-LR (MC-LR) is one of the most prevalent and potent cyanotoxins around the world, as well as in Ohio, and ecological studies have found an association between primary liver cancer incidence and the presence of MC-LR in water sources used for human consumption. Additional evidence suggests a potential association between MC-LR and colorectal cancer in humans, but little work has been done to study the potential carcinogenicity of cyanotoxins in other organs beyond the liver. This dissertation seeks to contribute to what is known about the association between cyanobacterial blooms and cancer incidence at the population level through the following objectives: 1. Survey historic remote sensing data from the European Space Agency’s Envisat mission to study the occurrence and intensity of cyanobacterial blooms in water bodies that are detectable with satellite remote sensing across Ohio. 2. Examine the spatial heterogeneity of colorectal and pancreatic cancers in Ohio--the state’s second and third leading causes of cancer-related deaths--at the census tract level to study the importance of spatial resolution in spatial analyses of cancer incidence. 3. Create a series of generalized linear models to determine whether areas potentially served by cyanobacterial bloom-impacted surface water drinking water sources have higher cancer incidence rates than areas that rely on groundwater as a drinking water source. Our 10-year survey of cyanobacteria blooms in Ohio identified 78 waterbodies potentially impacted by cyanobacterial blooms; just 42 (54%) of which have any reported in situ microcystins measurement results from Ohio Department of Health and Ohio Environmental Protection Agency monitoring programs. Of concern for public health, 90% of the waterbodies identified reached bloom intensities representative of levels potentially hazardous to public health, based on estimated phycocyanin concentrations and current World Health Organization recreational water recommendations. Results of colorectal and pancreatic cancer cluster analyses at the census tract level identified 13 clusters of higher-than-expected colorectal cancer incidence, including many small clusters in Ohio’s major cities, as well as a single elevated cluster of pancreatic cancer incidence in Cleveland. Our findings support the use of census tract-level analyses as an improvement upon recent county-level analyses for the identification of areas of health disparity concerning cancer incidence within the state. Our negative binomial generalized linear models revealed that census tracts served by cyanobacteria bloom-impacted surface waters showed significantly higher hepatocellular carcinoma incidence rates compared to tracts served by groundwater (Incidence Rate Ratio [IRR]: 1.19; 95% Confidence Interval [CI]: 1.10-1.25). This was also true of testicular cancer incidence (IRR: 1.12; 95% CI: 1.01-1.23) and ovarian cancer incidence (IRR: 1.06; 95% CI: 1.00-1.10), though the results for these reproductive cancers were dependent upon the exposure classification method used. To our knowledge, this is the first ecological study to find a significant, positive association between cyanobacterial bloom-impacted drinking water sources and testicular and ovarian cancer incidence rate.
Jiyoung Lee, Ph.D. (Advisor)
Elisabeth Root, Ph.D. (Committee Co-Chair)
C. K. Shum, Ph.D. (Committee Member)
Randall Harris, M.D., Ph.D. (Committee Member)
Ayaz Hyder, Ph.D. (Committee Member)
127 p.
Public Health
cyanobacterial blooms; environmental risk factor for various cancer types

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Citations

  • Gorham, T. J. (2017). Investigation of cyanobacterial blooms as an environmental risk factor for various cancer types [Doctoral dissertation, Ohio State University]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=osu1494055981679989

    APA Style (7th edition)

  • Gorham, Tyler. Investigation of cyanobacterial blooms as an environmental risk factor for various cancer types. 2017. Ohio State University, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=osu1494055981679989.

    MLA Style (8th edition)

  • Gorham, Tyler. "Investigation of cyanobacterial blooms as an environmental risk factor for various cancer types." Doctoral dissertation, Ohio State University, 2017. http://rave.ohiolink.edu/etdc/view?acc_num=osu1494055981679989

    Chicago Manual of Style (17th edition)

osu1494055981679989
102
© 2017, all rights reserved.
This open access ETD is published by The Ohio State University and OhioLINK.
Release 3.2.12