Abstract 4946: Liver disease risk: Cyanotoxins in water and food sources in Guam
Authors: Ella Marie Macatugal
Journal: Cancer Research (2025)

Abstract Liver cancer is the third most common cancer among males in Guam, where incidence rates are 2.6 times higher than the U.S. average. Rates of liver cancer among Pacific Islanders are even higher in comparison with incidence among Micronesians and CHamorus at 4.6 and 2.8 times greater respectively. Chronic liver disease, including non-alcoholic fatty liver disease (NAFLD), cirrhosis, which serve as risk factors for hepatocellular carcinoma (HCC), account for a significant health burden in Guam’s Asian American and Pacific Islander (AAPI) population. This health disparity has consistently plagued the community for decades and its cause remains unknown. Emerging evidence implicates microcystins (MCs), liver-damaging toxins produced by cyanobacteria, as a potential environmental contributor to liver disease and HCC prevalence. MCs are widespread in tropical freshwater and marine ecosystems and can bioaccumulate in human biospecimens (serum, saliva, and urine). In preliminary studies, MCs have been detected in residents of Guam and Hawaii. This study served to more comprehensively quantify sources of MCs in food and water sources on Guam while also examining the correlation between MC levels in human biospecimens and primary sources of drinking water and produce. This study analyzed water and produce samples from residents of Guam who participated in a previous University of Guam Liver Study and consented to follow-up research (CHRS#: IRB-21-110). Participants completed detailed surveys regarding their drinking water sources (tap, filtered, or store-bought), village of residence, and the top three fruits and vegetables they consumed. Each participant provided samples of their tap and drinking water, while produce consumption patterns guided the collection of local and imported produce. MCs in water and produce samples were quantified using the Abraxis Microcystins-ADDA SAES ELISA, a sensitive assay for detecting microcystin congeners. Tap water samples were more frequently MC-positive compared to filtered water. Detectable levels of MCs were found in both locally sourced produce and imported produce, highlighting multiple routes of exposure. A moderate positive correlation was also observed between participants’ serum MC levels and the MC content of their water samples. Although MC concentrations in water and produce were generally minute, the potential for bioaccumulation is significant, particularly given the elevated levels detected in serum samples. These findings suggest that chronic exposure to MCs through tap water and produce consumption may contribute to liver disease disparities in Guam’s AAPI communities. Further research is warranted to examine how these environmental toxins may contribute to the etiology of liver disease in this community, providing critical insights to inform public health interventions aimed at reducing exposure and mitigating health disparities. Citation Format: Ella Marie Macatugal. Liver disease risk: Cyanotoxins in water and food sources in Guam [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2025; Part 1 (Regular Abstracts); 2025 Apr 25-30; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2025;85(8_Suppl_1):Abstract nr 4946.