Investigating Mercury and Selenium Interactions in Sharks and Shark-Derived Products to Improve Health Risk Assessments

Authors

Laura Garcia Barcia, Florida International UniversityFollow

Document Type

Dissertation

Degree

Doctor of Philosophy (PhD)

Major/Program

Biology

First Advisor's Name

Demian D. Chapman

First Advisor's Committee Title

Co-Committee Chair

Second Advisor's Name

Michael R. Heithaus

Second Advisor's Committee Title

Co-Committee Chair

Third Advisor's Name

Heather Bracken-Grissom

Third Advisor's Committee Title

Committee Member

Fourth Advisor's Name

Elizabeth A. Babcock

Fourth Advisor's Committee Title

Committee Member

Fifth Advisor's Name

Yong Cai

Fifth Advisor's Committee Title

Committee Member

Keywords

Mercury, sharks, methylmercury, selenium, shark fin soup, arsenic, shark meat, ocean, health, risk assessment

Date of Defense

2-22-2023

Abstract

Shark meat and fin soup are commodities exported and consumed worldwide. Because sharks are large and slow growing predators they tend to accumulate a large amount of mercury in the form of methylmercury, a potent neurotoxicant, posing potential health risks to them and human consumers. Due to this, many nations have blanket advisories urging citizens to avoid consuming shark-derived products. Assessing the consumption health risks of different shark species is needed because these products can represent an important source of protein. In chapter II, I analyzed shark fins from mainland China and Hong Kong (HK) markets for mercury, methylmercury, and arsenic, to inform consumers, policy makers and public health officials on the health risks of ingesting fins from common shark species in the trade. Fins from all species frequently exceed Hg limits established by HK authorities. Species-of-origin was a significant predictor of heavy metal concentrations, with higher mercury concentrations associated with coastal sharks.

The distribution of mercury is not uniform in the ocean and its negative health effects can be mitigated by the presence of selenium. In chapter III, I investigated the factors influencing mercury, methylmercury, and selenium accumulation in a heavily fished upper trophic level predator: the bull shark (Carcharhinus leucas) in waters of the Gulf of Mexico and western North Atlantic. Mercury toxicity in bull sharks varies based on their location for the first few years of life. Juveniles in nurseries of southwest Florida had higher total mercury and methylmercury concentrations than those of Texas. Despite having higher mercury concentrations overall, the mercury toxicity risk is lower in large bull sharks because of the mitigating effects of selenium that accumulates faster they shift to a marine diet.

In chapter IV, I use health risk assessment calculations to investigate the risk of consuming shark fin soup and meat from commonly consumed species. While many shark fin and meat samples exceed maximum safe consumption limits suggested by governments, a more thorough assessment taking mode of consumption into account reveals a more nuanced risk profile. Results indicate that three species of large hammerhead shark should be avoided by consumers, especially by pregnant women.

Identifier

FIDC011017

ORCID

https://orcid.org/0000-0002-0402-7564

Previously Published In

Barcia, Laura Garcia, Juana Argiro, Elizabeth A. Babcock, Yong Cai, Stanley KH Shea, and Demian D. Chapman. "Mercury and arsenic in processed fins from nine of the most traded shark species in the Hong Kong and China dried seafood markets: The potential health risks of shark fin soup." Marine pollution bulletin 157 (2020): 111281.

García Barcia, Laura, Annette E. Valdes, Aljoscha Wothke, Lanya Fanovich, Ryan S. Mohammed, Stanley Shea, Cindy González, Yong Cai, and Demian Chapman. "Health Risk Assessment of Globally Consumed Shark-Derived Products." Exposure and Health (2022): 1-15.

Recommended Citation

Garcia Barcia, Laura, "Investigating Mercury and Selenium Interactions in Sharks and Shark-Derived Products to Improve Health Risk Assessments" (2023). FIU Electronic Theses and Dissertations. 5306.
https://digitalcommons.fiu.edu/etd/5306