| Mercury, Food Webs, and Marine Mammals: Implications of Diet and Climate Change for Human Health Shawn Booth and Dirk Zeller Fisheries Centre, University of British Columbia, Vancouver, British Columbia, Canada Abstract
We modeled the flow of methyl mercury, a toxic global pollutant, in the Faroe Islands marine ecosystem and compared average human methyl mercury exposure from consumption of pilot whale meat and fish (cod, Gadus morhua) with current tolerable weekly intake (TWI) levels. Under present conditions and climate change scenarios, methyl mercury increased in the ecosystem, translating into increased human exposure over time. However, we saw greater changes as a result of changing fishing mortalities. A large portion of the general human population exceed the TWI levels set by the World Health Organization [WHO ; 1.6 µg/kg body weight (bw) ], and they all exceed the reference dose (RfD) of 0.1 µg/kg bw/day set by the U.S. Environmental Protection Agency (EPA ; equivalent to a TWI of 0.7 µg/kg bw) . As a result of an independent study documenting that Faroese children exposed prenatally to methyl mercury had reduced cognitive abilities, pregnant women have decreased their intake of whale meat and were below the TWI levels set by the WHO and the U.S. EPA. Cod had approximately 95% lower methyl mercury concentrations than did pilot whale. Thus, the high and harmful levels of methyl mercury in the diet of Faroe Islanders are driven by whale meat consumption, and the increasing impact of climate change is likely to exacerbate this situation. Significantly, base inflow rates of mercury into the environment would need to be reduced by approximately 50% to ensure levels of intake below the WHO TWI levels, given current levels of whale consumption. Key words: climate change, Ecopath, Ecosim, Ecotracer, mercury, pollutant, trophic modeling. Environ Health Perspect 113:521-526 (2005) . doi:10.1289/ehp.7603 available via http://dx.doi.org/ [Online 2 February 2005]
Address correspondence to D. Zeller, Fisheries Centre, 2259 Lower Mall, University of British Columbia, Vancouver, British Columbia, Canada V6T 1Z4. Telephone: (604) 822-1950. Fax: (604) 822-8934. E-mail: d.zeller@fisheries.ubc.ca We thank V. Christensen, C. Walters, D. Pauly, and three anonymous reviewers for helpful comments ; D. Bloch for information on whaling ; and P. Weihe for human consumption patterns of Faroe Islanders. We acknowledge the support of the Pew Charitable Trusts (Philadelphia, PA) for initiating and funding the Sea Around Us project. The authors declare they have no competing financial interests. Received 24 September 2004 ; accepted 2 February 2005.
The full version of this article is available for free in HTML or PDF formats. |
