Advertisement

Diet- and Mercury-induced Visual Loss

  • Cian E. Collins
Chapter

Abstract

Inorganic mercury in our environment is absorbed into our bodies in the form of organic methylmercury. Diet is the main source of methylmercury in people not involved in mercury-related industries. Our knowledge of the toxic effects of mercury poisoning is based on two major industrial accidents, which resulted in widespread illness, ranging from neurological disease such as ataxia and paraplegia up to seizures and death. Visual symptoms reported from the aftermath of these accidents include sudden cortical blindness, constricted visual fields, optic atrophy, and poor night vision. As the average person is exposed to much lower doses of mercury through their diet, the toxic effects on methylmercury are less clearly defined. With many other confounding factors associated with diet and exposure, we describe the different investigations that are used to examine changes in visual function associated with exposure to methylmercury. MRI and electrophysiological testing are described and the abnormal findings associated with methylmercury toxicity are highlighted. Color vision testing can identify dyschromatopsia (color confusion) associated with mercury exposure and in some cases these changes persist for many years after exposure. We describe the recommended guidelines on fish consumption in place to limit exposure to mercury and other heavy metals. We discuss recent studies that look at fish consumption during pregnancy and the evidence on its effect on childhood neurodevelopment. Finally, we emphasize that on balance, the positive benefits of fish consumption outweigh the risks associated with mercury exposure.

Keywords

Fish Consumption Visual Evoke Potential Inorganic Mercury Color Discrimination Mercury Exposure 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

Abbreviations

EPA

The Environmental Protection Agency

MR

Magnetic resonance

SCDS

The Seychelles Child Development Study

VEP

Visual evoked potential

References

  1. Bakir F, et al. Methylmercury poisoning in Iraq. Science. 1973;181:230–41.PubMedCrossRefGoogle Scholar
  2. Cavalleri A, Gobba F. Color vision impairment in workers exposed to neurotoxic chemicals fabriziomaria Gobba1, Alessandro Cavalleri. Neurotoxicology. 1998;24(2003):693–702.Google Scholar
  3. Davidson G, et al. Effects of prenatal and postnatal methylmercury exposure from fish consumption on neurodevelopment: outcomes at 66 months of age in the Seychelles Child Development Study. JAMA. Feb 17 1998;280(8):701–7.PubMedCrossRefGoogle Scholar
  4. Feitosa-Santana C, et al. Irreversible color vision losses in patients with chronic mercury vapor intoxication. Vis Neurosci. May-Jun 2008;25(3):487–91.PubMedCrossRefGoogle Scholar
  5. Gochfeld M. Cases of mercury exposure, bioavailability and absorption. Ecotoxicol Environ Saf. 2003;56:174–9.PubMedCrossRefGoogle Scholar
  6. Harada M. Minamata disease: methylmercury poisoning in Japan caused by environmental pollution. Crit Rev Toxicol. 1995;25(1):1–24, Review.PubMedCrossRefGoogle Scholar
  7. Korogi Y, Takahashi M, Shinzato J, Okajima T. Am J Neuroradiol. Sep 1994;15(8):1575–8.PubMedGoogle Scholar
  8. Korogi Y, Takahashi M, Hirai T, Ikushima I, Kitajima M, Sugahara T, Shigematsu Y, Okajima T, Mukuno K. Representation of the visual field in the striate cortex: comparison of MR findings with visual field deficits in organic mercury poisoning (Minamata disease). Am J Neuroradiol. Jun-Jul 1997;18(6):1127–30.PubMedGoogle Scholar
  9. Letz R, Gerr F, Cragle D, et al. Residual neurologic deficits 30 years after occupational exposure to elemental mercury. Neurotoxicology. 2000;21:459–74.PubMedGoogle Scholar
  10. Mozaffarian D, Rimm EB. Fish intake, contaminants, and human health: evaluating the risks and the benefits. JAMA. Oct 18 2006;296(15):1885–99.PubMedCrossRefGoogle Scholar
  11. Myers GJ, Davidson PW. Prenatal methylmercury exposure and children: neurologic, developmental, and behavioral research. Environ Health Perspect. 1998 Jun;106(Suppl 3):841–7, Review.PubMedCrossRefGoogle Scholar
  12. Myers GJ, Davidson PW. Maternal fish consumption benefits children’s development. Lancet. Feb 17 2007;369(9561):537–8.PubMedCrossRefGoogle Scholar
  13. Raymond LJ, Ralston NV. Mercury: selenium interactions and health implications. Seychelles Med Dent J. 2004;7:72–7.Google Scholar
  14. Risher JF. Too much of a good thing (fish): methylmercury case study. J Environ Health. Jul/Aug 2004;67(1):9–14.PubMedGoogle Scholar
  15. Saint-Amour D, et al. Alterations of visual evoked potentials in preschool Inuit children exposed to methylmercury and polychlorinated biphenyls from a marine diet. Neurotoxicology. 2006;27:567–78.PubMedCrossRefGoogle Scholar
  16. Saldana M, Collins C, Gale R, Backhouse O. Diet-related mercury poisoning resulting in visual loss. Br J Ophthalmol. 2006;90: 1432–4.PubMedCrossRefGoogle Scholar
  17. Seppanen K, Kantola M, Laatikainen R, et al. Effect of supplementation with organic selenium on mercury status as measured by mercury in pubic hair. J Trace Elem Med Biol. 2000;14:84–87.PubMedCrossRefGoogle Scholar
  18. Tsubaki T, Takahashi H. (editors) Recent advances in minimata disease studies: methylmercury poisoning in Minimata and Nigiita, Japan. Tokyo, Japan; 1986.Google Scholar
  19. Urban P, Gobba F, Nerudova J, Lukas E, Cabelkova Z, Cikrt M. Color discrimination impairment in workers exposed to mercury vapor. Neurotoxicology. 2003 Aug;24(4–5):711–6.PubMedCrossRefGoogle Scholar
  20. US Environmental Protection Agency. Controlling power plant emissions: emissions progress. Washington: US Environmental Protection Agency; 2009a. http://www.epa.gov/mercury.
  21. US Environmental Protection Agency. Mercury Study report to Congress. Washington: US Environmental Protection Agency; 2009b. http://www.epa.gov/mercury/report.htm.
  22. US Environmental Protection Agency. What you need to know about mercury in fish and shellfish. Washington: US Environmental Protection Agency; 2009c. http://www.epa.gov/waterscience/fishadvice/advice.html.
  23. Van Wijngaarden E, Beck C, Shamlaye CF, Cernichiari E, Davidson PW, Myers GJ, Clarkson TW. Benchmark concentrations for methyl mercury obtained from the 9-year follow-up of the Seychelles Child Development Study. Neurotoxicology. 2006 Sep;27(5):702–9.PubMedCrossRefGoogle Scholar
  24. Ventura DF, Costa MT, Costa MF, et al. Multifocal and full field electroretinogram changes associated with colour-vision loss in mercury vapour exposure. Visual Neurosci. 2004;21:421–9.CrossRefGoogle Scholar

Copyright information

© Springer Science+Business Media, LLC 2011

Authors and Affiliations

  1. 1.Princess Alexandra Eye PavilionEdinburghUK

Personalised recommendations