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Toxic inorganic arsenic species found in Japanese seaweed food


It is common believing that arsenic in different seafood products is mainly present as organoarsenic compounds of low toxicity such as arsenobetaine, arsenocholine and arsenosugars. Inorganic arsenic species such as arsenite and arsenate are highly toxic and are considered to be cancerogen and therefore cannot be tolerated in food products.

Hijiki (hizikia fusiforme) is a brown sea vegetable growing wild around the coasts of Japan and China. It is a traditional food and has been freely sold and used as part of a balanced diet in Japan for centuries. Hijiki is known to be rich in dietary fibre and essential minerals and according to Japanese folklore hijiki aids health and beauty and the thick, black, lustrous hair of the Japanese is connected to this regular consumption of small amounts of hijiki. Hijiki has been sold in UK natural products stores for 30 years and hijiki's culinary uses have been adopted in the West.

In 2001 the Canadian Food Safety Authorities expressed their concern about inorganic arsenic found in Hijiki. 3 years later the UK Food authorities "alerted" by their Canadian collegues also advised the consumers not to eat Hijiki. Actually the information about inorganic arsenic in Hijiki is even older: In 1997 the Japanese Environmental Research Institute had issued the Certified Reference Material NIES No-14 made from Hijike that came with certified inorganic arsenic levels. First reports about in organic arsenic in brown algae have appeared in 1990 (see below).

The question is, how risky is the consumption of Hijiki for the human conumer ?

The new study:
To clarify the risks of Hijiki ingestion, a multidisciplinary group of japanese researchers designed an experiment in which a 42-year-old male volunteer ingested 825 µg of iAs compounds contained in eight servings of commercial Hijiki food, after refraining from eating seafood for 3 months. In order to determine the distribution of arsenic species in his urine, arsenic compounds were determined by arsenic speciation analysis using HPLC-ICP-MS. The results of this experiment are published in the september issue of Applied Organometallic Chemistry. The maximum concentrations of arsenate (AsV), arsenite (AsIII), monomethylarsonic acid (MMA) and dimethylarsinic acid (DMA) were found at 4, 6.5, 13 and 17.5 h after ingestion, respectively. Arsenobetaine concentration was very low, and almost constant throughout the observation period. A total of 28% of ingested arsenic was excreted in urine. The total amounts of AsV, AsIII, MMA and DMA excreted in urine over 50 h were 11.2, 31.8, 40.9 and 104.0 µg, respectively. After eating one serving of Hijiki, arsenic intake and urinary excretion were at levels similar to those in individuals affected by arsenic poisoning. The researchers concluded that long-term ingestion of Hijiki might thus have the potential to cause arsenic poisoning.

There is an important body of evidence that especially certain brown algae do contain high amounts of arsenic with varying speciation including toxic inorganic species (see the literature below) depending on the particular algae species and growing conditions (season). Inorganic arsenic is considered to be cancerogen and therefore should not be tolerated in foodstuff for human consumption. Toxins in food is believed to be one of the major sources for the development of cancer in humans. Therefore the precautional principle should guide the food authorities to ban such food from the market. The argument that such food has traditionally been used with no "bad signs" is not a good argument, because the development of cancer is not something that can be recognized without very detailed and lengthy studies which because of ethic reasons cannot be easily performed.

Michael Sperling

The original study:

Yoshiaki Nakajima, Yoko Endo, Yoshinori Inoue, Kenzo Yamanaka, Koichi Kato, Hideki Wanibuchi, Ginji Endo, Ingestion of Hijiki seaweed and risk of arsenic poisoning, Appl. Organomet. Chem., 20 (2006) 557-564. doi:10.1002/aoc.1085

Related studies:

M. Morita, Y. Shibata, Chemical form of arsenic in marine macroalgae, Appl. Organomet. Chem., 4/3 (1990) 181-190. doi: 10.1002/aoc.590040303

J. Yoshinaga, Y. Shibata, T. Horiguchi, M. Morita, NIES certified reference materials for arsenic speciation, Accred. Qual. Assur., 2/3 (1997) 154-156. doi: 10.1007/s007690050122

Doris Kuehnelt, Kurt J. Irgolic, Walter Goessler, Comparison of three methods for the extraction of arsenic compounds from the NRCC standard reference material DORM-2 and the brown alga Hijiki fuziforme, Appl. Organomet. Chem., 15/6 (2001) 445-456.  doi: 10.1002/aoc.189

K. Hanaoka, K. Yosida, M. Tamano, T. Kuroiwa, T. Kaise, S. Maeda, Arsenic in the Prepared Edible Brown Alga Hijiki, Hizikia fusiforme, Appl. Organomet. Chem., 15/6 (2001) 561-565. doi: 10.1002/aoc.195

A. Geiszinger, Walter Goessler, S.N. Pedersen, Kevin A. Francesconi, Arsenic Biotransformation by the Brown Macroalga Fucus Serratus, Environ. Toxicol. Chem., 20/10 (2001) 2255-2262. doi: 10.1897/1551-5028(2001)020<2255:ABBTBM>2.0.CO;2

R. Tukai, W.A. Maher, I.J. McNaught, Michael J. Ellwood, M. Coleman, Occurence and chemical form of arsenic in marine macroalgae from the east coast of Australia, Mar. Freshwater Res., 53 (2002) 971-980. doi: 10.1071/MF01230

Ute Kohlmeyer, Jürgen Kuballa, Eckard Jantzen, Simultaneous separation of 17 inorganic and organic arsenic compounds in marine biota by means of high-performance liquid chromatography/inductively coupled plasma mass spectrometry, Rapid Commun. Mass Spectrom., 16/10 (2002) 965-974.  doi: 10.1002/rcm.671

Wei-hua Li, Chao Wei, Chao Zhang, Marijn Van Hulle, Rita Cornelis, Xin-rong Zhang, A survey of arsenic species in Chinese seafood, Food Chem. Toxicol., 41 (2003) 1103-1110. doi:10.1016/S0278-6915(03)00063-2

Ute Kohlmeyer, Eckard Jantzen, Jürgen Kuballa, Sandra Jakubik, Benefits of high resolution IC-ICP-MS for the routine analysis of inorganic and organic arsenic species in food products of marine and terrestrial, Anal. Bioanal. Chem., 377/1 (2003) 6-13. doi: 10.1007/s00216-003-2064-1

Daniele Fattorini, Carlos M. Alonso-Hernandez, Misael Diaz-Asencio, Alain Munoz-Caravaca, F.G. Pannacciulli, M. Tangherlini, F. Regoli, Chemical speciation of arsenic in different marine organisms: Importance in monitoring studies, Mar. Environ. Res., 58 (2004) 845-850.  doi:10.1016/j.marenvres.2004.03.103

Sathrugnan Karthikeyan, Shizuko Hirata, Ion chromatography-inductively coupled plasma mass spectrometry determination of arsenic species in marine samples, Appl. Organomet. Chem., 18/7 (2004) 323-330. doi: 10.1002/aoc.642

Andrea Raab, Peter Fecher, Jörg Feldmann, Determination of Arsenic in Algae - Results of an Interlaboratory Trial: Determination of Arsenic Species in the Water-Soluble Fraction, Mikrochim. Acta (Wien), 151/3-4 (2005) 153-166. doi: 10.1007/s00604-005-0395-7

Ferdi L. Hellweger, Dynamics of arsenic speciation in surface waters: As(III) production by algae, Appl. Organomet. Chem., 19/6 (2005) 727-735. doi: 10.1002/Aoac.894

Volker Nischwitz, Spiros A. Pergantis, Improved Arsenic Speciation Analysis for Extracts of Commercially Available Edible Marine Algae Using HPLC-ES-MS/MS, J. Agri. Food Chem., 54/18 (2006) 6507-6519. doi: 10.1021/jf060971j

Volker Nischwitz, Katerina Kanaki, Spiros A. Pergantis, Mass spectrometric identification of novel arsinothioyl-sugars in marine bivalves and algae, J. Anal. At. Spectrom., 21/1 (2006) 33. doi: 10.1039/b509111j

S.G. Salgado, M.A. Quijano Nieto, M.M. Bonilla Simon, Optimisation of sample treatment for arsenic speciation in alga samples by focussed sonication and ultrafiltration, Talanta, 68/5 (2006) 1522-1527. doi:10.1016/j.talanta.2005.08.004

Concepción Almela, M. Jesús Clemente, Dinoraz Vélez, Rosa Montoro, Total arsenic, inorganic arsenic, lead and cadmium contents in edible seaweed sold in Spain, Food Chem. Toxicol., 44/11 (2006) 1901-1908. doi:10.1016/j.fct.2006.06.011

Satoshi Ichikawa, Michiko Kamoshida, Ken'ichi Hanaoka, Megumi Hamano, Tamio Maitani, Toshikazu Kaise, Decrease of arsenic in edible brown algae Hijikia fusiforme by the cooking process, Appl. Organomet. Chem., 20/9 (2006) 585-590. doi: 10.1002/aoc.1102

Shin'ichi Miyashita, Kenji Kinoshita, Yumiko Yamashita, Emiko Okazaki, Toshikazu Kaise, Decrease of Mineral Components in Hijiki by Soaking in Water and Warm Water, Trace Nutrients Res., 23 (2006) 42-46. available at: http://www.jtnrs.com/sym23/23_042.pdf

Eric Amster, Asheesh Tiwary, Marc B. Schenker, Case Report: Potential Arsenic Toxicosis Secondary to Herbal Kelp Supplement, Environ. Health Perspect., 115/4 (2007) 606-608. doi:10.1289/ehp.9495

Related information:

UK Food Standards Agency, July 28 2004: Seaweed warning 
ATSDR: Case Studies in Environmental Medicine: Arsenic Toxicity Exposure Pathways

Related News:

EVISA News, August 25, 2004: Toxicity of organoarsenicals revisited
Sydney Morning Herald, November 22, 2004: Arsenic fear puts seaweed off the menu at trendy eateries
EVISA News, February 8, 2005: The use of arsenic in "poultry industry"
EVISA News, August 3, 2005: Surprisingly high concentrations of toxic arsenic species found in U.S. rice
EVISA News, April 6, 2006: Testing finds: Arsenic added to feedstuff finds its way into chicken meat
EVISA News, September 7, 2006: New Agilent HPLC column for routine determination of arsenic species in human urine by HPLC-ICP-MS
HealthNewsDigest, April 5, 2007: Study Finds High Arsenic Levels in Herbal Kelp Supplements
American Herbal Products Association, April 25, 2007: AHPA Challenges Kelp Product Case Report

last time modified: December 5, 2007

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