It is difficult to determine the individual arsenic species in order of their toxicity, because the toxicity of these chemical forms is very different not only in different organisms but even between organs. One factor that makes arsenic more interesting is that arsenic is an essential GSK-3 inhibition element for some animals, like rats and goats (Püssa, 2008 and Ratnaike, 2003) and interindividual susceptibility in humans to the adverse effects caused by arsenic compounds has been reported (Huang et al., 2004). The initiation and progression mechanisms of human carcinogenesis caused by arsenic

exposure are still not entirely clear (Shi, Shi, & Liu, 2004). However, chronic exposure to inorganic arsenic not only causes, but also can evoke hypertension, skin lesions, diabetes and cardiovascular disease and furthermore it can affect the vascular system (Hughes, 2002 and Jomova et al., 2011). Acute exposure to high levels of arsenic can cause cardiomyopathy, hypotension, gastrointestinal discomfort, vomiting, diarrhea, bloody urine, anuria, shock, convulsions, coma and in death

in the most severe cases (Hughes, 2002 and Jomova et al., 2011). According to the International Agency for Research Sirolimus on Cancer (IARC) arsenic is a class I carcinogen (International Agency for Research on Cancer, 1987). In 2004 IARC declared that arsenic could cause lung, skin and urinary bladder cancer in humans (International Agency for Research on Cancer, 2004). In 2010, the Joint FAO/WHO Expert Committee on Food Additives (JECFA) estimated that BMDL0.5 for inorganic arsenic species would be 3 μg/kg bw/day (Joint FAO/WHO Expert Committee on Food Tacrolimus (FK506) Additives, 2010). This conclusion replaced the old PTWI-value for inorganic arsenic (15 μg/kg bw/week) which had been established in 1989. The European Food Safety Authority (EFSA) set the BMDL0.1 value at 0.3 – 8 μg/kg bw/day in 2010

(European Food Safety Authority, 2010). At present, there are no regulations about organic or inorganic arsenic species in food or beverages except for that in drinking water. In 1993, WHO provided a reference value of 10 μg/L of total arsenic compounds in drinking water, previously the reference value had been set at 50 μg/L (World Health Organization, 1993). In 2008 the Data Collection and Exposure Unit (DATEX) of EFSA collected information on the arsenic levels in food from the EU member states and Norway (EFSA, 2010). According to the DATEX survey, the total arsenic level was highest in fish and seafood and miscellaneous dietary products. The miscellaneous group consisted of diverse foodstuffs, e.g. algae, algae based food supplements, spices, herbs, different baby foods and formulas. It is well-known that a significant part of total arsenic in fish and seafood exists in the organic arsenic forms, particularly arsenobetaine (Nam et al., 2010, Sloth et al., 2005 and Suner et al.