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Arsenic - As


Arsenic : N° CAS : 7440-38-2

- Atomic number : 33
- Atomic weight : 74,92
- Melting point: 817 °C
- Boiling point : 614 ℃


Arsenic is a widely spread trace element in the biosphere. Chemically it is characterized as a metalloid since it has both properties of metals and non metals. In some areas As-concentrations in soil or water are strongly enriched, either naturally, either as a result of human activities.

Arsenic (As)


Due to its toxic properties, environmental contamination with As is a matter of public concern; historically, the same properties made As the poison of choice for many murders.


Usefull human applications of As include the use of CCA as wood protection agent (application recently decreasing due to regulations), and its use as insecticide in agriculture. To a smaller extent As is used e.g. in glass and pigment industries, in electronic applications and in alloys. A number of As compounds was/is also used in medical applications (e.g. in anti-parasite and anti-cancer treatments). For this variety of applications arsenic is usually produced as a by-product of copper, lead, nickel or gold smelting (sulphide ores).

In compounds, arsenic typically exists in one of three oxidation states, -3, +3, and +5.


Arsenic compounds can be categorized as inorganic compounds (without an arsenic-carbon bond), and organic compounds (with an arsenic-carbon bond).


Speciation is of critical importance for arsenic compounds because the various species differ largely with respect to their toxicity. The toxicity of As species commonly found in food is generally reported to be in de order: arsenite (AsIII), arsenate (ASV), dimethylarsinic acid (DMA), monomethylarsinic acid (MMA), arsenobetaine (AsB).


During the past decades a lot of progress has been made in understanding the speciation and toxicity of As in food. While seafood contributes to a large extent to the total human As exposure (due to its high total As content), this As is almost exclusively present as arsenobetaine, a species which is not toxic.


Grains (e.g. rice or wheat) and vegetable crops on the contrary, have much lower total As concentrations, but a considerable fraction of this As is inorganic, which has a much higher toxicity.


Because of these differences, setting regulations for As-intake (maximum acceptable concentrations, tolerable intakes) based on total As concentrations is of little use.


Recent progress in lowering the quantification limits and accuracy of speciation methods may help to contribute to the possibility to take speciation aspects into account in future regulations. Arsenic (As)

Classification according to Regulation (EC) No 1272/2008 of 16 December 2008 :

Index number: 033-001-00-X
Acute Tox. 3*; H301: toxic if swallowed
Acute Tox. 3*; H331: toxic if inhaled
Aquatic Acute 1: H400: Very toxic to aquatic life
Aquatic Chronic 1; H410: Very toxic to aquatic life with long lasting effects.


Reference: Regulation (EC) No 1272/2008 of the European Parliament and of the Council of 16 december 2008 on classification, labeling and packaging of substances and mixtures, amending and repealing Directives 67/548/EEC and 1999/45/EC, and amending Regulation (EC) No 1907/2006. Official Journal of the European Union L353/1.


Maximum arsenic content in ambient air
Directive 2004/107/EC of the European Parliament and of the Council of 15 December 2004 relating to arsenic, cadmium (Cd), mercury (Hg), nickel and polycyclic aromatic hydrocarbons in ambient air.
Target value for arsenic in ambient air: 6 ng/m3.


Maximum arsenic content in products intended for animal feed
DIRECTIVE 2002/32/EC OF THE EUROPEAN PARLIAMENT AND OF THE COUNCIL of 7 May 2002 on undesirable substances in animal feed.


Products intended for animal feed

Maximum arsenic content in mg/kg (ppm) relative to a feedingstuff with a moisture content of 12 %

Feed materials with the exception of:
- meal made from grass, from dried lucerne and from dried clover, and dried sugar beet pulp and dried molasses sugar beet pulp
- phosphates and feedingstuffs obtained from the processing of fish or other marine animals
Complete feedingstuffs with the exception of:
- complete feedingstuffs for fish
Complementary feedingstuffs with the exception
-mineral feedingstuffs


Arsenic (As)

Restrictions on the marketing and use of arsenic

COUNCIL DIRECTIVE of 27 July 1976 on the approximation of the laws, regulations and administrative provisions of the Member States relating to restrictions on the marketing and use of certain dangerous substances and preparations (76/769/EEC)


Maximum arsenic content in water intended for human consumption
COUNCIL DIRECTIVE 98/83/EC of 3 November 1998 on the quality of water intended for human consumption.
The maximum arsenic content in water intended for human consumption is fixed at 10µg/L.


Tolerable human intake levels
Arsenic was last evaluated by JECFA at its thirty-third meeting in 1988 and a PTWI of 0.015 mg/kg body weight (bw) was established. A large amount of scientific data has become available since then, including epidemiological studies, which warrants a re-evaluation and review of the PTWI (will be discussed in Rome, February 2010).



Speciation research in the Trace Elements Unit at CODA-CERVA started in 2008, after the purchase of an LC-ICP-MS. This system allows the separation of different element species on a chromatographic column, followed by a quantification step by means of ICP-MS.



Arsenic speciation research is of particular importance because the various As species have different toxicities. Our activities related to As speciation in food include e.g. the development/optimisation of (a) method(s) for extraction and detection of five As species, being : arsenite (AsIII), arsenate (ASV), dimethylarsinic acid (DMA), monomethylarsinic acid (MMA) and arsenobetaine; the sampling and analysis of total As and As speciation in several different matrices such as sea fish, crustaceans, river fish, cereals and cereal products, root and bulb crops, drinks (wine beer, milk,...) and food supplements; the creation of a database containing As speciation data in food; and human risk evaluation for As based on the data in our database (e.g. comparison between actual intake based on Belgian diet and PTWI for inorganic arsenic-set by WHO (World Health Organization) at 0.015 mg/kg bw).


This research should also contribute to an improved insight in the possibilities of defining speciation based As- regulations.


This study is carried out as research contract from the FPS Public Health Food Chain Safety and Environment.

The "Trace Element" Unit at CODA-CERVA is mainly dedicated to scientific research and services in the field of food safety, public and animal health. We provide analytical facilities for third parties by the determination of trace elements in food and animal feed. The analyses of total Arsenic, Cadmium, Mercury and Lead (Pb) are accredited according to the European Quality norm ISO 17025. In the future As speciation analysis may become part of our services.


CODA-CERVA is the Belgian National Reference laboratory (NRL) for the determination of total trace element concentrations in food and animal feed.


Ann Ruttens
Nadia Waegeneers

Karlien Cheyns



- Ruttens, A., Blanpain, A.-C., De Temmerman, L. and Waegeneers, N. 2012. Arsenic speciation in food in Belgium. Part 1: fish, molluscs and crustaceans. Journal of the Geochemical Exploration, 121: pp. 55-61.