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EC number: 231-901-9 | CAS number: 7778-39-4
- Life Cycle description
- Uses advised against
- Endpoint summary
- Appearance / physical state / colour
- Melting point / freezing point
- Boiling point
- Density
- Particle size distribution (Granulometry)
- Vapour pressure
- Partition coefficient
- Water solubility
- Solubility in organic solvents / fat solubility
- Surface tension
- Flash point
- Auto flammability
- Flammability
- Explosiveness
- Oxidising properties
- Oxidation reduction potential
- Stability in organic solvents and identity of relevant degradation products
- Storage stability and reactivity towards container material
- Stability: thermal, sunlight, metals
- pH
- Dissociation constant
- Viscosity
- Additional physico-chemical information
- Additional physico-chemical properties of nanomaterials
- Nanomaterial agglomeration / aggregation
- Nanomaterial crystalline phase
- Nanomaterial crystallite and grain size
- Nanomaterial aspect ratio / shape
- Nanomaterial specific surface area
- Nanomaterial Zeta potential
- Nanomaterial surface chemistry
- Nanomaterial dustiness
- Nanomaterial porosity
- Nanomaterial pour density
- Nanomaterial photocatalytic activity
- Nanomaterial radical formation potential
- Nanomaterial catalytic activity
- Endpoint summary
- Stability
- Biodegradation
- Bioaccumulation
- Transport and distribution
- Environmental data
- Additional information on environmental fate and behaviour
- Ecotoxicological Summary
- Aquatic toxicity
- Endpoint summary
- Short-term toxicity to fish
- Long-term toxicity to fish
- Short-term toxicity to aquatic invertebrates
- Long-term toxicity to aquatic invertebrates
- Toxicity to aquatic algae and cyanobacteria
- Toxicity to aquatic plants other than algae
- Toxicity to microorganisms
- Endocrine disrupter testing in aquatic vertebrates – in vivo
- Toxicity to other aquatic organisms
- Sediment toxicity
- Terrestrial toxicity
- Biological effects monitoring
- Biotransformation and kinetics
- Additional ecotoxological information
- Toxicological Summary
- Toxicokinetics, metabolism and distribution
- Acute Toxicity
- Irritation / corrosion
- Sensitisation
- Repeated dose toxicity
- Genetic toxicity
- Carcinogenicity
- Toxicity to reproduction
- Specific investigations
- Exposure related observations in humans
- Toxic effects on livestock and pets
- Additional toxicological data
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Endpoint summary
Administrative data
Description of key information
Additional information
There are no existing studies investigating the environmental fate of arsenic acid (AA), however there is an extensive array of published information on the environmental fate of arsenic (As). The published data on As has been previously compiled and reviewed in several published reviews. The technical dossier of AA compiles some of these reviews and recommendations. The relevant reviews/publications are listed here under:
-ATSDR, 2007, Toxicological profile for Arsenic, In: Agency for toxic substances and disease registry, Division of toxicology and environmental medicine/applied toxicology branch, 297, Atlanta, USA.
-Lepper P, Sorokin N, Maycock D, Crane M, Atkinson C, Hope S-J, Comber, S, 2007, Proposed EQS for Water Framework Directive Annex VIII substances: arsenic (total dissolved), Published by UK Environment Agency, Science report: SC040038/SR3, 101 p.
-United States Environmental Protection Agency (US EPA), 2004, Volume II - Geochemistry and Available Kd Values for Selected Inorganic Contaminants, In: Understanding Variation in Partition Coefficient, Kd, Values, Office of Air and Radiation, EPA 402-R-04-002C, July 2004, 188p.
-United States Environmental Protection Agency (US EPA), 2004, Technical Summary of Information Available on the Bioaccumulation of Arsenic in Aquatic Organisms, Office of Science and Technology, Office of Water, EPA-822-R-03-032.
-WHO, 2001, Arsenic and arsenic compounds, Environmental Health Criteria 224, United Nations Environment Programme, International Labour Organisation, World Health Organization, International Programme on Chemical Safety.
The environmental fate of arsenic species and bioavailability are influenced by environmental factors such as redox conditions, pH, and presence of ligands and biotransformations reactions. Irrespective of the species that As is introduced into the environment, the actual species present vary according to various reversible equilibria which are driven according to the local conditions. In addition, arsenic is a naturally occurring chemical which concentration varies greatly according to region.
Concentrations of As in the environment
The FOREGS Database provides the median concentrations of As in the environment: 6.02 mg/kg (subsoil), 7.03 (topsoil), 0.63 µg/L (water, filtered < 0.45 µm), 6 mg/kg (stream sediment, floodplain sediment). The FOREGS Data provide a present overview of As in the environment. Since they do not provide a historical variation, these concentrations cannot be considered as true natural background concentration. Furthermore, those concentrations include several fractions as bioavailable and non bioavailable ones.
Stability in contact with water
As(+5) is a thermodynamically stable form of As. In water and under aerobic conditions, arsenic acid exists as a mixture of arsenate ions based on its pKa:
H3AsO4 <-> H+ H2AsO4- pKa1=2.22
H2AsO4- <-> H+ + HAsO42- pKa2=6.98
HAsO42- <-> H+ + AsO43- pKa3=11.53
Considering the influence of pH alone, the protonated form H3AsO4 is the dominant form of arsenate at very low pH. Under most environmental conditions (pH 5 - 9), H2AsO4- and HAsO42- are the dominant forms of arsenate ions.
Stability in contact with light
Photolysis has no influence on the behaviour and transformation of arsenate in waters.
Biotransformation
Modes of biotransformation involve redox transformation between arsenite and arsenate, reduction and methylation of As, biosynthesis of organoarsenic compounds. The biomethylation and bioreduction are considered the most important pathways. Such biotransformation of As species occurs in the soil, in sediments, in plants and animals, and in zones of biological activity in the oceans.
Under aerobic conditions, the mixed microbial cultures of lake sediments were able to reduce arsenate (the predominant from of arsenic in water) to arsenite and a variety of methylated arsenicals, and also to oxidise arsenite to arsenate. Under anaerobic conditions, however, only reduction occurs.
Partitioning and distribution
Partitioning and distribution of arsenic will depend upon the oxidation state of arsenic and the interactions with the ligands present in the system. All forms of arsenic are adsorbed to most types of soil and sediment to a greater or a lesser degree. The following discussion aims to give an overview of the main current understandings.
Partitioning in water/sediment system
In water, As is mainly found in the particulate phase and it is suggested that sorption/desorption and co-precipitation processes are responsible of the regulation of the dissolved concentrations of As. Precipitation of As may occur with calcium, sulphur, iron, aluminium and barium unless these reactions are low. Adsorption is believed to be an important removal process of As from solution with 80% being removed on entering estuarine waters.
In aerobic conditions, As cycle in sediment is dominated by inorganic forms. Both adsorption of As on iron-rich oxides on the surface of sediments and incorporation of As into sediments by co-precipitation with hydrous iron oxides are factors controlling mobilisation of As in sediment. Aluminium compounds and organic matter have also been implicated in adsorption of As to sediments. The amount of arsenate adsorbed increases as the pH of the system increases. The major As species leached is arsenate which is found to be related to total iron and free iron oxides in the sediments. Finally, not all the adsorbed As is non bioavailable and it is expected that a fraction may be bioavailable to benthic organisms.
Partitioning in soil system
As compounds tend to adsorb to soils to a greater or a lesser degree being stronger adsorbed in clay soil than in sandy soil. The main factors that affect As adsorption to soil include: Fe and Al soil content, OC content, soil clay content, soil pH, phosphate concentrations and concentrations of other cations. Among them, the most influential factor is the iron content of the soil.
Under oxidizing conditions, leached As from soil is transported over only short distance. Therefore, leaching does not appear to be a significant route of As loss from soil. In agricultural soils, As is largely immobile and it tends to concentrate and remain in upper soil layers.
Under reducing conditions, arsenite compounds are dominant forms in soil but As(-3) and As(0) can also be present. As would be present as H2AsO4 - in well-drained and acids soil or as HAsO42 - in well-drained and alkaline soils. In the porewater of aerobic soils, arsenate is the dominant form of As. The amount of As sorbed from solution increases as the free iron oxide, magnesium oxide, aluminium oxide or clay content of the soil increases.
Transport
As is emitted to atmosphere as dust and fine particles which can be transported by winds and air prior to deposition to terrestrial compartment.
Bioaccumulation
As bioaccumulation depends on various factors such as the compartment considered (e.g. freshwater, seawater), the exposure concentration and the route of exposure. The range of BCF values for aquatic organisms suggest that As is accumulated to a greater or a lesser degree with fish BCF being generally below 2000. As does not appear to biomagnify between trophic levels.
Information on Registered Substances comes from registration dossiers which have been assigned a registration number. The assignment of a registration number does however not guarantee that the information in the dossier is correct or that the dossier is compliant with Regulation (EC) No 1907/2006 (the REACH Regulation). This information has not been reviewed or verified by the Agency or any other authority. The content is subject to change without prior notice.
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