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EC number: 231-843-4
CAS number: 7758-94-3
If the submission item category member soluble iron salts will
-following the supported uses- arrive in environmental waters, they will
after transformation steps be present as an equilibrated mixture of
chemical species, which depend on the geochemical conditions in the
waters, sediments and soils, while the original oxidation state and the
counteranions are irrelevant. Therefore the submission category is well
justified as demonstrated in the section on physical and chemical
properties, where the data are presented in the Reporting Format for the
Chemical Category according to ECHA Guidance on QSARs and grouping of
chemicals (2008, R.184.108.40.206).
For the purpose of the EURAS critical review a significant literature
screening was conducted (Vangheluwe & Versonnen 2004). Another
literature review and evaluation was performed by the U.K. environmental
agency (Johnson 2007).
The effects in short-term tests are observed at nominal exposure
concentrations in the range 10 – 1000 mg/L salt with the majority being
in the range 10 – 100 mg/L. Effects arising from long-term exposures are
observed at nominal concentrations in the order of 1 - 10 mg/L. At all
of these concentrations it can be expected that, under the test
conditions, most of the iron will be present as undissolved and
precipitated ferric hydroxide. It is therefore highly likely that
observed effects on fish and invertebrates will be due to smothering or
clogging of the gills or respiratory membranes. Filtrating organisms
like daphnids would ingest precipitating particles and therefore by
unable to feed normally. Effects on aquatic plants and algae will be due
to impairment of photosynthesis by light interception. Growth of aquatic
plants and algae can also be inhibited as a consequence of nutrient
As discussed in the section on Sediment and Soil Toxicity, the
submission category belongs to the lowest “soil hazard category 1” and
thus the straightforward application of the EPM for derivation of PNECs
for sediments and soils is enabled, but as no aquatic PNECs were derived
this is obsolete and no PNECs for sediments or soils are required.
The effects of iron salts to the aquatic life have been assessed earlier
by Johnson et al (2007) with the result that no meaningful threshold
level can be derived. On the basis of these data and the ones in the
review of Vangheluwe & Versonnen (2004) the lack of intrinsic toxicity
to aquatic, sediment and terrestrial organisms is considered.
Accordingly absence of relevant effects to sediment and terrestrial
organisms (U.S. EPA OSWER 2003) can be concluded. However a large number
of publications report effects, none of the experimental approaches
fulfils the Hill (1965) criteria for causation of intrinsic toxicity.
These criteria were first published by Austin Bradford Hill (1965)
establishing cause and effect in medical diagnosis and are generally
accepted for reasoning and assessing causation. Nine factors are to
consider “before we cry causation” (Hill 1965, p 299):
Table: Overview on the Hill criteria of causation (Hill 1965)
A correlation coefficient of 1 indicates maximum strength of the association between the supposed cause and effect and the closer the actual value the more causation is supported.
Consistency(between observations in nature and experiment)
The agreement of different observations in nature and experimental settings covering a wide range of circumstances is desirable and supports causation.
Specificity(monocausation of effects)
The assumption of causation is supported if the relationship is specific, i.e. if there is no other plausible explanation of the observable effects.
Temporality(time relationship between treatment and effect)
A close time relationship between the supposed cause and the observed effects are postulated unless the mode of action explains different circumstances.
Biological gradient(clear dose response relation)
The dose-response relationship should show a clear dose dependency of the observed effects. Nonetheless this does not need to be a simple linear relationship and may have minimum and maximum thresholds, excursive characteristics in the mid-range argue against monocausation.
Plausibility(mode of action model desirable)
This is a feature that cannot be demanded however it supports causation to have an idea of the relevant mode of action.
Laboratory experiments and external everyday evidence should be in alignment.
Experiment(to confirm epidemiologic correlations)
Evidence from experiments should be used to confirm epidemiologically based assumptions whenever possible.
Analogy(analogue causation must be excluded)
When something is suspected of causing an effect, then other factors similar or analogous to the supposed cause should also be considered and identified as a possible cause or otherwise eliminated from the investigation.
Checking the criteria 2 and 3 in the studies for aquatic ecotoxicology
revealed relevant inevitable weaknesses of the available laboratory
tests (Johnson et al 2007, Vangheluwe & Versonnen 2004) and possible
future experiments for ecotoxicological endpoints with soluble iron
salts. Considering the unavoidableness of these problems standard
testing is not insightful for assessing the aquatic environmental
hazards and an adequate amendment of the protocol seems technically not
Regarding the Consistency (criterion 2) the appropriate choice of the
test organisms should be regarded. Generally standardized laboratory
organisms were used in such studies. These clones were bred over
generations in media composed on the basis of their needs rather than
natural background concentrations of metal species, which were actively
incorporated and specific bio-regulation applies. Thus the normal
acclimation and adaptation gets lost. This constitutes an artificial
situation as metals are naturally occurring in significant levels. It is
in consequence questionable if laboratory animals are the relevant
representative organisms of the three main trophic levels of the aquatic
environment (micro-organisms are assumed to be less concerned) under
these circumstances. The lack of consistency between non-anthropogenic
natural background concentrations and aquatic effect or threshold levels
of toxicity in tests is critical. An environmental threat may be not
caused by these levels as contingent effects base on an artefact
produced by sudden exposure of inadequate test organisms, which may have
acclimated and adapted with time. These concerns are of general nature
and relevant for all naturally occurring materials.
No Specificity (criterion 3) of the observed effects (mono-causation) is
assured. Molecular modes of action are not the only ones in case
flocculation, coagulation, sorption and fouling of the test item can
hamper mechanically vital functions of the test organisms. In
semi-static or flow-through designs these processes start daily anew or
go on permanently.
Sorption to surfaces of organisms or ingestion by filtrating organisms
may constitute unrealistic exposure. Increased acidity, resulting from
binding of hydroxyl ions (OH-) obtained from the ligand water molecules
(to form iron hydroxyl complexes) with the release of hydrogen ions, may
be detrimental to the test organisms, but is in the standard guideline
tests excluded by buffering and pH control. Nutrient chelation, i.e. in
particular the complexation and effective removal of dissolved phosphate
plant nutrients may hamper the growth of plants and algae. In test
employing photosynthetically active organisms, the reduction of
availability of light through interception by precipitated or colloidal
hydroxides may be another cause for reduced growth. In addition to that,
fouling may encrust sensitive organs e.g. the filtration apparatus in
cladocerans or the gills in fish, and hamper their efficiency up to
dysfunction. The kinetics of the transformation processes of soluble
iron salts are quick enough to affect the tests and may thus cause the
recorded effects. No visual microscopic inspection was performed to give
evidence for such mechanisms or their absence in the reliable literature
studies available (Johnson et al 2007, Vangheluwe & Versonnen 2004).
The use of soluble iron salts in nominal concentrations above the final
water solubility in equilibrium leads to exposure of the test organisms
to in situ hydrolysing, polymerising and flocculating, precipitating or
adhering iron species. This results in a generally unclear exposure to a
number of chemical species, whose composition changes probably with the
time. The iron species causative for the effects keep thus unclear.
Incorporation of else solute toxicants bound in the in larger particles
resulting from flocculation cannot be excluded. This is even more
relevant as the flocculation behaviour can result in oral exposure due
to ingestion of iron complex clusters.
In result mixed effects of media exposure to unknown and variable
dissolved materials and/or sorption and encrustation effecting
mechanical blockage and/or ingestion and thus oral exposure and/or
adhesion and thus enhanced bioavailability of unknown and variable
undissolved materials may have caused the observed effects. Neither the
substances (iron species) bioavailable to the test animals can be named
nor whether the effects were caused by ingestion, media contact, surface
sorption or mechanical blockage. Thus this Specificity criterion is
clearly violated as several basic mechanisms could be involved in the
In conclusion true, intrinsic toxicity of iron kation in aerobic
aquatic test organisms cannot be determined in studies when the
solubility of the dissolved ferric kation (as the ferrous form will
readily be oxidized to ferric species) is exceeded.
As discussed in the section on Environmental fate and pathways the
environmental assessment of the submission item must be based on the
metal kations considering their speciation, while the anions can be
considered nontoxic and ubiquitary present in the environment in
The levels considered as background concentrations in the present
assessment are given in the section on Environmental fate and pathways.
These background concentrations can be used in the environmental risk
assessment and be compared with the respective PNEC according to ECHA
(2008, R.7.13-2): In case the background is found significant compared
to the PNEC, the Added Risk Approach will be to be applied, while in
case PNECs are in the order of the background the Total Risk Approach
will be used. Whenever no PNEC can be derived the background levels will
be compared with PECadd (increase of the total concentration caused by
the uses of the submission item). Insignificant PECadd compared to the
background concentrations, will be evaluated as not hazardous to the
environment. This can be assumed in the present cases of the submission
item, particularly considering the fact that the bioavailable iron
fraction results from geochemical conditions rather than release. Due to
the rapid equilibration
the released fraction contributes to immobilized soil and sediment
species and will be buried in the important environmental sinks in
sediments, suspended matter and soils evidenced by the significant
natural background concentrations (section on Environmental fate and
pathways). In consequence the PECadd will always be insignificant where
dissolved ferric and ferrous irons are present at their level of
solubility in environmental waters. This is generally the case with the
sole exception of iron deficient biotopes.
However establishing formally PNECs, which is omitted here as the PNEC
cannot be established on the basis of intrinsic toxicity (this
restriction does not apply to the EQSs according to the WFD, Directive
2000/60/EC of the European Parliament and of the Council of 23 October
2000), the evaluation of aquatic iron effects performed by the U.K.
authorities (Johnson et al 2007) negates their usability: “The ‘added
risk’ approach could be appropriate when setting EQSs for iron. This is
because iron is a naturally occurring substance that organisms will have
been exposed to over an evolutionary timescale. In this case, the PNEC
applies only to the ‘added’ contribution over and above the background
level. A practical consequence of this is that compliance assessment
would need to consider background levels of iron, at least at a regional
scale, if not a local scale. However, natural background concentrations
for iron are expected to be very high in comparison to anthropogenic
inputs. In this case, a realistic option for implementation would be to
set EQSs at background levels rather than on the basis of the PNECs
Iron is an essential trace element for fish, aquatic invertebrates,
plants and algae its absence is detrimental for the environmental life
and as iron plays an important role in biological processes its
homeostasis in organisms is under strict control
Thus it is concluded that the derivation of a meaningful PNEC (a PNEC
which can be compared with measured concentrations to indicate a risk to
the environmental life) is not adequate and not required.
Johnson et al (2007) summarized “Iron is an essential element that has
been shown not to bioaccumulate in higher organisms. This is because
absorption of iron depends on an organism’s requirements for iron and
this is regulated so that excessive amounts of iron are not stored in
the body. It is, therefore, considered unnecessary to derive a PNEC
addressing secondary poisoning of predators.”
Iron is an essential micronutrient and present in all organisms in
considerable amounts. IOM (2001) evaluated the total iron intake as
follows (values refer to elemental iron assuming a body weight of 60
kg): “The Recommended Dietary Allowance (RDA) for all age groups of men
and postmenopausal women is 8 mg/day; the RDA for premenopausal women is
18 mg/day. The median dietary intake of iron is approximately 16 to 18
mg/day for men and 12 mg/day for women. The Tolerable Upper Intake Level
(UL) for adults is 45 mg/day of iron, a level based on gastrointestinal
distress as an adverse effect.”
The following statements base on DSD, the Commission Directive
2001/59/EC (28th ATP of Council Directive 67/548/EEC), and CLP (5th ATP
of Regulation (EC) No 1272/2008 of the European Parliament and of the
Council) as implementation of UN-GHS in the EU.
Iron (II) chloride and the soluble iron (III) salts are not legally
(harmonized) classified in accordance with DSD and GHS/CLP regulations,
while iron (II) sulphate in its anhydrous (index number 026-003-00-7)
and heptahydrate (index number 026-003-01-4) forms is listed in Tables
3.1 and 3.2, but not considered toxic to the aquatic environment.
The Rapid biodegradability condition applies
As discussed in the section on biodegradation in water: screening tests
iron can be treated like rapidly biodegradable substances with regard to
As discussed in the section on aquatic toxicity the submission item
category member soluble iron salts are considered not toxic to the
As demonstrated by in ECHA guidance on CLP (2012, Table IV.7.1, p 553,
Example D), the EURAS Critical review on acute and chronic aquatic
ecotoxicity data (Vangheluwe & Versonnen 2004) can be employed for
classification purposes of iron salts and to select the relevant studies
for these endpoints, however the Klimisch rating of them may be
revisited as precipitation of insolute test items may have caused test
artefacts. In any case, i.e. even if using these data, no necessity for
environmental is to be concluded.
In conclusion no classification for environmental hazard is required.
Table: Labelling elements based on the classification
Hazards to the ozone layer
A substance shall be classified as hazardous to the ozone layer
(Category 1) if the available evidence concerning its properties and its
predicted or observed environmental fate and behaviour indicate that it
may present a danger to the structure and/or the functioning of the
stratospheric ozone layer.
Volatilisation can generally be ignored for metals, except for several
organometallic compounds, which are neither present in the submission
item nor formed in the environment. Entering the atmosphere from water
is irrelevant for the submission item due to the ionic nature of the
constituents and no relevant release to the atmosphere is expected. Iron
as contained in the submission item may exist in air as suspended
particulate matter originating from industrial emissions or erosion of
soils. Most of the metal species present in the atmosphere will be bound
to aerosols, i.e. the aerosol-bound fraction is almost one. Metal
containing particles are assumed to be mainly removed from the
atmosphere by gravitational settling, with large particles tending to
fall out faster than small particles. The half-life of airborne
particles is assumed to be in the order of days. Some removal by washout
mechanisms such as rain may also occur, although it is of minor
significance in comparison to dry deposition. Indirect photolysis by
hydroxyl radicals and direct phototransformation in the air are
considered irrelevant, while speciation in airborne droplets may occur
and include (photo)oxidation and hydrolysis.
In conclusion there is no indication that the soluble iron salt
category could present a danger to the ozone layer as it is unlikely
that it reaches the stratosphere. Thus no classification is required.
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.Reproduction or further distribution of this information may be subject to copyright protection. Use of the information without obtaining the permission from the owner(s) of the respective information might violate the rights of the owner.
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