Iron sulfate

CHEMICAL SUBSTANCE IDENTIFICATION

Chemical name

Iron sulfate

Synonyms

Ferrous sulfate, Green vitriol, Iron vitriol, Copperas, Melanterite, Szomolnokite

IUPAC name

Iron(II)sulfate or iron(2+) sulfate

CAS No

7720-78-7  iron(II)sulfate anhydrous

17375-41-6  iron(II)sulfate monohydrate

7782-63-0  iron(II)sulfate heptahydrate

REACH registration number

−

EC No

231-753-5 iron(II)sulfate anhydrous

Molecular formula

iron(II) sulfate anhydrous FeO₄S

iron(II) sulfate monohydrate FeH₂O₅S

iron(II) sulfate heptahydrate FeH₁₄O₁₁S

Substance group/chemical family

Heavy metal salts

Appearance

Physical state

Odour

Form

Colour

solid

odourless

crystalline

pale green

USES AND HANDLING ISSUES

Relevant identified uses

Used in fertilisers, pH regulators and water treatment products, laboratory chemicals, water treatment chemicals, plant protection products, fillers, putties, plasters, modelling clay and metal surface treatment products. This substance has an industrial use resulting in manufacture of another substance (use of intermediates). This substance is used in the following areas: agriculture, forestry and fishing, building & construction work, scientific research and development and formulation of mixtures and/or re-packaging. [2]

Also used in iron electroplating baths; in fertilizer; as food and feed supplement; in radiation dosimeters; as reducing agent in chemical processes; as wood preservative; as weed killer; in prevention of chlorosis in plants; in other pesticides; in writing ink; in process engraving and lithography; as dye for leather; in etching aluminum; in water treatment; in qualitative analysis ("brown ring" test for nitrates); as polymerization catalyst.

Veterinary uses: In iron deficiency, astringent. [8]

Used in metallurgy, and leather tanning. [9]

Handling considerations

Wear a mask if dust is present. [5]

PHYSICO-CHEMICAL PROPERTIES

Molecular weight

iron(II) sulfate anhydrous 151.8 g/mol

iron(II) sulfate monohydrate 169.9 g/mol

iron(II) sulfate heptahydrate 277.8 g/mol

Bulk density/Specific gravity

3.56 g/cm³ [6]

pH

not applicable

EC

not applicable

Melting point

90 °C (iron(II)sulfate heptahydrate)

Boiling point

300 °C (iron(II)sulfate heptahydrate)

Flash point

not applicable

Flammability

not applicable

Vapour density

not applicable

Vapour pressure

< 10^-5 Pa at 20°C (not applicable)

Solubility in water

256−266 g/L at 20 °C [1]

486 g/L at 50 °C [1]

Solubility in organic solvents

not soluble in non-polar organic solvents [1]

Hydrolysis

It is soluble in water and gets hydrolyzed to give acidic salt solution as it is salt of strong acid and weak base. [1]

Ionicity in water

Iron(II)sulfate is a salt that completely dissociates in water. [1]

Surface tension

Not relevant. Iron(II)sulfate is a fully dissociating salt and thus it is not expected to be surface active. [1]

Dispersion properties

not relevant [1]

Stability and reactivity

Chemical stability

Stable under ordinary conditions [5]

Reactivity hazards

Iron(II)sulfate does not contain chemical groups that can be ignited with a flame. [1]

Corrosivity

Considering the chemical structure of ferrous sulfate, oxidising properties are not expected. [1]

Polimerization

not relevant

Incompatibility with various substances

Incompatible with alkalies, sol carbonates, gold and silver salts, lead acetate, lime water, potassium iodide, potassium and sodium tartrate, sodium borate, tannin, vegetable astringent infusions and decoctions. [4]

Special remarks on reactivity

May ignite on contact with arsenic trioxide and sodium nitrate. Potentially explosive reacition with methyl isocyanoacetate at 25 °C. [3]

Physical, chemical and biological coefficients

Koc

K_OC (L/kg): Fe²⁺, SO₄^2- = 0 [1]

Kow

In non-polar organic solvents the salt iron(II)sulfate is not soluble. Therefore, log Kow was not determined. [1]

pKa

Fe²⁺: 6,74

Henry-constant

< 6 x 10^-7 Pa m3 mol^-1 [1]

ENVIRONMENTAL FATE AND BEHAVIOUR

Artificial pollution sources

Due to the applications listed under the section of relevant identified uses.

General terrestrial fate

Iron sulfate is an inorganic salt that dissociates in the soil solution to iron- and sulfate-ions. Both iron- and sulfate-ions are naturally occurring components of terrestrial ecosystems. At agriculturally relevant pH values, nearly all sulfate present is in the soil solution, while the concentration of dissolved Fe in the soil solution is rather low, due to the low solubility of its oxide/hydroxide forms. [1]

General aquatic fate

Iron sulfate is highly soluble in water and, when dissolved in water, it readily dissociates to iron- and sulfate ions. [1]

General atmospheric fate

Not applicable.

General persistence and degradability

It readily dissociates to iron- and sulfate ions. [1]

Abiotic degradation and metabolites

It readily dissociates to iron- and sulfate ions. [1]

Biodegradation and metabolites

Not applicable to inorganic salts

Bioconcentration

Log P_OW -0.37

Volatilization

Not applicable

Photolysis

Not applicable

Hydrolysis

Not applicable

Soil adsorption and mobility

Sulfate: Mobile in soils and readily leached. Sorption is pH dependent: sorption increases with decreasing pH. Above pH 6 all sulfate is found in solution.

Iron: Under typical aerobic environmental conditions (pH 5 – pH 9), the highly soluble Fe (II) salts will be rapidly oxidised to less soluble Fe (III) oxides and hydroxides. Due to the low solubility of the oxide/hydroxide forms, the concentration of dissolved Fe in the soil solution is rather low (< 0.01 - 0.5 mg/L).

ENVIRONMENTAL CONCENTRATIONS

Measured data

ECOTOXICOLOGICAL INFORMATION

General adverse effects on ecosystem

Acute toxicity (LC50, EC50)

Aquatic systems

Terrestrial systems

Brachydanio rerio: 96 hr (semi-static) Mortality, nom LC₅₀=181.1 mg FeSO₄/L [1]

Oncorhynchus mykiss:96 hr (flow-through) Mortality, nom LC₅₀=45.1 mg FeSO₄/L [1]

Daphnia magna: 48-hour (semi-static) Mortality, EC₅₀=31.2 mg FeSO₄/L [1]

Anabaena variabilis: 96 h (static) Biomass: EC₅₀=36.2 mg FeSO₄/L; Growth rate: ErC₅₀ >76.6 mg FeSO₄/L

Chlorella vulgaris: 72 h (static) Growth rate: ErC₅₀=22 FeSO₄ mg /L [1]

Selenastrum capricornutum: 72-hour static Biomass and growth rate EC₅₀ > 23.8 mg FeSO₄/L [1]

Lemna gibba: 7 d (semi-static) Biomass, growth rate and frond number EC₅₀ >103.4 mg FeSO₄/L [1]

Earthworms (Iron sulphate heptahydrate): LC₅₀(14 days) > 3829 mg FeSO₄/kg soil. [1]

Chronic toxicity (NOEC, LOEC)

Aquatic systems

Terrestrial systems

Oncorhynchus mykiss: 21 d (semi-static) Growth nom NOEC=3.4 mg FeSO₄/L [1]

Daphnia magna: 21 d (semi-static) Reproduction, NOEC < 1.08 mg FeSO₄/L [1]

Earthworms (Iron sulphate heptahydrate): NOEC < 70 kg FeSO₄/ha. [1]

HUMAN HEALTH EFFECTS and PROTECTION

Routes of human exposures

From the molecular structure (inorganic salt), it is suggested that it is unlikely that significant amounts of ferrous sulfate (Fe(II)SO4) can be resorbed through intact skin.

The vapour pressure of the inorganic salt is negligible at ambient temperature. Therefore, no toxicologically relevant exposure occurs. [1]

General effects

Acute intoxications [1]:

- vomiting

- GIT bleeding

- diarrhoea

- liver dysfunction

Chronic intoxication:

- liver / haemosiderosis / cirrhosis

- spleen / haemosiderosis

- kidney / renal failure GIT / fibrosis

Mice: liver and spleen / haemosiderosis

Endocrine disruption

Mutagenicity

Genotoxicity

No data

Overall, no genotoxic potential based on a range of in vitro and in vivo studies including negative in S. typhimurium point mutation assay; genetic analysis for induction of diploid and aneuploid cells in Saccharomyces cerevisiae; and negative in vivo micronucleus assays in 57 BL mice and in male ddY mice at dose levels of up to 180 mg/kg bw. Positive finding in in vitro chromosomal aberration study in Chinese hamster fibroblasts. [1]

Carcinogenicity

No carcinogenic potential

Reprotoxicity

Developmental toxicity

No data

Reduced body weight in dams at 1200 mg/kg bw/day. Increase in dams with no live fetuses and increased implantation loss at 1200 mg/kg bw/day.

Relevant maternal NOAEL: 380 mg/kg bw/day FeSO₄ – rat; 380 mg/kg bw/day FeSO₄ – mice

Relevant developmental NOAEL: 380 mg/kg bw/day FeSO₄ – rat; 380 mg/kg bw/day FeSO₄ – mice [1]

Teratogenicity

No data

Skin, eye and respiratory irritations

Skin irritation: Irritant. Classified with R38 (human data – precautionary, based on physical properties, only one old reference with other citations in literature as moderate irritant without further evidence.

Eye irritation: Irritant (R36) (human data – precautionary, based on physical properties,)

Skin sensitisation: Non-sensitising [1]

Metabolism:

absorption, distribution & excretion

Rate and extent of oral absorption: Rapidly absorbed (10 % up to 60 % in case of iron deficiency) within 2 to 6 hours.

Rate and extent of excretion: 0.01 to 0.02 % of the absorbed iron are excreted daily.

Distribution: Uniformly distributed via blood. Greatest concentrations in liver, bone marrow, and spleen.

Potential for accumulation: Excessive iron is stored in liver, endocrine organs (pancreas) and spleen.

Fe2+ and Fe3+ can be converted into each other. Most iron is bound to proteins such as haemoglobin, myoglobin, ferritin, and haemosiderin. [1]

Exposure limits

Rat LD₅₀ oral: 1185 – 1750 mg/kg bw FeSO₄ (R22) ‘Harmful if swallowed’ [1]

Drinking water MAC

EPA 300 µg/L /Iron/ [10]

Other information

No potential to induce neurotoxicity [1]

Animal toxicity data

Acute toxicity (LD50)

Chronic toxicity (NOEL, LOEL)

Oral NOAEL: 90-day study in mice: 120 ppm (100 mg/kg bw/day FeSO₄)

ADI: 0.8 mg/kg bw/day (ferrous iron) derived from human intakes

AOEL: 0.4 mg/kg bw/day (Ferrous iron) - Derived from human intakes, supported by teratogenicity study in mice and rats

AOEL: 1.3 mg/kg bw/day (sulfate ion) – Human data [1]

ENVIRONMENTAL STANDARDS AND REGULATIONS

EINECS regulation

̵

OSHA regulations etc.

Hazardous by definition of Hazard Communication Standard (29 CFR 1910.1200)

OTHER INFORMATION, SPECIAL REMARKS

Classification and proposed labelling with regard to toxicological data

R22 – ‘Harmful if swallowed’ (based on data) R38 – ‘Irritating to skin’ (precautionary – indicated in human data but with limited characterisation of effect) R36 – ‘Irritating to eyes’ (precautionary – indicated in human data but with limited characterisation of effect). [1]

CREATED, LAST UPDATE

Created

6^th of April, 2018

Last update

6^th of April, 2018

REFERENCES

[1] European Food Safety Authority (EFSA). Conclusion on the peer review of the pesticide risk assessment of the active substance iron sulfate. Italy, Parma. 2012.

[2] European Chemicals Agency (ECHA). Substance information. Accessed from: https://echa.europa.eu/substance-information/-/substanceinfo/100.028.867. Cited: 06.04.2018.

[3] [Lewis, R.J. Sax's Dangerous Properties of Industrial Materials. 9th ed. Volumes 1-3. New York, NY: Van Nostrand Reinhold, 1996., p. 1644]

[4] [Budavari, S. (ed.). The Merck Index - Encyclopedia of Chemicals, Drugs and Biologicals. Rahway, NJ: Merck and Co., Inc., 1989., p. 635]

[5] TOXNET – Toxicology Data Network. https://toxnet.nlm.nih.gov/cgi-bin/sis/search2/f?./temp/~ddSkbD:3

[6] [Lide, DR (ed.). CRC Handbook of Chemistry and Physics. 81st Edition. CRC Press LLC, Boca Raton: FL 2000, p. 4-65] 

[7] NIOSH. NIOSH Pocket Guide to Chemical Hazards. DHHS (NIOSH) Publication No. 97-140. Washington, D.C. U.S. Government Printing Office, 1997., p. 366] 

[8] [O'Neil, M.J. (ed.). The Merck Index - An Encyclopedia of Chemicals, Drugs, and Biologicals. 13th Edition, Whitehouse Station, NJ: Merck and Co., Inc., 2001., p. 717]

[9] Kirk-Othmer Encyclopedia of Chemical Technology. 4th ed. Volumes 1: New York, NY. John Wiley and Sons, 1991-Present., p. V14: 873 (1995)]

[10] USEPA/Office of Water; Federal-State Toxicology and Risk Analysis Committee (FSTRAC). Summary of State and Federal Drinking Water Standards and Guidelines (11/93) To Present