U.S. Environmental Protection Agency
Hazard Characterization
June, 2015
SCREENING-LEVEL HAZARD CHARACTERIZATION
Cobalt Stearate and Fatty Acids, Tall Oil, Cobalt Salts Category
Fatty acids, tall-oil cobalt salts
Cobalt stearate
CASRN 61789-52-4
CASRN 13586-84-0
The High Production Volume (HPV) Challenge Program1 was conceived as a voluntary initiative aimed
at developing and making publicly available screening-level health and environmental effects
information on chemicals manufactured in or imported into the United States in quantities greater than
one million pounds per year. In the Challenge Program, producers and importers of HPV chemicals
voluntarily sponsored chemicals; sponsorship entailed the identification and initial assessment of the
adequacy of existing toxicity data/information, conducting new testing if adequate data did not exist, and
making both new and existing data and information available to the public. Each complete data
submission contains data on 18 internationally agreed to "SIDS" (Screening Information Data Set1'2)
endpoints that are screening-level indicators of potential hazards (toxicity) for humans or the
environment.
The Environmental Protection Agency's Office of Pollution Prevention and Toxics (OPPT) is evaluating
the data submitted in the HPV Challenge Program on approximately 1400 sponsored chemicals by
developing hazard characterizations (HCs). These HCs consist of an evaluation of the quality and
completeness of the data set provided in the Challenge Program submissions. They are not intended to
be definitive statements regarding the possibility of unreasonable risk of injury to health or the
environment.
The evaluation is performed according to established EPA guidance2'3 and is based primarily on hazard
data provided by sponsors; however, in preparing the hazard characterization, EPA considered its own
comments and public comments on the original submission as well as the sponsor's responses to
comments and revisions made to the submission. In order to determine whether any new hazard
information was developed since the time of the HPV submission, a search of the following databases
was made from one year prior to the date of the HPV Challenge submission to the present: (ChemID to
locate available data sources including Medline/PubMed, Toxline, HSDB, IRIS, NTP, ATSDR, IARC,
EXTOXNET, EPA SRS, etc.), STN/CAS online databases (Registry file for locators, ChemAbs for
toxicology data, RTECS, Merck, etc.), Science Direct and ECHA.4 OPPT's focus on these specific
sources is based on their being of high quality, highly relevant to hazard characterization, and publicly
available.
OPPT does not develop HCs for those HPV chemicals which have already been assessed internationally
through the HPV program of the Organization for Economic Cooperation and Development (OECD)
and for which Screening Initial Data Set (SIDS) Initial Assessment Reports (SIAR) and SIDS Initial
Assessment Profiles (SIAP) are available. These documents are presented in an international forum that
involves review and endorsement by governmental authorities around the world. OPPT is an active
1 U.S. EPA. High Production Volume (HPV) Challenge Program; http://www.epa.gov/chemrtk/index.htm.
2 U.S. EPA. EtPV Challenge Program - Information Sources; http://www.epa.gov/chemrtk/pubs/general/guidocs.htm.
3 U.S. EPA. Risk Assessment Guidelines; http://cfpub.epa.gov/ncea/raf/rafguid.cfm.
4 European Chemicals Agency, http: //echa. europa.eu.
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U.S. Environmental Protection Agency June, 2015
Hazard Characterization
participant in these meetings and accepts these documents as reliable screening-level hazard
assessments.
These hazard characterizations are technical documents intended to inform subsequent decisions and
actions by OPPT. Accordingly, the documents are not written with the goal of informing the general
public. However, they do provide a vehicle for public access to a concise assessment of the raw
technical data on HPV chemicals and provide information previously not readily available to the public.
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U.S. Environmental Protection Agency June, 2015
Hazard Characterization
Chemical
Abstract Service
Registry Number
(CASRN)
61789-52-4
13586-84-0
Chemical
Abstract Index
Name
Fatty acids, tall-oil cobalt salts
Octadecanoic acid, cobalt salt
Structural
Formula
0
0 Co2+
SMILES:
0=C(0[Co]OC(CCCCCCCCCCCCCCCCC)=0)CCCCCCCCCCCCCCCCC
0
Co2+
ch3
Representative SMILES:
0=C(CCCCCCCC=CCCCCCCCC)0[Co]OC(CCCCCCCC=CCC=CCCCCC)=0
Summary
Cobalt stearate is a purple solid possessing moderate water solubility and negligible vapor pressure.
Fatty acids, tall-oil, cobalt salts is a mixture of cobalt salts of fatty acids derived from pine trees. The
tall oil fatty acids are primarily composed of oleic, linoleic, stearic and palmitic acids. Fatty acids, tall-
oil, cobalt salts is a tacky, purple-red solid possessing moderate water solubility and negligible vapor
pressure. These substances are expected to have low mobility in soil. Volatilization of the cobalt
stearates is considered negligible since these are salts. These substances are expected to dissociate in
water to the cobalt cation and the high molecular weight carboxylic acid or its conjugate base, both of
which are stable in water. The rate of atmospheric photooxidation is rapid to moderate; however, this is
not a relevant environmental degradation pathway since these substances are not expected to exist in
the vapor phase in the atmosphere. Cobalt stearate and Fatty acids, tall-oil, cobalt salts are expected to
have low persistence (PI) and low bioaccumulation potential (Bl).
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U.S. Environmental Protection Agency
Hazard Characterization
June, 2015
The acute oral toxicity of the cobalt stearate in rats is low. Cobalt stearate is not irritating to human skin
in vitro or rabbit eyes in vivo. Cobalt stearate is a skin sensitizer in mice. No data are available for the
repeated-dose, reproductive, developmental and genetic toxicity (gene mutation and chromosomal
aberrations) endpoints.
There were no data available to address aquatic toxicity endpoints for the cobalt stearate and fatty
acids, tall oil, cobalt salts.
Data gaps for the biodegradation, repeated-dose, reproductive, developmental and genetic (gene
mutation and chromosomal aberrations) toxicity, and acute toxicity to fish and aquatic invertebrates,
and toxicity to aquatic plants endpoints were identified under the HPV Challenge Program.
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U.S. Environmental Protection Agency June, 2015
Hazard Characterization
The sponsor, Metal Carboxylates Coalition, submitted a test plan and robust summaries to EPA for the
cobalt stearate and fatty acids, tall oil, cobalt salts category on September 28, 2005. EPA posted the
submission on the ChemRTK HPV Challenge website on November 9, 2005
("http://www.epa. gov/oppt/chemrtk/pubs./suro.ro.aries./me' itc.htmY The cobalt stearate and
fatty acids, tall oil, cobalt salts category is a subcategory to the original Metal Carboxylates Category for
which an original test plan and robust summaries were submitted to EPA on December 27, 2002. EPA
posted comments on the original category submission to the ChemRTK website on May 22, 2003.
Public comments were also received and posted to the website. The cobalt stearate and fatty acids, tall
oil, cobalt salts category consists of the following substances:
Fatty acids, tall-oil cobalt salts CASRN 61789-52-4
Cobalt stearate CASRN 13586-84-0
Category Justification
The sponsor proposed the cobalt stearate and fatty acids, tall oil, cobalt salts category, which contains
two sponsored chemicals that are functionally similar and have the same ionizable substituents and
metal cation, as well as a structurally similar carboxylic acid group. Fatty acids, tall-oil cobalt salts
(CASRN 61789-52-4) and cobalt stearate (CASRN 13586-84-0) are closely related cobalt salts of
carboxylic acids, and both substances are members of the metal carboxylates group. EPA agrees that
based on the similar structures of category members, they are reasonably expected to exhibit similar
environmental fate and toxicological properties.
Justification for Supporting Chemical
The sponsor submitted data for three supporting chemicals, stearic acid (CASRN 57-11-4); cobalt
chloride (CASRN 7646-79-9); and fatty acids, tall oil (CASRN 61790-12-3).
The submitter expects extensive to complete dissociation of the sponsored chemical to these supporting
chemicals at environmentally and physiologically relevant pH values. However, EPA considers that the
submitter did not adequately address the issue of stability of the metal-ligand complex and instead
submitted an acid (pKa) dissociation constant study. Therefore, the stability of the metal-ligand complex
still needs to be addressed. It is very possible that this compound is stable and does not readily dissociate
at neutral pH.
The submitter also justifies the use of the supporting chemicals based on assumed bioequivalency of the
cobalt ion in the sponsored chemical to the cobalt ion in soluble cobalt salts, such as cobalt chloride.
However, the data submitted to support bioequivalency rely heavily on theory and several in vitro
studies that cannot be interpreted because the sponsors presented insufficient detail about the
experimental method in either the test plan or the robust summaries. In addition, these studies are
applicable only to oral exposures, and provide no information relevant to dermal or inhalation exposure
scenarios.
Furthermore, EPA considers that separate evaluation of the dissociation products does not address
potential interactions (e.g., additivity, synergism or antagonism) among the various associated and
dissociated species that may be present in different biological environments.
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U.S. Environmental Protection Agency
Hazard Characterization
June, 2015
Therefore, the proposed use of supporting chemicals is not supported for either human health or aquatic
toxicity assessment and the submitted data for these chemicals are not used in this hazard
characterization.
1. Chemical Identity
1.1 Identification and Purity
The cobalt stearates category consists of two members: Cobalt stearate and Fatty acids, tall-oil, cobalt
salts. Cobalt stearate is a purple solid possessing moderate water solubility and negligible vapor
pressure. Fatty acids, tall-oil, cobalt salts is a tacky, purple-red solid possessing moderate water
solubility and negligible vapor pressure.
1.2 Physical-Chemical Properties
The physical-chemical properties of the category members are summarized in Table 1.
Table 1. Physical-Chemical Properties of the Cobalt Stearates Category1
Property
Cobalt Stearate
Fatty acids, tall-oil, cobalt salts
CASRN
13586-84-0
61789-52-4
Molecular Weight
625.89
619.84 (typical)
Physical State
Purple solid
Very tacky, red-purple solid
Melting Point
45.1 to 79.3°C (measured)
-39 to -38°C (measured)
Boiling Point
Decomposes at 177°C (measured)
>400°C (measured)
Vapor Pressure
10 (estimated)2'3
>10 (estimated)2'3
1 The Metal Carboxylates Coalition. 2004. Test Plan and Robust Summary for the Cobalt Stearates. Available
online at http://www.epa.gov/chemrtk/pubs/summaries/metalcarb/c 14172tc.htm as of September 6, 2011.
2U.S. EPA. 2011. Estimation Programs Interface Suite™ for Microsoft® Windows, v4.10. U.S. Environmental
Protection Agency, Washington, DC, USA. Available online at
http://www.epa.gov/opptintr/exposure/pubs/episuitedl.htm as of September 6, 2011.
3 EPIWIN has not been validated for chemicals that contain metals, such as cobalt, in their molecular structure;
therefore, there is uncertainty associated with the calculated values and they should be used with caution whenever
they are reported.
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U.S. Environmental Protection Agency
Hazard Characterization
2. General Information on Exposure
June, 2015
2.1 Production Volume and Use
The Cobalt Stearate Category chemicals had an aggregated production and/or import volume in the
United States less than one million pounds during calendar year 2005.
CASRN 13586-84-0:
Non-confidential information in the IUR indicated that the industrial processing and uses of the
chemical include all other chemical product and preparation manufacturing as "other." Non-
confidential commercial and consumer uses of this chemical include paints and coatings.
CASRN 61789-52-4:
Non-confidential information in the IUR indicated that the industrial processing and uses of the
chemical include all other chemical product and preparation manufacturing as "other." Non-
confidential commercial and consumer uses of this chemical include "other."
2.2 Environmental Exposure and Fate
Cobalt stearate and Fatty acids, tall-oil, cobalt salts are expected to possess low mobility in soil. No
biodegradation data were submitted for the sponsored substances. Rather, data from stearic acid and
various biodegradation studies for tall oil fatty acids were employed to suggest that the cobalt stearates
are not persistent in the environment. Stearic acid was degraded 77% after 28 days using the manometric
respirometry test (OECD 301F) and was characterized as readily biodegradable. Tall oil, fatty acids
(CASRN 61790-12-3) achieved 56% of its theoretical biochemical oxygen demand (BOD) over the
course of a 28-day incubation period using the closed bottle (OECD TG 30 ID) test. It was readily
biodegradable, degrading 84% after 28 days using the manometric respirometry (OECD TG 301F) test.
Tall oil, fatty acids degraded 74% as measured by CO2 evolution using the modified Sturm (OECD TG
301B) test. Tall oil, fatty acids (low boiling) (CASRN 65997-03-2) achieved 44% of its theoretical BOD
over the course of a 28-day incubation period using the closed bottle (OECD TG 301D) test. Fatty
acids, C16-18 and C18-unsatd., branched and linear (CASRN 68955-98-6) was degraded 67% over 28
days using a CO2 evolution test similar to the modified Sturm (OECD TG 301B) test. Octadecanoic
acid, branched and linear (CASRN 68201-37-6) was degraded 47% after 28 days using the modified
Sturm (OECD TG 301B) test. Fatty acids, tall-oil, sodium salts (CASRN 61790-45-2) was inherently
biodegradable, degrading 98.4% in 28 days using the Zahn-Wellens (OECD TG 302B) test.
Volatilization of the cobalt stearates is considered negligible since these are salts. These substances
dissociate in water to the cobalt cation and the high molecular weight carboxylic acid or its conjugate
base, both of which are stable in water. The rate of atmospheric photooxidation is rapid to moderate;
however, this is not a relevant environmental degradation pathway since these substances are not
expected to exist in the vapor phase in the atmosphere. Assuming that the cobalt metal does not inhibit
biodegradation of the stearate moiety, it is expected that Cobalt stearate and Fatty acids, tall-oil, cobalt
salts have low persistence (PI) and low bioaccumulation potential (Bl).
• CASRN 13586-84-0:
• CASRN 61789-52-4:
< 500,000 pounds ;
< 500,000 pounds ;
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U.S. Environmental Protection Agency
Hazard Characterization
June, 2015
Table 2. Environmental Fate Characteristics of the Cobalt Stearates Category1
Property
Cobalt Stearate
Fatty acids, tall-oil, cobalt salts
CASRN
13586-84-0
61789-52-4
Photodegradati on
Half-life
2.9 hours (estimated)2'3
0.6 hours (estimated)2'3
Hydrolysis Half-life
Stable
Stable
Biodegradation5
77% after 28 days (readily
biodegradable)
56% in 28 days (not readily
biodegradable);
84% after 28 days (readily
biodegradable);
74% after 28 days (readily
biodegradable);
41%) after 28 days (not readily
biodegradable);
67% after 28 days (readily
biodegradable);
47% after 28 days (not readily
biodegradable);
98%o after 28 days (inherently
biodegradable)
Bioaccumulation
Factor
BAF = 2.6 (estimated)2'3
BAF = 10.6 (estimated)2'3
Log Koc
7.9 (estimated)2'3
7.9 (estimated)2'3
Fugacity
(Level III Model)2,3
Air (%)
Water (%)
Soil (%)
Sediment (%)
0.2
15.9
83.9
<0.1
0.2
94.4
5.4
<0.1
Persistence4
PI (low)
PI (low)
Bi oaccumul ati on4
Bl (low)
Bl (low)
'The Metal Carboxylates Coalition. 2004. Test Plan and Robust Summary for the Cobalt Stearates. Available online
at http://www.epa.gov/chemrtk/pubs/summaries/metalcarb/c 14172tc.htm as of September 6, 2011.
2U.S. EPA. 2011. Estimation Programs Interface Suite™ for Microsoft® Windows, v4.10. U.S. Environmental
Protection Agency, Washington, DC, USA. Available online at
http://www.epa.gov/opptintr/exposure/pubs/episuitedl.htm as of September 6, 2011.
3 EPIWIN has not been validated for chemicals that contain metals, such as cobalt, in their molecular structure;
therefore, there is uncertainty associated with the calculated values and they should be used with caution whenever
they are reported.
4Federal Register. 1999. Category for Persistent, Bioaccumulative, and Toxic New Chemical Substances. Federal
Register 64, Number 213 (November 4, 1999) pp. 60194-60204.
5Data presented are for potential degradation products without including potential influence of cobalt on
degradation.
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U.S. Environmental Protection Agency June, 2015
Hazard Characterization
Conclusion: Cobalt stearate is a purple solid possessing moderate water solubility and negligible vapor
pressure. Fatty acids, tall-oil, cobalt salts is a mixture of cobalt salts of fatty acids derived from pine
trees. The tall oil fatty acids are primarily composed of oleic, linoleic, stearic and palmitic acids. Fatty
acids, tall-oil, cobalt salts is a tacky, purple-red solid possessing moderate water solubility and
negligible vapor pressure. These substances are expected to have low mobility in soil. Volatilization of
the cobalt stearates is considered negligible since these are salts. These substances are expected to
dissociate in water to the cobalt cation and the high molecular weight carboxylic acid or its conjugate
base, both of which are stable in water. The rate of atmospheric photooxidation is rapid to moderate;
however, this is not a relevant environmental degradation pathway since these substances are not
expected to exist in the vapor phase in the atmosphere. Cobalt stearate and Fatty acids, tall-oil, cobalt
salts are expected to have low persistence (PI) and low bioaccumulation potential (Bl).
3. Human Health Hazard
A summary of health effects data submitted for SIDS endpoints is provided in Table 3. The table also
indicates where data for tested category members are read-across (RA) to untested members of the
category.
Acute Oral Toxicity
Cobalt stearate (CASRN13586-84-0)
(1) Rats (5/dose) (strain and number per sex per group were not specified) were administered cobalt
stearate via gavage in propylene glycol at 1000, 2000, 4000, 8000, 16,000 or 32,000 mg/kg and
observed for 14 days following dosing. Mortalities at the high-dose occurred within the first 24 hours
following dosing and mortalities at 8000 and 16,000 mg/kg occurred between 4 and 6 days following
dosing.
LDso = 9820 mg/kg
(2) See information for an acute study by up and down procedure [OECD TG 425] in female rats
submitted to ECHA at: http://echa.europa.eu
LD50 > 2000 mg/kg
Repeated-Dose, Reproductive and Developmental Toxicity
No adequate data.
Genetic Toxicity — Gene Mutation and Chromosomal Aberrations
No adequate data.
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U.S. Environmental Protection Agency
Hazard Characterization
Additional Information
June, 2015
Skin Irritation
Cobalt stearate (CASRN13586-84-0)
(1) In an in vitro Human Skin Model test, EST-1000™ [OECD TG 431] tissues were exposed to 25 mg
of cobalt stearate in deionized water for 3 or 60 minutes. Negative (vehicle) and positive controls were
tested concurrently and responded appropriately. The relative absorbance values were reduced to 84.4%
after 3 minutes and 57.9% after 1 hour. Study details from ECHA at: http://echa.europa.eu.
Cobalt stearate was not corrosive to a human skin model in this study.
(2) In an in vitro skin irritation assay [OECD TG 439], reconstructed human epidermis was exposed to
10 mg of cobalt stearate in deionized water for 15 minutes. Negative (vehicle) and positive controls
were tested concurrently and responded appropriately. The relative absorbance values were decreased to
74.2%) which is above the threshold for irritancy. Study details from ECHA at: http://echa.europa.eu.
Cobalt stearate was not irritating to reconstructed human epidermis in this study.
Eye Irritation
Cobalt stearate (CASRN 13586-84-0)
(1) New Zealand White rabbits (3 male) were treated in one eye with 0. lg/animal cobalt stearate and
observed at 1, 24, 48 and 72 hours. One animal was evaluated at 7 days. The treated eyes were not
rinsed after instillation. There were no abnormal findings in the cornea or iris. One hour after
instillation, slight reddening of the conjunctivae and sclera was observed in all animals and slight
discharge was observed in two animals and slight swelling of the conjunctivae in one animal. Slight
reddening of the sclera and conjunctivae was observed at 24 and 72 hours, respectively. The irritation
scores were zero. Study details from ECHA at: http://echa.europa.eu.
Cobalt stearate was not irritating to rabbit eyes in this study.
(2) In an in vitro Bovine Corneal Opacity and Permeability Assay (BCOP) [OECD TG 437], three
bovine corneas were exposed to 0.75 mL of cobalt stearate in saline for 240 minutes. Negative (vehicle)
and positive controls were tested concurrently and responded appropriately. Relative to the negative
control, cobalt stearate did not cause any permeability of the cornea but did have slight opacity. The
calculated mean in vitro score was 4.20 which corresponds to a mild irritant. Study details from ECHA
at: http://echa.europa.eu.
Cobalt stearate was mildly irritating to bovine corneas in this study.
Skin Sensitization
Cobalt stearate (CASRN 13586-84-0)
In a mouse local lymph node assay (LLNA) [OECD TG 429] female CBA mice (5/dose) were
administered 12.5%, 25% or 50% cobalt stearate (vehicle: acetone/olive oil). No mortalities or clinical
signs of toxicity were observed. Negative and positive controls elicited the appropriate response. The
three tested concentrations exceeded the stimulation index suggesting the potential for sensitization.
Study details from ECHA at: http://echa.europa.eu.
Cobalt stearate was a potential skin sensitizer in this study.
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U.S. Environmental Protection Agency June, 2015
Hazard Characterization
Conclusion: The acute oral toxicity of the cobalt stearate in rats is low. Cobalt stearate is not irritating
to human skin in vitro or rabbit eyes in vivo. Cobalt stearate is a skin sensitizer in mice. No data are
available for the repeated-dose, reproductive, developmental and genetic toxicity (gene mutation and
chromosomal aberrations) endpoints.
Table 3. Summary Table of Screening Information Data Set and Other Data for the U.S. H PV
Challenge Program - Human Health Data
Endpoints
Fatty acids, tall-oil cobalt
Cobalt stearate
salts
(13586-84-0)
(61789-52-4)
Acute Oral Toxicity
No Data
9820
LDso (mg/kg)
9820
(RA)
Repeated-Dose Toxicity
No Data
No Data
Reproductive Toxicity
No Data
No Data
Developmental Toxicity
No Data
No Data
Genetic Toxicity - Gene
Mutations
No Data
In vitro
Genetic Toxicity - Chromosomal
No Data
No Data
Aberrations
Additional Information
Skin Irritation
Eye Irritation
Skin Sensitization
No Data
No Data
No Data
Not irritating (in vitro)
Not irritating (in vivo)
Sensitizing
Measured data in bold; (m) = male; (f) = female
4. Hazard to the Environment
Acute Toxicity to Fish and Aquatic Invertebrates and Toxicity to Aquatic Plants
There were no data available to address aquatic toxicity endpoints for the cobalt stearate and fatty acids,
tall oil, cobalt salts.
5. References
NTP (National Toxicology Program). 2004. Eleventh Report on Carcinogens. Substance profile for
cobalt sulfate available at: http://ntp.niehs.nih.gov/ntp/roc/eleventh/profiles/s048zcob.pdf.
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