2

Table of Contents

EXECUTIVE SUMMARY ................................................................................................ 3

I. BACKGROUND ................................................................................................................ 6

II. INERT INGREDIENT PROFILE ...................................................................................... 8

A. Summary of Uses.................................................................................................... 8

B. Physical Chemical Properties ................................................................................. 9

III. HUMAN HEALTH ASSESSMENT................................................................................ 10

A. Summary of Toxicity Data.................................................................................... 10

B. Toxicity Endpoint Selection ................................................................................. 23

C. Special Considerations for Infants and Children .................................................. 23

IV. EXPOSURE ASSESSMENT ........................................................................................... 23

A. Dietary Exposure: ................................................................................................. 23

i. Acute exposure ...................................................................................................23

ii. Chronic exposure...............................................................................................24

iii. Cancer exposure ...............................................................................................24

B. Residential (Non-Occupational) Exposure: .......................................................... 24

i. From non-dietary exposure.................................................................................24

V. OCCUPATIONAL EXPOSURE/RISK PATHWAY....................................................... 24

VI. CUMULATIVE EXPSOURE .......................................................................................... 24

VII. ENVIRONMENTAL JUSTICE STATEMENT............................................................... 25

VIII. ENVIRONMENTAL FATE CONSIDERATIONS ......................................................... 26

IX. ECOTOXICITY................................................................................................................ 26

X. RISK CHARACTERIZATION........................................................................................ 30

REFERENCES ............................................................................................................................. 33
3

EXECUTIVE SUMMARY

Technology Sciences Group on behalf of BYK Additives Inc. (1600 West Hill Street 

Louisville, KY 40210) submitted a petition to the EPA to amend 40 CFR 180.920 by 

establishing an exemption from the requirement of a tolerance for the use of quaternary 

ammonium compounds, benzylbis(hydrogenated tallow alkyl)methyl, bis(hydrogenated tallow 

alkyl)dimethylammonium salts with sepiolite (CAS Reg. No. 1574487-61-8) as an inert 

ingredient (suspending or structuring agent) in pesticide formulations applied to growing crops in 

accordance with 40 CFR 180.920 with limitations of 2.0% in formulation, asbestos free and 

containing less than 1% crystalline silica. 

A variety of clays treated with quaternary ammonium compounds are used throughout 

this document as structurally similar analogs to quaternary ammonium compounds, 

benzylbis(hydrogenated tallow alkyl)methyl, bis(hydrogenated tallow alkyl)dimethylammonium 

salts with sepiolite. These clays are often named for the predominant, but not exclusive mineral 

in a particular deposit, so variation between the substances may not be as great as it would 

initially appear. Most of the substances referenced were also used in the OECD HPV Chemical 

Program for the SIDS dossier on organoclays. The diversity of closely-related treated clays is 

partly a result of the different combinations of the four different but related clays: smectites, 

hectorite, bentonite, and montmorillonite. These four are closely/inter- related and have been 

described in some datasets interchangeably. Smectite is actually the name describing a group of 

clay minerals, of which hectorite, bentonite, and montmorillonite and sepiolite (the clay type in 

the petitioned substance) are members. It is primarily the identity of counter ions that 

distinguishes these clays. Where saponite contains calcium, magnesium and iron, 

bentonite/montmorillonite contains sodium, calcium, aluminum, and magnesium, and hectorite 

has sodium, lithium, and magnesium counter ions. In treated clays, the naturally-occurring 

counter ions on the clays' surface have been readily exchanged for quaternary ammonium ions. 

The diversity of the structurally similar treated clays is further derived from the combinations of 

quaternary ammonium compounds that have been exchanged for counter ions on the clays' 

surface. These quaternary ammonium compounds can have between one and four 

substitutions/R-groups: 1-2 methyls, 0-1 benzyls, and/or 1-3 alkyl C14-C22 groups derived from 

tallow oil.

Despite this diversity, the treated smectite clays described in this petition have similar

structures, toxicological properties, and physical-chemical properties, including particle size

distribution, to one another and to the petitioned substance, quaternary ammonium compounds, 

benzylbis(hydrogenated tallow alkyl)methyl, bis(hydrogenated tallow alkyl)dimethylammonium 

salts with sepiolite.

Based on data in structurally similar clay substances, quaternary ammonium compounds,

benzylbis(hydrogenated tallow alkyl)methyl, bis(hydrogenated tallow alkyl)dimethylammonium

salts with sepiolite has low acute toxicity via the oral, dermal and inhalation routes in rats. The

substance is expected to be a slight skin and eye irritant. A structurally similar substance did not

cause skin sensitization in guinea pigs. 
4

In multiple 28-day repeat-dose studies consistently showed high No Observed Adverse 

Effect Levels (NOAELs), typically the highest dose tested, which was 1000 mg/kg/day in rats. 

There was an absence of test substance-related toxicologically significant effects at any of the 

doses administered, including for neurological and immunological endpoints. Similarly, there 

were no effects on reproductive or developmental endpoints and no evidence for genotoxicity in 

multiple in vitro and in vivo assays (OECD 471, 474 and 476 on multiple quaternary ammonium 

compounds). 

Clays treated with quaternary ammonium compounds have low water solubility, a high 

hydrophobic partition coefficient and relatively high molecular weight. All three factors indicate 

likely limited absorption following ingestion, dermal exposure or inhalation. Based on 

similarities in treated clays (high molecular weights, low water solubility, high hydrophobicity), 

the treated sepiolite would also be almost completely eliminated from the body shortly after oral 

dosing. Therefore, the biological availability is expected to be low.

The available toxicity studies indicate that of quaternary ammonium compounds, 

benzylbis(hydrogenated tallow alkyl)methyl, bis(hydrogenated tallow alkyl)dimethylammonium 

salts with sepiolite has a very low overall toxicity. The NOAELs were >1000 mg/kg/day (limit 

dose). Since signs of toxicity were not observed at the limit dose an endpoint of concern for risk 

assessment purposes was not identified. Therefore, since no endpoint of concern was identified 

for the acute and chronic dietary exposure assessment and for short and intermediate dermal and 

inhalation exposure, a quantitative risk assessment for of quaternary ammonium compounds, 

benzylbis(hydrogenated tallow alkyl)methyl, bis(hydrogenated tallow alkyl)dimethylammonium 

salts with sepiolite is not necessary.

Since there is no endpoint of concern selected for dermal or inhalation routes of 

exposure, a qualitative occupation exposure assessment was not completed and occupational 

exposure is not of concern.

Acute ecotoxicity testing of treated clays having structural similarity to quaternary 

ammonium compounds, benzylbis(hydrogenated tallow alkyl)methyl, bis(hydrogenated tallow

alkyl)dimethylammonium salts with sepiolite typically gave results in the low or slight concern

category (10 - >100 mg/L) for aquatic and terrestrial organisms including fish, aquatic

invertebrates, algae, and earthworms. Chronic ecotoxicity tests suggest a moderate concern for

aquatic invertebrates and fish. However, at least part of the toxicity was attributed to a physical

effect of the test substance, rather than a true toxicological effect.

Potential areas of environmental justice concerns, to the extent possible, were considered 

in this human health risk assessment, in accordance with U.S. Executive Order 12898, "Federal 

Actions to Address Environmental Justice in Minority Populations and Low-Income 

Populations," http://www.eh.doe.gov/oepa/guidance/justice/eo12898.pdf.

Taking into consideration all available information on quaternary ammonium

compounds, benzylbis(hydrogenated tallow alkyl)methyl, bis(hydrogenated tallow

alkyl)dimethylammonium salts with sepiolite, EPA concludes that there is a reasonable certainty 

that no harm to any population subgroup will result from aggregate exposure to quaternary 
5

ammonium compounds, benzylbis(hydrogenated tallow alkyl)methyl, bis(hydrogenated tallow

alkyl)dimethylammonium salts with sepiolite when considering occupation, dietary exposure and 

all other nonoccupational sources of pesticide exposure for which there is reliable information. 

Therefore, the establishment of an exemption from tolerance under 40 CFR 180.920 for residues 

of quaternary ammonium compounds, benzylbis(hydrogenated tallow alkyl)methyl, 

bis(hydrogenated tallow alkyl)dimethylammonium salts with sepiolite (CAS Reg. No. 1574487-

61-8) when used as an inert ingredient (suspending or structuring agent) in pesticide 

formulations applied to growing crops with limitations of 2.0% in formulation, asbestos free and 

containing less than 1% crystalline silica can be considered assessed as safe under section 408(q) 

of the FFDCA.
6

I. BACKGROUND

Technology Sciences Group on behalf of BYK Additives Inc. (1600 West Hill Street 

Louisville, KY 40210) submitted a petition to the EPA to amend 40 CFR 180.920 by 

establishing an exemption from the requirement of a tolerance for the use of quaternary 

ammonium compounds, benzylbis(hydrogenated tallow alkyl)methyl, bis(hydrogenated tallow 

alkyl)dimethylammonium salts with sepiolite (CAS Reg. No. 1574487-61-8) as an inert 

ingredient (suspending or structuring agent) in pesticide formulations applied to growing crops in 

accordance with 40 CFR 180.920 with limitations of 2.0% in formulation, asbestos free and 

containing less than 1% crystalline silica. 

A variety of clays treated with quaternary ammonium compounds are used throughout 

this document as structurally similar analogs to of quaternary ammonium compounds, 

benzylbis(hydrogenated tallow alkyl)methyl, bis(hydrogenated tallow alkyl)dimethylammonium 

salts with sepiolite. These clays are often named for the predominant, but not exclusive mineral 

in a particular deposit, so variation between the substances may not be as great as it would 

initially appear. Most of the substances referenced were also used in the OECD HPV Chemical 

Program for the SIDS dossier on organoclays, which was submitted by industry and reviewed by 

OECD member countries and US EPA (OECD 2007).

Table 1. Treated Smectitle Clays Referenced in this Petition

Treated Clay (and synonyms, abbreviations) CAS Reg. No. (and equivalent 

CAS Reg. No.)

Stearalkonium Bentonite

(Benzenemethanaminium, N,N-dimethyl-N-octadecyl-, reaction products 

with bentonite;

Commercial names: Tixogel VZ-V, Tixogel VZ)

130501-87-0**

Quaternary ammonium compounds, benzyl(hydrogenated tallow 

alkyl)dimethyl, chlorides, compounds with hectorite 

(Stearalkonium hectorite;

[B(Alk)2M] hectorite)

71011-26-2

(94891-33-5; 12691-60-0)

Quaternary ammonium compounds, benzyl(hydrogenated tallow 

alkyl)dimethyl, chlorides, compounds with bentonite

{[BfAlk)2M] bentonite)

71011-24-0

(71011-25-1; 121888-68-4; 

89749-78-0)

Quaternary ammonium compounds, benzylbis(hydrogenated tallow 

alkyl)methyl, chlorides, compounds with bentonite

([B(2Alk)M] bentonite)

68153-30-0

(121888-66-2; 89749-77-9)

Quaternary ammonium compounds, benzylbis(hydrogenated tallow 

alkyl)methyl, salts with hectorite

([B(2Alk)M] hectorite)

121888-67-3

Quaternary ammonium compounds, bis(hydrogenated

tallow alkyl)dimethyl, salts with bentonite

Quaternium-18 bentonite

([2M(2Alk)] bentonite)

68953-58-2

(1340-69-8; 73138-28-0)

Quaternary ammonium compounds, bis(hydrogenated tallow alkyl)dimethyl, 

chlorides, compounds with hectorite

([2M(2Alk)] hectorite)

71011-27-3; 94891-31-3; 97280-

96-1; 12001-31-9

Bis(hydrogenated tallow alkyl)dimethylammonium with smectite

([2M(2Alk)] smectite)

91081-06-0***

Bis(hydrogenated tallow alkyl) dimethylarnmonium with montmorillonite

([2M(2Alk)] montmorillonite)

68911-87-5
7

Quaternary ammonium compounds, benzylbis(hydrogenated tallow 

alkyl)methyl, salts with montmorillonite

([B(2Alk)M] montmorillonite)

97952-68-6

Quaternary ammonium compounds, benzyl(hydrogenated tallow alkyl) 

dimethyl, chlorides, compounds with smectite

([B(Alk)2M] smectite)

91080-57-8; 91080-567***

*AII alkyl R-groups are C14-C22, except ** is C22 and *** is di-C10-C22 alkyl

Compared to those in the petitioned substance, the quaternary ammonium compounds 

("quats") on the clays in Table 1 are the same or similar. The quaternary ammonium compound 

R- 10 of 43 groups in Table 1 are benzyl, methyl, and/or alkyl- (primarily C14-C22) substituted 

and derived from tallow oil. The fact that the organic components of the treated clays are 

essentially the same adds validity to the use of data on the treated smectites in Table 1 to 

describe properties of the treated sepiolite. A comparison of the physical properties of these 

quats to the representative quat benzyldimethylstearylammonium chloride (i.e. stearalkonium 

chloride; CAS Reg. No. 122-19-0) confirms this (Table 2). Stearalkonium chloride R-groups are 

dimethyl, C18 alkyl, and benzyl. All quats in Table 2 have negligible water solubility, a high 

octanol-water partitioning coefficient, and a high propensity to adsorb, rather than mobilize. 

Additionally, benzyl methyl dialkyl ammonium chloride and dimethyl dialkyl ammonium 

chloride are considerably less soluble and have higher Kow/Koc values than stearalkonium 

chloride. All other things being equal, this suggests that Benzyl methyl dialkyl ammonium

chloride and Dimethyl dialkyl ammonium chloride are actually more likely to stay adsorbed to 

surfaces than stearalkonium chloride. Furthermore, a similar trend is apparent for measured 

values of the stearalkonium bentonite, the treated clay analog and a stearalkonium chloride 

derivative (see Table 2). Hence the use of stearalkonium bentonite as an analog is expected to be 

a conservative strategy for describing the potential bioavailability of the quaternary compounds 

on treated sepiolite.

Table 2. Physical Properties of some Quaternary Ammonium Compounds and Stearalkonium Bentonite 

(Data are from NICNAS 2013a)

Name CAS Reg. 

No. 

Solubility (g/L) Log Kow Log Koc

Benzyl methyl dialkyl ammonium 

chloride

61789-73-9 5.47 x10-10 (est) 10.29 (est) 6.530 (est)

Dimethyl dialkyl ammonium chloride 61789-80-8 4.85 x10-8(est) 8.59 (est) 5.589 (est)

Stearalkonium chloride (reference quat) 122-19-0 2.08 x10-5(est) 5.87 (est) 4.085 (est)

Stearalkonium bentonite (treated clay 

analog)

130501-87-0 <4.0x 10-5

(meas)

5.87 (meas) unable to 

determine

The clay component of the structurally similar treated clay analogs shown in Table 1 is 

smectite. Smectite is actually the name describing a group of clay minerals, of which hectorite, 

bentonite, and montmorillonite are members. These four are closely/inter- related and have been

described in some datasets interchangeably (OECD 2007). Smectites are sheet silicates

consisting of two tetrahedral layers of SiO4 and one octahedral layer typically of AlO4. Smectites

all have large surface areas (700-800 m2/g; Brady 1990) and can accommodate additional

interlayers of water, which cause them to swell. Each individual crystal is about one nanometer

thick and up to 1000 nanometers across. Each crystal carries a net negative charge of

approximately 0.8-1.5 mEq/g, making smectites highly hydrophilic (OECD 2007). The net

negative charge on smectites can be accounted for by isomorphous substitution of Mg2+ for Al
8

3+ or Al3+ for Si4+, and by pH (Brady 1990). The CEC of smectites is high, ranging from 80 to

120 cmol positive charge per kg.

Although the sepiolite clays are physically dissimilar to the smectite group clays that are 

listed in Table 1, once they are treated with quaternary ammonium compounds, the treated clays 

are expected to have very similar physical and toxicological properties. In treated clays of either

type, the naturally-occurring counter ions on the clays' surface have been readily exchanged for

quaternary ammonium ions. As the CEC of smectites is higher, they can be said to have more

capacity to bind cations via the CEC mechanism compared to sepiolite. However at high quat

loading the CEC sites will eventually saturate and the chain-chain interactions become more

important.

The ions are strongly bound to the clays' surface through ionic and hydrophobic forces 

and this is not expected to be different between sepiolite and smectites. As a result, both treated

sepiolite and smectite are expected to be non-reactive in the environment and essentially

unavailable biologically. This supports the use of treated smectite group clay minerals as proxies 

for treated sepiolite in both environmental fate and toxicological properties.

Another argument supporting the validity of bridging data on the treated clays in Table 1 

to describe properties of Quaternary ammonium compounds, benzylbis(hydrogenated tallow

alkyl)methyl, bis(hydrogenated tallow alkyl)dimethylammonium salts with sepiolite is that they

have similar particle size distributions. 

II. INERT INGREDIENT PROFILE

A. Summary of Uses

A trade name the inert mixture of which Quaternary ammonium compounds, 

benzylbis(hydrogenated tallow alkyl)methyl, bis(hydrogenated tallow alkyl)dimethylammonium 

salts with sepiolite is a component, is used as a rheological additive for epoxy and vinyl ester 

systems and solvent born systems.

Sepiolite alone (i.e. untreated) has multiple household uses; it is in cat litter and other 

products that require or function as moisture and odor control. It also functions as an industrial 

absorbent, contaminant remediation tool, chemical carrier, and stabilizer in fertilizers. Sepiolite 

is used in roof panels and other construction materials to improve binding and increasing 

resistance to the elements, including fire. It is a common rheological additive for organic systems 

including solvent-based paints, greases, resins and inks. Sepiolite is also registered in the ED as a

technological additive for animal feed (E-562). It lends binding and anti-caking properties to 

feed and acts as a suspending agent in liquid feeds for pigs and ruminants (IMA Europe, 

undated). The Cosmetics Ingredient Review (CIR) Expert Panel and British and US 

Pharmacopeias list sepiolite as magnesium trisilicate (Lopez-Galindo 2007). The CIR Expert 

Panel concluded that sepiolite/magnesium trisilicate is "safe as currently used in cosmetic 

formulations." Magnesium trisilicate is also listed in the OTC Active Ingredient State Report as 

being used in antacids, digestive aids, and overindulgence remedies (CIR 2003).
9

B. Physical Chemical Properties

The clay component is sepiolite (CAS Reg. No. 63800-37-3) and the quaternary 

ammonium compounds are:

 Quaternary ammonium compounds, benzylbis(hydrogenated tallow alkyl)methyl, 

chlorides (CAS Reg. No. 61789-73-9) (top molecule shown below under 

structure).

 Quaternary ammonium compounds, bis(hydrogenated tallow alkyl)dimethyl, 

chlorides (CAS Reg. No. 61789-80-8) (bottom molecule shown below under 

structure).

Sepiolite is a hydrated magnesium silicate with fibrous morphology with the ideal 

formula Si12Mg8O30(OH)4(OH2)4.8H2O. One magnesium octahedron is sandwiched between two

tetrahedra of silicon arranged as a quincunx where every 6 or 4 silicon tetrahedra, the structure

inverts 180° creating a structure of chains parallel to the a axis, each of which has a 2:1 structure. 

This creates open channels making the clay highly porous and giving sepiolite a high surface 

area of about 300 m2/g (IMA undated). The clay is highly hydrophilic due to silanol groups (-

SiOH) on the surface. The high density of silanol groups (-SiOH) on the surface explains the 

hydrophilicity of this clay. The silicate chain has a low negative charge giving the clay a low 

cation exchange capacity (CEC). The channels in the structure and the outer surface contain the 

native counter ions that can readily exchange for organic cations like quaternary ammonium 

compounds, resulting in treated clay that is highly hydrophobia Once bound, the quaternary 

ammonium compound is unlikely to dissociate under natural conditions as ionic and adsorbing 

forces would need to be overcome simultaneously, requiring a material with a very high cation 

exchange capacity that is also able to solubilize the quaternary ammonium moiety (OECD 2007).

NICNAS (2013b) reported the melting point of stearalkonium bentonite to be >390°C 

and the boiling point of stearalkonium hectorite, per OECD TG 103, to be >500°C at 101.3 kPa.

However, these values are somewhat misleading in that, although extreme heat may degrade 

treated clays somewhat, they will not technically melt or boil. Similarly, treated clays do not

dissolve measurably in water (see Table 3) or in or in lipids/octanol (OECD 2007). Therefore the

concept of partitioning between these phases (Kow) is not relevant. Likewise, the organic carbon 

partitioning coefficient (Koc) cannot be realistically measured for organoclays. Vapor pressure 

and volatility are not applicable because this substance is essentially an inorganic solid. If fine 

particles are released to the air, they will tend to settle onto the ground. Those released into water 

will also eventually settle out and become part of soil/sediment. These substances will not 

hydrolyze or react with acids or bases over a pH range of 3-11 (OECD 2007), nor will they 

migrate between environmental compartments.

Table 2. Physical and Chemical Properties of Quaternary Ammonium Compounds, 

Benzylbis(hydrogenated tallow alkyl)methyl, bis(hydrogenated tallow alkyl)dimethylammonium salts with 

sepiolite

Parameter Value Source
10

Structure Petition

CAS Reg. No. 1574487-61-8

Molecular Weight (g/mol)

Common Names Not Available

Physical State Solid

Melting Point (°C) Not Applicable

Boiling Point (°C) @ 19 hPa Not Applicable

Density (g/cm3 @ 20°C)

Vapor Pressure (mmHg @ 25°C) Not Applicable

Partition Coefficient (Log P) Not Applicable

Water Solubility (g/L) Not Applicable

pH

Henry's Law Constant

III. HUMAN HEALTH ASSESSMENT

A. Summary of Toxicity Data 

Based on data in structurally similar clay substances, quaternary ammonium compounds,

benzylbis(hydrogenated tallow alkyl)methyl, bis(hydrogenated tallow 

alkyl)dimethylammonium salts with sepiolite has low acute toxicity via the oral, dermal 

and inhalation routes in rats. The substance is expected to be a slight skin and eye irritant. 

A structurally similar substance did not cause skin sensitization in guinea pigs. Repeatdose studies consistently showed high No Observed Adverse Effect Levels (NOAELs), 

typically the highest dose tested, which was 1000 mg/kg/day in rats. There was an 

absence of test substance-related toxicologically significant effects at any of the doses 

administered, including for neurological and immunological endpoints. Similarly, there 

were no effects on reproductive or developmental endpoints and no evidence for 

genotoxicity in multiple in vitro and in vivo assays. The data presented in the following 

section support the notion that Quaternary ammonium compounds,

benzylbisfhydrogenated tallow alkyl)methyl, bisfhydrogenated tallow 

alkyl)dimethylammonium salts with sepiolite is a biologically inactive substance that will 

not result in adverse health effects when used as an inert material in pesticide 

formulations intended for pre-harvest use.

Acute Oral Toxicity
11

Stearalkonium bentonite (CAS Reg. No. 130501-87-0; trade name: Tixogel VZ-V) was 

administered orally to 5 male and 5 female rats at 5000 mg/kg. The test substance was 

prepared in a 12.5% gravimetric corn oil suspension. After a 14-day observation period, 

the LD50 was determined to be >5000 mg/kg based on 1/10 deaths (CRT 1981 a). 

An acute oral LD50 of >5000 mg/kg [B(Alk)2M] hectorite (CAS Reg. No. 71011-26-2) 

was established in rats. The test method was considered similar to OECD guideline 401 

(OECD 2008c). The test substance was prepared in corn oil as a 50% suspension. 

Sprague Dawley rats (5/sex) received a gavage dose of 5000 mg/kg and were monitored 

for 14 days. There were no deaths during the study. Two males had diarrhea; there were 

no other clinical signs of toxicity. 

Similar results (LD50 values exceeding 5000 mg/kg) were obtained in acute oral studies 

in rats with [B(2Alk)M] bentonite, [2M(2Alk)] bentonite (CAS Reg. No. 68953-58-2 

(OECD 2008d); B(Alk)2M bentonite, B(Alk)2M smectite, 2M(2Alk) hectorite, 

2M(2Alk) montmorillonite, 2M(2Alk) smectite, B(2Alk)M hectorite, and B(2Alk)M 

montmorillonite (OECD 2007).

Dermal Toxicity

An acute dermal toxicity study (OECD guideline 402) was carried out on stearalkonium 

bentonite (CAS Reg. No. 130501-87-0; trade name: Tixogel VZ-V). Stearalkonium 

bentonite at 2000 mg/kg was administered to the dorsal thoracal region of 5 male and 5 

female Sprague Dawley rats for 24 hours. Body weights were measured 7 and 15 days 

post-administration. There were no significant changes in body weight nor was there any 

mortality. The LD50 was determined to be >2000 mg/kg (ARC 2004). 

Inhalation Toxicity

An acute inhalation toxicity test similar to OECD guideline 403 was carried out using 

dust of B(Alk)2M bentonite (CAS Reg. No. 71011-24-0). Sprague-Dawley rats (5/sex)

were whole-body exposed to 5.2 mg/L (nominal) for four hours and then observed and 

weighed during the next 14 days. There were no deaths during the study. Some (6/10) 

animals showed a reduction in activity on day 2 that was not apparent by day 4. Other 

observations were nasal discharge (7 animals, day 2), respiratory irregularity (1 animal, 

days 2-3), transient decrease in average group body weight (not evident by day 8). The 4-

hour inhalation LC50 was >5.2 mg/L (OECD 2008b).

Two OECD TG 403 acute inhalation toxicity tests of [2M(2Alk)J bentonite (CAS Reg. 

No. 68953-58-2) had similar results. One was a 4-hour test at a concentration of 12.7 

mg/L and one was a 1 hr exposure at 200 mg/L. There were no deaths, but some labored 

breathing. The 4-hr and 1-hr LC50 values were >12.7 and >200 mg/L, respectively 

(OECD 2008d).

B(2Alk)M] bentonite (CAS Reg. No. 68153-30-0) was also tested for acute inhalation 

toxicity in rats. The 4-hour LC50 was >5.4 mg/L (OECD 2007).
12

An OECD TG 403 study of B(2Alk)M hectorite (CAS Reg. No. 97952-68-6) derived an 

LC50 value of >5.2 mg/L in rats. Another acute inhalation study employed a lower dose 

of B(2Alk)M hectorite to assess the inflammatory/cytotoxic response in the lung 

following inhalation of aerosols. The MMAD was 6.6 μm, with 75% of particles less than 

12 μm in size. Rats were exposed to 0.65 mg/L for four hours and then sacrificed after 

two weeks. There were no treatment-related differences in body weight but lung weights 

were slightly higher compared to controls. Analysis of the bronchoalveolar lavage fluid 

revealed elevated levels of protein, lactate dehydrogenase, beta-glucuronidase and Nacetyl glucosaminidase and measurement of cellular parameters revealed a greater 

number of cells, including inflammatory cells, in the bronchoalveolar lavage fluid in rats 

exposed to the test material. Compared to negative controls these changes indicated some 

level of biological activity of the test compound; however, changes were not as marked 

as those seen in positive control rats (OECD 2007).

Primary Eye Irritation

Stearalkonium bentonite (CAS Reg. No. 130501-87-0; trade name: Tixogel VZ-V) was 

administered at 0.1 g to the eyes of 6 New Zealand rabbits (CRT 1981c). One eye in each 

rabbit served as the control. The eyes were not washed for 24 hours and observations 

were scored according to the method of Draize at 24, 48, and 72 hours and 4 and 7 days 

after treatment. Observations of eyes indicated that Stearalkonium bentonite was a 

moderate ocular irritant. In a more recent, OECD test guideline 405 eye irritation study of 

the same test substance, 0.1 mL instilled into the eye of rabbits produced only mild ocular 

lesions (conjunctival redness and chemosis), all of which were reversible within 72 hours 

(ARC 2005a). 

Eye irritation of [B(Alk)2M] hectorite (CAS Reg. No. 71011-26-2) was evaluated in 

rabbits and reported by OECD (OECD 2008c). A volume of 0.1 ml of undiluted test 

article was instilled in one eye of nine rabbits, and the untreated eye served as a control. 

Six animals' treated eyes were not rinsed for the duration of the test. Three animals' eyes 

were exposed for 4 seconds and then rinsed. Rabbit eyes were examined with sodium 

fluorescein at 24, 48 and 72 hours and scored using the Draize Scale for Scoring Ocular 

Lesions. There was no irritation in the rinsed eyes at any time (mean score = 0). For the 

eyes that were not rinsed, at 24 hours the Maximum Mean Total Score was 20.2, which is 

considered mildly irritating using the standard Kay and Calandra scoring system. By day 

7, the mean score was 3.2, which is minimally irritating. OECD considered the test 

substance moderately irritating.

[2M(2Alk)] bentonite (CAS Reg. No. 68953-58-2) was not irritating to rabbit eyes in 

three primary eye irritation studies using the FHSLA guidelines described in 16 CFR 

1500.42 or by Draize methodology. The substance was moderately irritating in a fourth 

study that employed a GLP modified Draize methodology in which 0.1 g of undiluted 

substance was added to one eye of six rabbits for 24 hours (OECD 2008d).

2M(2Alk) hectorite gave mixed results in five ocular irritation tests in rabbits. All tests 

scored eyes by the method FHSLA (16 CFR §1500.42). In two tests, some of the rabbits 

had positive scores, according to the FHSLA grading system. In the three other studies, 
13

ocular reaction to 0.1 mL instilled into rabbit eyes and graded on the same scale was 

found not to be irritating (OECD 2007).

Both [B(2Alk)M] bentonite (CAS Reg. No. 68153-30-0) and [B(2Alk)M] hectorite (0.1 

g) were tested in rabbit eyes using the same procedure, where test material was rinsed 

from eyes of three of nine rabbits after 30 seconds. The eyes of the remaining six rabbits 

were not rinsed. The bentonite salt was minimally irritating to rabbits regardless of 

rinsing while the hectorite was not irritating to rabbit eyes under any condition tested 

(OECD 2007).

Primary Skin Irritation

Stearalkonium bentonite (CAS Reg. No. 130501-87-0; trade name: Tixogel VZ-V) was 

administered at 0.5 g to two sites on each of six New Zealand white rabbits (CRT 1981b). 

One site was intact and one abraded. Both were occluded for 24 hours and then observed 

one time and then again at 72 hours. Based on a Primary Irritation Index of 0.3, 

stearalkonium bentonite was not considered a primary dermal irritant to rabbits under 

conditions of this test.

A 50% solution (0.5 g in 0.5 mL saline) of [B(Alk)2M] hectorite was applied to the 

clipped abraded and intact skin of 6 rabbits and covered with occlusive wrap. After 24 

hours the sites were rinsed and examined and scored for erythema and edema. The sites 

were examined and scored again after 72 hours. The test substance was determined to be 

not irritating. This study did not follow a specific guideline, but was considered 

comparable to a guideline study and "valid with restrictions" by OECD (OECD 2008c). 

Similarly, a guideline primary skin irritation study (FHSA, 16 CFR 1500.41) of 

[2M(2Alk)] bentonite (CAS Reg. No. 68953-58-2) and [B(2Alk)M] bentonite (CAS Reg. 

No. 68153-30-0) were negative for irritation when exposed on intact and abraded rabbit 

skin for 24 hours. [2M(2Alk)] hectorite and [2M(2Alk)] bentonite were also not irritating 

to rabbit skin (OECD 2007).

Dermal Sensitization

2M(2Alk) bentonite (CAS Reg. No. 68953-58-2) in a 0.1% suspension in physiological 

saline solution was administered intracutaneously to 12 guinea pigs (OECD 2007). Ten 

injections of 0.05-0.1 ml were delivered followed by the challenge dose of 0.05 ml. No 

sensitization reaction was observed. A guinea pig maximization test (OECD test 

guideline 406) was carried out using B(Alk)2M bentonite (CAS Reg. No. 71011-24-0). 

Twenty animals received an intradermal injection of 0.5% of the test substance in liquid 

paraffin as an induction dose. The topical challenge dose was 30 and 15% (w/w) in liquid 

paraffin. Ten animals were used as controls. The test substance did not induce a 

sensitization reaction (OECD 2008b). 

The results of the available acute toxicity studies are summarized in Table 2.

Acute Toxicity
14

Table 3. Acute Toxicity Profile of Quaternary Ammonium Compounds, Benzylbis(hydrogenated tallow 

alkyl)methyl, bis(hydrogenated tallow alkyl)dimethylammonium salts with sepiolite

Study Type Results

Toxicity 

Category MRIDs # /Reference

Acute Oral – rat

Stearalkonium bentonite 

(CAS Reg. No. 130501-

87-0)

LD50 >5000 mg/kg IV CPT 1981a

Acute Oral – rat

[B(Alk)2M] hectorite 

(CAS Reg. No. 71011-

26-2)

LD50 >5000 mg/kg IV OECD 2008c

Acute Dermal – rat

Stearalkonium bentonite 

(CAS Reg. No. 130501-

87-0)

LD50 >2000 mg/kg III ARC 2004

Acute Inhalation – rat

B(Alk)2M bentonite 

(CAS Reg. No. 71011-

24-0)

LC50 > 5.2 mg/L IV OECD 2008b

Acute Inhalation – rat

[2M(2Alk)] bentonite 

(CAS Reg. No. 68953-

58-2)

LC50 > 12.7 mg/L (4-hr)

LC50 > 200 mg/L (1-hr)

IV OECD 2008d

Acute Inhalation – rat

B(2Alk)M] bentonite 

(CAS Reg. No. 68153-

30-0)

LC50 > 5.4 mg/L (4-hr) IV OECD 2007

Acute Inhalation – rat

B(2Alk)M hectorite 

(CAS Reg. No. 97952-

68-6)

LC50 > 5.2 mg/L IV OECD 2007

Primary Eye Irritation –

rabbit

Stearalkonium bentonite 

(CAS Reg. no. 130501-

87-0)

Moderate irritant III CPT 1981c

Primary Eye Irritation –

rabbit

Stearalkonium bentonite 

(CAS Reg. no. 130501-

87-0)

Mild ocular lesions (reversible 

72 hrs)

III ARC 2005a

Primary Eye Irritation –

rabbit

[B(Alk)2M] hectorite 

(CAS Reg. No. 71011-

26-2)

Minimally irritating N/A OECD 2008c

Primary Eye Irritation –

rabbit

[2M(2Alk)] bentonite 

(CAS Reg. No. 68953-

58-2)

Not irritating in 3 studies

Moderately irritating in 1 study

N/A OECD 2008d

Primary Eye Irritation –

rabbit

2M(2Alk) hectorite 

Not irritating in 3 studies N/A OECD 2007
15

Table 3. Acute Toxicity Profile of Quaternary Ammonium Compounds, Benzylbis(hydrogenated tallow 

alkyl)methyl, bis(hydrogenated tallow alkyl)dimethylammonium salts with sepiolite

Study Type Results

Toxicity 

Category MRIDs # /Reference

Primary Eye Irritation –

rabbit

[B(2Alk)M] bentonite 

(CAS Reg. No. 68153-

30-0)

Minimally irritating N/A OECD 2007

Primary Eye Irritation –

rabbit

[B(2Alk)m] hectorite 

Not irritating N/A OECD 2007

Dermal Irritation – rabbit

Stearalkonium bentonite 

(CAS Reg. No. 130501-

87-0)

Not dermal irritant N/A CPT 1981b

Dermal Irritation – rabbit 

[B(Alk)2M] hectorite 

(CAS Reg. No. 71011-

26-2)

Not irritating N/A OECD 2008c

Dermal Irritation –

[2M(2Alk)] bentonite 

(CAS Reg. No. 68953-

58-2)

Negative for irritation N/A OECD 2007

Dermal Irritation –

[2M(2Alk)] bentonite 

(CAS Reg. No. 68153-

30-0)

Negative for irritation N/A OECD 2007

Dermal Sensitization -

guinea pigs 

2M(2Alk) bentonite 

(CAS Reg. No. 68953-

58-2)

Not dermal sensitizer N/A OECD 2007

Dermal Sensitization -

guinea pigs 

B(Alk)2M bentonite 

(CAS Reg. No. 71011-

24-0)

Not dermal sensitizer N/A OECD 2008b

Subchronic Toxicity -

Three 28-day OECD test guideline 407 studies (or close variations) were identified for 

three treated clays that are structurally similar to Quaternary ammonium compounds,

benzylbis(hydrogenated tallow alkyl)methyl, bis(hydrogenated tallow 

alkyl)dimethylammonium salts with sepiolite. 

A 28-day repeated dose oral toxicity study was carried out on stearalkonium bentonite 

(CAS Reg. No. 130501-87-0) under OECD test guideline 407. Rats received gavage

doses of 0, 100, 316, or 1000 mg/kg/day of the test substance in a 0.1% aqueous solution 

of sodium carboxymethylcellulose. An additional high dose and control group of rats 

(5/sex/group) were kept for 14 days after cessation of dosing to assess possible 

reversibility or persistence of lesions. Body weights and feed consumption were 

monitored throughout the study. Clinical biochemistry and hematology examinations 
16

were performed after the last dose and at necropsy, a gross pathological exam, organ 

weight measurements, and histopathological examination. There were no substancerelated effects after 28 days of dosing. The recovery group/high dose females had 

statistically lower body weights (163.6 g on day 42 versus 172.6 g for control/recovery 

rats on day 42) and lower absolute brain (1712 mg) and heart weights (632 mg) after 

recovery compared with control/recovery rats (1768 mg brain and 680 mg heart). 

Because these effects were absent in the non-recovery high dose group, they are not 

considered biologically relevant. The NOAEL in this study was the highest dose, 1000 

mg/kg/day stearalkonium bentonite (ARC 2003).

Charles River/CD rats (5/sex/dose) received gavage doses of 0 or 1000 mg/kg/day of 

[B(Alk)2M] bentonite (CAS Reg. No. 71011-24-0) for 28 days (method similar to OECD 

test guideline 407). The test material was formulated daily as a 20% w/v suspension in 

corn oil. Animals were monitored for clinical signs, body weight, and food consumption 

throughout the study. Full clinical chemistry analysis and hematology battery were 

conducted after the dosing period, and then a complete necropsy was carried out. There 

were no mortalities, clinical signs of toxicity, effects on body weight or food 

consumption, or statistically significant findings for hematology or clinical chemistry. 

The relative liver weights of female but not male rats were lower than in controls (p < 

0.05). There were no accompanying macroscopic or microscopic findings in livers and 

therefore study authors considered the difference to be not toxicologically significant.

Authors concluded that the NOAEL was the highest dose, 1000 mg/kg/day [B(Alk)2M]

bentonite (OECD 2008b).

A 28-day gavage rat study was conducted with [B(2Alk)M] hectorite (CAS Reg. No. 

121888-67-3) (OECD 2008a). The test method was comparable to OECD guideline 407 

and used Charles River/CD rats (5/sex) and the single limit dose of 1000 mg/kg/day. The 

endpoints monitored were the same as above study. There were no mortalities, clinical 

signs of toxicity, changes in body weight gains, food consumption or hematological 

parameters. In some measured parameters (thrombotest time (females), cholesterol 

(males), calcium levels (females)) there were statistically significant differences in 

treated rats compared to controls, but because these differences were small and values 

were all within normal ranges, they were not considered an effect of the test substance. 

Chloride levels were slightly reduced in female treated rats; authors did not consider this 

effect to be toxicologically significant because the difference compared to control 

animals was small and only was seen in females. In treated males, statistically significant 

higher adrenal weights were noted. There were no accompanying abnormalities observed 

in a macroscopic exam and all values were within the range of normal. Also, the control 

population was noted to have adrenal weights in the lower range of normal, perhaps 

accounting for some of the difference between them and the treated males. For these 

reasons, the study authors did not consider the adrenal weight effect to be toxicologically 

important. None of the histopathological findings was considered toxicologically 

significant by the study authors. The NOAEL is considered to be 1000 mg/kg/day 

(OECD 2008a).
17

In a test method similar to OECD TG 407, rats (6/sex/group) were fed diets containing 0,

1, 5, or 25% [2M(2Alk)] bentonite (CAS Reg. No. 68953-58-2) for 12 weeks. A fifth 

group of rats received 25% bentonite (untreated) in the diet. Monitored endpoints 

included food consumption, body weight, and clinical signs. Two rats per group 

underwent a hematological examination and all rats underwent necropsy that included 

measurement of liver and kidney weights. Growth rate was depressed in both groups 

receiving 25% dietary supplementation indicating that the effect was a result of reduced 

caloric intake rather than a systemic test substance effect. The efficiency of food 

utilization was not different in the control, 1% or 5% dose group, but was reduced in the

two 25% groups. Authors concluded that 2M(2Alk) bentonite had no significant effect on 

growth or food utilization except that which was accounted for by reduced nutrient intake 

at high levels of replacement of basal diet (OECD 2008d). The NOAEL was the highest 

dose: 25%, or 12,500 - 25,000 mg/kg/day [2M(2Alk)] bentonite.

Chronic Oral Toxicity -

No chronic studies were available in the database for quaternary ammonium compounds,

benzylbis(hydrogenated tallow alkyl)methyl, bis(hydrogenated tallow 

alkyl)dimethylammonium salts with sepiolite.

Mutagenicity and Genotoxicity

Stearalkonium bentonite (CAS Reg. No. 130501-87-0) was tested for mutagenicity in two 

independent reverse mutation assays in Salmonella typhimurium strains TA98, TA100, 

TA102, TA1535, and TA1537 (LPT 2000). Both assays were carried out in the presence 

and absence of metabolic activation. Five stearalkonium bentonite concentrations ranged 

from 3.16 to 316 μg/plate; cytotoxicity was observed at 316 μg/plate and higher with

metabolic activation and in several strains at 31.6 μg/plate without activation. There was 

not a significant increase in the frequency of revertant colonies in any strain at any 

concentration with or without metabolic activation.

A micronucleus test (OECD test guideline 474) in mice was run with stearalkonium 

bentonite (ARC 2005b). The substance was suspended in carboxymethylcellulose, 

sodium salt (0.1% w/v in deionized water) and administered at 1000, 1500, or 2000 

mg/kg by gavage to Crl:NMRI BR mice (5/sex). Two negative control groups with 

carboxymethylcellulose and one positive control group with cyclophosphamide were run. 

Mice were sacrificed after 24 or 48 hours. At the high dose there was a statistically 

significant increase in micronucleated polychromatic erythrocytes (PCE) compared to the 

negative control group. However, the frequency of micronucleated PCEs was still within 

the range of historical negative control data. Therefore, study authors concluded that 

there was no effect of Stearalkonium bentonite on chromosomes or the mitotic apparatus 

of mice under conditions of this assay.

OECD (2008b) reported an OECD test guideline 471 bacterial reverse mutation assay 

carried out on [B(Alk)2M] bentonite (CAS Reg. No. 71011-24-0). The substance, 

suspended in dimethylsulfoxide, was tested on Salmonella typhimurium strains TA98, 

TA100, TA1535, TA1537, and TA1538. Bacteria were exposed to 50, 150, 500, 1500, or 

5000 μg/plate in the presence or absence of metabolic activation. Negative and solvent 
18

control group were implemented concurrently. The highest concentration tested was 

slightly cytotoxic. The frequency of reverse mutations did not increase in any bacterial 

strain under any condition tested. These results indicate that B(Alk)2M bentonite is not 

mutagenic.

[2M(2Alk)] bentonite (CAS Reg. No. 68953-58-2) was also tested in an Ames assay 

using S. typhimurium strains TA98, TA100, TA1535, TA1537, and TA1538. There was 

no significant increase in the frequency of reverse mutations at concentrations of 10-3000 

μg/plate in the presence of absence of metabolic activation (OECD 2008d).

A bacterial reverse mutation assay (OECD test guideline 471) was also carried out on

[B(Alk)2M] hectorite (CAS Reg. No. 71011-26-2). The substance, suspended in 

dimethylsulfoxide, was tested on Salmonella typhimurium strains TA98, TA100, 

TA1535, TA1537, and TA1538. Bacteria were exposed to 50, 150, 500, or 1500 μg/plate 

in the presence or absence of metabolic activation with Aroclor 1254 induced rat liver 

preparation and co-factors. The frequency of reverse mutations did not increase in any 

bacterial strain under any condition tested. These results indicate that this treated clay is 

not mutagenic (OECD 2008b).

A mouse lymphoma assay (OECD test guideline 476) was carried out on the same 

substance, [B(Alk)2M] hectorite (CAS Reg. No. 71011-26-2). Mouse lymphoma L5178Y 

cells were exposed to 1-50 g/mL test substance in the absence of Aroclor 1254 induced 

rat liver mix and to 5-70 μg/mL in the presence of S-9 mix. No biologically significant 

increases in mutant frequency were observed under these test conditions suggesting that 

[B(Alk)2M] hectorite is not mutagenic (OECD 2008b).

An in vivo micronucleus assay equivalent to OECD test guideline 474 and a modified

mammalian bone marrow chromosome aberration assay were identified in the literature 

for [B(Alk)2M] bentonite (CAS Reg. No. 71011-24-0). In the micronucleus assay, 

Charles River CD rats (5/sex) received 1000 mg/kg daily (i.e., the limit dose) of the test 

compound or corn oil for 28 days. Femur bone marrow specimens were obtained 24 

hours after last dosing, stained and examined for micronucleated cells in polychromatic 

erythrocytes (PCEs). No positive control was used. [B(Alk)2M] bentonite did not induce 

a significant increase in micronuclei in bone marrow PCEs or a significant decrease in the 

ratio of polychromatic to normochromatic erythrocytes and was therefore not considered 

clastogenic under the conditions of this assay (OECD 2008b).

In the chromosome aberration assay, Charles River CD rats (5/sex) received 1000 

mg/kg/day [B(Alk)2M] bentonite (C14-C22) for 28 days. Control rats received corn oil. 

No positive control group was run. Following the dosing period, blood was drawn, 

cultured and stimulated with mitogen for 48 hours. The culture was then treated with 

colchicine and chromosomes were evaluated for aberrations. No significant increase in 

the frequency of chromosomal aberrations was noted in treated rats versus controls. 

These results provide further evidence that [B(Alk)2M] bentonite is not clastogenic 

(OECD 2008b).
19

Carcinogenicity

There are no data specific to the carcinogenicity of Quaternary ammonium compounds,

benzylbis(hydrogenated tallow alkyl)methyl, bis(hydrogenated tallow 

alkyl)dimethylammonium salts with sepiolite or any of the structurally similar treated 

clays. Carcinogenicity of some mineral clays is associated with the presence of respirable 

crystalline silica (e.g., quartz or cristabolite), a known human carcinogen, as an impurity. 

It should be noted that the Quaternary ammonium compounds, benzylbis(hydrogenated 

tallow alkyl)methyl, bis(hydrogenated tallow alkyl)dimethylammonium salts with 

sepiolite when used in a specific trade name formulation does not contain detectable 

levels of crystalline silica (NICNAS 2013a). This trade name formulation with treated 

clays and other processed clay minerals that are used in pharmacy, cosmetics and other 

commercial products are processed prior to manufacture. Processing includes purification 

and removal of carcinogenic impurities like quartz and cristabolite. In general, sepiolite is 

highly highly (>95%) pure even before processing (Lopez-Galindo et al. 2007). 

The presence of fibers in clay is sometimes related to its carcinogenicity. Santaren et al. 

(1994) and IARC (1997) reviewed potential health hazards of sepiolite because of its 

fibrous morphology. In both reviews, authors made the distinction between geographical 

origins of different sepiolites. Animal studies on this clay, including inhalation, 

intrapleural and intraperitoneal (ip) studies have shown that the sepiolite from VallecasVicalvaro, Spain is not a health hazard. On the other hand, sepiolite with nonsedimentary geological origins (i.e. from Finland and China) could be a health risk. The 

sepiolite clay in this Garamite product is derived from Spain (Mattingly 2014a).

Bellmann et al. (1997) and IARC (1997) investigated sepiolite samples and 

recommended the potential carcinogenicity of sepiolite was linked to the length of the 

fibers. Because the fibers in Vallecas-Vicalvaro sepiolite were not longer than 6 or 8 urn, 

they did not have the potential to increase tumor incidence. The IARC concluded that 

"Sepiolite cannot be classified as to its carcinogenicity to humans (Group 3)".

The Spanish sepiolite used in these studies is derived from the same geographical 

location as the clay in the petitioned substance and is less than 6 urn (Mattingly 2014a). 

Because of this and because Garamite 1958 does not contain detectable levels of 

crystalline silica, there is not expected to be a significant risk for carcinogenicity from 

inhalation exposure to this treated clay.

Developmental and Reproductive Toxicity

A one-generation reproductive toxicity study on [B(2Alk)M] hectorite (CAS Reg. No. 

121888-67-3) using OECD guideline 415 (OECD 2008e). Female and male Sprague 

Dawley rats (24 sex/group) were dosed for 74 or 18 days, respectively, prior to mating. 

Rats continued to be dosed during mating (21 days), throughout gestation and lactation, 

through post-natal day 21. Doses were 0, 50, 225, and 1000 mg/kg test substance 

suspended in PEG 400. There was also a vehicle-dosed group. On post-natal day (PND) 

21, survivors from the parental generation were sacrificed and examined microscopically 

and selected tissues/organs were examined histopathologically. Periodically throughout 

the study the following were checked: morbidity/mortality, clinical signs, bodyweight 
20

and food consumption during maturation, mating and gestation. Number of live/dead 

offspring, litter body weight and litter clinical signs were recorded. Litters were assessed 

for developmental landmarks including reflexes. Other parameter monitored were food 

conversion ratio; mating performance and fertility; pre-coital interval; fertility indices 

(mating index and pregnancy index); gestation length; gestation and parturition index; 

lactation data including live birth index, viability indices; sex ratio; and offspring

physical development and reflexology. The only statistically significant effect of 

[B(2Alk)M] hectorite was on the mean litter weight in the high dose group on PNDs 7-

21. The mean number of pups per litter was less in this dose group, but could be 

attributed to a single dam's litter of only 2 pups. There was not an effect on the mean 

individual offspring weight. Therefore, the difference in mean litter body weights was not 

considered to be toxicologically important. There were no effects on other developmental 

endpoints. The NOAEL for systemic and reproductive/developmental effects to be the 

highest dose, 1000 mg/kg/day [B(2Alk)M] hectorite (OECD 2008e).

In the 28-day toxicity study of stearalkonium bentonite described above, there were no 

histopathological findings in any reproductive organ including testis, epididymis, ovary, 

prostate, or uterus (ARC 2003).

Immunotoxicity

Due to the nonreactive nature of quaternary ammonium compounds, 

benzylbis(hydrogenated tallow alkyl)methyl, bis(hydrogenated tallow 

alkyl)dimethylammonium salts with sepiolite, as well as its minimal absorption into 

mammalian systems, effects on the immune system are not anticipated. OECD Test 

Guideline 407, the Repeated Dose 28-day Oral Toxicity Study in Rodents is designed to 

identify chemicals with immunotoxic potential so that further testing can be carried out 

on them (OECD 1995). Relevant endpoints measured in this test include thymus and 

spleen weights and histopathology. In the OECD TG 407 study of stearalkonium 

bentonite described above, there were no test substance-related effects on rats that 

indicated immunotoxicity (ARC 2003).

Neurotoxicity

Due to the nonreactive nature of quaternary ammonium compounds, 

benzylbis(hydrogenated tallow alkyl)methyl, bis(hydrogenated tallow 

alkyl)dimethylammonium salts with sepiolite, as well as its minimal absorption in 

mammalian systems, effects on the nervous system are not anticipated. OECD Test 

Guideline 407, the Repeated Dose 28-day Oral Toxicity Study in Rodents Includes 

endpoints such as brain and peripheral nerve weight and histopathology, and general 

behavioral observations that may indicate neurological effects (e.g. reactivity and reflex 

tests, observations of walking, sitting, and other daily behaviors). In the OECD TG 407 

study of stearalkonium bentonite described above, there were no test substance related 

effects on rats that indicated neurotoxicity (ARC 2003).

Metabolism and Pharmacokinetics
21

Clays treated with quaternary ammonium compounds have low water solubility, a high 

hydrophobic partition coefficient and relatively high molecular weight. All three factors 

indicate likely limited absorption following ingestion, dermal exposure or inhalation.

A study of the treated clay quaternary ammonium compounds, benzylalkyl (C14-C22) 

dimethyl, salts with bentonite (B(Alk)2M bentonite; CAS Reg. No. 71011-24-0) showed 

that only a negligible concentration of treated clays is absorbed by orally dosed rats. 

Under methods similar to OECD test guideline 417, male rats (Alpk/ApfSD; bile duct 

cannulated) received single doses of 5 or 500 mg/kg radiolabeled organoclay by gavage. 

Urine, feces and CO2 were collected over the subsequent 48 hours. Most of the 

radioactivity was eliminated in 48 hours via feces: 99% of the higher dose and about 97% 

of the lower dose. Urine contained 1.2-1.5% of the original dose and expired air 

accounted for less than 0.06% of the original dose. At the 24-hour mark whole body 

autoradiography indicated radioactivity was only present in the gastrointestinal tract. The 

concentration in other tissues including blood and in bile was very low. After 48 hours, 

0.16% and 0.95% of the administered dose remained in the carcass of low- and high-dose 

rats, respectively. OECD rated this study "valid with restrictions" as it was comparable to 

a guideline study (OECD 2008b).

Based on similarities in treated clays (high molecular weights, low water solubility, high 

hydrophobicity), the treated sepiolite would also be almost completely eliminated from 

the body shortly after oral dosing. Therefore, the biological availability of the petitioned 

substance is expected to be low.

Given that Quaternary ammonium compounds, benzylbis(hydrogenated tallow 

alkyl)methyl, bis(hydrogenated tallow alkyl)dimethylammonium salts with sepiolite 

contains particles in the respirable size range, there is potential for accumulation 

following inhalation exposure of the raw material if it is still in dry particle form. 

Clearance from the lungs shows two phased clearance in which most of the fibers are 

cleared in the first phase. Fibers of sepiolite derived from Vallecas-Vicalvaro, Spain, 

such as those in the petitioned substance, have a total half-rate of clearance from the 

lungs of 89 days, with 95% of the fiber mass eliminated with a half-rate of 39 days 

(Bellman et al. 1997).

Table 4. Toxicology Profile for Quaternary ammonium compounds, benzylbis(hydrogenated tallow 

alkyl)methyl, bis(hydrogenated tallow alkyl)dimethylammonium salts with sepiolite

Guideline No./ Study 

Type

Doses Levels Results MRID No. 

(year)/References

28-day oral toxicity – rats 

(gavage)

OECD 407

CAS Reg. No. 130501-87-

0

0, 100, 316 or 1000 mg/kg/day NOAEL = 1000 

mg/kg/day

LOAEL = N/A

ARC 2003
22

Table 4. Toxicology Profile for Quaternary ammonium compounds, benzylbis(hydrogenated tallow 

alkyl)methyl, bis(hydrogenated tallow alkyl)dimethylammonium salts with sepiolite

Guideline No./ Study 

Type

Doses Levels Results MRID No. 

(year)/References

28-day oral toxicity – rats 

(gavage)

OECD 407 (similar)

CAS Reg. No. 71011-24-0

0 or 1000 mg/kg/day NOAEL = 1000

mg/kg/day

LOAEL = N/A

OECD 2008b

28-day oral toxicity – rats 

(gavage)

OECD 407 (similar)

CAS Reg. No. 121888-67-

3

0 or 1000 mg/kg/day NOAEL = 1000 

mg/kg/day

LOAEL = N/A

OECD 2008a

12-week oral toxicity 

study – rats (diet)

OECD 407 (similar)

CAS Reg. No. 68953-58-2

0, 1, 5, or 25% NOAEL = 25% (12,500-

25,000 mg/kg/day)

LOAEL = N/A

OECD 2008d

1-Generation 

Reproductive Toxicity –

rats

OECD 415

CAS Reg. No. 121888-67-

3

0, 50, 225, and 1000 mg/kg/day 

in PEG 400

NOAEL (repro/develop) 

= 1000 mg/kg/day

LOAEL = N/A

OECD 2008e

Reverse Mutation Assay in 

Salmonella typhimurium

CAS Reg. No. 130501-87-

0

3.16 to 316 μg/plate 

with/without metabolic 

activation

Negative LPT 2000

Micronucleus Test 

(gavage)

OECD 474

1000, 1500, or 2000 mg/kg Negative ARC 2005b

Bacterial Reverse 

Mutation Assay

OECD 471

CAS Reg. No. 71011-24-0

50, 150, 500, 1500 or 5000 

μg/plate with/without metabolic 

activation

Not mutagenic OECD 2008b

Ames Assay using S. 

Typhimurium

CAS Reg. No. 68953-58-2

10-3000 μg/plate with/without 

metabolic activation

Negative OECD 2008d

Bacterial Reverse 

Mutation Assay

OECD 471

CAS Reg. No.71011-26-2

50, 150, 500 or 1500 μg/plate 

with/without metabolic 

activation

Not mutagenic OECD 2008b

Mouse Lymphoma Assay

OECD 476

CAS Reg. No. 71011-26-2

1-50 g/mLwithout Aroclor 1254

5-70 μg/mL with S-9 mix

Not mutagenic OECD 2008b
23

Table 4. Toxicology Profile for Quaternary ammonium compounds, benzylbis(hydrogenated tallow 

alkyl)methyl, bis(hydrogenated tallow alkyl)dimethylammonium salts with sepiolite

Guideline No./ Study 

Type

Doses Levels Results MRID No. 

(year)/References

In vivo Micronucleus 

Assay

OECD 474 (similar)

CAS Reg. No. 71011-24-0

1000 mg/kg/day Negative OECD 2008b

Chromosome Aberration 

Assay

1000 mg/kg/day Negative OECD 2008b

B. Toxicity Endpoint Selection

The available toxicity studies indicate that quaternary ammonium compounds, 

benzylbis(hydrogenated tallow alkyl)methyl, bis(hydrogenated tallow 

alkyl)dimethylammonium salts with sepiolite has a very low overall toxicity. The 

NOAELs were >1000 mg/kg/day (limit dose). Since signs of toxicity were not observed 

at the limit dose an endpoint of concern for risk assessment purposes was not identified. 

Therefore, since no endpoint of concern was identified for the acute and chronic dietary 

exposure assessment and short and intermediate dermal and inhalation exposure, a 

quantitative risk assessment for of quaternary ammonium compounds, 

benzylbis(hydrogenated tallow alkyl)methyl, bis(hydrogenated tallow 

alkyl)dimethylammonium salts with sepiolite is not necessary.

C. Special Considerations for Infants and Children

As part of its qualitative assessment, the Agency did not use safety factors for assessing 

risk, and no additional safety factor is needed for assessing risk to infants and 

children. Based on the lack of toxicity of ammonium acetate in the available studies and 

its chemical properties, EPA has concluded that there are no toxicological endpoints of 

concern for the U.S. population, including infants and children.

IV. EXPOSURE ASSESSMENT

A. Dietary Exposure:

In evaluating dietary exposure to the quaternary ammonium compounds, 

benzylbis(hydrogenated tallow alkyl)methyl, bis(hydrogenated tallow alkyl)dimethylammonium 

salts with sepiolite, EPA considered exposure under the petitioned for exemptions from the 

requirement of a tolerance. EPA assessed dietary exposures from quaternary ammonium 

compounds, benzylbis(hydrogenated tallow alkyl)methyl, bis(hydrogenated tallow 

alkyl)dimethylammonium salts with sepiolite in food as follows:

i. Acute exposure. No adverse effects attributable to a single exposure of quaternary 

ammonium compounds, benzylbis(hydrogenated tallow alkyl)methyl, bis(hydrogenated 

tallow alkyl)dimethylammonium salts with sepiolite were seen in the toxicity databases. 

Therefore, acute dietary exposure assessment for quaternary ammonium compounds, 
24

benzylbis(hydrogenated tallow alkyl)methyl, bis(hydrogenated tallow 

alkyl)dimethylammonium salts with sepiolite is not required.

 ii. Chronic exposure. No adverse effects attributable to chronic exposures of quaternary 

ammonium compounds, benzylbis(hydrogenated tallow alkyl)methyl, bis(hydrogenated 

tallow alkyl)dimethylammonium salts with sepiolite were seen in the toxicity databases. 

Therefore, chronic dietary exposure assessment for quaternary ammonium compounds, 

benzylbis(hydrogenated tallow alkyl)methyl, bis(hydrogenated tallow 

alkyl)dimethylammonium salts with sepiolite is not required.

iii. Cancer exposure.

Quaternary ammonium compounds, benzylbis(hydrogenated tallow alkyl)methyl, 

bis(hydrogenated tallow alkyl)dimethylammonium salts with sepiolite is not genotoxic 

and no effects suggestive of potential carcinogenicity were observed in the available 

database. Therefore, based on the lack of concern for carcinogenicity of quaternary 

ammonium compounds, benzylbis(hydrogenated tallow alkyl)methyl, bis(hydrogenated 

tallow alkyl)dimethylammonium salts with sepiolite a cancer dietary exposure 

assessment is not necessary to assess cancer risk.

B. Residential (Non-Occupational) Exposure:

i. From non-dietary exposure. The term ‘‘residential exposure’’ is used in this 

document to refer to non-occupational, non-dietary exposure (e.g., for lawn and garden 

pest control, indoor pest control, termiticides, and flea and tick control on pets). In the 

case of quaternary ammonium compounds, benzylbis(hydrogenated tallow alkyl)methyl, 

bis(hydrogenated tallow alkyl)dimethylammonium salts with sepiolite, the request is for 

use as an inert ingredient in pesticide formulations for use on pre-harvest crops. 

Quaternary ammonium compounds, benzylbis(hydrogenated tallow alkyl)methyl, 

bis(hydrogenated tallow alkyl)dimethylammonium salts with sepiolite may also be used 

in personal care products and in products that are registered for specific uses that may 

result in residential exposure. However, based on the lack of toxicity, an exposure 

assessment from “residential exposures” was not performed.

V. OCCUPATIONAL EXPOSURE/RISK PATHWAY

The Agency believes that establishing a tolerance exemption to include 40 CFR § 

180.920 will not significantly/measurably increase occupational exposure. Since there is no 

endpoint of concern selected for dermal or inhalation routes of exposure, a qualitative occupation 

exposure assessment was not completed and occupational exposure is not of concern.

VI. CUMULATIVE EXPSOURE 
25

Cumulative effects from substances with a common mechanism of toxicity. Section 

408(b)(2)(D)(v) of FFDCA requires that, when considering whether to establish, modify, or 

revoke a tolerance, the Agency consider “available information” concerning the cumulative 

effects of a particular pesticide's residues and “other substances that have a common mechanism 

of toxicity.”

EPA has not found quaternary ammonium compounds, benzylbis(hydrogenated tallow 

alkyl)methyl, bis(hydrogenated tallow alkyl)dimethylammonium salts with sepiolite to share a 

common mechanism of toxicity with any other substances, and that quaternary ammonium 

compounds, benzylbis(hydrogenated tallow alkyl)methyl, bis(hydrogenated tallow 

alkyl)dimethylammonium salts with sepiolite does not appear to produce a toxic metabolite 

produced by other substances. For the purposes of this tolerance action, therefore, EPA has 

assumed that quaternary ammonium compounds, benzylbis(hydrogenated tallow alkyl)methyl, 

bis(hydrogenated tallow alkyl)dimethylammonium salts with sepiolite does not have a common 

mechanism of toxicity with other substances. For information regarding EPA's efforts to 

determine which chemicals have a common mechanism of toxicity and to evaluate the 

cumulative effects of such chemicals, see EPA's website at 

http://www.epa.gov/pesticides/cumulative.

VII. ENVIRONMENTAL JUSTICE STATEMENT 

Potential areas of environmental justice concerns, to the extent possible, were considered 

in this human health risk assessment, in accordance with U.S. Executive Order 12898, "Federal 

Actions to Address Environmental Justice in Minority Populations and Low-Income 

Populations," http://www.eh.doe.gov/oepa/guidance/justice/eo12898.pdf.

As a part of every pesticide risk assessment, OPP considers a large variety of consumer 

subgroups according to well-established procedures. In line with OPP policy, RD estimates risks 

to population subgroups from pesticide exposures that are based on patterns of that subgroup’s 

food and water consumption, and activities in and around the home that involve pesticide use in 

a residential setting. Extensive data on food consumption patterns are compiled by the USDA 

under CSFII and are used in pesticide risk assessments for all registered food uses of a pesticide. 

These data are analyzed and categorized by subgroups based on age, season of the year, ethnic 

group, and region of the country. Additionally, OPP is able to assess dietary exposure to smaller, 

specialized subgroups and exposure assessments are performed when conditions or 

circumstances warrant. Whenever appropriate, non-dietary exposures based on home use of 

pesticide products and associated risks for adult applicators and for toddlers, youths, and adults 

entering or playing on treated areas post-application are evaluated. Further considerations are 

currently in development as OPP has committed resources and expertise to the development of 

specialized software and models that consider exposure to bystanders and farm workers as well 

as lifestyle and traditional dietary patterns among specific subgroups
26

VIII. ENVIRONMENTAL FATE CONSIDERATIONS

Bentonite has two silica tetrahedral sheets joined to a central octahedral alumina sheet, an 

arrangement that gives smectites a relatively high cation exchange capacity (CEC). In contrast, 

sepiolite has two tetrahedral sheets without the continuous octahedral sheet. This yields a more 

fiber-like mineral that contains less accessible internal pores. The CEC of sepiolite is therefore 

lower than that of the smectites: 15-45 mEq/100g versus 50-150 mEq/100g. However the 

quaternary ammonium compound can still adsorb to sepiolite's external surfaces and into the 

pores, if it is small enough, and both sepiolite and smectite group minerals are considered to have 

high adsorption capacities via both CEC and hydrophobic interactions and will therefore both 

strongly bind the quaternary ammonium compounds.

For both clay types, the quaternary ammonium compounds associated with these clays 

are not expected to dissociate or otherwise extract from the clay under ambient conditions 

because the ionic and adsorbing forces are very strong (OECD 2007). These forces would need 

to be overcome simultaneously, requiring a material with a very high cation exchange capacity 

that is also able to solubilize the quaternary ammonium moiety. This is unlikely in the 

environment as soil adsorption coefficients (Koc) of quaternary ammonium compounds are high 

(for e.g., dialkyl (C8-C18) dimethyl ammonium chloride and mono and dialkyl (C8-C18) 

methylated ammonium chloride compounds, log Koc 4.66 (US EPA 2006)), indicating a strong 

propensity to remain associated with clay under ambient conditions (see Table 3). This reality, 

combined with the fact that both quats in Garamite 1958 are substantially more hydrophobic than 

the comparison compound (stearalkonium chloride), suggest that stearalkonium bentonite can 

conservatively represent quat adsorption for both of these products.

Once organoclays settle into soil or sediment, some biotic and abiotic degradation of the

quaternary ammonium compound part of the substance may take place over time, although the

inorganic clay portion of the substance does not degrade, as it is a mineral. Degradation products 

of the organic moiety would be water and oxides of carbon and nitrogen. Stearalkonium 

bentonite was considered not readily biodegradable when tested in the OECD TG 301B assay. In 

the 28-day test, an average of 23% and a maximum of 33% of the original stearalkonium 

bentonite biodegraded, as measured by CO2 generation (NICNAS 2013a; Springer 2000). 

Similarly in seawater the percent biodegradability of 1.8 and 3.7 mg/L [B(2Alk)M] bentonite 

(CAS Reg. No. 68153-30-0) was 19.2 and 33.4%, respectively after 28 days, as measured by 

OECD TG 306 test. A different OECD TG 306 test with the same substance demonstrated 5.0 

and 10.0 mg/L concentrations biodegrading by 7.4% and 4.7%, respectively, in saltwater. Yet 

another OECD TG 306 test showed 18.3 and 3.3% degradation after 28 days for 3.0 and 7.0 

mg/L [B(2Alk)M] bentonite, respectively, in seawater (OECD 2008a). All of these results 

suggest limited biodegradability of the treated clays in seawater.

IX. ECOTOXICITY

Acute ecotoxicity testing of treated clays having structural similarity to Quaternary 

ammonium compounds, benzylbis(hydrogenated tallow alkyl)methyl, bis(hydrogenated tallow

alkyl)dimethylammonium salts with sepiolite typically gave results in the low or slight concern
27

category (10 - >100 mg/L) for aquatic and terrestrial organisms including fish, aquatic

invertebrates, algae, and earthworms. Chronic ecotoxicity tests suggest a moderate concern for

aquatic invertebrates and fish. However, at least part of the toxicity was attributed to a physical

effect of the test substance, rather than a true toxicological effect.

Acute Ecotoxicity

Acute toxicity studies were conducted on B(Alk)2M bentonite (CAS Reg. No. 71011-24-

0) using rainbow trout (Oncorhynchus mykiss). The test method was the 1975 EPA 

Methods for Acute Toxicity Tests with Fish, Macroinvertebrates and Amphibians. Fish 

(n=10/group x duplicate groups) were exposed in static conditions to 0 or 500 ppm 

B(Alk)2M bentonite with triethylene glycol (TEG) or just TEG. Daily records of 

mortality, temperature, dissolved oxygen and pH were kept for 96 hours. There was no 

mortality in any group. The 96-hour LC50 was >500 mg/L for rainbow trout (OECD 

2008b).

The acute toxicity of stearalkonium bentonite to zebra fish was tested in the standard 

acute toxicity for fish test provided under Annex 5 to Commission Directive 92/32/EEC

(ARC 2005c). Aqueous extracts were of 10, 18, 32, 56, and 100 mg/L loading rate were

obtained by filtration after 24 hours of stirring. Test solutions were made by diluting the 

extracts with water. Temperature, pH and dissolved oxygen levels were monitored 

throughout. The 96- hour LC50 for zebra fish was > 100 mg/L; no fish died in any of the 

concentration groups and all control groups were within acceptable limits.

Using the 1975 EPA Methods for Acute Toxicity Tests with Fish, Macroinvertebrates 

and Amphibians, Daphnia magna (n=10/group x duplicate groups) were exposed to 50, 

72, 103, 149, 214, 309 or 370 ppm B(Alk)2M bentonite with 240 ppm TEG. A TEG 

control and blank group were run concurrently. Mortality, temperature, dissolved oxygen 

and pH were recorded at 0, 24, 47, 72, and 96 hours. There were no deaths in the two 

control groups or the lowest two dose groups. There was 100% mortality at 370 ppm. The 

48-hour LC50 was 300ppm (95% Cl 283-318 ppm) and 96-hour LC50 was 230 ppm (95% 

Cl 209-253 ppm). OECD determined that both of these studies were valid with 

restrictions (comparable to GLP, but not guideline) (OECD 2008b).

A Daphnia magna toxicity study was carried out using B(2Alk)M hectorite (CAS Reg. 

No. 121888-67-3) under criteria set forth in the Official Journal of the European 

Communities: Part C: Methods for the Determination of Ecotoxicity. Culture medium 

and B(2Alk)M hectorite were sonicated together for two hours. The volume was adjusted 

to give a stock dispersion of 200 mg/L. Clay particles were allowed to settle out, then the 

aqueous phase was removed for testing. Sample preparation followed recommendations 

of Whitehouse and Mallet (1993: Aquatic Toxicity Testing for Notification of New 

Substances. An Advisory Document on dealing with 'Difficult' Substances. Report No: 

CP722 to the Chemical Notification Unit, U.K. Department of the Environment). TEG 

(300 ppm) was used as a solvent but the test medium still appeared to be primarily a fine 

dispersion, in which the test substance was in suspension or settled out onto the bottom of 

the test chamber. Daphnia were exposed for 72-hours in a preliminary range finding

study at 0.10, 1.0, 10 and 100 mg/L, and then at 100 mg/L in the definitive study for 96
28

hours under static conditions. The actual concentration of the test substance in the test 

medium was determined analytically at the start of the test and after 72 hours; these 

values were not reported. Temperature of the incubator was controlled and measured and 

recorded daily.pH was determined in each test vessel at the beginning and end of the test. 

Each of six replicate chambers held 5 Daphnia. A blank control was run concurrently in 

triplicate. The 96-hour LC50 was determined to be >100 mg/L B(2Alk)M hectorite. 

OECD (2008a) considered this study to be reliable with restrictions.

Stearalkonium bentonite (98% pure) was tested using OECD TG 202, the Daphnia 

magna acute immobilization test (Lebertz 2000). The test substance was prepared by

diluting the aqueous extract of Stearalkonium bentonite with water to achieve the desired

concentration for testing, shaking until equilibrium was reached, and then filtering. In the

screening study D. magna were exposed to nominal concentrations of 0, 1, 10 or, 100 

mg/L and in the main study, 0, 0.25, 0.5, 1.0, 2.0, or 4.0 mg/L. Analytical measurements 

of the test substance were made as Total Organic Carbon; however, TOC measurements 

did not correspond to relative concentrations, therefore only nominal concentrations were 

available. Each chamber held 5 Daphnia and replicate chambers were run per 

concentration (2 in the screening study and 4 in the main study). Temperature, pH and 

dissolved oxygen were measured at 0 and 48 hours, and were always within 

recommended guideline levels. The 48- hour EC50 and NOEC were calculated to be 0.7 

mg/L and 0.3 mg/L, respectively.

In a follow up study, the acute toxicity of Stearalkonium bentonite (>97%) to Daphnia 

magna was tested in the standard acute toxicity test provided under Annex 5 (92/69/EEC) 

to Commission Directive 92/32/EEC (Part C, Methods for determination of ecotoxicity, 

publication No. L383, 29 Dec. 1992: C.2. Acute Toxicity for Daphnia). Nominal aqueous 

extracts of 10, 18, 32, 56, and 100 mg/L were prepared by dilution of the test substance 

with reconstituted water. These suspensions were stirred for 24 hours and then filtered 

(0.2-μm pore size). Temperature, pH and dissolved oxygen levels were monitored

throughout and were always within recommended guideline levels. An attempt to 

measure the actual concentration of the test substance was made by measuring the 

dissolved Si concentration at 0 and 48 hours. However, the Si concentration in all dose 

levels was approximately the same, most likely reflecting the poor water solubility of the 

test substance. The 48-hour LC50 for Daphnia magna was >100 mg/L (nominal 

concentration); there was no significant immobilization of Daphnia in any of the 

concentration groups or the negative control group (ARC 2005d).

In the Lebertz (2000) toxicity study of Stearalkonium bentonite on the invertebrate 

Daphnia, the toxicity of the aqueous fraction of the treated clay was high (48-hr EC50 <1 

mg/L), while in the follow up study of Stearalkonium bentonite (ARC 2005d) and the 

two other Daphnia studies reported for treated clays (OECD 2008a,b), the EC50 was 

consistently greater than 100 mg/L after 48 and 96 hours, indicating these substances are 

practically nontoxic to Daphnia. All studies were reported to be guideline studies or 

modifications of guideline studies (modified because the test substance is not soluble in 

water and must be filtered). BYK reported that the difference in stearalkonium bentonite 

toxicity was due to improvements in their manufacturing process between 2000 and 2005 
29

that led to drastically reduced soluble quaternary ammonia in the final stearalkonium 

bentonite product (Mattingly 2014c). The low toxicity of stearalkonium bentonite in 

particular and structurally similar treated clays in general is further supported by toxicity 

testing described above for fish, as well as toxicity testing in marine invertebrates, algae,

and earthworms described below. All results indicate that these substances are at most 

slightly toxic (acute toxicity values between 10 and 100 mg/L) and otherwise practically 

nontoxic (EC50 and LC50 values over 100 mg/L).

The marine copepod Acartia tonsa (n=5/concentration and 6/control x 4 replicates) was 

used to test the acute toxicity of water accommodated fractions of B(2Alk)M bentonite 

(CAS Reg. No. 68153-30- 0) in a GLP study under test guideline ISO/CD 14669. 

Nominal concentrations of 100, 211.5, 477.2, 945.7, and 2000 mg/L were prepared in 

filtered natural seawater. Parameters monitored included dissolved oxygen, pH and 

temperature. The %-immobilization of A. tonsa was measured at 24 and 48 hours. The 

48-hour EC50 > 2000 mg/L (OECD 2008a).

The amphipod Corophium volutator was exposed to 1000, 1778.3, 3162.3, 5623.4 and 

10000 mg B(2Alk)M bentonite per kg dry weight (dw) of sediment for 10 days. Mortality 

never exceeded 40% in any test group and so the 10-day LC50 for this marine crustacean 

was determined to be >10,000 mg/kg dw (OECD 2008a).

B(2Alk)M bentonite (CAS Reg. No. 68153-30-0) was tested for its toxicity to the marine 

algae Skeletenoma costatum in three tests under ISO/DIS 10253 and in one ISQ/TC 147 

assay. Methods were similar for all four tests; water accommodated fractions of the test 

material were prepared and the test substance had time to settle to the bottom of 

chambers before exposure. Dissolved oxygen (DO), pH and temperature were determined 

and mean cell numbers were measured at 0, 24, 48, and 72 hours. Nominal test 

concentrations were reported for three of the studies. In two studies, they ranged from 

100-1000 mg/L B(2Alk)M bentonite, and in another they ranged from 1.0 to 100 mg/L. 

The 72-hour EC50 values in both 100-1000 mg/L studies were reported as >1000 mg/L. In 

one of these, the NOEC was 1000 mg/L and in one the NOEC was 562 mg/L. In the 

study where exposure ranged from 1.0-100 mg/L, the EC50 was 82.3 mg/L. In a fourth 

study, S. costatum were exposed to nominal concentrations of 10-100 mg/L. The actual 

concentration was measured in the "100 mg/L" test vessels at time 0 as 26.3 mg/L and at 

72 hours as 16.9 mg/L. This was thought to be the result of the test substance settling on

the bottom more and more over time. Based on complete inhibition of cell growth at this 

highest concentration, the 72-hour EC50 was equal to 23.8 mg/L B(2Alk)M bentonite 

(actual concentration). The NOEC was 10 mg/L (OECD 2008a).

An OECD TG 201 study was carried out on B(2Alk)M hectorite using the freshwater 

algae Scenedesmus subspicatus. Cells were exposed for 72 hours to a nominal 

concentration of 100 mg/L B(2Alk)M hectorite. The concentration of B(2Alk)M hectorite 

was measured at time 0 as 26.3 mg/L and at 72 hours as 16.9 mg/L. There was no effect 

of the test substance on the biomass or growth rate of algae cells. The 72 hour EC50 was 

>100 mg/L (>16.9 mg/L actual concentration of B(2Alk)M hectorite)(OECD 2008a).
30

An OECD TG 207 study (Earthworm, Acute Toxicity Test) was carried out in which 

earthworms (Eisenia fetida) were exposed for 14 days to B(Alk)2M bentonite at 1-1000 

mg/kg soil dry weight (dw). There was no test substance-related mortality in this rangefinding portion of the study. In the definitive test, there was a single death in worms 

exposed to 1000 mg/kg dw. OECD (2008b) reported that this was not due to the test 

substance. The NOEC for earthworms was reported as 1000 mg B(Alk)2M bentonite/kg 

dw. This outcome suggests slight (at most) or negligible toxicity to earthworms. OECD 

rated the study "valid without restrictions" (OECD 2008b).

Subchronic/Chronic Ecotoxicity

A 21-day toxicity test of [B(2Alk)M] hectorite (CAS Reg. No. 121888-67-3; purity 

>97%) was conducted in rainbow trout under OECD TG 204. The nominal concentration 

of the test substance was 1.0 mg/L, which included the surfactant Tween 80. A vehicle 

control group and blank control were also assessed. The water temperature, pH, dissolved 

oxygen concentration, and appearance of the test medium were recorded daily. There 

were no substance-related mortalities or signs of toxicity. The 21-day LC50 was >1.0 

mg/L [B(2Alk)M] hectorite and the NOEC was 1.0 mg/L (OECD 2008a).

The Daphnia magna Reproduction Test was conducted on B(2Alk)M hectorite (CAS 

Reg. No. 121888- 67-3; 95% purity). Dispersions of the test substance were nominally at 

0.32, 1.0, 3.2, 10 and 32 mg/L and were verified throughout the test. In this study, the 

actual test concentrations were measured but could not be used to determine an EC50

because measurement of the concentration of B(2Alk)M hectorite in the lowest two dose 

groups was below the limit of detection. In the higher three test groups, concentration 

variation was high, ranging from 0- 109% of nominal. Renewal of test medium was made 

three times per week and dissolved oxygen, pH and temperature were measured before 

and after renewal. Live and dead "parental" (P1) generation Daphnia were counted daily. 

The number of Daphnia with eggs or young in the brood pouch, the number of discarded, 

unhatched eggs and the numbers of live and dead "filial" (F1) Daphnia were determined 

at each test media renewal. The 21-Day EC50 for immobilization was 7.6 mg/L. In the 

high dose test group, mortalities were considered to be due at least partly to the physical 

effect of the test substance. Exposure at this dose resulted in an immediate lethal effect, 

and at 10 mg/L a prolonged mortality effect. The 21-day EC50 for reproduction was 

between 3.2 and 10 mg/L as those two groups produced approximately 18% and 94% 

fewer young per adult, respectively, than the control group. The 3.2 and 10 mg/L test

groups produced approximately 82% and 2% respectively of the total number of young

produced by the control group. The NOEC was 3.2 mg/L based on no significant 

differences in immobilization or reproduction between that group and the control (OECD 

2008e).

X. RISK CHARACTERIZATION 

Technology Sciences Group on behalf of BYK Additives Inc. (1600 West Hill Street 

Louisville, KY 40210) submitted a petition to the EPA to amend 40 CFR 180.920 by 
31

establishing an exemption from the requirement of a tolerance for the use of quaternary 

ammonium compounds, benzylbis(hydrogenated tallow alkyl)methyl, bis(hydrogenated tallow 

alkyl)dimethylammonium salts with sepiolite (CAS Reg. No. 1574487-61-8) as an inert 

ingredient (suspending or structuring agent) in pesticide formulations applied to growing crops in 

accordance with 40 CFR 180.920 with limitations of 2.0% in formulation, asbestos free and 

containing less than 1% crystalline silica. 

A variety of clays treated with quaternary ammonium compounds are used throughout 

this document as structurally similar analogs to of quaternary ammonium compounds, 

benzylbis(hydrogenated tallow alkyl)methyl, bis(hydrogenated tallow alkyl)dimethylammonium 

salts with sepiolite. These clays are often named for the predominant, but not exclusive mineral 

in a particular deposit, so variation between the substances may not be as great as it would 

initially appear. Most of the substances referenced were also used in the OECD HPV Chemical 

Program for the SIDS dossier on organoclays. The diversity of closely-related treated clays is 

partly a result of the different combinations of the four different but related clays: smectites, 

hectorite, bentonite, and montmorillonite. These four are closely/inter- related and have been 

described in some datasets interchangeably. Smectite is actually the name describing a group of 

clay minerals, of which hectorite, bentonite, and montmorillonite and saponite (the clay type in 

the petitioned substance) are members. It is primarily the identity of counter ions that 

distinguishes these clays. Where saponite contains calcium, magnesium and iron, 

bentonite/montmorillonite contains sodium, calcium, aluminum, and magnesium, and hectorite 

has sodium, lithium, and magnesium counter ions. In treated clays, the naturally-occurring 

counter ions on the clays' surface have been readily exchanged for quaternary ammonium ions. 

The diversity of the structurally similar treated clays is further derived from the combinations of 

quaternary ammonium compounds that have been exchanged for counter ions on the clays' 

surface. These quaternary ammonium compounds can have between one and four 

substitutions/R-groups: 1-2 methyls, 0-1 benzyls, and/or 1-3 alkyl C14-C22 groups derived from 

tallow oil.

Despite this diversity, the treated smectite clays described in this petition have similar

structures, toxicological properties, and physical-chemical properties, including particle size

distribution, to one another and likely to the petitioned substance, Quaternary ammonium

compounds, benzylbis(hydrogenated tallow alkyl)methyl, bis(hydrogenated tallow

alkyl)dimethylammonium salts with sepiolite.

The available toxicity studies indicate that of quaternary ammonium compounds, 

benzylbis(hydrogenated tallow alkyl)methyl, bis(hydrogenated tallow alkyl)dimethylammonium 

salts with sepiolite has a very low overall toxicity. The NOAELs were >1000 mg/kg/day (limit 

dose). Since signs of toxicity were not observed at the limit dose an endpoint of concern for risk 

assessment purposes was not identified. Therefore, since no endpoint of concern was identified 

for the acute and chronic dietary exposure assessment and short and intermediate dermal and 

inhalation exposure, a quantitative risk assessment for of quaternary ammonium compounds, 

benzylbis(hydrogenated tallow alkyl)methyl, bis(hydrogenated tallow alkyl)dimethylammonium 

salts with sepiolite is not necessary.

Since there is no endpoint of concern selected for dermal or inhalation routes of 
32

exposure, a qualitative occupation exposure assessment was not completed and occupational 

exposure is not of concern.

Acute ecotoxicity testing of treated clays having structural similarity to quaternary 

ammonium compounds, benzylbis(hydrogenated tallow alkyl)methyl, bis(hydrogenated tallow

alkyl)dimethylammonium salts with sepiolite typically gave results in the low or slight concern

category (10 - >100 mg/L) for aquatic and terrestrial organisms including fish, aquatic

invertebrates, algae, and earthworms. Chronic ecotoxicity tests suggest a moderate concern for

aquatic invertebrates and fish. However, at least part of the toxicity was attributed to a physical

effect of the test substance, rather than a true toxicological effect.

Potential areas of environmental justice concerns, to the extent possible, were considered 

in this human health risk assessment, in accordance with U.S. Executive Order 12898, "Federal

Actions to Address Environmental Justice in Minority Populations and Low-Income 

Populations," http://www.eh.doe.gov/oepa/guidance/justice/eo12898.pdf.

Taking into consideration all available information on quaternary ammonium

compounds, benzylbis(hydrogenated tallow alkyl)methyl, bis(hydrogenated tallow

alkyl)dimethylammonium salts with sepiolite, EPA concludes that there is a reasonable certainty 

that no harm to any population subgroup will result from aggregate exposure to quaternary 

ammonium compounds, benzylbis(hydrogenated tallow alkyl)methyl, bis(hydrogenated tallow

alkyl)dimethylammonium salts with sepiolite when considering occupation, dietary exposure and 

all other nonoccupational sources of pesticide exposure for which there is reliable information. 

Therefore, the establishment of an exemption from tolerance under 40 CFR 180.920 for residues 

of Quaternary ammonium compounds, benzylbis(hydrogenated tallow alkyl)methyl, 

bis(hydrogenated tallow alkyl)dimethylammonium salts with sepiolite (CAS Reg. No. 1574487-

61-8) when used as an inert ingredient (suspending or structuring agent) in pesticide 

formulations applied to growing crops with limitations of 2.0% in formulation, asbestos free and 

containing less than 1% crystalline silica can be considered assessed as safe under section 408(q) 

of the FFDCA.
33

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