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**UNITED STATES ENVIRONMENTAL PROTECTION AGENCY**

WASHINGTON, D.C. 20460

OFFICE OF

PREVENTION, PESTICIDES

AND TOXIC SUBSTANCES

January 31, 2002

MEMORANDUM

FROM: Kathryn Boyle, CoChair IIFG

and

Kerry Leifer, CoChair IIFG

TO: Robert Forrest, Chief

Minor Use, Inerts, and Emergency Response Branch

SUBJECT: November 13, 2001 and December 18, 2001 Meeting of the IIFG

Decision Memo

Please find attached the Inert Ingredient Focus Group recommendations
for the inert

ingredients associated with the "weathered materials" grouping.

INERT INGREDIENT FOCUS GROUP MEETING

November 13, 2001 and December 18, 2001

**Chemical Name:** Several, see below.

**Category:** Weathered materials.

**CAS Reg. No.:** Several, see below.

**PC Code:** Several, see below.

[Introduction:]{.underline}

There were two meetings of the Inert Ingredient Focus Group to discuss
the "weathered materials" grouping. The first was held on November 13,
2001, and the second on December 18, 2001. Focus Group members in
attendance at both meetings were: Kathryn Boyle (RD), Kerry Leifer (RD),
Michael Doherty (HED), Pauline Wagner (HED), Diana Locke (HED), Sid Abel
(EFED), and Mark Perry (SRRD). Robert Forrest (RD), Tom Brennan (HED),
Henry Craven (EFED),and Larry Schnaubelt (SRRD) were present for the
November 13 meeting only. Kelly O'Rourke (HED) attended only the
December 18 meeting. The presenters were: Kathryn Boyle (RD) and Sid
Abel (EFED). The Executive Secretary for the November 13 meeting was
Linda Gerber (RD). Also in attendance at the November 13 meeting were:
John Redden (RD), Jeanie McAndrew (RD), Christina Jarvis (RD), and Carol
Christensen (HED). Jeanie McAndrew also attended the December 18
meeting.

At both meetings the available information on various weathered
materials were discussed to determine if sufficient information were
available to make tolerance reassessment decisions assessment on the
various materials and to make the determination as to whether the
various materials should be classified as List 4A or List 4B substances.
The available information consisted of information retrieved from
various websites, such as,

-   EPA ([www.epa.gov]{.underline}),

-   CDC ([www.atsdr.cdc.gov/toxprofiles/),]{.underline}

-   NIOSH, ([www.cdc.gov/niosh/ipcsneng/neng0000.html]{.underline}) and
    (www.cdc.gov/niosh/npg/npg.html)

-   TOXNET ( [www.toxnet.nlm.nih.gov.)]{.underline},

-   NTP ([ntp-server.niehs.nih.gov.)]{.underline},

-   Firstgov ([www.firstgov.gov/),]{.underline}

-   IARC ([www.iarc.fr/]{.underline})

Additional information included parts of the FDA GRAS assessment of
sodium silicoaluminate.. Also, SAR (structure-activity-relationship)
assessments as performed by OPPT were available for some of the oxides
and silicates.

Three handouts were provided at the meeting on the 13th: (1) a listing
of the substances for which there are existing tolerance exemptions; (2)
a short summary dividing the substances into 15 groups for discussion
purposes; and (3) the following description/explanation of weathered
materials.

[Description of Weathered Materials]{.underline}

Weathered materials is the term that the Agency is using to describe a
group of substances that could also be referred to as rocks and
minerals. Generally, weathered materials are decayed or weathered rocks
that are mostly unrefined, i.e., not altered or manufactured by man.
When referring to weathered materials as mostly unrefined, the Agency is
including the mechanical grinding of larger rocks into smaller pieces
that are essentially the same, but not the chemical or physical
alteration of the rock into a different substance.

A mineral is a naturally-occurring, inorganic solid substance
characterized by a definite chemical composition or a range of chemical
compositions and by a specific, regular architecture of the atoms that
make it up. Simply put, minerals are chemicals arranged in an orderly
regular pattern to form a substance that cannot be separated
mechanically, i.e., by crushing, into different substances. Quartz, a
very common mineral, is made of the basic elements silicon and oxygen.
By simply crushing the quartz, silicon and oxygen cannot be separated;
but crushed finely, quartz is a major component of the sand found at the
beach or in the soil around our homes. Some minerals can be seen with
the naked eye especially in coarse grain rocks, but others need
magnifying glasses or powerful microscopes to be seen. There are several
thousand minerals, each with characteristic chemical and physical
properties.

Minerals are the building blocks of rocks. Minerals can be combined,
aggregated, in a great variety of patterns just as bricks may make up a
walkway in an infinite array of schemes. Rocks are not as uniquely
defined by their properties as minerals because of the immense number of
ways the thousands of minerals can be combined. The major divisions of
rocks are igneous (formed from cooling magmas), sedimentary (formed from
the settling, cementing and compacting of eroding igneous and
metamorphic rock), and metamorphic (igneous or sedimentary rock that has
undergone change due to heat and pressure). Weathered materials are
derived from these major groups.

Rocks are "weathered" by a twofold process, mechanical weathering (the
physical breakdown, grinding, of the rocks into smaller pieces), and
chemical weathering (the breaking of the chemical bonds between
elements). Both processes operate together, each assisting the other in
the slow progress of decomposing the rock to materials such as sands and
clays or dissolving the rock altogether as happens when water flows over
limestone. The smaller the rock pieces, the greater the surface area,
the faster the breakdown. Over great periods of time, the weathering of
rocks may become the great deposits of weathered minerals that are mined
or become part of the soils in the gardens that are around our homes.

The conditions (climate) under which this weathering occurs can
determine the minerals formed. Feldspar of granite (an igneous rock) may
decay to form kaolinite, a common mineral and in its pure form, a raw
material for everyday pottery and china. Under certain climatic
conditions, kaolinite will dissolve leaving a solid residue called
gibbsite. Gibbsite makes up the great deposits of bauxite, the earthy
ore known as the major source of extractable aluminum. Phosphate rocks
(marine shale and limestones enriched in phosphate -- both sedimentary
rocks) are the major raw materials of the fertilizer industry, but are
also components of the natural soils along the coastal plain of the
major continents.

The remnants of rock are all around us in our daily life: they are the
materials in and of the earth. We are exposed to them in a variety of
ways every day. It is the decay and weathering of rocks that give us the
soils in which we grow our food and the ore deposits that provide the
materials of everyday life.

[Ecotoxicity, and Environmental Fate and Effects:]{.underline}

This presentation was performed by Sid Abel.

EFED's hazard characterization was based on the fact that all of these
substances are naturally occurring. Since these are naturally occurring
substances, no adverse environmental effects are anticipated.

[Toxicology Data]{.underline}

This presentation was performed by Kathryn Boyle (RD) based on the
information contained in the previously mentioned websites. A brief
summation of the available information(see below) was given for each of
the groups. If available, the CAS Reg. No. is given in parenthesis.
*Comments made during the discussion that pertained only to a specific
group are in italics below.* *Current List classification is also in
(italics).*

8.  Calcium carbonate (471-34-1) *(4A)*: The weathered materials would
    be: chalk, marble, calcite (13397-26-7), limestone
    (1317-65-3)*(4A)*, magnesium-lime, and could even include oyster
    shells and calcareous shale. Also includes dolomite
    (16389-88-1)*(4A)* which is calcium magnesium carbonate.

\- No concerns identified

9.  Carbon in various forms: Includes carbon, graphite
    (7782-42-5)*(4A)*, and activated charcoal (7440-44-0).

> \- Activated charcoal is not pure carbon. It is not absorbed, but can
> adsorb other drugs and chemicals on its surface
>
> \- Carbon RED 1991 examined carbon and graphite, but did not include
> activated charcoal.

10. Gypsum also referred to as natural calcium sulfate (13397-24-5)
    *(4A),* plaster of paris which is hydrated calcium sulfate
    (26499-65-0), and calcium sulfate (7778-18-9) (10101-41-4)*(4B)*:

> \- Ingestion of plaster of paris *per se* with little water may result
> in obstruction with resultant surgical removal *It was determined that
> this type of ingestion is probably not a concern for pesticide
> products.*

\- Irritant

> \- Calcium sulfate is the most common of the naturally occurring
> sulfates and is FDA GRAS

\- Gypsum is used to treat alkali soils

Plaster of Paris (total dust), calcium sulfate (total dust), and gypsum
(total dust) Chemical Sampling Information Cards described the threshold
limit value for all three chemicals as particulate matter containing no
asbestos and less than 1% crystalline silica.

11. Lime (12001-27-3)*(4A)*, which is calcium oxide (1305-78-8)*(4B)*:

\- Dust is irritating to nose and throat

\- Some inhalation concerns

\- CaO is a food additive (GRAS with no limitations)

*Can be purchased for non-pesticidal home use*

12. Vermiculite (hydrated laminar magnesium-aluminum-iron-silicate)
    (1318-00-9)*(4A)* There can be asbestos contamination:

*Discussion focused on ways to define asbestos-free vermiculite*.

After the first meeting, information was obtained from the Schindler
Company website ([www.schundler.com]{.underline}) and the Agency's
Asbestos-Contaminated Vermiculite Fact Sheet. Vermiculite (a hydrated
laminar magnesium-aluminum-iron-silicate), like most other
naturally-occurring materials, often contain a range of other minerals
including, in some cases, asbestos. However, it is known that only a few
vermiculite deposits contain more than trace amounts of asbestos.
(Example: Libby) EPA has tested samples of vermiculite to determine the
amounts of asbestos present. Most samples were non-detect (no detectable
levels of asbestos) using a quantifiable level of 0.1 percent by weight.
The vermiculite industry has also tested various vermiculite ores with
similar results.

13. Bentonite (1302-78-9)*(4A)* or Montmorillonite Clay
    (1318-93-0)*(4A)*:

\- Practically non-toxic

\- Biologically inert when ingested

\- Some lung irritation (not silicosis) after years of exposure

> \- aka Fuller's earth (8031-18-3) (claylike material composed
> primarily of montmorillonite); low/moderate concern (SAR)

14. Attapulgite-clay (12174-11-7)*(4A)* (complex metallic (magnesium
    aluminum) silicate), also known as palygorskite:

\- Long fibers are carcinogenic (\> 5 um) when inhaled

\- Short fibers are not carcinogenic (\< 5 um)

\- Medical Uses (activated attapulgite)

\- Absorbent in pet litter

\- Not absorbed from GI tract

\- has colloidal and sorptive properties

*Discussion focused on ways to check the fiber size*

15. Kaolin (1332-58-7)*(4A)* which are aluminum silicates.

\- Inert after oral administration

\- Medicinal uses

\- Some inhalation concerns, kaolinosis

\- Kaolin RED

Kaolin Chemical Sampling Information Card described kaolin as not
classifiable as to carcinogenicity, with the comment for particulate
matter containing no asbestos and less than 1% crystalline silica
(respirable fraction).

16. Silicon dioxide: includes crystalline forms: silica/quartz
    (14808-60-7), cristobalite (14464-46-1)*(3)*, tridymite
    (15468-32-3), tripoli (1317-95-9); includes amorphous silica
    (112926-00-8, 76313-69-5, 7631-86-9), sand *(3)*, diatomaceous earth
    (61790-53-2)*(4B)*, granite, vitreous silica (60676-86-0)*(4B)* and
    silica gel (63231-67-4, 112926-00-8)*(4B)*.

\- Considered to be inert when ingested

\- Crystalline forms are carcinogenic when inhaled from occupational
sources

\- Cristobalite is moderate concern (SAR)

> \- Silicosis occurs by prolonged and extensive exposure to respirable
> free crystalline silica.

\- Food additive/feed additive

Information was also obtained from the 9^th^ Report on Carcinogens
(revised January 2001): "Inhalation of excessive levels of crystalline
silica is best known as a cause of pneumoconiosis, an occupational lung
disease. It is unclear whether the carcinogenic risk of crystalline
silica is because it is a traditional carcinogen that interacts with
nuclear macromolecules or because of an epigenetic process associated
with cell damage and healing."

17. Talc (14807-96-6)*(3)* is a finely powdered magnesium silicate
    hydroxide, also known as steatite:

\- The nonasbestiform cosmetic grade was determined to be carcinogenic.

\- Talc pneumoconiosis

\- Soapstone (1343-90-4)*(4A)* is a granular form of talc.

> \- Pyrophyllite (12269-78-2)*(4B)* is a hydrous aluminum silicate with
> a structure similar to that of talc; it is a color additive mixture
> for drugs and cosmetics exempt from certification

Both forms of talc (asbestiform and non-asbestiform) have been proposed
for review for listing in the 10^th^ Report on Carcinogens. Additional
information was found on the NIOSH Sampling Guide which described talc
as "containing no asbestos and less than 1% quartz". OSHA Chemical
Sampling Information Cards have two descriptions of talc "containing
asbestos" and "containing no asbestos". While the CAS Reg. Nos. are the
same, the descriptors are different, with the first being described as
carcinogenic, and the second being described as not classifiable as to
carcinogenicity, with the comment for particulate matter containing no
asbestos and less than 1% crystalline silica (respirable fraction). The
International Chemical Safety Card refers to "Talc (exempt de silice et
de fibres)"

18. Mica (12003-38-2)*(4A)* (hydrated potassium aluminum silicate) and
    feldspar (potassium aluminum silicate)(68476-25-5), low/moderate
    concern (SAR)

\- Pneumconiosis

The OSHA Chemical Sampling Information Card referred to a value for
particulate matter containing no asbestos and less than 1% crystalline
silica (respirable fraction). Also, a different CAS Reg. No. was
referenced: 12001-26-2

19. Zeolites *(3)*

Zeolites are crystalline alumino-silicate minerals with cage-like
crystal structures. This is probably the most extensive family of
minerals in the earth's crust. (1318-02-1, 12173-10-3, 12271-42-0,
67240-23-7, 12173-98-7, 12445-20-4, 66732-10-3, 68652-75-5, 12174-18-4,
61027-84-7, 66733-09-3, 68989-22-0, 68989-23-1, and 79982-98-2) There
are both naturally-occurring and synthetic versions of zeolites. Both
can be fibrous or non-fibrous. Terms used to describe zeolites include
clinoptilolite, mordenite, and phillipsite. The SAR assessment performed
by OPPT indicated moderate concern for the 68989-22-0 form of zeolite.

One form, erionite (66733-21-9), was determined to be carcinogenic, by
IARC (8^th^ Annual Report on Carcinogens). Erionite consists of
crystals, and is not know to occur in other than fibrous form. When
administered by inhalation erionite induces plural mesotheliomas.
Natural erionite has been replaced by synthetic non-fibrous zeolites.
Erionite is not known to be currently in use in the US.

20. Refined silicates

Refined silicates (both hydrous and anhydrous forms) are not the
naturally occurring forms of silicate, but the more refined chemicals
that are either derived from the naturally occurring forms or
manufactured specifically through the reaction of other chemicals for
selling in commerce. According to information in the FDA's GRAS
assessment of silicates, there are at least 30 to 40 silicate compounds
that could be consumed by humans. Most silicon compounds (except
potassium and sodium) are insoluble or only slightly soluble in water:

> \- Sodium (1344-09-8, 6834-92-0, and 10213-79-3)*(4B)* forms a
> gelatinous (very alkaline) mixture in water, corrosive, extreme eye
> irritant; also a sodium metasilicate (10213-79-3, 13870-28-5, and
> 15593-82-5) which is more caustic than sodium
>
> \- Calcium (1344-95-2)*(4B)* is GRAS with limitations, in
> pharmaceuticals; also a tricalcium form which is used in cement;
> occurs naturally as wollastonite (13983-17-0) moderate concern (SAR)
>
> \- Magnesium (14987-04-3, 1343-88-0, 13776-74-4, and 1343-90-4)*(4B)*
> is classified as practically non-toxic; low/moderate concern (SAR)
>
> \- Sodium aluminum (12003-51-9 and 1344-00-9) has low ecotoxicity,
> negative for mutagenicity, silicon excreted in rats; it was the
> predominate silicate added to foods in the US in 1979; low/moderate
> concern (SAR)
>
> \- Potassium aluminum (1327-44-2) is moderate concern (SAR)

\- Potassium (1312-76-1)*(3)*

\- Sodium potassium aluminum (12736-96-8, 37244-96-5)*(3)*

> \- Aluminum (1327-36-2) is low/moderate concern (SAR); hydrated
> (1335-30-4)*(3)*

\- Aluminum calcium silicate

\- Aluminum magnesium silicate (1327-43-1)*(3)*

\- Perlite (93763-70-3) (a naturally occurring polysilicate/glass)

21. Refined Oxides:

> \- Metal fume fever: produced by inhalation of metal ions at high
> temperatures from occupational exposures such as cutting and welding
> *Fumes are only produced at high temperatures. Therefore, should not
> be a concern when used in a pesticide product*.
>
> \- Zinc (1314-13-2)*(4B)* is also known as C.I. pigment white 4; no
> concerns identified in SAR; used in sunscreen products and calamine
> lotion; positive mutagenicity results were reported in two studies; no
> evidence of carcinogenicity was found in feeding zinc oxide at 34.4 mg
> zinc per day to rats for 29 weeks; in rats growth is retarded at 1%
> zinc oxide and developmental impacts occurred at 4000 ppm; used as an
> animal feed nutritional supplement; Zinc Salts RED indicated that
> people are usually not exposed to such large amounts of zinc through
> the diet
>
> \- Aluminum (1344-28-1)*(4B)* is low/moderate (SAR) for health, high
> for ecotoxicity (this was the only 3)
>
> \- Magnesium (1309-48-4)*(4B)* is low concern (SAR), mutagenicity
> studies were negative
>
> \- Iron also known as rust (1345-25-1, 1309-37-1, 1317-61-9 and
> 12259-21-1)*(4B)* is low concern (SAR); inhalation if iron oxide can
> cause siderosis which is a benign condition (takes 6 to10 years to get
> and can be slowly cleared from rat lungs; IARC monograph - not
> classifiable (Group 3)

\- Iron magnesium oxide (12068-86-9)*(3)*

\- Zinc iron oxide (12063-19-3)*(3)*

22. Sulfur (7704-34-9) *(3)*:

\- Used as a fertilizer or soil amendment

\- 1991 RED - low toxicity

\- EPA designation under 40 CFR 180.2

> \- MSDS indicates airborne exposure limits have not been established.

[Discussion]{.underline}

By consensus, the group determined that these materials are generally,
with some exceptions, low toxicity substances. There would be no
concerns for ecotoxicity, or for most dietary or dermal human exposure.
All existing tolerance exemptions can be reassessed.

However, there are inhalation concerns for some of these substances.
Several of these substances have suspected or documented chronic
inhalation exposure/risk issues including carcinogenicity, silicosis or
pneumoconiosis. At the November 13 meeting, the IIFG did not come to a
complete conclusion for these inhalation concerns. In response to these
concerns, Tom Brennan (HED) researched how these inhalation
exposure/risk concerns, that are of concern in industrial settings,
might translate to exposure/risk concerns of these same materials used
as an inert ingredients in pesticides. His analysis is summarized in the
paragraph below:

Generally mining, processing, packaging and transporting weathered
materials are full time industrial occupations that may lead to daily
exposures over the course of many years. These industrial activities
will create exposures to the raw (extracted) product as well as more
refined products. It is very likely that routine worker activities will
create the possibility of routine exposure to respirable-sized
particles. By contrast, mixing/loading and applying granular or dust
pesticide products that have these same weathered materials will not
have the same level or types of exposures. The first major difference is
the time and duration of exposure. For most cases the pesticide
applicators will not be exposed on a daily basis. In fact, it is much
more likely that pesticide applicators, both professional operators and
homeowners, will have only short-term exposures (i.e., those occurring
for 1 day to a month -- over a year's time). Additionally, the
applicator's exposure to the inert ingredient is in a formulated product
-- not the raw weathered material.

Classification of an inert ingredient to List 4A means that the inert
can be used in 25(b) deregulated products, without the need for acute
end-product toxicity testing for the Agency to determine the appropriate
labeling language. Thus, List 4A reclassification requires consideration
of other routes of exposure for the pesticide product. The List 4A
classification would depend not only on the dietary exposure, but also
on the likelihood of dermal and/or inhalation concerns.

There is various information from OSHA/NIOSH (Occupational Safety and
Health Administration/National Institute for Occupational Safety and
Health), such as that on a Chemical Sampling Information Card or an
International Safety Card. A threshold limit value (TLV)s is a limit on
inhalation exposure in the workplace (40 years, usually 8 hours per
day). Generally a level of 10 mg/m^3^ is considered to be a nuisance
level dust standard, which implies for inhalation concerns, that the
chemical is non-toxic, not irritating. TLVs are developed exclusively
for occupational settings, assuming healthy workers. It is possible that
the general public could be more susceptible. IIFG believes that TLVs
are sufficient for use as benchmarks.

TLVs and other endpoints such as NIOSH RELs (recommended exposure
limits) or OSHA PELs (permissible exposure limits) were obtained from
various sources such as the Chemical Sampling Information Cards. All
units are mg/m^3^. The TWA (time-weighted average) is usually for 8
hours. If information were available for both the total dust and the
respirable dust, then the total dust was used. (See below)

attapulgite not established

bentonite 10 OSHA PEL: 15

calcium carbonate 10 (TWA) NIOSH REL: 10 (TWA)

calcium oxide 2 NIOSH REL: 2

calcium silicate NIOSH REL: 10 (TWA)

calcium sulfate 10 (TWA) NIOSH REL: 10

graphite, natural 2 (TWA) NIOSH REL: 2.5 (TWA)

graphite, synthetic 15 (TWA)

gypsum 10 (TWA) NIOSH REL: 10 (TWA)

iron oxide not established

kaolin 10 (TWA)

limestone 10 (TWA) NIOSH REL: 10 (TWA)

magnesium oxide 10 (TWA fume)

marble 10 (TWA) NIOSH REL: 10 (TWA)

mica 3 (TWA) NIOSH REL: 3 (TWA)

montmorillonite not established

perlite 10 (TWA)

sand 0.05 (TWA)

silica, amorphous 10

silica, amorphous, NIOSH REL: 6 (TWA)

diatomaceous earth

silica, amorphous, NIOSH REL: 6 (TWA)

precipitated and gel

silica, crystalline cristobalite 0.05 (TWA) NIOSH REL: 0.05 (TWA)

silica, crystalline quartz 0.1 (TWA) NIOSH REL: 0.05 (TWA)

silica, crystalline tripoli 0.1 (TWA) NIOSH REL: 0.05 (TWA)

silica, crystalline tridymite 0.05 (TWA) NIOSH REL: 0.05 (TWA)

silica, fused 0.1 (TWA) NIOSH REL: 0.05 (TWA)

silica, quartz NIOSH REL: 0.05 (TWA)

soapstone 6 (TWA) NIOSH REL: 6 (TWA)

sodium metasilicate none listed

sulfur none listed

talc (asbestos free) 2 (TWA) NIOSH REL: 2 (TWA)

talc 0.1 fiber/cc (100 min TWA)

vermiculite not established

zinc oxide 10 (TWA) NIOSH REL: 5 (TWA)

At the December 18 meeting the group discussed using information such as
TLVs to perform a screen level inhalation assessment. Kelly O'Rourke
(HED) developed such an inhalation screen for residential exposures for
comparison with TLVs. Weathered materials are oftentimes used as solid
carriers or diluents. Therefore, for these screening level exposure
assessments it was assumed the product was a granular formulation and
that the weathered material comprised 100% of the formulation. Two
scenarios were considered: broadcast treatment of half an acre taking
approximately 1 hour, and spot treatment of 1000 square feet taking
approximately half an hour. The point estimate for broadcast treatment
is 0.18 mg/m^3^ and for spot treatment is 0.6 mg/m^3^. It was necessary
to convert these point estimates to a time weighted average over 8 hours
for comparison to time weighted averages such as TLVs. The weighted
average is 0.023 mg/m^3^ for broadcast and 0.038 mg/m^3^ for spot
treatment. For most of the substances the estimated weighted averages
are less than the TLVs by at least two orders of magnitude. However, for
some substances for which there was already information indicative of
inhalation concerns, the lowest TLVs (0.05 mg/m^3^ and 0.01 mg/m^3^ for
sand and various crystalline silicas) are in the range of the estimated
weighted averages. Such substances would not be considered for List 4A
classification.

There was also a concern for the use of aluminum oxide due to aquatic
ecotoxicty. According to the OPPT Chemical Categories Report, soluble
salts of aluminum are known to be highly toxic to green algae and
moderately toxic to fish and aquatic invertebrates. A screening level
assessment was performed to determine the maximum application rate for
aluminum oxide to avoid exceeding estimated toxicity endpoints for
aquatic organisms. This assessment assumed the direct application of a
pesticide containing aluminum oxide to either a farm pond or to a
shallow waterbody or wetland. The lowest application rate that would not
exceed a level of concern was 2.1 pounds of aluminum oxide per acre.
Aluminum oxide will be classified as List 4B.

**[IIFG Recommendations]{.underline}**

By consensus there were no objections to the following:

All existing tolerance exemptions can be reassessed. In 40 CFR 180.2
lime and sulfur. In 40 CFR 180.1001(c): aluminum oxide ,
attapulgite-type clay; bentonite; calcareous shale; calcite; calcium
carbonate; calcium oxide; calcium silicate; charcoal, activated;
diatomite (diatomaceous earth); dolomite, granite, graphite, gypsum,
iron oxide; kaolinite-type clay; magnesium lime; magnesium oxide;
magnesium silicate; mica; montmorillonite-type clay; potassium aluminum
silicate; pyrophyllite; sand; silica, hydrated; soapstone; sodium
aluminum silicate; sodium metasilicate; sodium silicate; talc;
vermiculite; zeolite (hydrated alkali aluminum silicate); and zinc
oxide. In 40 CFR 180.1001(d): graphite. In 40 CFR 180.1001(e):
attapulgite-type clay; calcium carbonate; calcium silicate, hydrated
calcium silicate; calcium sulfate; diatomite (diatomaceous earth);
graphite; iron oxide; kaolinite-type clay; magnesium silicate, hydrated
magnesium silicate; montmorillonite-type clay; silica, hydrated silica;
silica aerogel (finely powdered microcellular silica foam having a
minimum silica content of 89.5 %); soapstone; sulfur; talc; and zinc
oxide. Also 40 CFR 180.1017.

Tolerance exemptions maybe established for those chemicals evaluated for
which there is not currently an existing exemption.

By consensus the following List classifications have been determined:

1.  Calcium carbonate, chalk, marble, calcite, limestone, magnesium
    lime, and dolomite: List 4A based on the fact that no concerns were
    identified.

2.  Activated charcoal: List 4B given its adsorptive properties.

Carbon and graphite: List 4A given the properties of and lack of
toxicity of carbon.

3.  Gypsum, plaster of paris, and calcium sulfate: List 4A with the
    following specification: (no asbestos, less than 1% crystalline
    silica).

4.  Lime: List 4A since agricultural lime is prepared by calcining
    materials consisting largely of calcium carbonate such as limestone,
    or oyster, clam or fossil shells. Carbon dioxide is driven off.
    Thus, agricultural lime contains the original impurities in the
    starting materials. This material is openly available for purchase
    in lawn and garden centers.

> Calcium oxide: List 4B given the liberation of heat and dehydration of
> tissues possible from this more refined material.

5.  Vermiculite: List 4A with the following specification: no asbestos,
    less than 1% crystalline silica

6.  Bentonite, Montmorillonite clay, and Fuller's earth : List 4A based
    on the fact that no concerns were identified.

7.  Attapulgite clay: Reclassified to List 4B based on carcinogenic
    concerns for fibers greater in length than 5 um.

8.  Kaolin: List 4A based on the RED, with the following specification:
    (no asbestos, less than 1% crystalline silica ( respirable
    fraction))

9.  Crystalline forms of silica/quartz including cristobalite,
    tridymite, and tripoli: List 4B based on concerns for
    carcinogenicity when inhaled.

> Granite: List 4B based on the fact that it contains 25 to 30% quartz.
>
> Silica sand and flours: List 4B based on the many forms and varieties
> available which contain crystalline quartz in various amounts
>
> Amorphous silica, vitreous silica, and silica gel: List 4A given that
> there are no carcinogenic concerns for non-crystalline forms of
> silica/quartz.
>
> Diatomaceous earth: List 4A when specified as silica, amorphous,
> diatomaceous earth (less than 1% crystalline silica)

10. Talc: List 4B based on concerns for carcinogenicity in the NTP study
    which was performed with non asbestiform cosmetic grade talc, with
    the following specification (no asbestos, less than 1% crystalline
    silica ( respirable fraction))

Soapstone: List 4A given that it is a granular form of talc.

> Pyrophillite: List 4B given its similarities to talc, and the lack of
> information on its carcinogenicity.

11. Mica: List 4A with the following specification (no asbestos, less
    than 1% crystalline silica ( respirable fraction)).

12. Natural and synthetic zeolites: List 4A with an exclusion for
    erionite due to concerns for carcinogenicity.

13. Sodium silicate and sodium metasilicate: List 4B given the
    corrosive, caustic nature of the chemical.

Potassium silicate: List 4B given its similarities to sodium silicate.

> Calcium silicate: List 4A given the SAR assessment, the low
> ecotoxicity, and the role of calcium in bone-formation.
>
> Magnesium silicate: List 4A given the SAR assessment, the low
> ecotoxicity, and that magnesium is an essential nutrient.

Aluminum silicate: List 4A given the SAR assessment and the low
ecotoxicity.

> Sodium aluminum silicate: List 4A given its low ecotoxicity and the
> SAR assessment.
>
> Potassium aluminum silicate: List 4A given the SAR assessment and its
> similarities to sodium aluminum silicate.

Sodium potassium aluminum silicate: List 4A given the above assessments.

Aluminum calcium silicate: List 4A based on the assessments for aluminum
and calcium.

> Aluminum magnesium silicate: List 4A based on the assessments for
> aluminum and magnesium.
>
> Perlite: List 4A with the following specification: (no asbestos, less
> than 1% crystalline silica ( respirable fraction)).

14. Zinc oxide: List 4A given the SAR assessment, the RED, and that zinc
    is an essential nutrient.

> Aluminum oxide: List 4B given that the SAR assessment is low/moderate
> for health and high for ecotoxicity (this was the only 3)
>
> Magnesium oxide: List 4A given the SAR assessment and that magnesium
> is an essential nutrient
>
> Iron oxide: List 4A given the low concern in the SAR assessment
>
> Iron magnesium oxide: List 4A based on the assessments for iron oxide
> and magnesium oxide.

Zinc iron oxide: List 4A based on the assessments for iron oxide and
zinc oxide.

15. Sulfur: List 4A based on the low toxicity, the fact that it is
    metabolized in the body, and the RED.