Kaolin	Last updated: 12/09/2025
(Also known as: argilla; bentone; china clay; porcelain clay; neokaolin ; aluminium silicate hydrate; hydrated aluminium silicate)

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GENERAL INFORMATION

Description	Aluminum silicate administered as animal feed supplement
Examples of veterinary uses	Mainly used as a treatment for diarrhoea by adsorbing water, toxins and bacteria, contributing to firmer stools and so reducing fluid loss
Examples of species treated	Pigs; Dogs; Cats; Poultry

Approval status

VMR 2013/2033 approval status (GB/UK)	Approved - usually authorised as a veterinary medicine for general sale (AVM-GSL)
EU Regulatory approval status	Approved

Chemical structure

Isomerism	None
Chemical formula	H₄Al₂O₉Si₂
Canonical SMILES	O.O.O=[Al]O[Si](=O)O[Si](=O)O[Al]=O
Isomeric SMILES	-
International Chemical Identifier key (InChIKey)	NLYAJNPCOHFWQQ-UHFFFAOYSA-N
International Chemical Identifier (InChI)	InChI=1S/2Al.O5Si2.2H2O.2O/c;;1-6(2)5-7(3)4;;;;/h;;;2*1H2;;/q2*+1;-2;;;;
2D structure diagram/image available?	Yes

General status

Veterinary substance type	Feed additive
Other bioactivity & uses	Coating agent
Substance groups	Inorganic compound
Minimum active substance purity	-
Known relevant impurities	-
Substance origin	Natural
Mode of action	For crop protection it mainly has a non-toxic mode of action, acting via its physical properties. It may also interfere with feeding behaviour and egg-laying. For animal health it can bind toxins, bacteria, and excess water in the gut. It adheres to the gastrointestinal mucosa, forming a protective coating that helps prevent the absorption of harmful substances.
Molecular targets	[No specific molecular target]
CAS RN	1332-58-7
EC number	310-194-1
CIPAC number	None allocated
US EPA chemical code	100104
PubChem CID	56841936
CLP index number	No data found
Therapeutic Class	Alimentary tract & metabolism: Intestinal antiinfectives
ATCvet Code	QA07AA51
Controlled Drug?	No
Regulation 37/2010 MRL Classification	-
Molecular mass	258.16
PIN (Preferred Identification Name)	-
IUPAC name	oxo-oxoalumanyloxy-[oxo(oxoalumanyloxy)silyl]oxysilane;dihydrate
CAS name	aluminium silicate hydrate
Forever chemical	-
Other status information	-
Relevant Environmental Water Quality Standards	-
Physical state	Off-white coloured powder

Commercial

Property	Value
Availability status	Current
Introduction & key dates	1997, first registered as pesticide USA
Example manufacturers & suppliers of products using this active now or historically	Stoller Enterprises Inc. Zeotis UK Ltd KL Pharmaceutical Ltd
Example products using this active	Surround Crop Protectant Kaogel VP Oral Suspension KL One Minute Poultice
Formulation and application details	Usually formulated as a powder, granules, oral suspensions and poultices
Commercial production	Kaolin is produced commercially through several key steps. Firstly, kaolin mineral deposits are typically extracted from open-pit mines. The extracted kaolin is mixed with water to create a slurry. This process, known as blunging, helps to break down the clay and remove impurities. The slurry is then screened to remove coarse particles and centrifuged to separate the kaolin from sand and other impurities. Further refinement involves de-gritting, where finer particles are separated from the kaolin slurry. The refined kaolin slurry is filtered to remove excess water and then dried. This can be done using rotary dryers, spray dryers, or filter presses. For certain applications, kaolin may be calcined (heated to high temperatures) to enhance its properties, such as brightness and hardness. The dried kaolin is milled to achieve the desired particle size and consistency.
Impact on climate of production and use	According to emissions modeling based on the ecoinvent database wet-process kaolin production emits approximately 0.13–0.25 kg CO₂e per kg of kaolin produced.

ENVIRONMENTAL FATE

Property		Value	Source; quality score; and other information	Interpretation
Solubility - In water at 20 °C (mg l⁻¹)		5.0	Q3 Q = Miscellaneous data from online sources 3 = Unverified data of known source	Low
Solubility - In organic solvents at 20 °C (mg l⁻¹)		-	-	-
Melting point (°C)		1760	Q3 Q = Miscellaneous data from online sources 3 = Unverified data of known source	-
Boiling point (°C)		-	-	-
Degradation point (°C)		-	-	-
Flashpoint (°C)		-	-	-
Octanol-water partition coefficient at pH 7, 20 °C	P	Not applicable	-	-
	Log P	Not applicable	Q3 Q = Miscellaneous data from online sources 3 = Unverified data of known source	Not applicable
Fat solubility of residues	Solubility	-	-	-
	Data type	-	-	-
Density (g ml⁻¹)		2.6	Q3 Q = Miscellaneous data from online sources 3 = Unverified data of known source	-
Dissociation constant pKa) at 25 °C		-	-	-
		-
Vapour pressure at 20 °C (mPa)		-	-	-
Henry's law constant at 25 °C (Pa m³ mol⁻¹)		-	-	-
Volatilisation as max % of applied dose lost	From plant surface	-	-	-
	From soil surface	-	-	-
Maximum UV-vis absorption L mol⁻¹ cm⁻¹		-	-	-
Surface tension (mN m⁻¹)		-	-	-
Refractive Index		1.620	Q3 Q = Miscellaneous data from online sources 3 = Unverified data of known source	-
Environmental release		-

Degradation

Property		Value	Source; quality score; and other information	Interpretation
Soil degradation (days) (aerobic)	DT₅₀ (typical)	1000	Q3 Q = Miscellaneous data from online sources 3 = Unverified data of known source	Very persistent
	DT₅₀ (lab at 20 °C)	-	-	-
	DT₅₀ (field)	-	-	-
	DT₉₀ (lab at 20 °C)	-	-	-
	DT₉₀ (field)	-	-	-
	Note	Kaolin is a non-degradable natural component of the environment
Manure DT₅₀ (days)		-	-	-
Aqueous photolysis DT₅₀ (days) at pH 7	Value	-	-	-
	Note	-
Aqueous hydrolysis DT₅₀ (days) at 20 °C and pH 7	Value	-	-	-
	Note	-
Water-sediment DT₅₀ (days)		-	-	-
Water phase only DT₅₀ (days)		-	-	-
Sediment phase only DT₅₀ (days)		-	-	-
Air degradation		As this parameter is not normally measured directly, a surrogate measure is used: ‘Photochemical oxidative DT₅₀’. Where data is available, this can be found in the Fate Indices section below.
Decay in stored produce DT₅₀		-

Soil adsorption and mobility

Property		Value	Source; quality score; and other information	Interpretation
Linear	Kd (mL g⁻¹)	-	-	-
	Koc (mL g⁻¹)	-
	Notes and range	Kaolin is a natural component of the environment
Freundlich	Kf (mL g⁻¹)	-	-	-
	Kfoc (mL g⁻¹)	-
	1/n	-
	Notes and range	-
pH sensitivity		-

Fate indices

Property		Value	Source; quality score; and other information	Interpretation
GUS leaching potential index		-	-	-
Bio-concentration factor	BCF (l kg⁻¹)	20	Q3 Q = Miscellaneous data from online sources 3 = Unverified data of known source Low risk	Low potential
	CT₅₀ (days)	-		-

Known metabolites

None

ECOTOXICOLOGY

Terrestrial ecotoxicology

Property		Value	Source; quality score; and other information	Interpretation
Mammals - Acute oral LD₅₀ (mg kg⁻¹)		> 5000	R4 R = Peer reviewed scientific publications 4 = Verified data Rat	Low
Mammals - Short term dietary NOEL	(mg kg⁻¹)	-	-	-
	(ppm diet)	-		-
Mammals - Chronic 21d NOAEL (mg kg⁻¹ bw d⁻¹)		-	-	-
Birds - Acute LD₅₀ (mg kg⁻¹)		> 5000	R3 R = Peer reviewed scientific publications 3 = Unverified data of known source Unknown species	Low
Birds - Short term dietary (LC₅₀/LD₅₀)		-	-	-
Birds - Chronic 21d NOEL (mg kg⁻¹ bw d⁻¹)		-	-	-
Earthworms - Acute 14 day LC₅₀ (mg kg⁻¹)		> 2000	R3 R = Peer reviewed scientific publications 3 = Unverified data of known source Eisenia foetida	Low
Earthworms - Chronic NOEC, reproduction (mg kg⁻¹)		-	-	-
Soil micro-organisms		-	-	-
Collembola	Acute LC₅₀ (mg kg⁻¹)	-	-	-
	Chronic NOEC (mg kg⁻¹)	-	-	-
Non-target plants	Vegetative vigour ER₅₀ (g ha⁻¹)	-	-	-
	Seedling emergence ER₅₀ (g ha⁻¹)	-	-	-
Honeybees (Apis spp.)	Contact acute LD₅₀ (worst case from 24, 48 and 72 hour values - μg bee⁻¹)	> 100	R4 R = Peer reviewed scientific publications 4 = Verified data Apis mellifera	Low
	Oral acute LD₅₀ (worst case from 24, 48 and 72 hour values - μg bee⁻¹)	> 100	R4 R = Peer reviewed scientific publications 4 = Verified data Apis mellifera	Low
	Unknown mode acute LD₅₀ (worst case from 24, 48 and 72 hour values - μg bee⁻¹)	-	-	-
	Chronic	-	-	-
	Notes	-
Bumblebees (Bombus spp.)	Contact acute LD₅₀ (worst case from 24, 48 and 72 hour values - μg bee⁻¹)	-	-	-
		-
	Oral acute LD₅₀ (worst case from 24, 48 and 72 hour values - μg bee⁻¹)	-	-	-
		-
Mason bees (Osmia spp.)	Contact acute LD₅₀ (worst case from 24, 48 and 72 hour values - μg bee⁻¹)	-	-	-
	Oral acute LD₅₀ (worst case from 24, 48 and 72 hour values - μg bee⁻¹)	-	-	-
Other bee species (1)	Acute LD₅₀ (worst case from 24, 48 and 72 hour values - μg insect⁻¹)	-	-	-
	Mode of exposure	-
Other bee species (2)	Acute LD₅₀ (worst case from 24, 48 and 72 hour values - μg insect⁻¹)	-	-	-
	Mode of exposure	-
Beneficial insects (Ladybirds)		-	-	-
Beneficial insects (Lacewings)		-	-	-
Beneficial insects (Parasitic wasps)		-	-	-
Beneficial insects (Predatory mites)		-	-	-
Beneficial insects (Ground beetles)		-	-	-

Aquatic ecotoxicology

Property		Value	Source; quality score; and other information	Interpretation
Temperate Freshwater Fish - Acute 96 hour LC₅₀ (mg l⁻¹)		> 2500	R3 R = Peer reviewed scientific publications 3 = Unverified data of known source Unknown species	Low
Temperate Freshwater Fish - Chronic 21 day NOEC (mg l⁻¹)		-	-	-
Tropical Freshwater Fish - Acute 96 hour LC₅₀ (mg l⁻¹)		-	-	-
Temperate Freshwater Aquatic invertebrates - Acute 48 hour EC₅₀ (mg l⁻¹)		> 2500	R3 R = Peer reviewed scientific publications 3 = Unverified data of known source Unknown species	Low
Temperate Freshwater Aquatic invertebrates - Chronic 21 day NOEC (mg l⁻¹)		-	-	-
Tropical Freshwater Aquatic invertebrates - Acute 48 hour EC₅₀ (mg l⁻¹)		-	-	-
Aquatic crustaceans - Acute 96 hour LC₅₀ (mg l⁻¹)		-	-	-
Sediment dwelling organisms - Acute 96 hour LC₅₀ (mg l⁻¹)		-	-	-
Sediment dwelling organisms - Chronic 28 day NOEC, static, water (mg l⁻¹)		-	-	-
Sediment dwelling organisms - Chronic 28 day NOEC, sediment (mg kg⁻¹)		-	-	-
Aquatic Plants (free-floating, fonds growth, fresh) - 7 day (mg l⁻¹)		-	-	-
Aquatic plants (rooted, growth rate, fresh) - 14 day (mg l⁻¹)		-	-	-
Algae - Acute (growth rate, fresh; mg l⁻¹) (EC₅₀)		> 2500	A3 A = EU regulatory and evaluation data as published by EC, EFSA (RAR, DAR & Conclusion dossiers), EMA (e.g. EU Annex III PIC DGD) (EU - Pesticides database; EFSA Scientific Publications ) 3 = Unverified data of known source Unknown species	Low
Algae - Chronic (growth rate, fresh; mg l⁻¹)		-	-	-
Mesocosm study data	NOEAEC mg l⁻¹	-	-	-
	NOEAEC mg l⁻¹	-	-	-
Marine bivalves		-	-	-

HUMAN HEALTH AND PROTECTION

General

Property		Value	Source; quality score; and other information	Interpretation
Threshold of Toxicological Concern (Cramer Class)		High (class III)	-	-
Mammals - Acute oral LD₅₀ (mg kg⁻¹)		> 5000	R4 R = Peer reviewed scientific publications 4 = Verified data Rat	Low
Mammals - Dermal LD₅₀ (mg kg⁻¹ body weight)		5000	R4 R = Peer reviewed scientific publications 4 = Verified data Rat	-
Mammals - Inhalation LC₅₀ (mg l⁻¹)		-	-	-
Other Mammal toxicity endpoints		-	-	-
ADI - Acceptable Daily Intake (mg kg⁻¹ bw day⁻¹)		None allocated	A5 A = EU regulatory and evaluation data as published by EC, EFSA (RAR, DAR & Conclusion dossiers), EMA (e.g. EU Annex III PIC DGD) (EU - Pesticides database; EFSA Scientific Publications ) 5 = Verified data used for regulatory purposes	-
ARfD - Acute Reference Dose (mg kg⁻¹ bw day⁻¹)		None allocated	A5 A = EU regulatory and evaluation data as published by EC, EFSA (RAR, DAR & Conclusion dossiers), EMA (e.g. EU Annex III PIC DGD) (EU - Pesticides database; EFSA Scientific Publications ) 5 = Verified data used for regulatory purposes	-
AAOEL - Acute Acceptable Operator Exposure Level (mg kg⁻¹ bw day⁻¹)		-	-	-
AOEL - Acceptable Operator Exposure Level - Systemic (mg kg⁻¹ bw day⁻¹)		None allocated	A5 A = EU regulatory and evaluation data as published by EC, EFSA (RAR, DAR & Conclusion dossiers), EMA (e.g. EU Annex III PIC DGD) (EU - Pesticides database; EFSA Scientific Publications ) 5 = Verified data used for regulatory purposes	-
Dermal penetration studies (%)		-	-	-
Dangerous Substances Directive 76/464		-	-	-
Exposure Routes	Public	-
	Occupational	-
Mammalian dose elimination route and rate		Poorly absorbed from the gastrointestinal tract, has a short half-life and is nearly all excreted unchanged	Q3 Q = Miscellaneous data from online sources 3 = Unverified data of known source	-

Health issues

Specific human health issues		Carcinogen Genotoxic Endocrine disruptor ✓Yes, known to cause a problem A0 A = Chromosome aberration (EFSA database) 0 = No data ; B0 B = DNA damage/repair (EFSA database) 0 = No data ; C0 C = Gene mutation (EFSA database) 0 = No data ; D0 D = Genome mutation (EFSA database) 0 = No data ; E3 E = Unspecified genotoxicity type (miscellaneous data source) 3 = Negative XNo, known not to cause a problem Reproduction / development effects Acetyl cholinesterase inhibitor Neurotoxicant ✓Yes, known to cause a problem XNo, known not to cause a problem XNo, known not to cause a problem Respiratory tract irritant Skin irritant Skin sensitiser ?Possibly, status not identified ✓Yes, known to cause a problem ?Possibly, status not identified Eye irritant Phototoxicant   ✓Yes, known to cause a problem No data found
General human health issues		Inhalation may cause pneumoconiosis (Kaolinosis) May produce gastrointestinal disturbances as high doses Possible respiratory sensitiser May cause toxic responses via inhalation CLP data - known human carcinogen

Handling issues

Property	Value and interpretation
General	No information available
CLP classification 2013	Health: H315, H319, H334, H335, H350, H370, H372, H373
WHO Classification	Not listed (Not listed)
UN Number	-
Waste disposal & packaging	-
Shelf-life, storage, stability and reactivity	-

TRANSLATIONS

Language	Name
English	kaolin
French	kaolin
German	Porzellanerde
Danish	kaolin
Italian	caolino
Spanish	caolin
Greek	kaoline
Polish	-
Swedish	kaolin
Hungarian	porcelanfold
Dutch	kaolien
Norwegian	-

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Record last updated:	12/09/2025
Contact:	aeru@herts.ac.uk
Please cite as:	Lewis, K.A., Tzilivakis, J., Warner, D. and Green, A. (2016) An international database for pesticide risk assessments and management. Human and Ecological Risk Assessment: An International Journal, 22(4), 1050-1064. DOI: 10.1080/10807039.2015.1133242