Dimethyl phthalate

Dimethyl phthalate	Last updated: 16/09/2025
(Also known as: DMP)

GENERAL INFORMATION

Description

An obsolete insect repellent used on animals

Examples of veterinary uses

Used to control fleas, chiggers and flies and as a mosquito repellents

Examples of species treated

Hirses; Cattle

Approval status

VMR 2013/2033 approval status (GB/UK)

Not approved

EU Regulatory approval status

Not approved

Chemical structure

Isomerism

None

Chemical formula

C₁₀H₁₀O₄

Canonical SMILES

COC(=O)C1=CC=CC=C1C(=O)OC

Isomeric SMILES

International Chemical Identifier key (InChIKey)

NIQCNGHVCWTJSM-UHFFFAOYSA-N

International Chemical Identifier (InChI)

InChI=1S/C10H10O4/c1-13-9(11)7-5-3-4-6-8(7)10(12)14-2/h3-6H,1-2H3

2D structure diagram/image available?

Yes

General status

Veterinary substance type

Ectoparaistic

Substance groups

Diethyl ester insecticide; Phthalate ester insecticide

Minimum active substance purity

Known relevant impurities

Substance origin

Synthetic

Mode of action

Repellency

Molecular targets

[None - laregly inert]

CAS RN

131-11-3

EC number

205-011-6

CIPAC number

None allocated

US EPA chemical code

028002

PubChem CID

8554

CLP index number

No data found

Therapeutic Class

Ectoparasiticides, including insecticides and repellents

ATCvet Code

QP53GX02

Controlled Drug?

Regulation 37/2010 MRL Classification

Molecular mass

194.19

PIN (Preferred Identification Name)

dimethyl benzene-1,2-dicarboxylate

IUPAC name

dimethyl benzene-1,2-dicarboxylate

CAS name

dimethyl 1,2-benzenedicarboxylate

Forever chemical

Other status information

Relevant Environmental Water Quality Standards

UK Environment Agency non-statutory standard for the protection of aquatic life in freshwater and saltwater: 800 µg l⁻¹ as annual average; 4000 µg l⁻¹ as max acceptable conc.

Physical state

Colourless oily liquid with faint aromatic odour

Commercial

Property

Value

Availability status

Considered obsolete but may be available in some countries

Introduction & key dates

Early 20th century, industrial synthesis begins; Mid 20th century, vet use introduction; 2013, not approved UK

Example manufacturers & suppliers of products using this active now or historically

Glentham Life Sciences

Example products using this active

Formulation and application details

Was usually supplied in ready-to-use formulations such as aerosols, creams and oil-based solutions

Commercial production

Dimethyl phthalate is produced through an esterification reaction between phthalic acid (or phthalic anhydride) and methanol, using sulphuric acid as a catalyst. The process begins by combining the reactants in a reactor at a molar ratio of approximately 1:2–3 (phthalic acid to methanol), with sulphuric acid added at 1–3% of the phthalic acid’s mass. The mixture is heated and stirred to promote ester formation. After the reaction, the solution is cooled and neutralised with an alkaline absorbent to remove residual acid.

Impact on climate of production and use

While exact numbers vary by company and energy source, producing 1 kg of dimethyl phthalate likely emits between 2–5 kg of CO₂e, based on similar low-molecular-weight phthalates and standard petrochemical synthesis.

ENVIRONMENTAL FATE

Property

Value

Source; quality score; and other information

Interpretation

Solubility - In water at 20 °C (mg l⁻¹)

4300

High

Solubility - In organic solvents at 20 °C (mg l⁻¹)

Melting point (°C)

5.5

Boiling point (°C)

284

Degradation point (°C)

Flashpoint (°C)

146

(closed cup)

Octanol-water partition coefficient at pH 7, 20 °C

3.98 X 10⁰¹

Calculated

Log P

1.6

Low

Fat solubility of residues

Solubility

Data type

Density (g ml⁻¹)

1.196

Dissociation constant pKa) at 25 °C

Vapour pressure at 20 °C (mPa)

800

Highly volatile. If applied directly to plants or soil, drift is a concern & mitigation is advisable

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

Environmental release

Degradation

Property

Value

Source; quality score; and other information

Interpretation

Soil degradation (days) (aerobic)

DT₅₀ (typical)

DT₅₀ (lab at 20 °C)

DT₅₀ (field)

DT₉₀ (lab at 20 °C)

DT₉₀ (field)

Note

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

K_d (mL g⁻¹)

K_oc (mL g⁻¹)

Notes and range

Freundlich

K_f (mL g⁻¹)

K_foc (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)

CT₅₀ (days)

Known metabolites

None

ECOTOXICOLOGY

Terrestrial ecotoxicology

Property

Value

Source; quality score; and other information

Interpretation

Mammals - Acute oral LD₅₀ (mg kg⁻¹)

8200

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)

Birds - Short term dietary (LC₅₀/LD₅₀)

Birds - Chronic 21d NOEL (mg kg⁻¹ bw d⁻¹)

Earthworms - Acute 14 day LC₅₀ (mg kg⁻¹)

> 3160

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)

Oral acute LD₅₀ (worst case from 24, 48 and 72 hour values - μg bee⁻¹)

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)

350

Lepomis macrochirus

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)

> 16.0

Daphnia magna

Moderate

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) (96 hr EC₅₀)

42.7

Raphidocelis subcapitata

Low

Algae - Chronic (growth rate, fresh; mg l⁻¹)

Mesocosm study data

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)

Low (class I)

Mammals - Acute oral LD₅₀ (mg kg⁻¹)

8200

Rat

Low

Mammals - Dermal LD₅₀ (mg kg⁻¹ body weight)

4800

Rat

Mammals - Inhalation LC₅₀ (mg l⁻¹)

Other Mammal toxicity endpoints

Intraperitoneal LD₅₀ = 3.34 mg kg⁻¹

Rat

ADI - Acceptable Daily Intake (mg kg⁻¹ bw day⁻¹)

ARfD - Acute Reference Dose (mg kg⁻¹ bw day⁻¹)

AAOEL - Acute Acceptable Operator Exposure Level (mg kg⁻¹ bw day⁻¹)

AOEL - Acceptable Operator Exposure Level - Systemic (mg kg⁻¹ bw day⁻¹)

Dermal penetration studies (%)

Dangerous Substances Directive 76/464

Exposure Routes

Public

Occupational

Mammalian dose elimination route and rate

Rapidly metabolised and eliminated via urine

Health issues

Specific human health issues

Carcinogen

Genotoxic

Endocrine disruptor

; ; ; ;

No data found

Reproduction / development effects

Acetyl cholinesterase inhibitor

Neurotoxicant

No data found

Respiratory tract irritant

Skin irritant

Skin sensitiser

Eye irritant

Phototoxicant

No data found

General human health issues

Possible kidney & respiratory system toxicant

Handling issues

Property

Value and interpretation

General

Will emit toxic gases when heated to decomposition
Highly corrosive

CLP classification 2013

Handling: H242
Health: H302, H314, H317
Environment: H411

WHO Classification

U (Unlikely to present an acute hazard)

UN Number

Waste disposal & packaging

Shelf-life, storage, stability and reactivity

TRANSLATIONS

Language

Name

English

dimethyl phthalate

French

phtalate de dimethyle

German

Danish

Italian

Spanish

Greek

Polish

Swedish

Hungarian

Dutch

Norwegian

Record last updated:	16/09/2025
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