Herbicide safety

Page last updated: Monday, 2 February 2015 - 5:08pm

Please note: This content may be out of date and is currently under review.

Toxicity of herbicides

Pesticides usually have several toxicity ratings. They are oral, dermal, acute and chronic.

Oral toxicity

The oral toxicity of a herbicide is determined by laboratory testing at various doses. From these trials the LD50 value is calculated. This is the amount of chemical tested in animals, expressed as mg of active ingredient per kilogram of body weight, required to kill 50% of the test group (usually rats or mice). The lower the LD50 number, the more toxic is the chemical.

Oral LD50 of some well known compounds

Caffeine

DDT

Aspirin

Penicillin

Salt

Petroleum oils

150mg/kg

420mg/kg

750mg/kg

1000mg/kg

3000mg/kg

1000–

10 000mg/kg

LD50 of some well known herbicides*

Trade name

Active ingredient

Oral LD50mg/kg

Dermal LD50mg/kg

2,4-D

2,4-D

639–764

>1600–2400

2,4-DB

2,4-DB

700

n/a

Ally®/Brush-off®

metsulfuron methyl

>5000

>2000

Amitrole

amitrole

1100–24 600

>2500–10 000

Atrazine

atrazine

1869–3090

>3100

Basta®

glufosinate

2000

>4000

Broadstrike™

flumetsulam

>5000

>2000

Bromicide®

bromoxynil

190-270

>2000

Casoron®

diclobenil

2700-6000

>2000

Diuron

diuron

3400-3700

>2000

DSMA

DSMA

1800-2800

>10 000

Eclipse®

metosulam

>5000

>2000

Garlon™

triclopyr

713

>2000

Glean®, Lusta™ etc

chlorsulfuron

5545

>2500

Gramoxone®

paraquat

112-150

911

Hoegrass®

diclofop-methyl

481–693

>5000

Hyvar® X, Bromacil

bromacil

2000

>5000

Kamba, Banvel™

dicamba

1707

>2000

Linuron

linuron

1000-4000

>2000

Logran®

triasulfuron

>5000

>2000

Londax®

bensulfuron

>5000

>2000

Lontrel™

clopyralid

>4300

>2000

MCPA

MCPA

800

>4000

MCPB

MCPB

4700

>2000

Propon

2,2-DPA

3860-9330

>2000

Ramrod®

propachlor

1200

>20 000

Reglone®

diquat

230–440

>793

Roundup®

glyphosate

5600

>5000

Simazine

simazine

500–10 000

>2000

Spinnaker®

imazethapyr

>5000

>2000

Spray.Seed®

paraquat + diquat

150

911

Starane™

fluroxypyr

2450

>5000

Terbutryn

terbutryn

500–2500

>2000–20 000

Tigrex®

diflufenican

>2000

>2 000

Tordon™ 75D

2,4-D + picloram

n/a

n/a

Tordon™ Double Strength

triclopyr + picloram

n/a

n/a

Tordon™ granules

picloram

8200

>2000

Tribunil®

methabenzthiazuron

>5000

>5000

Trifluralin

trifluralin

>5000

>5000

Velpar®

hexazinone

1 690

>5278

* The above acute LD50s for herbicides commonly used in Western Australia were extracted from 'The Pesticide Manual: a world compendium' (12th edition) 2000, the British Crop Protection Council.

Although the toxicity of some herbicides varies with the route of entry into the body (oral, inhalation, dermal), in general, the acute oral LD50 figures gives a good indication of the relative toxicity of the herbicide. The poison schedule is dependent on other factors as well as LD50 of the product. For example, all arsenics are carcinogenic and hence are placed in the S7 category.

Contact information

Pest and Disease Information Service (PaDIS)
+61 (0)8 9368 3080
Andrew Reeves
+61 (0)8 9780 6224