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Publication #PI282

Toxicity of Common Indoor Household Insecticides Registered in Florida1

Frederick M. Fishel2

Background

Insecticides are designed to kill insect pests, but, if used incorrectly, they may damage desirable plants and animals, including humans. Some pesticides are so highly toxic that very small quantities can cause illness or eye damage, burn the skin, or even cause death. Because common pesticides, such as those intended for household use, can irritate the skin, eyes, nose, or mouth, it is a good idea to understand the toxicity of household insecticides so you can follow practices designed to reduce exposure to people, pets, and other nontarget organisms. This document addresses the acute toxicity of common indoor household insecticide active ingredients registered in Florida and provides a table with mammalian toxicity values for each of these insecticides.

Acute Toxicity

The acute toxicity of a chemical refers to its ability to do systemic damage as a result of a one-time exposure to relatively large amounts of the chemical. A pesticide with a high acute toxicity may be deadly if even a very small amount is absorbed or ingested. The Environmental Protection Agency (EPA) designates signal words on a pesticide label to inform users of the toxicity level. The signal words on the label (Table 1) are based on the acute toxicity of the pesticide and are divided into four categories based on the amount that causes damage. Acute toxicity may be measured as acute oral (through the mouth), acute dermal (through the skin), and acute inhalation (through the lungs or respiratory system). For more information about signal words and pesticide labeling, please refer to https://edis.ifas.ufl.edu/pi137.

Acute Toxicity Measures

The commonly used term to describe acute toxicity is LD50. LD means lethal dose (deadly amount) and the subscript 50 means that the dose was acutely lethal to 50% of the animals to whom the chemical was administered under controlled laboratory conditions. The test animals, most commonly rats, mice, and/or rabbits, are given specific amounts of the chemical in either one oral dose, by a single injection, or dermally, and they are then observed for a specified time.

The lower the LD50 value, the more acutely toxic the pesticide—it takes less of it to cause harm. Therefore, a pesticide with an oral LD50 of 500 mg/kg would be much less toxic than a pesticide with an LD50 of 5 mg/kg. LD50 values are expressed as milligrams per kilogram (mg/kg), which means milligrams of chemical per kilogram of body weight of the animal. Milligram (mg) and kilogram (kg) are metric units of weight. Milligrams per kilogram is the same measure as parts per million. To put these units into perspective, 1 ppm is analogous to 1 inch in 16 miles or 1 minute in 2 years.

For example, if the oral LD50 of the insecticide parathion is 4 mg/kg, a dose of 4 parts of parathion for every million parts of body weight would be lethal to at least half of the test animals. As an example, the LD50 of caffeine is 150–200 mg/kg, and the LD50 of table salt is about 3,000 mg/kg.

LD50 values are generally expressed based on active in­gredient. If a commercial product is formulated to contain 50 percent active ingredient, it would take two parts of the material to make one part of the active ingredient. In some cases, other chemicals mixed with the active ingredient for formulating the pesticide product may cause the toxicity to differ from that of the active ingredient alone. Each pesticide product label lists its common name under the active ingredient statement to identify what is in the product. Then, knowing the active ingredient(s), you may use Table 2 to determine the LD50 value of the product.

Another designation is LC50, which measures acute inhalation toxicity. LC means lethal concentration. Concentration is used instead of dose because the amount of pesticide inhaled in the air is being measured. LC50 values are measured in milligrams per liter. Liters are metric units of volume that are similar to a quart. The lower the LC50 value, the more toxic the pesticide.

Additional Information

National Pesticide Information Center (1-800-858-7378 or http://npic.orst.edu/).

Nesheim, O. N., F. M. Fishel, and M. A. Mossler. 2005. Toxicity of Pesticides. PI-13. Gainesville: University of Florida Institute of Food and Agricultural Sciences. http://edis.ifas.ufl.edu/pi008

Tables

Table 1. 

Acute toxicity measures and warnings.

   

Categories of acute toxicity

 
   

LD50

LC50

 

Categories

Signal word

Oral mg/kg

Dermal mg/kg

Inhalation mg/l

Oral lethal dose1

I Highly toxic

DANGER, POISON (skull and crossbones)

0 to 50

0 to 200

0 to 0.2

A few drops to a teaspoon

II Moderately toxic

WARNING

50 to 500

200 to 2,000

0.2 to 2.0

Over a teaspoon to one ounce

III Slightly toxic

CAUTION

500 to 5,000

2,000 to 20,000

2.0 to 20

Over one ounce to one pint

IV Relatively nontoxic

CAUTION (or no signal word)

5,000+

20,000+

20+

Over one pint to one pound

1 Probable for a 150-pound person.

Table 2. 

Acute toxicity values for commonly used indoor household insecticides.

Common name

Oral LD50 (mg/kg)1

Dermal LD50 (mg/kg)1

Inhalation LD50 (mg/l)1

Abamectin

221

330

2.2

Acetamiprid

>2,000

>2,000

>3.5

Allethrin, d-cis,trans allethrin

685

>11,000

>3.8

Bifenthrin

632

>2,000

1.0

Bioallethrin (see d-cis,trans allethrin)

     

Boric acid

>5,000

>5,050

---

Cyfluthrin

960

>2,000

4.0

Cyhalothrin—gamma

>5,000

>5,000

0.3 – 0.4

Cyhalothrin—lambda

>5,000

>2,000

0.06

Cypermethrin

294

>2,000

>2.02

Deltamethrin

2,613

>5,000

>1.02

Dichlorobenzene—para

500

>2,000

>6.0

Dichlorvos

25

59

15.0

Dinotefuran

>2,000

>2,000

>2.07

d-limonene

>5,000

>5,000

---

Esfenvalerate

1,470

>2,000

2.93

Fipronil

>5,000

>5,000

5.16

Hydramethylnon

>5,000

>2,000

2.9

Imidacloprid

>4,820

>2,000

2.25

Imiprothrin

1,800

2,000

>5.1

Mineral oil

>2,000

>2,000

>5

Napthalene

13,900

N/A

>340

Permethrin

1,030

>2,000

25.7

Phenothrin

>5,000

>5,000

10.4

Prallethrin

640

>2,000

0.66–0.86

Propoxur

50

>5,000

>2.11

Pyrethrins

>2,000

>2,000

>2.11

Pyriproxyfen

>5,000

>2,000

>7.60

Sumithrin (d-phenothrin)

>10,000

>10,000

>2.10

Tetramethrin

>5,000

>5,000

5.63

1 Oral toxicity based on male rat testing. Dermal toxicity based on rabbit or rat testing. Inhalation toxicity most often based on rat testing.

Footnotes

1.

This document is PI282, one of a series of the Agronomy Department, UF/IFAS Extension. Original publication date September 2019. Visit the EDIS website at https://edis.ifas.ufl.edu for the currently supported version of this publication.

2.

Frederick M. Fishel, professor, Agronomy Department, and director, Pesticide Information Office; UF/IFAS Extension, Gainesville, FL 32611.

Use insecticides safely. Read and follow directions on the manufacturer's label.


The Institute of Food and Agricultural Sciences (IFAS) is an Equal Opportunity Institution authorized to provide research, educational information and other services only to individuals and institutions that function with non-discrimination with respect to race, creed, color, religion, age, disability, sex, sexual orientation, marital status, national origin, political opinions or affiliations. For more information on obtaining other UF/IFAS Extension publications, contact your county's UF/IFAS Extension office.

U.S. Department of Agriculture, UF/IFAS Extension Service, University of Florida, IFAS, Florida A & M University Cooperative Extension Program, and Boards of County Commissioners Cooperating. Nick T. Place, dean for UF/IFAS Extension.