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Publication #PI-51

Pesticide Toxicity Profile: Carbamate Pesticides1

Frederick M. Fishel2

This document provides a general overview of human toxicity, provides a listing of laboratory animal and wildlife toxicities and a cross-reference of chemical, common and trade names of many carbamate pesticides registered for use in Florida.

General

Carbamate pesticides are derived from carbamic acid and kill insects in a similar fashion as organophosphate insecticides. They are widely used in homes, gardens and agriculture. Like the organophosphates, their mode of action is inhibition of cholinesterase enzymes, affecting nerve impulse transmission. The first carbamate, carbaryl, was introduced in 1956 and more of it has been used throughout the world than all other carbamates combined. Because of carbaryl's relatively low mammalian oral and dermal toxicity and broad control spectrum, it has had wide use in lawn and garden settings. Most of the carbamates are extremely toxic to Hymenoptera, and precautions must be taken to avoid exposure to foraging bees or parasitic wasps. Some of the carbamates are translocated within plants, making them an effective systemic treatment.

Toxicity

The signs and symptoms of carbamate poisonings are similar to those caused by the organophosphate pesticides. The carbamate's principal route of entry is either by inhalation or ingestion or secondarily by the dermal route. Dermal exposure tends to be the less toxic route than inhalation or ingestion. For example, carbofuran has a rat oral LD50 of 8 mg/kg, compared to a rat dermal LD50 of greater than 3,000 mg/kg, making it much more toxic when ingested. The carbamates are hydrolyzed enzymatically by the liver; degradation products are excreted by the kidneys and the liver. Respiratory depression combined with pulmonary edema is the usual cause of death from poisoning by carbamate compounds. As with organophosphates, the signs and symptoms are based on excessive cholinergic stimulation. Unlike organophosphate poisoning, carbamate poisonings tend to be of shorter duration because the inhibition of nervous tissue acetylcholinesterase is reversible, and carbamates are more rapidly metabolized. Muscle weakness, dizziness, sweating and slight body discomfort are commonly reported early symptoms. Headache, salivation, nausea, vomiting, abdominal pain and diarrhea are often prominent at higher levels of exposure. Contraction of the pupils with blurred vision, incoordination, muscle twitching and slurred speech have been reported. Mammalian toxicities for carbamate pesticides are shown in Table 1. Table 2 lists the toxicities to wildlife by the common name of the carbamate pesticide. Table 3 provides a cross listing of many of the trade names that these products are registered and sold by in Florida.

Additional Information

Table 1. 

Carbamate pesticide mammalian toxicities (mg/kg of body weight).

Common name

Rat oral LD50

Rabbit dermal LD50

Aldicarb

1

20

Carbaryl

500 – 850

>2,000

Carbofuran

8

>3,000

Fenoxycarb

16,800

>2,000

Methiocarb

60 – 1,000 depending on product

>2,000 (rat)

Methomyl

30 – 34

>2,000

Oxamyl

5.4

2,960

Thiodicarb

66

>2,000

Table 2. 

Carbamate pesticide wildlife toxicity ranges.

Common name

Bird acute oral LD50 (mg/kg)*

Fish LC50 (ppm)**

Bee†

Aldicarb

MT

HT

PNT

Carbaryl

PNT

HT

HT

Carbofuran

HT

HT

Not available

Fenoxycarb

PNT

HT

PNT

Methiocarb

HT

HT

Not available

Methomyl

HT

MT

HT

Oxamyl

VHT

MT

HT

Thiodicarb

HT

HT

MT

*Bird LD50: PNT = >2,000; ST = 501 – 2,000; MT = 51 – 500; HT = 10 – 50; VHT = <10.

**Fish LC50: PNT = >100; ST = 10 – 100; MT = 1 – 10; HT = 0.1 – 1; VHT = <0.1.

†Bee: HT = highly toxic (kills upon contact as well as residues); MT = moderately toxic (kills if applied over bees); PNT = relatively nontoxic (relatively few precautions necessary).

Table 3. 

Cross-reference list of common, trade and chemical names of carbamate pesticides.

Common name

Trade names*

Chemical name

Aldicarb

Temik®

2-methyl-2-(methylthio)propionaldehyde O-(methylcarbamoyl)oxine

Carbaryl

Carbaryl®, Prokoz® and Sevin®

1-naphthyl methylcarbamate

Carbofuran

Furadan®

2,3-dihydro-2,2-dimethyl-7-benzofuranyl methylcarbamate

Fenoxycarb

Award® and Logic®

Ethyl [2-(4-phenoxyphenoxy)ethyl] carbamate

Methiocarb

Mesurol®

3,5-dimethyl-4-(methylthio)phenyl methylcarbamate

Methomyl

Lannate®

S-methyl N-[(methylcarbamoyl)oxy]thioacetimidate

Oxamyl

Vydate®

S-methyl N,N-dimethyl-N-(methylcarbamoyloxy)-1-thio-oxamimidate

Thiodicarb

Larvin®

Dimethyl N,N-(thiobis(methylimino)carbonyloxy)bis(ethanimidothioate)

*Does not include manufacturers' prepackaged mixtures.

Footnotes

1.

This document is PI-51, one of a series of the Agronomy Department, Florida Cooperative Extension Service, Institute of Food and Agricultural Sciences, University of Florida. Original publication date June 2005. Reviewed August 2008. Visit the EDIS Web Site at http://edis.ifas.ufl.edu.

2.

Frederick M. Fishel, Associate Professor, Agronomy Department, and Director, Pesticide Information Office; Florida Cooperative Extension Service, Institute of Food and Agricultural Sciences, University of Florida, Gainesville, FL 32611.

The use of trade names in this publication is solely for the purpose of providing specific information. UF/IFAS does not guarantee or warranty the products named, and references to them in this publication does not signify our approval to the exclusion of other products of suitable composition. Use pesticides 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 extension publications, contact your county Cooperative Extension service.

U.S. Department of Agriculture, Cooperative Extension Service, University of Florida, IFAS, Florida A. & M. University Cooperative Extension Program, and Boards of County Commissioners Cooperating. Millie Ferrer-Chancy, Interim Dean.