|  |
Pesticide Toxicity Profile: Carbamate Pesticides1
Frederick M. Fishel2This 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).
- Crop Protection Handbook. 2005. vol. 91. Willoughby, Ohio: Meister Publishing Co. http://www.meisterpro.com/mpn.
- Nesheim, O.N. 2002. Toxicity of pesticides. UF/IFAS EDIS Document PI-13. http://edis.ifas.ufl.edu/PI008 .
- Reigart, J.R. and J.R. Roberts. 1999. Recognition and management of pesticide poisonings, 5th ed. United States Environmental Protection Agency Publication EPA-735-R-98-003.
- Seyler, L.A., et.al. 1994. Extension toxicology network (EXTOXNET). Cornell University and Michigan State University. http://extoxnet.orst.edu/index.html. Visited July 2005.
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. Larry Arrington, Dean.
Copyright Information
This document is copyrighted by the University of Florida, Institute of Food and Agricultural Sciences (UF/IFAS) for the people of the State of Florida. UF/IFAS retains all rights under all conventions, but permits free reproduction by all agents and offices of the Cooperative Extension Service and the people of the State of Florida. Permission is granted to others to use these materials in part or in full for educational purposes, provided that full credit is given to the UF/IFAS, citing the publication, its source, and date of publication.