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Publication #PI-63

Pesticide Toxicity Profile: Thiophthalimide Pesticides1

Frederick M. Fishel2

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

General

There are currently only two members of the chemical family of thiophthalimide pesticides that remain on the market in the United States: captan and folpet. Captan, one of the most widely used fungicides in the world, has many crops on its label, including fruits, nuts, and ornamentals, and is used for control of fungal and bacterial diseases. It also has application as a seed protectant. Practically every acre of Florida strawberries receives captan applications as well as approximately half of the US apple acreage. The first commercially available captan product entered the US market in 1949. Current commercial formulations available include wettable powders, dusts, water-dispersible granules, and flowables. There are also many products containing captan formulated especially for home garden use. There are limited numbers of uses for folpet in Florida, but it is labeled as a foliar treatment for control of scab on avocado. It is formulated as a wettable powder for this use. There are several commercial products of folpet in combination with bis(tributyltin) oxide. This combination is applied to wood products as a stain for prevention of damage caused by mildew and other wood decay organisms. Folpet first entered the market in 1962.

Toxicity

These fungicides may cause moderate irritation of the skin, respiratory tract, and eyes. Captan has a low acute toxicity and generally carries the signal word, CAUTION. It is not likely that captan would cause reproductive effects in humans at usual levels of exposure. Although the EPA concluded that captan does not produce birth defects or mutagenicity, they classify captan as a probable human carcinogen. Animal studies have shown that captan is rapidly metabolized, and residues are excreted in the urine. Folpet is considered slightly toxic by ingestion. Long-term effects have varied in laboratory animals exposed to folpet. Mammalian toxicities for the thiophthalimide pesticides are shown in Table 1. Table 2 lists the toxicities to wildlife by the common name of the pesticide. Table 3 provides a cross listing of some trade names under which these products are registered and sold in Florida.

Additional Information

  • Crop Protection Handbook. 2014. vol. 100. Willoughby, Ohio: Meister Publishing Co. http://www.meistermedia.com/publications/handbook.html

  • Nesheim, O.N., F.M. Fishel and M.A. Mossler. 2005. Toxicity of pesticides. UF/IFAS EDIS Document PI-13. http://edis.ifas.ufl.edu/PI008.

  • Reigart, J.R. and J.R. Roberts. 2013. Recognition and management of pesticide poisonings, 6th ed. United States Environmental Protection Agency Publication EPA-735K-13001.

  • 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.

Tables

Table 1. 

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

Common name

Rat oral LD50

Rabbit dermal LD50

Captan

9,000

---

Folpet

>10,000

>5,000

Table 2. 

Thiophthalimide pesticide wildlife toxicity ranges.

Common name

Bird acute oral LD50 (mg/kg)*

Fish (ppm)**

Bee

Captan

ST

HT

PNT

Folpet

ST

HT

PNT

*Bird LD50: Practically nontoxic (PNT) = >2,000; slightly toxic (ST) = 501 – 2,000; moderately toxic (MT) = 51 – 500; highly toxic (HT) = 10 – 50; very highly toxic (VHT) = <10.

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

Bee: HT = highly toxic (applied product and residues kill upon contact); 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 thiophthalimide pesticides.

Common name

Trade names*

Chemical name

Captan

Captan®, Captec, Cap-Up, Fungitrol

N-trichloromethylthio-4-cyclohexene-1,2-dicarboximide

Folpet

Folpet®

N-[(trichloromethyl)thio]phthalimide

*Does not include manufacturer's prepackaged mixtures.

Footnotes

1.

This document is PI-63, one of a series of the Agronomy Department, UF/IFAS Extension. Original publication date September 2005. Revised March 2014. Reviewed March 2014. Visit the EDIS website at http://edis.ifas.ufl.edu.

2.

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