3-decen-2-one DP Number: 373085

PC Code: 068403 EPA File Symbol No.: 5481-LAI

Type of Review: Human Health Toxicity

OFFICE OF CHEMICAL SAFETY

AND POLLUTION PREVENTION

UNITED STATES ENVIRONMENTAL PROTECTION AGENCY

WASHINGTON, D.C. 20460

MEMORANDUM

DATE: August 22, 2012

SUBJECT: Preliminary Human Health Assessment for the Registration Review of Cytokinins 

(as Kinetin) [Chemical Name, 1-H-Purin-6-amine, N-(2-furanylmethyl)-].

Registration Review Case Number: 4107

Chemical Class: Biochemical

PC Codes: 116801 and 116802

CAS Number: 525-79-1

Active Ingredient Tolerance Exemption: 40 CFR § 180.1157

Type of Review: Human Health Assessment

FROM: Colin G. Walsh, M.S., Biologist /s/ 08/22/2012

Biochemical Pesticides Branch

Biopesticides & Pollution Prevention Division (7511P)

TO: Leonard Cole, Senior Regulatory Action Leader

Biochemical Pesticides Branch

Biopesticides & Pollution Prevention Division (7511P) 

ACTION REQUESTED

The following scoping document contains the preliminary human health assessment for the 

biopesticide, cytokinins (as kinetin), in support of the development of the Registration Review 

Preliminary Work Plan. 

Executive Summary
Cytokinins (as Kinetin) PC Codes: 116801 and 116802

Type of Review: Human Health Assessment (Registration Review)

2

Based on the available data and information, the Agency does not foresee the need for new data 

or for new risk assessments for this active ingredient, cytokinins (as kinetin). Hazard and 

exposure information as well as Agency risk assessments on cytokinins (as kinetin) were 

evaluated against current safety standards established by the Agency’s scientific policies and 

regulations and it was determined that there is no need to conduct additional risk assessments. 

The active ingredient is naturally occurring, has a non-toxic mode of action, is of low toxicity, 

and has very low use rates. There is reasonable certainty of no harm to the general population 

from exposure to this chemical in pesticide products when it is used according to label 

instructions. 

 

I. Background

Cytokinin is comprised of the following four naturally occurring cytokinins derived from 

aqueous extract of seaweed meal: zeatin, N6-methylaminopurine, N6-dimethylaminopurine, and 

N

6

-isopentenylaminopurine (EPA, 1995). Kinetin [chemical name, 1-H-Purin-6-amine, N-(2-

furanylmethyl)-] is a synthetic version of cytokinin and acts as a plant growth regulator (PGR)

that is used to enhance the growth and development of plants. Cytokinins are used on growing 

crops, young trees, ornamentals, and golf courses to increase fruit size, yield, blossoms,

branching, healthy appearance, and other desirable growth effects (EPA, 1995). Historically, the 

Agency has classified kinetin as a synthetic cytokinin; however, more recent data indicate that 

the chemical is naturally occurring in plants and animals (Barciszewski et al., 2000; EPA, 2001). 

The active ingredient was first registered by the Agency in 1978. There are currently 50

registered products containing the active ingredient (PC Codes 118601 and 118602). Three of 

these products are manufacturing-use products (MPs); the remaining 47 are end-use products 

(EPs). Of the 47 EPs, 19 contain cytokinins (as kinetin) as the sole active ingredient; the 

remaining 28 contain the active ingredient along with another active ingredient(s). In general, 

cytokinins (as kinetin) are found in very low concentrations in EPs with the highest

concentration at 1.11% (42 of 47 EPs at an a.i. concentration of less than 0.15%).

The chemical is currently not approved for use as an inert ingredient in pesticide products. 

 

II. Tolerances

Cytokinins (specifically: aqueous extract of seaweed meal and kinetin) are exempt from the 

requirement of a tolerance under 40 CFR § 180.1157 in or on all food commodities when used as 

plant regulators on plants, seeds, or cuttings and on all food commodities after harvest in 

accordance with good agricultural practices. [64 FR 31505, June 11, 1999] 

III. Incidents
Cytokinins (as Kinetin) PC Codes: 116801 and 116802

Type of Review: Human Health Assessment (Registration Review)

3

According to the Incident Data System, there have been no reported incidents from the use of 

EPA-registered products that contain the active ingredient, cytokinins, between January 1, 1992 

and August 15, 2012. 

IV. Toxicity Profile

Sufficient data have been provided to fulfill the biochemical pesticide data requirements under 

40 CFR § 158.2050 for the current use patterns for this active ingredient, cytokinins (as kinetin). 

The data available to the Agency are summarized in Table 1 below.
Cytokinins (as Kinetin) PC Codes: 116801 and 116802

Type of Review: Human Health Assessment (Registration Review)

4

Table 1: Human Health Assessment Data Requirements for Cytokinins (40 CFR § 158.2050)

Study/OCSPP Guideline No. Results Toxicity 

Category/Description MRID

Acute oral toxicity (rat)

(870.1100)

LD50 > 5,000 mg/kg body weight in male and 

female rats Toxicity Category IV 45453301

Acute dermal toxicity (rat)

(870.1200)

LD50 > 5,000 mg/kg body weight in male and 

female rats Toxicity Category IV 45453302

Acute inhalation toxicity (rat)

(870.1300) LC50 > 2.09 mg/L in male and female rats Toxicity Category IV 45453303

Primary eye irritation (rabbit)

(870.2400)

One hour after test substance instillation, all 

three treated eyes exhibited conjunctivitis and 

at 24 hours two eyes exhibited corneal 

opacity. The overall incidence and severity of 

irritation decreased with time. All animals 

were free of ocular irritation by 72 hours. Test

substance is classified as mildly irritating to 

the eye.

Toxicity Category III 45453304

Primary dermal irritation (rabbit)

(870.2500)

Animals did not exhibit any dermal irritation 

at any test site during the study. Test 

substance is classified as non-irritating to the 

skin. 

Toxicity Category IV 45453305

Dermal sensitization (guinea pig)

(870.2600) Test substance is not a dermal sensitizer. - 45453306

90-Day oral toxicity

(870.3100)

The data requirement has been historically 

waived because of low acute mammalian 

toxicity and very low use rates which would 

not significantly increase dietary intake over 

natural consumption in foods. The historical 

information to support the data requirement is 

adequate.

-

EPA RED 

(1995)

90-Day dermal toxicity

(870.3250)

The Agency has historically concluded that 

these occupational exposures and subsequent 

risks will be negligible because of the low 

acute mammalian toxicity and very low use 

rates. In addition, any unlikely dermal 

exposure will be mitigated on the label by 

precautionary statements and PPE 

requirements. The historical information to 

support the data requirement is adequate.

-

EPA RED 

(1995)

90-Day inhalation toxicity

(870.3465)

The Agency has historically concluded that 

these occupational exposures and subsequent 

risks will be negligible because of the low 

acute mammalian toxicity and very low use 

rates. In addition, any unlikely inhalation 

exposure will be mitigated on the label by 

precautionary statements and PPE 

requirements. The historical information to 

support the data requirement is adequate.

-

EPA RED 

(1995)

Developmental toxicity

(870.3700)

The data requirement has been historically 

waived because of low acute mammalian

toxicity and very low use rates which would 

not significantly increase dietary intake over 

natural consumption in foods. The historical 

information to support the data requirement is 

adequate.

-

EPA RED 

(1995)

Mutagenicity The data requirement has been historically - EPA RED 
Cytokinins (as Kinetin) PC Codes: 116801 and 116802

Type of Review: Human Health Assessment (Registration Review)

5

Table 1: Human Health Assessment Data Requirements for Cytokinins (40 CFR § 158.2050)

Study/OCSPP Guideline No. Results Toxicity 

Category/Description MRID

(870.5100, 5300 and 5375) waived because of low acute mammalian 

toxicity and very low use rates which would 

not significantly increase dietary intake over 

natural consumption in foods. The historical 

information to support the data requirement is 

adequate.

(1995)

V. References

Barciszewski, J, G. Siboska, SIS. Rattan. 2000. Occurrence, biosynthesis and properties of 

kinetin (N-6-furfuryladenine). Plant Growth Regulation. Vol. 32(2-3): 257-265.

EPA. 1995. Reregistration Eligibility Document (RED) for Cytokinin and R.E.D. Fact Sheet for 

Cytokinin, Kinetin, and N6-Benzyladenine. U.S. Environmental Protection Agency Office of 

Prevention, Pesticides and Toxic Substances. December 1995.

http://www.epa.gov/oppsrrd1/REDs/4107.pdf

http://www.epa.gov/pesticides/biopesticides/ingredients/factsheets/factsheet_116801.htm

EPA. 2001. Biopesticides Fact Sheet for Cytokinin. U.S. Environmental Protection Agency

Office of Prevention, Pesticides and Toxic Substances. December 2001.

http://www.epa.gov/opp00001/chem_search/reg_actions/registration/fs_G-29_01-Dec-01.pdf

cc: Colin G. Walsh, Leonard Cole, BPPD Science Review File, IHAD/ARS, Colin G. Walsh, FT, 

PY-S, August 22, 2012