kt1tnd S t Offi of P tIcid end Toxic S ancus
Envlronmsnt.I P,ot .on off.c of P idd. Pvoqrsms ITS-766C)
Aguncy W iInq n. DC 20460
&EPA Pesticide
Fact Sht.
Name of Chemical: i EIC HYDRAZIDE
Date Issued: JUNE 30, 1988
Fact Sheet Number: 170
1. Description of th nical
Generic Name: 1 , 2-dihydro-3 ,6-pyridazinedione
Cc imon Name: Maleic Nydrazide
Trade Names: Drexel Sucker-Stuff, Super Sucker tuf, Retard, &irtolin,
Deo.it, Drexel Sprout Stop, Fair 2, Fair Plus, RMH, Maintain
3, Malazide, Mazide, Regulox W, Regulox SCM, Stuntman,
Super-De-Sprcxit, VendaJhyde, Vondrax, Royal MH-30, Royal
MH-30 SG, Royal Slo-Gro, Malazide Sb Gro.
EPA Shaughnessy Codes: Maleic Hydrazide: 051501
Potassi xn Salt of Maleic Hydrazide: 051503
Diethanolarnine Salt of Maleic Hydrazide: 051502
Chenical Abstracts Service (CAS) Nuther: 123-33-1
Year of Initial Registration: 1952
Pesticide 1 pe: Herbicide, Plant GrcMth Regulator
U. S • and Fore ig i Producers: Drexel thanical
Trans Chanical Industries
2. Use Patterns and Formulations :
Application Sites: Terrestr al food (potatoes, onions, cranberries),
terrestrial nonfood (nonbearing citrus and nonbearing apples, tobacco),
terrestrial none rop.
rpes and Methods of Application: Primarily as a foliar spray with sane
use by tree injection.

Pests Controlled: Sucker control for tobacco, sprout infiltration in
onions and potatoes, growth retardant of quackgrass, wild onions,
and rlic.
Application Rates:
Terrestrial Food Crops: 0.7 lb acid eauivalent (ae)/A to 15 lb ae/A
Terrestrial Nonfood Crops: 1.5 to 4.5 lb ae/A
Ornamental Plants and Forest Trees: 0.06 to 6 lb ae/A
Turf: 0.75 to 6.6 lb ae/A
Rights—of—way: 0.66 to 6.6 lb ae/A
Types of Formulation:
90%, 95%, 97%, and 99% technical grade of the active ingredient
( TcAI)
0.66 to 2.25 lb ae/gal uulsifiable concentrate (EC)
0.6, 1.5, 2.0, 2.25, and 2.5 ae/gal soluble concentrate/liquid
Usual Carrier: Water
3. Science Findinqs
Suirmary Science Statement : Maleic hydrazide (MH) has 1cM acute toxicity
(Category III) for primary eye irritation and is in Category IV for
acute oral toxicity, acute dermal toxicity, and primary dermal irri-
tation. MH caused no adverse reproductive effects and was not
oncogenic in mice. The teratology study in rabbits had a teratogenic
NOEL of 100 mg/kg with malformed scapulae occurring in the mid and
high d e. Additional information has been r uested to clarify
this effect.
MR was stable to hydrolysis and photodegradation in soil. It
photodegraded in buffered aueous solutions at pH 5, 7, and 9. MR
was very irobile in five soils and has a l potential to bicaccuiru—
1. te in ftsh. Addit cnai r r 1s ence - d 1e ±inrj d t arc r ded
o evaLiate M i potential co contaminate grc ind wacer.
NH is cori idered pr ctical1y nontox c to bir3s, uatic inver ebrates.
fresh’ ater fisti, or boney bees. nd ngered nirrai species a .e not
expected to be adversely affected by the use of MR. Since no endan-
gered plant species are listed for tobacco cropland, citrus, apples,
or cropland with onions, potatoes, or cranberries, little risk to
endangered plants is expected fran these uses. The hazard evaluation
for listed plants and the right—of—way uses is being deferred until
caripletion of the noncrops cluster.
Chemical Characteristics:
Color: White
Physical state: Crystalline solid

Odor: Faint
Melt!ng point: 292 °C wini r3Iri
Bulk density: 30 to 36 1b cubic feet (cu/f t)
(0.049 grams/milliliter g/ml)
Specific gravity: 1.6 at 20 °C
90% a.e.— 60 parts per million ( in) water
10 m isopro ’l alcohol
< 10 p n xylene
240 ppn dimethyl formamide
Vapor pressure: < 1 m Hg at 20 °C
Stable at 45 °C up to 61 days
Stable at 80 °C up to 30 days
Toxicology Characteristics:
Existing data are all based on NH (technical) or the potassium salt
(K salt), further data are requested on the diethano]amine (DEA) salt.
Acute Toxicology:
Acute Oral Toxicity (Rat):
Greater than C>) 5 grams/kilogram (g/kg)
Toxicity Category IV
Acute Dermal Toxicity (Rabbit):
> 20 g/kg
Toxicity Category IV
Primary Eye Irritation:
Primary Irritation Score (P 15) 0.4
Toxicity Category III
Primary Dermal Irritation:
slight Irritant
Toxicity Category IV
Acute Inhalation and dermal sensitization studies are not
available rd are beinq r 1u re f’v “H nd the DF .c lt.
Subthronic Toxicology Studies: There are no data available for
subchronic oral, dermal, or inhalation toxicity.
A 21—day dermal toxicity study is required for both NH
(technical NH or potassium (K) salt are considered equivalent)
and the diethanolamine (DEA) salt. Subchronic feeding
studies for a rodent and nonrodent are not required
because chronic feeding studies are required.
Chronic Feeding/Onco nicity Studies: Available chronic feeding
studies are inadequate to fulfill guideline requir nents
but are useful to calculate provisional allowable daily intake
(PADI). The chronic feeding study in rats indicates that
the no-observable—effect level (M)EL) is less than Co
500 milligrams/kilogram (rn/kg). Chronic feeding studies
on rodents and nonrodents are required for both NH and
its DEA salt.

Available oncogenic studies in rats are inadequate for maleic
hydrazide technical and K salt, no data are available for the
DEA salt, therefore data are required for both technical and
DEA salt. Two oncogenicity studies are available for mice.
Together they indicate that MM is not oncogenic in mice up to
1800 mg/kg. An oncogenic study in mice is required for the IDEA
Teratology and Reproduction Studies: A teratogenicity study in
rabbits sh ed that exposure to 300 or 1000 mg/kg resulted in
n lformed scapulae in offspring, while 100 mg/kg had no effects.
Additional information is required on parentage of affected off-
spring to fully evaluate this effect.
No teratology data are available for rats. Therefore, teratology
studies are required for both MM and its DEA salt. A teratology
study in rabbits is required for the DEA salt.
A 2—generation rat reproduction study indicated no incidence
of adverse reproductive effects up to 2250 mg/kg (highest dose
tested [ HDT)) with feLal toxic and maternal toxic NOEL of
750 mg/kg based on decreased body weights at the HDr. This
study satisfies the requirement for the MM technical. A
2—generation reproduction study in rats is required for the
DEA salt.
Mutagenicity Studies: A nutagenicity study of sex—linked recessive
lethal gene imitations in Drosophila revealed no sex—linked reces-
sive lethal imitations at cytotoxic doses of 0.4 to 1.0% K salt
of MM. All other mutagenicity data are required for MM. A full
set of mutagenicity studies for the DEA salt are required.
Met’ iis udj : ihere . re o m t oiiSi t uth z av ia l fo
MM technical or the DEA salt: therefore, these studies are
Physiolcsical and Behavioral Characteristics:
Foliar Absorption - Absorbed by roots and leaves.
Translocation — Rapidly translocated to leaves and grc ving

Me thanism of Pesticidal Action — A uracil antj.rnetabolite whidi
interferes with cell division, plant growth, and maturation.
Metabolism in Plants — Limited available data indicate that the
major residues in tobacco are maleic hydrazide and its
beta—D--glucoside conjugate. Additional plant metabolism
data are r uired for potatoes, onions and cranberries.
Metabolism in Animals — No data are available for metabolism in
animals; therefore, livestock metaboli data is r uired.

Environmental Characteristics:
Adsorption and Leaching in Basic Soil Types: was very mobile
in a silt loam, a sandy clay loam, a sandy loam, and two
sandy soils. Additional leaching and adsorption data are
re ui red.
Microbial Breakd m: Available aerobic/anaerobic soil metabolism
data are insufficient. Therefore, aerobic and anaerobic
soil metabolism studies are ra uired.
Loss fran Photodecanposition: Stable to photodegradation in soil.
Photodegraded in buffered ueous solutions at pH 5,and 7,and
9 with half—lives of 58 days, at ph 5 and 7 and 34 days at pH 9.
Bioaccuzrulation: L potential to bioacculTulate in fish.
Potential to Contaminate Ground Water: The available data are
inconclusive for defining potential of MH to leach into ground
water. ?U1 is persistent in water. Once persistence data fran
aerobic/anaerobic soil metabolism data and additional leaching
data are subnitted, the potential to contaminate ground water
will be evaluated.
Exposure to Humans: Humans may be exposed to maleic Hydrazide by ingestion
of residues on treated crops, and fran use of treated tobacco.
The major route of exposure for applicators is expected to be
dermal contact • An exposure assessment was performed for
application on tobacco, potatoes, onions, and rights—of-way.
Exposure ranged fran less than 0.5 lTg/kg/day to 16 mg/kg/day.
The greatest exposure occurred for the open—pour mixer loader.
Risk to Humans: The major routes of exposures are expected to be
dermal and eye contact. A risk assessment was performed
fcr d rr:3 p’xuc t applicators tias 2 cn i
teratogenic effect (malformed scapulae in offspring) seen in
rabbits. The risk assessment indicated that the margin of
F I-y (r’ O5) for mixer—lnad rs ia l cs Lh )OO and th reEore
of concern. Labels for end—use products (CPs) are being amended
to r uire long sleeve shirts, long pants, ch nical resistant
gloves at all times while handling, applying, mixing, or loading
the product.
Reentry: Reentry data are not r uired at this time because cultural
practices for existing uses indicate little likelihood of expo-
sure or lc exposure fran these uses. Because MH is placed in
Toxicity category iv for acute oral and derinal toxicity, minimal
risk to humans is expected.

Ecological Characteristics:
Avian Acute Adult Toxicity:
Technical: Mallard Duck > 4640 mg/kg
K salt: Mallard Duck > 2250 mg/kg
Avian Dietary Toxicity:
Mallard Duck > 10,000 n
Bobwhite Quail > 10,000 ppm
K salt: Mallard Duck > 5620 pn
Acute Toxicity to Freshwater Fish:
Rainbow Trout = 1435 n
Bluegill 1608 ppm
K salt: Rainbow Trout > 1000 n
Acute Toxicity to Freshwater Invertebrates:
Technical: 107.5 ppm
K salt: 1000 ppm
Acute Toxicity to Honey Bee: > 36.26 uqJbee
These data indicate that MH is considered “very low toxicity”
to avian species, both warmwater and col ater fish, freshwater
invertebrates, and honey bees.
Hazard to Endangered Species: Endangered animal species are not expected
to be adversely affected by the use of MH because of its low
toxicity to maiTunals, avian species, and uatic species.
Since MH Is a plant ar th tet rdant danc ered plant s ecIes
#ccurriIig I areas wh ce t H is used cc uId t. risk. Kci ’JE ver,
there are no endangered plant species listed for tobacco crcp-
land, citrus, apples, or cropl. nd planted with potatoes, onions,
Cr th ’ceforz n..., risk ( .0 er gercd p1. it p c iv s.
Evaluation of hazard to indangered plants fran use of MH on
right-of-way will await canpietion of noncrop cluster.
Tolerance Assessment: Tolerances are established in 40 CFR 180.175
for residues of the herbicide and plant growth regulator MH
(1,2—dihydro—3,6—pyridazinedione) in or on the following raw
agricultural cc*rinodities:

CaTunodity Parts per million
Cranberries 15.0
Onions, dry bulb 15.0
Potatoes 50.0
A tolerance is established in 21 CFR 193.270 for residues of the
herbicide and plant gr ith regulator (1,2—dihydro—3,6—pyrjdazine
dione) on potato chips at 160 ppm as a result of application of
the pesticide to the growing potato plant.
A Provisional Acceptable Daily Intake (PADI) for MR is currently
based on the finding of renal dysfunction in the rat chronic study.
The LOEL for this effect was 500 ng/kg/ day. Using a thousandfold
safety factor, the PADI for MR is 0.5 mg/kg/day. Existing tolerances
produce a theoretical maximum residue contribution ( MRC) of 0.085
mg/kqjday which occupies 17 percent of the PADI.
The tolerance assessment indicated that additional residue data
are needed for onions, potatoes, nonbea ring apples,
and nonbearing citrus. Additional plant metabolism data are
required for MN. No storage stability or animal metabolism data
are available; therefore, these data are required.
Available toxicology data that was used to calculate the PADI on
technical or K salt include oncogenicity studies in mice,
a teratology study in rabbits, and a 2—generation rat
reproduction study. Additional data required include
chronic feeding studies with a rodent (although the PADI was
established based on a supplementary feeding study in rats)
and nonrodent oncogenenicity and teratology studies in
rats, lnutaqer.icity testin9, and rat metabolis n data for
the techn±cdl or K salt. Data zequired to sup or tolerances
for the DEA salt include acute data, chronic feeding
studies with a rodent, non—rodent, oncongenicity studies in
rats €irc inic ter3tolcqy studies w:L raL u rabbits 2—ge c t1cn
rat reproduction study, mutagenicity testing and metabolism data.
Reported Pesticide Incidents
Data fran the Pesticide Incident Monitoring System (PIMS) reports
and the national study of hospitalized pesticide poisonings
(1971—76) show some cases of MN poisonings, mostly occupational.
There were an estimated eight persons hospitalized in the United
States each year fran 1974 to 1976. The circun tances that led
to these poisonings are not known.

4. Suirrnary of Requlatory Position and Rationale
A review of the available data indicate that no risk critera
listed in 40 CFR 154.7 have been met or exceeded for Ma.
The Agency will not approve any significant new uses of MH
until additional residue chemistry data are available to assess
existing uses.
The Agency is requiring that labeling on all EP5 include a
requirexrent for protective clothing long—sleeve shirt,
long pants and chemical resistant gloves at all times when
handing, applying, mixing, or loading pesticide.
Products bearing labelling not in caipliance with the registration
Standard may be released for shipment by the registrant only
until July 30, 1989. Such products may be distributed and sold
by other persons only until July 30 1990.
The Agency is requiring that additional leaching, aerobic!
anaerobic soil metabolism and dissipation data be sulinitted
to fully define the P I potential to leach and contaminate
The Agency is requiring that additional information be subnitted on
the rabbit teratology study and that a rat teratology be canpieted
within twelve (12) months.
The Agency will continue to require that the acceptable limit of
hydrazine occurring in technical products be l5ppai as required
by the PD—4
The Agency has determined that all toxicology studies will
be necessary for the diethanolamine salt of maleic hydrazide if
n nufacturers cir . 1 . Ych f-hr ria,a qi i.’iei. ich res’1 ed n
the suspensiofl of all DEA—NH products in November 1981.
The Agency has determined that all end use product chemistry data
for technical. Ma must be resubnitted and updated.
The Agency has determined that all products containing the DEA salt
must be tested for nitrosamines.
The Agency has determined that reentry data or restrictions are not
required at this time.

The Agency will not require labeling to protect endangered species at
this time for products containing maleic hydrazide.
The Agency has determined that Tier I nontarget area phytotoxicity
testing will be required for MH.
The Agency will not require additional residue data on cranberries.
The Agency will require additional residue data on potatoes, onions,
tobacco, nonbearing citrus, and nonbearing apples.
The Agency is requiring additional animal and plant metabolism data
and storage stability data on all residue data previously submitted
and any new residue data requested.
The Agency has determined that certain data essential to the Agency’s
assessment of this pesticide and its uses and/or that may trigger the
need for further data will receive iirmediate review when submitted.
These data include animal and plant metabolism data, data necessary
to determine the MN potential to contaminate ground water, and all
requested toxicology data.
5. Surrirbar.j of Major Data Gaps
R uir e ments Due Dates
Product Chemistry 6 to 15 months
Residue Data 6 to 24 months
Toxicology Data 9 to 50 months
Environmental Fate 9 to 39 months
Plant Protection 9 months
6. Contact Person at EPA :
Robert 7. Taylor (PM 25)
Fungicid6—} erbi iUe 3rat cL
Registration Division (TS—767C)
Environmental Protection Agency
401 M Street SW.
Washington, D.C. 20460
(703) 557—1800
DISCt IMER: The information presented in this Pesticide Fact Sheet
is for informational purposes only and may not be used to fulfill
data requirements for pesticide registration and reregistration.