Summary of Toxicological Studies on Quinoclamin
Registration Section, Development Department, Agro-Kanesho Co., Ltd.
(Received November 20, 1992)

DESCRIPTION OF QUINOCLAMIN
Quinoclamin, a naphthoquinone derivative, is a chemical that acts as an inhibitorof photo-synthesis when absorbed by the stems and leaves of grasses.
The chemical was first developed by Uni-Royal Co. as an algaecide for industrial
use in the 1960s. In Japan, it is being developed by Agro-Kanesho Co. since 1968 asa herbicide with excellent activity against aquatic weeds, including annual and perennialweeds in paddy fields as well as against mosses in lawns and potted plants.
The chemical structure and physicochemical properties of Quinoclamin are given
below;
Trade name : Mogeton
Chemical name : 2-amino-3-chloro-1,4-naphthoquinone (IUPAC)
Common name : Quinoclamin (ISO)Structural formula :ONH2ClO

Molecular formula : C10H6ClNO 2
Molecular weight : 207.62
Appearance : Orange colored crystal powder
Specific gravity : 1.66
Melting point : 197-200˚C
Solubility (g/l at 20˚C) : 0.022 in distilled water, 1.48 in ethyl acetate, 25.6 inacetone, 6.6 in methanol, and 37 in nitrobenzene.
Partition coefficient (log Pow) : 1.53
Vapour pressure (at 20˚C) : 2.3 x 10-7
Stability : Stable in acid, unstable on exposure to sun light or in hot alkalis

ACUTE TOXICITY STUDIESThe results of acute toxicity studies are summarized in Table 1.

Table 1
TestSpecies
Route ofSexa) LD50
substance
administration(mg/kg)Rat

Quinoclamintechnical(>95%)

Oral

M 1360F 1600Dermal
M >5000
F >5000
Intraperitoneal M315F375
Inhalation (4 hr) M > 0.79b)
F > 0.79

Testing facility(Reporting year)
Tokyo Women's Medical College(1972)
Tokyo Dental College(1978)
Tokyo Dental College(1978)
Huntingdon Research Centre(1986)

Mouse Oral

M 1350 Tokyo Women's Medical CollegeF 1260
(1972)
Dermal
M >2000 Tokyo Dental College
F >2000(1978)
Intraperitoneal M
412 Tokyo Dental CollegeF375(1978)

Rat

Wettablepowder(25%)

Granules
(9%)

Oral

M >5000 Toxicol Laboratories
F >5000(1985)
Dermal
M >2000 Toxicol Laboratories
F >2000(1985)b)
Inhalation (4 hr) M >1.73 Huntingdon Research Centre(1986)

Mouse Oral

M >5000 Toxicol Laboratories
F >5000(1985)

RatMFMF>5000 MECT Corporation>5000(1989)>2000 MECT Corporation>2000(1989)

M
F9694 MECT Corporation
6450(1989)

OralDermalMouse Orala)b)

M:Male, F:Female.
LC 50 (mg/l) as actual concentration.

On oral injection, Quinoclamin technica (hereinafter TECH) and 25% Wettable
Powder (WP) is unlikely to prove particularly to toxic to rats and mice, however 9%
Granule (GR) caused soft feces in rats, and depression, hunching and convulsion inmice.
There were no adverse skin reactions nor toxic signs by dermal administration
with TECH, WP and GR.
By intraperitoneal administration with TECH in rats and mice, depression, labored
respiration, urine brown stains, rough coat were observed at all dosing levels, andhunching, convulsion and anischuria were also noted at high dose levels.
In inhalation toxicity studies in rats with TECH and WP, some opacity in the eyes,salivation and infiammation of the penis were observed during the observation period.

IRRITATION STUDIES
1. Primary Eye lrritation Studies in Rabbits
1) 0.06 g each of TECH and WP was instilled into the conjunctival sac of the left
eye of 9 New Zealand White adult rabbits. The eyes of 3 rabbits which constituted
the rinsed group, were washed using distilled warm water 2 min after dosing. Theeyes of the other 6 rabbits which constituted the unrinsed group, were not washed.
Irritant responses were evaluated according to "Draize method."
Mild to moderate irritant responses were observed in the cornea, iris and conjunctival
mucosa within 24 hr after dosing ; however, 168 hr later they. had disappeared. The
irritant responses in the rinsed group were milder than those in the unrinsed groupadministered TECH, however the responses were almost the same in both groups
when WP was used.
The results suggested that TECH and WP nduced moderate irritation to rabbit
eyes. Eye-wash proved effective in case of TECH.
(Toxicol Laboratories Limited, 1985)
2) A similar test was carried out using 0.1 g of GR.
Mild to moderate irritant responses were observed in the cornea, iris and conjunctival
mucosa 24 hr after dosing; however, 11 days later they were no longer observed
except for 2 rabbits. The responses in the rinsed group were milder than those observedin the unrinsed group.
The results suggested, that GR induced a mild irritation to the rabbit .eyes. Eye-washproved effective in both cases.

(MECT Corporation, 1989)

2. Primary Skin lrritation Studies in Rabbits
0.5 g each of TECH, WP and GR was applied to the intact skin of 6 New ZealandWhite adult rabbits over an area of 6 cm X 6 cm during 4 hr.
Slight erythema was observed on the treated skin of one rabbit 1 hr after dosingwith TECH and GR. No other responses were noted.
These results suggested that TECH, WP and GR induced no irritation to rabbitskin.
(Toxicol Laboratories Limited, 1985)SENSITIZATION STUDIES
1. Dermal Sensitization Studies in Guinea Pigs with TECH, WP and GR1) The studies were carried out according to the open epicutaneous method using
8 female Hartley strain guinea pigs per group.
0.1 ml of ethanol solution containing 0.3, 1, 3, 10 or 30% of TECH and WP wasapplied for 21 consecutive days on the right clipped flank of each animal. Twenty
four hours and 14 days after the end of the induction treatment, all animals werechallenged by applying 0.025 ml of ethanol solution containing 1, 3, 10 and 30% of
the test substances on the left clipped flank.
In case of TECH, a slight erythema was observed in one animal when challenged
with a 30% Solution in the 10% induction group 24 hr after both challenges. No otherreactions were observed after each challenge in either group. As for in WP, no skinreactions were observed after either challenge.
The results suggested that neither TECH nor WP induced sensitization to the skinof guinea pigs.
(Toxicol Laboratories Limited, 1985)
2) The study was performed according to Buehler's method using 10 Hartley strain
guinea pigs per group. For the induction of sensitization, 0.5 ml of 50% suspended
solution of GR was applied for 6 hr to the clipped left flank on day 0, 7 and 14. On
day 28, twenty test animals were challenged with 0.5 ml of 50% suspended solution
applied for 6 hr to the clipped right flank. The skin was observed 24 and 48 hr after
the end of the challenge.
No skin reactions were noted after the challenge in the test animals.

The results suggested that GR did not induce sensitization to the skin of guinea
pigs.
(Safepharm Laboratories, 1989)

SUBACUTE TOXICITY STUDIES
1. Ninety-Day Toxicity Studies in Rats
1) Quinoclamin was administered via the diet to groups of 10 male and 10 female
SD strain rats at the dose levels of 0, 50, 200 and 1000 ppm for 90 days.
Increase of kidney weight and hemosiderosis in the spleen were observed in males
and females at the 200 and 1000 ppm dose levels. At the 1000 ppm dose level,
inhibition of body weight gain and increased liver and spleen. weight were alsoobserved.
The NOEL (maximum non-effect level) in this study was considered to be 50 ppm(3 mg/kg/day in males and females).
(Tokyo Women's Medical College, 1972)2) Quinoclamin was administered via the diet to groups of 10 male and 10 female
SD strain rats at the dose levels of 0, 60, 300 and 1500 ppm for 90 days.
Anemia, inhibition of body weight gain, decrease of hemoglobin, hematocrit anderythrocyte count, increase of total protein and AIP activity, and increased liver
weight were observed at the 300 and 1500 ppm dose levels. In addition to theseadverse effects, increase of the leukocyte count, GOT and weight of almost all organs
except lungs, adrenals and uterus were observed at the 1500 ppm dose level.
The NOEL in this study was considered to be 60 ppm (4 mg/kg/day in males and5 mg/kg/ day in females).
(Juntendo Medical College, 1972)

2. Ninety-Day Toxicity Studies in Mice1) Quinoclamin was administered via the diet to groups of 10 male and 10 female
ICR strain mice at the dose levels of 0, 50, 200 and 1000 ppm for 90 days.
Inhibition of body weight gain, changes in submaxillary glands and adrenals weight,
as well as hemosiderosis in the spleen were observed at the 200 and 1000 ppm doselevels. In addition to these adverse effects, changes in liver and spleen weight wereobserved at the 1000 ppm dose level.
The NOEL in this study was considered to be 50 ppm (7 mg/kg/day in males andfemales).
(Tokyo Women's Medical College, 1972)

2) Quinoclamin was administered via the diet to groups of 10 male and 10 female
ICR strain mice at the dose levels of 0, 50, 200 and 1000 ppm for 90 days.
Anemia was observed at the 200 ppm dose level. Anemia, increase of the leukocyte
count, neutrophil ratio, GOT and AIP activity, increased weight of the heart, liver,kidneys and spleen, and hemosiderosis in the spleen were observed at the 1000 ppm
dose level.
The NOEL in this study was considered to be 50 ppm (8 mg/kg/day in males and
12 mg/kg/day in females).
(Juntendo Medical College, 1972)

CHRONIC TOXICITY AND CARCINOGENICITY STUDIES
1. Chroleic Toxicity/Carcinogenicity Studies in Rats
1) Quinoclamin was administered via the diet to groups of 30 male and 30 female
SD strain rats at the dose levels of 0, 1, 5, 25, 125 and 500 ppm for 104 weeks. At
week 52, 5 males and 5 females per group were sacrified and subjected to detailed
examinations.
The only dose-related finding in this study was a slight inhibition of body weightat the 500 ppm dose level.
The NOEL in this study was considered to be 125 ppm (5.7 mg/kg/day in males
and 7.3 mg/kg/day in females). There were no indications of carcinogenic potential
even at the highest dose level.
(Hazleton Laboratories America, 1976)
2) Quinoclamin was administered via the diet to groups of 100 male and 100
female SD strain rats at the dose levels of 0, 4, 52 and 676 ppm for 104 weeks. Ten
males and 10 females per group were killed for clinical and pathological investigation
at week 27, 53 and 79 and other surviving rats were killed for clinical and pathologicalexaminations at the end of dosing.
A dose-related reduction in food consumption and body weight gain were noted at
the 676 ppm dose Ievel. In the pathological examination, atrophy of pancreatic acinus,
epithelial hyperplasia of urinary tracts, and transitional cell papilloma (benign tumor)
in urinary bladder developed from epithelial hyperplasia were observed at the 676
ppm dose level. At the 52 ppm dose level, atrophy of pancreatic acinus and epithelial
hyperplasia of urinary. tracts were observed.
The NOEL in this study was considered to be 4 ppm (0.21 mg/kg/day in males
and 0.28 mg/kg/day in females). Quinoclamin did not induce , any specific malignant

tumor even at the highest dose level.

(Toxicol Laboratories, 1991)

2. Chronic Toxicity Study in Dogs
Quinoclamin was administered via the diet to groups of 4 male and 4 female
Beagle dogs at the dose levels of 0, 2, 10, 50, 250 and 1000 ppm for 104 weeks.
Inhibition of body weight gain, decrease of the erythrocyte count, hematocrit andhemoglobin concentration, increase of GOT, GPT and AIP activity suggestive ofliver disorders, increase of spleen weight and decrease of thymus, testes and prostate
weight, and pathological changes in adrenals, Iiver, gallbladder, kidneys and spleen
were observed at the 1000 ppm dose level. At the 250 ppm dose level, increase ofGOT, GTP and AIP activity, and pathological changes in the adrenals, Iungs spleen,Iiver, urinary bladder and testes were observed.
The NOEL in this study was considered to be 50 ppm (1.4 mg/kg/day in males
and 1.3 mg/kg/day in females).
(Hazleton Laboratories America, 1976)

REPRODUCTION AND TERATOGENICITY STUDIES
1. Three-Generation Reproduction Study in Rats
Quinoclamin was administered via the diet to groups of 25 male and 25 female SD
strain rats at the dose levels of 0, 1, 25 and 500 ppm throughout three successive
generations. The parents were mated twice after feeding a diet containing Quinoclaminfor at least 9 weeks. The offspring from the first mating trials (F1a , F2a) were sacrificed
at weaning and those from the second mating trials were taken by cesarean section at
the end of the gestation period, or delivered and maintained through weaning or for 5weeks (F1b) or 3 months (F2b) postweamng.
A slight inhibition of body weight gain of the P-generation and the weights ofpups (F1a and F2a) at weaning were observed at the 500 ppm dose level, but no
extra-scheduled death, abnormal clinical signs or decreased food consumption wereobserved during the dosing period in either group. In the Fl-generation, the incidenceof gestation, litter size at parturition and body weight of the offspring at weaning in
the highest dose Ievel were lower than those of the control.
The NOEL in this study was considered to be 25 ppm (1.7mg/kg/day in males and2.0 mg/kg/day in females).
(Hazleton Laboratories America, 1975)

2. Teratogenicity Study in Rats
Quinoclamin was administered orally to groups of 24 mated female SD strain rats
at the dose levels of 0 (vehicle), 5, 20 and 75 mg/kg/day during organogenesis fromday 7 to 17 of gestation . Cesarean section was performed on day 20 and all fetuses
were examined for external characteristics. Half of fetuses were subjected to skeletal
examination and the others for visceral examination by Wilson's method.
A slight inhibition of body weight gain and decreased food consumption wereobserved in dams at the 75 mg/kg/day dose level except in the non-treated period, but
none of the dams, in either groups, showed abnormal clinical signs, death or abortion.
Significant decrease of ossification suggestive of growth retardation of the fetuses inrelation to the maternal effects of Quinoclamin was observed at the 25 and 75 mg/kg/day
dose levels.
The NOEL in this study was considered to be 5 mg/kg/day, but Quinoclamin did
not induce fetal abnormalities even at the highest dose level.
(Toxicol Laboratories Limited, 1986)

3. Teratogenicity Study in Rabbits
Quinoclamin was administered orally to groups of 16 mated female New ZealandWhite rabbits at the dose levels of 0 (vehicle), 2.5, 7.5, and 22.5 mg/kg/day duringorganogenesis from day 6 to 18 of gestation. The cesarean section was performed on
day 28, and all fetuses were examined for external, visceral and skeletal abnormalities.
At the 22.5 mg/kg/day dose level, slight inhibition of body weight gain wasobserved in dams only at the early phase of the treatment period, and a slight decreaseof fetal weight accompanied by retardation of ossification.
It was concluded that the NOEL in this study was 7.5mg/kg/day, and that
Quinoclamin did not induce fetal abnormalities at the highest dose level.
(Toxicol Laboratories Limited, 1986)

MUTAGENICITY STUDIES
1. Reverse Mutatian Study
Reverse mutation was investigated using 5 strain of Salmonella typhimurium andWP2hcr strain of Escherichia coli, according to the method of Ames in the presenceand absence of S9. All strains were incubated in,agar plates containing 0.1 to 500 /µgof Quinoclamin per plate.
A number of revertant colonies did not increase when cultured with or without S9at any concentration of the test substance. The results suggested that Quinoclamin did
not induce the gene mutation.
(Institute of Environmental Toxicology, 1978)

2. DNA Repair Study
DNA repair ability was investigated using H-17 and M-45 strains of Bacillus
subtilis, according to the method of streak at the concentration of 0.1 to 20 µg of
Quinoclamin per disk.
No differences on growth inhibition were observed at any concentration of thesubstance. The results suggested that Quinoclamin did not affect the DNA repair
ability.
(Institute of Environmental Toxicology, 1978)

3. Metaphase Analysis of Chromosome from Human Lymphocytes
Human lymphocytes were obtained from 2 different donors. Cells were cultured atdose levels of 2.25 to 18 µg/ml in the presence of S-9, or at dose levels of 1.125 to 9µg/ml in the absence of S-9.
No changes were observed in the incidence of chromosomal aberrations at any
dose level of Quinoclamin in the absence of S-9. However, the number of chromosomal
aberrations increased in the cells from one donor in the presence of S-9 at dose levelsof 9 and 18 µg/ml.
The results suggested that Quinoclamin did not induce chromosomal aberrations
in human lymphocyte in the absence of S-9, however the possibility of chromosomal
aberration induction in the presence of S-9 cannot be denied.
(Toxicol Laboratories Limited, 1987)
4. Micronucleus Test in Mice
Quinoclamin was administered intraperitoneally to groups of 15 male and 15
female LACA strain mice at the dose levels of 0, 125, 250 and 500 mg/kg. Bonemarrow smears were prepared 24, 48 and 72 hr after dosing.
There were no increases in the number of micronucleated polychromaticerythroblasts or in the proportion of polychromatic erythroblasts to the orthochromaticerythroblasts 24 to 72 hr after dosing.
These results suggested that Quinoclamin did not induce the formation of
micronucleated erythroblasts.
(Toxicol Laboratories Limited, 1987)

SUMMARY
A wide variety of toxicological studies on Quinoclamin have been conducted toassess its safety. The results of these studies support the view that this herbicide issafe in practical use when employed as recommended.
Mogeton Granule herbicide which contains Quinoclamin as its active ingredient
was registered by Ministry of Agriculture, Forestry, and Fisheries in Japan in 1968
and the "Standard for withholding registration" was established with 0.03 ppm forrice and vegetables.

Contact
Development Department, Agro-Kanesho Co., Ltd.
1-1, Marunouchi, 3-chome, Chiyoda-ku, Tokyo 100, Japan

問合せ
アクロ・カネショウ株式会社開発部〒100東京都千代田区丸の内3-1-1