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in 1996. EXTOXNET no longer updates this information, but it may be useful
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EXTOXNET primary files maintained and archived at Oregon State
Revised June 1996
Trade and Other Names:
Trade names for products containing metalaxyl include Apron,
Delta-Coat AD, Ridomil, and Subdue.
Metalaxyl is a slightly toxic compound in EPA toxicity class III.
It is a General Use Pesticide (GUP). Labels for products
containing metalaxyl must bear the Signal Word CAUTION.
Metalaxyl is a systemic, benzenoid fungicide used in mixtures as
a foliar spray for tropical and subtropical crops, as a soil
treatment for control of soil-borne pathogens, and as a seed
treatment to control downy mildews. Metalaxyl may be used on many
different food crops, including tobacco, ornamentals, conifer,
and turf applications.
is a systemic, benzenoid fungicide used in mixtures as a foliar
spray for tropical and subtropical crops, as a soil treatment for
control of soil borne pathogens, and as a seed treatment to
control downy mildews.
- Acute toxicity: The oral LD50 in rats is
669 mg/kg and the dermal LD50 is greater than 3100 mg/kg
, indicating slight toxicity by ingestion and dermal
application. Rabbits exhibited slight eye and skin
irritation, but guinea pigs displayed no sensitization
after metalaxyl exposure . No information was
available regarding the inhalation toxicity of metalaxyl.
- Chronic toxicity: A 90-day study of rats
exposed to 0.1 to 2.5 mg/kg/day in diet, showed some
cellular enlargement in the liver at the highest dose
. In a similar study with dogs fed diets of
approximately 0.04 to 0.8 mg/kg/day for 6 months, the
dogs were adversely affected by the highest dose.
Manifestations included increased blood alkaline
phosphatase and increased liver-to-brain weight ratio
- Reproductive effects: A three-generation
rat study where animals were fed up to 2.5 mg/kg/day
showed no compound related maternal toxicity or
reproductive effects . These data suggest that
metalaxyl is unlikely to cause reproductive effects.
- Teratogenic effects: Rats given a dosage
of 120 mg/kg/day by stomach tube on days 6 to 15 of
gestation exhibited no embryotoxicity or teratogenicity,
nor did rabbits given a dosage of 20 mg/kg/day by the
same route on days 6 to 18 . These data suggest that
metalaxyl is not teratogenic.
- Mutagenic effects: Studies including a
dominant lethal assay in male mice indicate that
metalaxyl has no mutagenic potential .
- Carcinogenic effects: Available studies
of the carcinogenicity of metalaxyl are inconclusive
- Organ toxicity: The liver is the primary
target organ for metalaxyl in animal systems.
- Fate in humans and animals: Studies with
rats and goats showed rapid metabolism and excretion via
the urine and feces . Metalaxyl is metabolized to a
variety of products before excretion . Forty-day
feeding studies with dairy cattle at 15 ppm/day, showed
less than 0.01 ppm was stored in the muscle and fat. The
liver contained 0.13 to 0.20 ppm and the kidney 0.26 to
0.83 ppm . Chickens fed for 28 days at 5 ppm in the
diet had less than 0.05 ppm in the eggs, skin, fat,
breast, and thigh, and less than 0.1 ppm in the liver
- Effects on birds: Metalaxyl is reported
to be practically nontoxic to birds .
- Effects on aquatic organisms: Metalaxyl
is practically nontoxic to freshwater fish. The 96-hour
LC50 values in rainbow trout, carp, and bluegill are all
above 100 mg/L . Freshwater aquatic invertebrates are
slightly more susceptible to metalaxyl. Daphnia magna, a
small freshwater crustacean, has an LC50 of 12.5 to 28
mg/L, depending on the product formulation . This
indicates that metalaxyl is slightly toxic to this
organism. There is little tendency for metalaxyl to
accumulate in the edible portion of fish. Metalaxyl did
not accumulate beyond seven times the background
concentration and it was quickly eliminated after exposed
fish were placed in fresh (metalaxyl-free) water .
- Effects on other organisms: Metalaxyl is
nontoxic to bees .
- Breakdown in soil and groundwater: Under
field conditions, metalaxyl has a half-life of 7 to 170
days in the soil environment . A representative
half-life in moist soils is about 70 days . Increased
sunlight may increase the rate of breakdown in the soil.
It is poorly sorbed by soils and highly soluble in water
; these properties in combination with its long
persistence pose a threat of contamination to
groundwater. It readily leaches in sandy soil, although
increased organic matter may decrease the rate of
leaching . In a large-scale, national survey,
metalaxyl was detected in the groundwater of several
states at concentrations of 0.27 ug/L to 2.3 mg/L .
- Breakdown in water: At pH levels of 5 to
9 and temperatures of 20 to 30 C, the half-life in water
was greater than 4 weeks . However, exposure to
sunlight reduced the half-life to 1 week .
- Breakdown in vegetation: Plants absorb
foliar applications through the leaves and stems, and can
translocate the compound throughout the plant. Metalaxyl
is not absorbed directly from the soil by plants. The
parent compound is the major residue in potato tubers and
grapes, but in potato leaves and on lettuce, metabolites
are the major product .
- Appearance: Metalaxyl is a colorless,
odorless crystal .
- Chemical Name:
- CAS Number: 57837-19-1
- Molecular Weight: 279.34
- Water Solubility: 7100 mg/L @ 20 C 
- Solubility in Other Solvents: v.s. in
methanol, benzene, and hexane 
- Melting Point: 71.8-72.3 C 
- Vapor Pressure: 0.293 mPa @ 20 C 
- Partition Coefficient: Not Available
- Adsorption Coefficient: 50 (estimated)
- ADI: 0.03 mg/kg/day 
- MCL: Not Available
- RfD: 0.06 mg/kg/day 
- PEL: Not Available
- HA: Not Available
- TLV: Not Available
P.O. Box 18300
Greensboro, NC 27419-8300
- Phone: 800-334-9481
- Emergency: 800-888-8372
References for the information in this PIP can be found in
Reference List Number 10
information in this profile does not in any way replace or
supersede the information on the pesticide product labeling or
other regulatory requirements. Please refer to the pesticide