|Chemical Abstract Number (CAS #)||
|Synonyms||Mexacarbate||Mexacarbole||Zectran||Carbamic acid, methyl-, 4-dimethylamino-3,5-xylyl ester||Phenol, 4-(di-methylamino)-3,5-dimethyl, methylcarbamate (ester)
||EPA Method 632|
Link to the National Library of Medicine's Hazardous Substances
Database for more details
on this compound.
|Use|| FORMERLY USED AS A MOLLUSCICIDE
Control out-of-doors & greenhouse pests of ornamental plants, turf & ground cover; control
forestry pests such as western spruce budworm & jack pine budworm; pests controlled included
mites, snails, slugs & a wide range of insect pests of the orders, Lepidoptera, Coleoptera,
Hemiptera, Homoptera & Orthoptera.
INSECTICIDE FOR NON-AGRICULTURAL USES-EG, LAWNS & TURF, FLOWERS,
GARDENS, VINES, & FOREST LANDS, WOODY SHRUBS & TREES.
|Apparent Color|| WHITE CRYSTALLINE SOLID
|Melting Point|| 85 DEG C
|Molecular Weight|| 222.29
|Environmental Impact|| If released to soil, mexacarbate should be mobile in soil. Rapid degradation of
(14)C-labeled mexacarbate has been observed in sandy loam and clay loam forest soil litters. The
half-lives for (14)CO2 evolution in the sand loam and clay loam litters ranged were 7.31 and 8.88
days, respectively, under aerobic conditions and 7.72 and 9.32, respectively, under submerged
conditions. Mexacarbate may biodegrade in soil and may photolyze at the soil surface.
Volatilization of mexacarbate from near-surface soils is not expected to be an important removal
process. If released to water, mexacarbate is expected to hydrolyze to a variety of products. The
half-lives for hydrolysis of mexacarbate in bufferred solutions at 20 deg C and pH 5.94, 7.0, and
8.42 were 46.5, 25.7, and 4.6 days, respectively. Photolysis and biodegradation may also occur.
Bioconcentration, adsorption to sediments, and volatilization are not expected to be significant. In
the atmosphere, vapor phase mexacarbate will react with photochemically generated hydroxyl
radicals with an estimated half-life of 7.9 hours. Human exposure to mexacarbate most likely
results from use of the pesticide on lawns, turfs, and flowers.
|Environmental Fate|| TERRESTRIAL FATE: Mexacarbate has the potential to leach to groundwater if it does
not degrade first. Rapid degradation of (14)C labeled mexacarbate has been observed in sandy
loam and clay loam forest soil litters. The half-lives for (14)CO2 evolution in the sand loam and
clay loam litters ranged were 7.31 and 8.88 days respectively, under aerobic conditions and 7.72
and 9.32, respectivelyl, under submerged conditions . In wet soils, especially alkaline ones,
mexacarbate is expected to hydrolyze to a variety of products. Biodegradation may occur and
photolysis may be important at the soil surface. Volatilization of mexacarbate from near surface
soils is not expected to be an important removal process.
AQUATIC FATE: A river die away test was conducted with mexacarbate in raw water from the
Little Miami River in Ohio. The river receives domestic and industrial wastes and farm runoff.
After one week, 85% of the initial amount of mexacarbate had degraded. All the initial
mexacarbate had degraded after 2 weeks . Mexacarbate hydrolyzes, especially under alkaline
conditions, to yield a variety of products. The half-lives for hydrolysis of mexacarbate in buffered
solutions at 20 deg C adn pH 5.94, 7.0, and 8.42 were 46.5, 25.7, and 4.6 days respectively .
Volatilization is not expected to be significant but biodegradation may occur. Photolysis may
occur near the water surface. Bioconcentration will not be significant and mexacarbate is not
expected to strongly adsorb to sediments.
ATMOSPHERIC FATE: The half-life of the reaction of vapor phase mexacarbate with
photochemically generated hydroxyl radicals in the atmosphere was estimated to be 7.90 hours .
AQUATIC FATE: Hydrolysis rates of zectran are analyzed in aqueous media. Rates were
measured in phosphate-buffered distilled water, and in natural waters where temperatures of 10
deg C, 20 deg C, and 28 deg C and pH values of 5.94, 7.00 and 8.42 were registered, whereas in
natural waters initial concentrations were 30 mg/l. The persistence of mexacarbate in natural
waters depends on the pH value and temperature.
The distribution and persistence of aerially applied mexacarbate were studied in a New Brunswick
aquatic forest environment after spraying twice at a dosage of 70 g/ha using a fixed-wing aircraft.
Average droplet density (drops/sq cm) and ground deposition (g/ha) between the 2 applications
differed considerably. The values for the first and second applications were respectively 1.7 and
0.73 and 5.2 and 2.0. But the average NMD (Number Median Diameter) 20 mum and VMD
(Volume Median Diameter) 36 mum values for both applications were nearly the same. The
maximum 1 hr post spray concentrations of mexacarbate in the stream and pond waters were
respectively 0.73 ppb and 18.74 ppb. Concentrations fell rapidly to below detection limits within
12 hr in stream and within 3 days in pond water. Cattails (Typha latifolia), manna grass (Glyceria
borealis) and bog moss (Sphagnum sp) collected from the pond contained peak 1 hr post-spray
concentrations of 720 ppb, 482 ppb, and 81 ppb, respectively. The concentration levels decreased
rapidly and the average half-lives of the chemical in them were about 3.9, 8.5, and 2.0 hr. Bog
moss, stream moss (Fontinalis sp), watercress (Nasturtium officinalis), buttercup (Ranunculus
aquatilis) and green algae (Draparnaldia sp) sampled from the stream sites did not contain
measurable levels of mexacarbate. Also, caged and wild tadpoles (Rana clamitans melanota) from
the pond, brook trout (Salvenilus fontinalis) (caged and wild), Atlantic salmon (Salmo salar)
(wild) and mayfly nymphs (Ephemerella sp) collected from the stream did not contain any of the
material. Mexacarbate was not detected in stream and pond sediments. The demethylated
products, 4-methylamino and 4-amino-3,5-xylyl methylcarbamate and the phenol,
4-dimethylamino-3,5-xylenol as transformation products were frequently detected in water and in
the aquatic plants which had accumulated the insecticide. The presence of these compounds
showed that demethylation and hydrolytic routes are the major metabolic pathways for the
dissipation of mexacarbate from these substrates.