CULT:2,4-D - longish
From: Chad Schroter <Chad.Schroter@quantum.com>
Here is some Information on 2,4-D: Complete text
Trade and Other Names:2,4-D is used in many commercial products. Commercial
names for products containing 2,4-D include Aqua-Kleen, Barrage, Lawn-Keep,
Malerbane, Planotox, Plantgard, Savage, Salvo, Weedone, and Weedtrine-II.
Regulatory Status: 2,4-D is a General Use Pesticide (GUP) in the U.S. The
diethylamine salt is toxicity class III- slightly toxic orally, but toxicity
class I- highly toxic by eye
exposure. It bears the Signal Word DANGER - POISON because 2,4-D has
produced serious eye and skin irritation among agricultural workers.
Introduction: There are many forms or derivatives of 2,4-D including esters,
amines, and salts. Unless otherwise specified, this document will refer to
the acid form of 2,4-D.
2,4-D, a chlorinated phenoxy compound, functions as a systemic herbicide and
is used to control many types of broadleaf weeds. It is used in cultivated
agriculture, in pasture and
rangeland applications, forest management, home, garden, and to control
aquatic vegetation. It may be found in emulsion form, in aqueous solutions
(salts), and as a dry compound.
The product Agent Orange, used extensively throughout Vietnam, was about 50%
2,4-D. However, the controversies associated with the use of Agent Orange
were associated with a contaminant (dioxin) in the 2,4,5-T component of the
Acute toxicity: The acid form is of slight to moderate toxicity. The
oral LD50 of 2,4-D ranges from 375 to 666 mg/kg in the rat, 370 mg/kg in
mice, and from less than 320 to
1000 mg/kg in guinea pigs. The dermal LD50 values are 1500 mg/kg in
rats and 1400 mg/kg in rabbits, respectively [1,5,7]. In humans, prolonged
breathing of 2,4-D causes
coughing, burning, dizziness, and temporary loss of muscle coordination
. Other symptoms of poisoning can be fatigue and weakness with possible
nausea. On rare occasions
following high levels of exposure, there can be inflammation of the
nerve endings with muscular effects .
Chronic toxicity: Rats given high amounts, 50 mg/kg/day, of 2,4-D in
the diet for 2 years showed no adverse effects. Dogs fed lower amounts in
their food for 2 years died,
probably because dogs do not excrete organic acids efficiently. A human
given a total of 16.3 g in 32 days therapeutically, lapsed into a stupor and
showed signs of incoordination, weak reflexes, and loss of bladder control
Reproductive effects: High levels of 2,4-D (about 50 mg/kg/day)
administered orally to pregnant rats did not cause any adverse effects on
birth weights or litter size. Higher
doses (188 mg/kg/day) resulted in fetuses with abdominal cavity
bleeding and increased mortality [1,5,7]. DNA synthesis in the testes was
significantly inhibited when mice were
fed large amounts (200 mg/kg/day) of 2,4-D . The evidence suggests
that if 2,4-D causes reproductive effects in animals, this only occurs at
very high doses. Thus reproductive
problems associated with 2,4-D are unlikely in humans under normal
Teratogenic effects: 2,4-D may cause birth defects at high doses. Rats
fed 150 mg/kg/day on days 6 to 15 of pregnancy had offspring with increased
such as delayed bone development and wavy ribs . This suggests that
2,4-D exposure is unlikely to be teratogenic in humans at expected exposure
Mutagenic effects: 2,4-D has been very extensively tested and was found
to be nonmutagenic in most systems. 2,4-D did not damage DNA in human lung
cells. However, in
one study, significant effects occurred in chromosomes in cultured
human cells at low exposure levels . The data suggest that 2,4-D is not
mutagenic or has low mutagenic
Carcinogenic effects: 2,4-D fed to rats for 2 years caused an increase
in malignant tumors . Female mice given a single injection of 2,4-D
developed cancer (reticulum-cell
sarcomas) . Another study in rodents shows a low incidence of brain
tumors at moderate exposure levels (45 mg/kg/day) over a lifetime [1,7].
However, a number of questions
have been raised about the validity of this evidence and thus about the
carcinogenic potential of 2,4-D. In humans, a variety of studies give
conflicting results. Several studies
suggest an association of 2,4-D exposure with cancer. An increased
occurrence of non-Hodgkin's lymphoma was found among a Kansas and Nebraska
associated with the spraying of 2,4-D [25,27]. Other studies done in
New Zealand, Washington, New York, Australia, and on Vietnam veterans from
the U.S. were all negative.
There remains considerable controversy about the methods used in the
various studies and their results . Thus, the carcinogenic status of
2,4-D is not clear.
Organ toxicity: Most symptoms of 2,4-D exposure disappear within a few
days, but there is a report of liver dysfunction from long-term exposure
Fate in humans and animals: The absorption of 2,4-D is almost complete
in mammals after ingestion and nearly all of the dose is excreted in the
urine. The compound is readily
absorbed through the skin and lungs. Men given 5 mg/kg excreted about
82% of the dose as unchanged 2,4-D. The half-life is between 10 and 20 hours
in living organisms. There is no evidence that 2,4-D accumulates to
significant level in mammals or in other organisms . Between 6 and 8
hours after doses of 1 mg/kg, peak concentrations of 2,4-D
were found in the blood, liver, kidney, lungs, and spleen of rats.
There were lower levels in muscle and brain. After 24 hours, there were no
detectable tissue residues. Only traces
of the compound have been found in the milk of lactating animals for 6
days following exposure. 2,4-D passes through the placenta in pigs and rats.
In rats, about 20% was
detected in the uterus, placenta, fetus, and amniotic fluid .
Chickens given moderate amounts of 2,4-D in drinking water from birth to
maturity had very low levels of the
compound in eggs .
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