Poison Poles - A Report About Their Toxic Trail and Safer Alternatives
A: Chemicals At A Glance
including contaminants, inerts, and by-products
(penta) is a chlorinated aromatic hydrocarbon, closely related to
other chlorophenols, hexachlorobenzene, polychlorinated dibenzo-p-dioxins
and furans, all of which are found in commercial grade penta, along
with secret "inert" ingredients. Pure pentachlorophenol can be produced
in a laboratory, but the commercial products contain these contaminants.
We address here penta as it exists in the environment--with contaminants.
Chlorophen, Pentacon, Penwar are some of penta's trade names.
In 1995: 39,734,000
gallons (8,588,000 gallons concentrate and 31,146,000 gallons solvent);
30,617,000 cubic feet of treated poles; 32,764,000 cubic feet of treated
is readily absorbed by lung, skin and stomach. Workers handling penta
or penta-treated wood receive the most significant exposure first
through skin contact and second through the air.
detoxification, and metabolism
While much of it
is excreted in urine, it accumulates in tissues, particularly muscle,
bone marrow, and fat.
is very toxic, and is labeled with the signal word DANGER. There are
about 50 known cases of poisoning from penta products, 30 of which
have resulted in death. Immersion of a man's hand in a 0.4 percent
penta solution for 10 minutes caused pain and inflammation.
Symptoms of mild penta poisoning include stuffy nose, scratchy throat,
and tears in the eyes. Skin contact can produce contact dermatitis
and chloracne. A person experiencing systemic poisoning by penta would
show symptoms of profuse sweating and intense thirst, rapid breathing
and heart rate, fever, abdominal pain, nausea, weakness, lack or coordination,
dizziness, anorexia, and coma.
The exact dose
required to produce illness in humans is not known. It is a short
jump from the "no effect" level to the "lethal" dose of pentachlorophenol.
For example, at a dose of 80 milligrams per kilogram, no experimental
animals died. At a dose of 100 milligrams 83% died and at 110 milligrams
The first report
of chronic poisoning from pentachlorophenol was reported in California
Health in June, 1970 in the case of a woman who had moved into a newly
constructed home which had been treated with penta. She experienced
rapid weight loss, weakening and tightening in her chest, and symptoms
which were suspected to be asthma and bronchitis, which were relieved
after she moved from the house. Exposure to penta has also been associated
with aplastic anemia, leukemia, and other blood disorders.
Penta targets the
liver, kidneys and central nervous system, with toxic effects occurring
at low doses. Autopsies of victims of fatal exposures revealed changes
in the brain, heart, kidneys, lungs, and liver. Liver damage has been
documented in people living in homes treated with pentachlorophenol.
Chronic exposure to pure pentachlorophenol causes acne and other skin
is associated with peripheral neuropathy and other nerve damage.
toxicity and teratogenicity
indicate that chronic exposure to pure pentachlorophenol affects reproduction
and induces birth defects. EPA has concluded that penta and possibly
its hexachlorodibenzo-p-dioxin (HxCDD) contaminants cause birth defects
and fetotoxic effects in test animals. Reported adverse effects in
fetuses from penta exposure include distorted sex ratios, increased
incidences of resorbed embryos, skeletal anomalies, subcutaneous edema
(excessive fluid), reduced survival, and reduced growth. Several studies
with rats and mice have shown birth defects due to the penta contaminant
HCB, including changes in rib development and cleft palate formation
in rats. Kidney malformations and decreased body weight were also
find that technical grade penta causes immune suppression in animals,
which has been linked to dioxins contained in penta.
EPA has established
a RfD for penta of 3X10-2 mg/kg/day, based on a NOAEL of 3 mg/kg/day
and LOAEL of 10 mg/kg/day and an uncertainty factor of 100 to account
for intra- and interspecies variability. These data are from the sole
study EPA located for effects of chronic exposure. Liver and kidney
pathology were the reported effects.
The studies indicating
that human exposure to pentachlorophenol products causes cancer go
back to 1978. They include studies of occupational exposure in the
lumber and sawmill industry linking penta with acute leukemias, Hodgkin's
and non-Hodgkin's lymphomas and multiple myelomas. EPA classifies
pentachlorophenol as a probable human carcinogen (B2). The agency
finds the sole human study examined by the agency to be inadequate.
EPA bases the B2 classification on animal studies that find that two
different preparations of pentachlorophenol cause statistically significant
increases in incidences of biologically significant tumor types in
both male and female mice: hepatocellular adenomas and carcinomas,
adrenal medulla pheochromocytomas and malignant pheochromocytomas,
hemangiosarcomas, and hemangiomas. Other animal tests and reviews
by other agencies support the conclusion of carcinogenicity. EPA estimates
a cancer potency (slope factor) of 1.2X10-1 (mg/kg/day)-1 based on
the incidence of hemangiosarcomas and pheochromocytomas in female
mice. The hexachlorobenzene and hexachlorodibenzo-p-dioxin contaminants
in penta are also carcinogens. Agriculture Canada has concluded that
the combined evidence from epidemiological studies on human with mixed
exposures to chlorophenols, dioxins, or pesticides contaminated with
these chemicals suggest that occupational exposure to chlorophenols
or phenoxy herbicides increases the risk of three kinds of cancer:
soft tissue sarcoma, Hodgkin's lymphoma, and non-Hodgkin's lymphoma.
National Toxicology Program studies showed the metabolite pentachloroanisole
to be carcinogenic in rats and mice.
Some tests have
indicated that pentachlorophenol and tetrachlorophenol can damage
genes. A penta metabolite, tetrachlorohydroquinone, has also been
shown to damage genes.
Exposure to penta
may result in adverse reproductive effects that are associated with
changes in the endocrine gland function and immunological dysfunction.
A number of women with histories of spontaneous abortion, unexplained
infertility and menstrual disorders had elevated levels of pentachlorophenol
and/or lindane in their blood.
and the contaminants found in penta products have immense ecological
of constant exposure as in aquatic organisms living in contaminated
water, pentachlorophenol bioaccumulates as much as 10,000 times the
background level.28 It may be taken up by plants from soil. In mammals,
it may accumulate in the liver, kidneys, plasma protein, brain, spleen,
and fat, until it is excreted unchanged in the urine. Pentachlorophenol
is not expected to concentrate as it moves up the food chain, but
the dioxin and dibenzofuran contaminants in penta products do bioconcentrate
and bioaccumulate in the environment. Most of these contaminants found
in an ecological system will be in animal fat. Dioxin contaminants
may concentrate to 100,000 times the environmental level.
and environmental fate
Most wood treated
with PCP solutions will "bleed", or move from the interior to the
surface of the wood. Penta may evaporate from the surface of the wood
into the air while some of the contaminants may not. About 48% of
Pentachlorophenol will eventually end up in terrestrial soil; about
45% will end up in aquatic sediments; about 5.3% will end up in water;
and about 1.4% will end up in air. After reaching soil, PCP is broken
down by sunlight and bacteria, and can leave the upper soil layer
by evaporation and leaching into groundwater. PCP degrades most rapidly
anaerobic soils. Pentachlorophenol is moderately soluble in water.
Concentrations of 1 to 1,000 milligrams will dissolve in a liter of
water. Pentachlorophenol concentrations in natural waters may be higher,
however, due to the presence of suspended solids. These solids provide
a source of penta that continues to leach into water. Pentachlorophenol
is moderately persistent in water. It may be degraded by sunlight
or microorganisms or bind to sediments and suspended particles and
does not evaporate to a significant degree. In water, biodegradation
occurs with a half-life ranging from hours to days, with most biodegradation
occurring at the surface. Penta has measured in the air of two towns
were up to 0.93 and 7.8 ppt. PCP has been detected at very low levels
in rivers and streams (0.01-16 ppb), surface water systems (1.3-12
ppb), and seawater (0.02-11 ppt). The compound has also been found
in ground water in California, Oregon and Minnesota at concentrations
ranging from 0.06 ppt to 0.64 ppb and in well water in Japan and Canada.
It was found in a concentration that exceeded EPA's maximum contaminant
level (MCL) in a public water supply well in the state of Washington.
The HCB contaminant of penta was found to completely degrade to pentchlorophenol
in hydrosoil samples. Evaporation was rapid on soil surfaces, but
less so when it is mixed into the soil. Hexachlorobenzene has been
found in well water in several states at concentrations ranging from
1 ppb to 5.6 ppb. It bioaccumulates to 570 times the ambient level
in algae. The dioxin contaminants are extremely stable and resistant
effects include the death of animals, birds, or fish, and death
or reduced growth rate in plants. Penta may kill or defoliate plants
and reduce germination of seeds. Pentachlorophenol has high acute
toxicity to aquatic life, which increases as the pH of the water
decreases. Chronic ecological effects of penta include reduced lifespan,
reproductive problems, lower fertility, and changes in appearance
or behavior. Cattle and other farm animals have ingested pentachlorophenol
by chewing and licking outdoor wood structures, or from being housed
in wooden pens that were treated with penta, causing sickness and
death in some animals. In late 1976, about 100 Michigan dairy farms
had herd health problems due to contact with penta-treated wood.
Penta and contaminants were detected in the milk of two herds. Pentachlorophenol
has high chronic toxicity to aquatic life. Penta is chronically
highly toxic to cold and warm water fish and moderately toxic to
other freshwater and marine organisms. Concentrations detected in
rivers, streams, or surface water systems have been generally below
lethal levels. Lethal levels have been exceeded during accidental
spills. Japanese quail tolerated diets containing 200 ppm HCB, but
had an LC50 of 568 ppm with the onset of signs at 3 days, indicating
that moderate toxicity to the quail. In pullets, more than half
of the residue was excreted in egg yolks within a months time. Hexachlorobenzene
is slightly toxic to fish, which bioaccumulates rapidly in aquatic
organism. Fish are the most sensitive organisms to the dioxin contaminants
in penta--concentrations in parts per quadrillion (pg/l) to parts
per trillion (ng/l) TCDD are acutely toxic to freshwater fish. Significant
adverse effects are present at levels of 0.6 pg/l TCDD.54 The hepta-
and hexachlorodibenzo-p-dioxins found in penta are considered to
be 0.01 to 0.1 times as toxic as TCDD.55 Available data also indicate
that the dioxins are extremely toxic to both birds and mammals.
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