Document bKj9EK183Ny69bmEoLVnQpo
STATEMENT FROM: MONSANTO COMPANY ST. LOUIS, MO.
Late in February, 1969, a West Coast newspaper
carried a major feature about "a menacing new pollutant"
found in the San Francisco Bay area. The article was based
on marine life research carried out by Dr. Robert Risebrough
of the University of California. The article stated that
residues of pesticides (DDT and DDE) and polychlorinated
biphenyl (PCB) were threatening the welfare of certain birds
and posed a long-term threat to humans.
Monsanto manufactures polychlorinated biphenyl and
markets it under our Aroclor trade name. (There are other
manufacturers in Europe and Japan.) We, therefore, would
like to present some additional facts.
The work done by Dr. Risebrough dates back to
earlier research by other scientists who, while analyzing
pesticide residues in wildlife, soil and water, encountered
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unknown or "interfering" substances in the parts-per-million
range.
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Several years ago, two Swedish scientists at
Stockholm University's Institution of Analytical Chemistry,
Professor Gunnar Widmark and Soren Jensen, reported they
had identified these other substances. They said some of
the materials were polychlorinated biphenyl or PCB. Since
PCBs are not "broadcast" or spread around the land as are
pesticides, the scientists theorized that the source must be "
the industrial wastes of PCB users.
In addition to the work of Dr.'Risebrough and the
Swedish scientists, there have been other studies which
indicate the presence of PCBs in the environment. Monsanto
is concerned over the situation and is cooperating fully with
these studies. (See attached statement on Monsanto's current
state of residue analysis.)
The common uses of commercial PCB would not normally
lead to its release into the natural environment.
A principal market for PCB is in electrical applications
where they are used as insulating fluids for transformers and
capacitors. In this use, the chemical is completely sealed
in metal containers. Another market is for heat-transfer
applications where the PCB fluid functions in a closed system.
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PCBs are also used in several applications where the chemical is incorporated into a polymer as an integral part of the solid material. Such polymers are used in highly specialized applications as an adhesive, elastomer or surface coating.
Polychlorinated biphenyls are not sprayed or dusted on crops, woodlands or any other areas, as are pesticides. To our knowledge, they are not used in tires, house paints, household products, or major vinyl plastics, as has been charged. Therefore, conclusions as to the source of PCB reportedly found in the environment are difficult to make.
It has also been implied that polychlorinated biphenyls are "highly toxic" chemicals. This is not true. Just like other industrial chemicals and home products now in widespread use, PCBs are not hazardous when properly handled and used. During more than 40 years of U.S. production and use, cases of any
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toxic effect have been extremely rare -- and then only where the simple precautions recommended for use were hot followed.
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Monsanto has research programs under way to identify
the compounds, reported to be PCB, and locate their source. The
programs involve precise analysis of environmental samples of
water and soil. Also under way are studies to determine the
biological effects of deliberate dosage of PCBs on fish
and mammalian animals. Special emphasis is being paid to
endocrinological effects, mineral metabolism and reproduction
physiology.
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Some preliminary biodegradibility studies are under
way. Further studies to clearly demonstrate this phenomenon
are contemplated.
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Very early results of chronic toxicity studies confirm
that PCBs are not highly toxic. In 90-day studies on rats and
other normal laboratory species, there have been no adverse
effects when feedings of up to 100 parts-per-million were
administered.
Monsanto has always cooperated on a regular basis
with federal, state and university laboratories in their analysis
of chlorinated hydrocarbon residues. We will continue to do so.
Additionally, Monsanto will continue to exercise the highest
degree of control in its manufacturing, shipping and storing
of PCB -- as we do with all products. In the functional fluids
market, we have carried out a program for several years for the
reclamation of used PCBs to reuse these valuable materials.
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The source of the marine life residue identified as PCB is not yet known. It will take extensive research on a worldwide basis, to confirm or deny these initial scientific conclusions.
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PRESENT STATE OF POLYCHLORINATED BIPHENYL RESIDUE ANALYSIS
When extracts of environmental samples are examined
by electron capture gas chromatography, peaks corresponding
to widely disseminated chlorinated hydrocarbon (CHC)
pesticides and their metabolites and break down products
appear on the resultant chromatograms. In addition to these
peaks pesticide researchers have been aware for some time
that it was not unusual for an additional series of as many
as 10 to 20 peaks, corresponding to unidentified compounds,
to also appear on these chromatograms. Little is known of
the structure and origin of these compounds except that they
possessed electron capture gas chromatographic properties
similar to the CHC pesticides.
In about 1965, it was established that these
unidentified materials were organochlorine in nature, with
substantial chlorine content and consequently possessed
electron-capturing properties. Early in 1967, Swedish researchers at the University of
Stockholm (Jensen and Widmark) announced that they had
succeeded in identifying a series of such peaks as higher
chlorinated biphenyls using gas chromatographic/mass
spectrometric techniques. -more-
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--2 POLYCHLORINATED BIPHENYL RESIDUE ANALYSIS xxx techniques.
Based on Jensen and Widmark's unpublished mass spectrometric identification of some similar unknown contaminants in a relatively small number of Swedish fish and bird extracts, some researchers in the United States and other parts of Europe precipitously began to report unidentified organochlorine materials as polychlorinated biphenyls with no supporting data other than relative retention times from electron capture gas chromatograms.
This would seem to indicate , in view of the well-known limitations of electron capture gas chromatographic analysis, that it would be scientifically prudent to continue the established practice of reporting these materials as organochlorine contaminants when positive structural -confirmation techniques such as mass spectrometry are not employed. This is especially true when one considers that any number of technical grade chlorinated materials (toxaphene, chlordane, chlorinated naphthalenes, etc.) produce electron capture gas chromatographic peaks with retention times corresponding to those produced by commercial PCB.
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--3 POLYCHLORINATED BIPHENYL RESIDUE ANALYSIS xxx PCB.
Furthermore, the response of an electron capture
detector to closely related isomers can vary considerably.
Theoretically, there are 210 possible PCB isomers. So it
should be clearly stated, at this point in time, that PCB
residue analysis using only electron capture gas chromatography
is neither positive nor quantitative.
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In attempts to make the less sophisticated and
more readily accessible technique of electron capture gas
chromatography more selective (positive), several laboratories
have introduced prior chemical treatments (saponification,
extraction with sulfuric acid, nitration, etc.). Unfortunately
the use of the nitration procedure has caused considerable
confusion. This treatment is essentially that used to remove
DDT and its metabolites from toxaphene.
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In our laboratories we have found that this treatment
results in the disappearance of the early eluding possible PCB
isomer peaks in the production of peaks with longer retention
times (nitrochlorobiphenyls). Additionally, the treatment is
not easily reproduced nor specific for PCB.
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--4 POLYCHLORINATED BIPHENYL RESIDUE ANALYSIS xxx PCB. Is is apparent that our primary concern at this
time should be to develop more specific and systematic analytical procedures which will allow us to accumulate enough unequivocal data to permit the ecologist to conscientiously assess the situation.
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