The Safe-Dose Myth
"There is simply no safe dose of
This is a
central tenet in the fields of molecular toxicology and cancer
– Dr. Wallace
LeStourgeon, PhD, Professor of Biological Sciences, Vanderbilt
Dr. LeStourgeon made these
statements to the Metropolitan Board of Public Health in Nashville
because of his professional concern about and opposition to using
ULV spraying of mosquitoes to try to control West Nile virus.
In a letter to the Board, Dr.
LeStourgeon, who teaches an advanced course in environmental toxins
at Vanderbilt, makes these additional sobering statements:
1. 95-98% of all cancers are
caused by mutations in somatic cells as we pass through life and
not by the inheritance of defective parental genes.
2. Today 46%, essentially half of all white males, and 39.5%
of all white females will be diagnosed with cancer in their
lifetime. [Note – the rate is only slightly less for African
3. Mutations are cumulative throughout our lifetimes . . .
This is why cancer is referred to as a disease of the elderly . .
. [this] is a misconception . . . cancer incidence and onset
correlates most directly with the "rate" and "magnitude" of DNA
damage and is not strictly correlated to age.
4. Tissues that show the maximum rate of increased cancer in
recent years are precisely the same tissues that are most in
harm's way from the mutagens in the environment.
For the non-specialists among us, Dr. LeStourgeon
explains: "mutagens are chemicals that directly or indirectly induce
DNA damage (a mutation). All mutagens are carcinogens
(chemicals that induce cancer-causing mutations). DNA is a
chemical, and the only way to modify a chemical is with another
chemical. While irradiation (X-ray, UV light, etc.) is a
powerful mutagen, at the molecular level, the DNA damage induced by
irradiation is actually chemical."
Relative to our local situation in Sacramento and
Yolo counties there is abundant evidence that the PBO/pyrethrum mix sprayed by SYMVCD
from airplanes over populated areas and Suspend SC, sprayed from backpacks
and containing the pyrethroid Deltamethrin, are mutagens (below see
the scientific references that accompanied Dr. LeStourgeon's letter
Dr. LeStourgeon's point 3 above deserves special
emphasis. In less technical language, this molecular biologist
says that there is nothing inherent about the aging process itself
that causes cancer or sets the stage for cancer in our bodies;
rather, the culprit is the exposure to mutagens and accumulation of
mutations throughout our lives. A lifetime exposure to low
doses is serious due to the fact that once a mutation occurs in a cell, the progeny of that
cell will carry the damage. So, we accumulate
mutations as we pass through life -– the concentration and DNA
damage increase, the elderly have had more time to accumulate the
mutations, and the probabilities of getting various cancers thus
increase over time. Against this backdrop do we really wish to
spray populated areas with what the Sacramento County Public Health
Officer has called "very potent chemicals" (see below)?
As to the full contents of the letter, Professor
LeStourgeon states "I
believe that if the general public knew this information, they
would choose not to expose themselves or their children to a risk
that likely exceeds that from mosquito-borne illness."
He explains his position in more detail in "Evidence that a Safe Dose of Mutagen Does
Not Exist." He also notes that, except for lung cancer
and several other easily diagnosed precancerous conditions, the
cancer rate is increasing, the exposure is cumulative, and "even the best
DNA repair system in the most healthy person can not detect and
repair all premutational lesions prior to DNA replication."
The scientific message, spelled out in more detail below, seems
clear that we must begin to decrease our exposure to environmental
toxins instead of spraying populated areas with them, particularly
since these particular ones are so completely ineffective at slowing the transmission of
WNv to humans.
Fact: It is against federal
law for pesticide applicators to claim that a pesticide is “safe.”
The pesticide used in our area, Evergreen 60-6 consists of 6%
pyrethrin, 60% piperonyl butoxide, and 34% unknown. PBO is listed by
the EPA as a Group C carcinogen. The remaining 34% are only listed
as “other ingredients.” However, “other” or “inert” ingredients are
not inert in the usual sense of the word; often they are neither
chemically, biologically, nor toxicologically inert (NCAP).
See references to other
papers about dose at the end of this page.
The Local Spray Politics.
In contrast to the clear and well-supported
scientific message from Dr. LeStourgeon, the political message from
local vector control and public health officials in this district
is, essentially, that the dose is so low that it can't hurt
you. Or, alternatively, the risk from WNv is much greater than
the risk of exposure to the spray. As examples, here are a few
excerpts from officials' testimony before the Sacramento
on August 9, 2007. A DVD of the session can be obtained
from the City Council office. Time zero on the DVD was the
beginning of the evening session, a few minutes after 6:00, and
council members asked about safety of the sprayed chemicals and
supporting studies at several points:
17:18: Dr. Glennah Trochet,
Sacramento County Public Health Officer: " . . . the risk
assessment is that the risk of the ultra-low volume pesticide that
is sprayed for 3 to 6 days a year, or every 2 years as it happens
in Sacramento, is so low compared to risk of somebody having a
life-changing event such as having paralytic disease from West
Nile virus that it is very well worth that risk."
19:26: Trochet: "There are some ongoing studies. Most
of them are looking at very high levels of pesticides. The
amounts of pesticide that people are exposed to through this
spraying are so low that to my knowledge there are no ongoing
studies. It is almost not worth the money."
21:30: David Brown, District Manager of SYMVCD: " . .
. at our very low doses there is minimal risk of the pesticides .
. . "
31:40: Brown: " . . . at the low dosages there is
minimal risk . . . "
32:38: Trochet: "Exposures to those pesticides at
those levels so far have not shown large amounts of cancer in
anyone other than the people who actually are exposed to the
pesticides, either in production or in the handling of them at
33:03: Trochet: "We may find in the future that there
33:24: "Unfortunately, it is impossible to have absolute
certitude about every public health intervention we have. .
. . But I am sorry but I cannot give you with absolute
certitude that someone 30 years from now won't have cancer.
What I can tell you with great certitude is that if we continue to
have high numbers of infected mosquitoes we will continue to have
death, people who are paralyzed for life and people who have
neuroinvasive disease. That I can tell you for
sure." [Emphasis ours.]
37:53: Trochet: "There is no question that these are very potent
chemicals, but the poison is in the dose."
42:57 Trochet: "The preponderance of the evidence is
that it does not have major health effects. Again, like
fluoride, like any chemical, the higher dose you take, the higher
the risk of having adverse consequences. But at the dosage used there
is no evidence that it has health consequences."
First, officials have shown no scientific
evidence or rigorous modeling to indicate that spraying 3 days a
year with insufficient
kill rates has any chance to make any difference whatsoever in
the transmission of WNv to humans, given a mosquito population that
grows exponentially during the better part of the season. Some
mosquitoes are killed, to be sure, but that is not the point.
The question is whether
enough mosquitoes are killed to slow the transmission of WNv to
humans, they have no solid scientific evidence of this, and there
is solid scientific evidence to the contrary (e.g. Pimentel, 2004;Reddy,
et al., 2006).
Second, Trochet seems to say that exposing
hundreds of thousands of citizens in this district to "very potent
chemicals" is justified if it can prevent even one person from
having a life-changing event through WNv, which is simply not a
proportional public health concern. According to county and
state information, there had been at most four neuroinvasive WNv
cases in Sacramento this year and none in Yolo County, as of
8/18/08. As to relative risk, in the vast majority of
infections WNv produces no symptoms, in about 20% of the cases it
produces very mild flu-like symptoms, and in about 0.67% of the
cases it produces a more severe disease that may become fatal.
While any fatality is tragic, note that an average of approximately
17 possible WNv deaths a year over the last four years in all of
California reveals an extremely
low relative risk, as this pales in comparison to the over
7000 deaths a year from flu and pneumonia in the state, for
Third, we do not have and have not had "high
numbers of infected mosquitoes." Officials declare an
"epidemic" if they find 5 infected mosquitoes per 1000 captured, but
we have asked for and received no justification for this figure they
use in their "risk assessment" – no models or studies. It
seems to have been borrowed from what has been done with St. Louis
Encephalitis, it does not come from any forecasting model that has
been revealed to us, but vector control presents it as one.
Both its predictive validity and its significance for WNv are very
questionable, as is their entire risk-assessment method.
It is also important to note that a new study has
just been published, which indicates that "Patients infected with
West Nile virus can develop long-term symptoms such as fatigue,
fuzzy thinking and movement difficulties but these symptoms go away
after about a year," according to a Reuters
Fourth, Dr. Trochet seems uninformed about the
current research about the safety of what is being sprayed.
She explicitly notes that she is unaware of any "low-dose"
studies. Contrast that with what Dr. LeStourgeon has supplied
(see the full detail below).
Fifth, the message could not be more clear that
these officials want us to believe that the danger is only in high
doses of these "very potent chemicals" – the poison is in the dose,
so they say – but the caveat that we may find problems in the future
and the contradictory statements about low risk (17:18 and 33:24)
and no evidence of health
consequences (42:57) of the spray suggest that they really
do not know what they are doing, at least in part because of their
lack of familiarity with the scientific literature. And, it is
important to point out that the community and physicians have not
been informed about symptoms of pesticide poisoning, and no program
was put in place for physicians to report health consequences.
If your eyes and ears are closed, the information indeed will not
And finally about the testimony before the
Council, it is not necessarily the case that the "poison is in the
dose" or that the "dose makes the poison," as inverted dose/response relationships
are present in some situations.
Indeed, as Dr. LeStourgeon explains "in classical
toxicology the phrase 'the poison is in the dose' is applicable only
for subthreshold doses of an acute toxin. Since dose/response
curves for mutagens extrapolate to zero [straight line dose-response
curve that shows no 'threshold.' In other words the line is
straight down to background] one must conclude that a single
molecule of mutagen may induce a single mutation. It is
important here to point out that the patient never feels the
mutation and thus usually concludes there is no problem." We
have previously commented about dose
considerations, with details more specific to this district,
and we explicitly noted the example that "Dioxin is yet another
chemical group that has some effect at any measurable dosage."
As another example of commentary by local
officials, on NPR's "Insight"
radio program, July 31, 2007, in the context of statements about use
of pesticides in places such as the city, the home, and on golf
courses, Trochet said "I do not accept the argument that it is OK to
use pesticides for these reasons, but it is not OK to use the small amount of pesticide
that is so far as we can tell safe in the amounts used to prevent some people
from getting life-threatening disease.” [Emphasis ours]
There are a number of troubling things about this statement, in
addition to the unsupported assumption that the amount of the
pesticide used is so small that it is safe. Many people would
not accept that it is OK to use pesticides in the amount used in the
other contexts either, particularly if they were aware of the facts
presented by Professor LeStourgeon. Furthermore, there is no evidence whatsoever that using this
pesticide will prevent anybody from getting the life-threatening
disease about which she speaks – the neuroinvasive form of West Nile
disease – and, again, only a very small fraction of the population
becomes infected with WNv, only 1 in 150 of those people get the
neuroinvasive form, and only a fraction of those die. In 2007,
the chances of a citizen getting the neuroinvasive disease in all of
California were a little over 4.3 in 1,000,000 (156 neuroinvasive
cases in a state with over 36,000,000 people). Whatever
Trochet's motivations are, the comments about the extremely rare
neuroinvasive disease serve to scare people. As we have
insisted from the start, our citizens deserve public health based on
facts and not fear.
We do not accept the argument Trochet is
essentially making: that we are awash in pesticides, so what does a
little more matter when we spray populated areas? We believe
that the increasing cancer rate, the cumulative exposure, and the
other disturbing scientific facts presented by Dr. LeStourgeon and
others are a wakeup call to use far less pesticides in far less
volume than we are doing now in all areas, without needlessly adding
to the total, particularly when the pesticide is completely ineffective at slowing or stopping WNv.
Resolving the Conflict – the Science.
Certainly the critical question for local
officials is what evidence they can supply to support their
position. And, by evidence we mean rigorously refereed studies
by independent scientists in legitimate scientific journals, as
opposed to review and publication in a growing number of "company"
journals supported by the chemical, oil, pharmaceutical, pesticide,
and other industries, with either non-scientists or acolytes
supplying the reviews. To date, vector control officials have
supplied no such references to us,
either about the safety or the efficacy of their aerial ULV spray
program over populated areas. The "Insight"
program of July 31, 2007, and the Sacramento
meeting of August 9, 2007, were classic cases in point –
numerous assertions were made about safety, efficacy was assumed,
but no specific references were offered, other than repeated mention
of the fatally flawed 2005 Sacramento study
about efficacy, an excellent example of a "company" study in a
"company" journal. Indeed, in her testimony before the
Sacramento City Council, noted above, Dr. Trochet says that she
knows of no low-dose studies about risk – they would almost not be
"worth the money."
To the contrary, for his testimony before the
Metro Board of Public Health, Dr. LeStourgeon supplied a packet
containing a large amount of scientific information, accompanying
the cover letter mentioned
above. Abstracts and short articles are posted here. The
appendices are as follows:
A brief explanation of the SEER program as administered by the
National Cancer Institute, a high quality national database that
is of great value because it allows epidemiologists and cancer
researchers to see trends in cause, incidence, diagnosis, and
therapy over a relatively long time span. Also, data from
the National Cancer Institute that emphasize that pollutants,
toxins, and endocrine disruptors continue to exist as an
increasing threat to all citizens, supporting the points in the
: Abstracts of peer-reviewed published
research in legitimate scientific publications dealing mainly with
the genotoxicity of piperonyl butoxide (PBO), the synergant used
in (and 60% of) the mix sprayed aerially by SYMVCD, clearly
demonstrating the chemical's ability to induce mutations and/or
modify normal patterns of gene expression and natural biochemical
: Abstracts of
peer-reviewed published research in legitimate scientific
publications dealing mainly with the estrogenic and general
endocrine disrupting properties of Sumithrin, a pyrethroid.
The pyrethroid Deltamethrin is sprayed by backpack by SYMVCD, and
David Brown stated to the Sacramento
on August 9, 2007
, that what is sprayed by air and what is
sprayed on the ground in this district have "no real difference"
(at 30:04 into the meeting).
: An abstract and two articles. The
abstract is that of a pesticide-industry funded research
project. It has been quoted by the pesticide industry in
public forums while the papers presented in Appendices II and III
are almost always ignored. Only one of the chemical isomers
that make up Sumithrin was tested, Sumithrin itself was not
tested, and the method used here has failed to yield positive
results with well characterized estrogenic compounds like
bisphenol-A. The two articles are about the special
vulnerability of children to carcinogens and the ever increasing
chemical pollution and ever increasing cancer incidences around
: Abstracts of four classic review articles
that document the evidence that 95-98% of all cancers are caused
by somatic mutations in the genes that control cell growth.
There seems to be some confusion about the
difference between pyrethrins and pyrethroids. Dr. LeStourgeon
clarifies: "Pyrethroids are synthetic pyrethrins. Pyrethroids
are much cheaper to make and have a similar chemical structure to
the natural pyrethrins and similar biological activity. Often
they are designed to have more lipid solubility, as lipid soluble
chemicals pass into cells more readily and often they are more
volatile." It is important to keep in mind that 60% of the aerail
spray mixture, Evergreen 60-6, is
PBO, and 34% consists of unknown, "inert," ingredients, which are
not inert in the usual sense of the word; often they are neither
chemically, biologically, nor toxicologically inert (NCAP).
A 2006 paper
studies the pyrethroid Bifenthrin, and the authors come to the
conclusion that "exposure to bifenthrin, even at 'acceptable' limits,
can increase the risk for and frequency of inflammatory responses
and diseases such as asthma" (emphasis ours). Additionally, a
study published in the September 15, 2008, issue of Environmental Science & Technology
has found pyrethroid
contamination in 100 percent of urban streams sampled.
Beyond Pesticides notes that "California is currently reevaluating
certain pyrethroid-containing pesticides as a result of increasingly
by Beyond Pesticides, the World Health Organization recently
released a report
about "children's heightened vulnerability to chemical exposures at
different periods of their growth and development," noting that
"children are not just small adults" and ". . . over 30% of
the global burden of disease in children can be attributed to
environmental factors, including pesticides." The report
"highlights the fact that for
children, the stage of their development when chemical exposure
occurs may be just as important as the magnitude of the exposure.
With respect to pesticides, the report cites several studies that
tie pesticide exposure during key periods of development to
neurobehavioral problems, Parkinson’s disease, and immunotoxicity,
including respiratory diseases" (emphasis ours). This of
course means that "the poison is in the dose" is even less true for
children than for adults.
Along these lines, a September 2008 study
indicates that "low-dose, short-term exposure to esfenvalerate, a
synthetic pyrethroid pesticide, delays the onset of puberty in rats
at doses two times lower than U.S. EPA’s stated no observable effect
level," according to an article
from Beyond Pesticides. The researchers conclude that "This
could potentially affect current established exposure levels for
humans, because the reference dose for [esfenvalerate] of 0.02
mg/kg/day is based directly on the rodent NOEL of 2.0 mg/kg/day."
The Pseudo Science.
As we have become more familiar with the very
compelling science on this issue and at the same time observed
public officials seemingly ignore it, we have been perplexed about
why this might be happening. It strikes us that it is possible
that public officials lack the experience and/or knowledge to move
from a possibly successful rural control program to handling a
perceived urban problem, particularly since somebody like Vicki
Kramer, Chief, Vector-Borne Disease Section of the CDPH, attached
her name to the fatally flawed report
without having any of the raw data (she supplied no data whatsoever
in response to a formal Public Records Act request). Her
qualifications list a PhD in entomology from UC Berkeley, but a
degree in entomology is not needed to see the fatal flaws.
This also hearkens back to the apparent lack
of knowledge about DDT on the part of Dr. Trochet.
Some skeptics have suggested that public
officials might ignore the science because of influence by various
commercial interests, and we have indeed begun to observe the new
pseudo-scientific "company" journals that publish fatally flawed reports, the corporate
influence in public agencies, etc. And, the disagreements over
proper public policy are nothing like honest scientific
disagreements that occur among dedicated scientists; rather, they
amount either to blatantly ignoring good science, to not having made
the effort to become familiar with it, or to conjuring up studies
that do not meet rigorous scientific standards. Note, for
example, when local officials first sprayed Sacramento in 2005 they
were not even aware of what they now
call the "encephalitis mosquito," which they now insist, well after
the fact, is the main threat here. They also completely mischaracterized the
differences in what is done in Washington, D.C. (very effective
control without aerial spray) and what is done here.
Furthermore, they submitted the "Louisiana
paper," essentially an administrative report and not
scientific evidence, when they were questioned about their
justification of the spray. And of course they continue to
offer up the fatally flawed Carney report
as their main example of "peer reviewed evidence."
As to influence by commercial interests, an
August 16, 2008, article
Washington Post, gives a good example of how the chemical
industry controls agencies like the FDA, relative to a timely issue
for those of us in this district, the use of BPA, given the
capitulation to that industry by our own Legislature on SB 1713 and
SB 1313 on August 18, 2008. This was due to "an avalanche of
lobbying" and "heavy-handed efforts to pressure [legislators] to
vote no," according to the Sacramento Bee
story. As to some industry brochures opposing one of the
bills, Assemblywoman Lois Wolk said "It is an extremely deceptive
tactic, and I think . . . we ought not to reward the American
Chemical Council by rejecting this bill."
Who is being rewarded by indiscriminate spraying
of populated areas with ineffective
pesticides for the purported control of WNv?
It is important to note that representatives of a
large number of EPA scientists recently sent a
letter to the Administrator of the US EPA complaining that
they were being coerced into making false and misleading safety
claims regarding pesticides. They said "We are concerned that
the Agency has lost sight of its regulatory responsibilities in
trying to reach consensus with those that it regulates, and the
result is that the integrity of the science upon which the Agency
decisions are based has been compromised," and "Our colleagues in
the Pesticide Program feel besieged by political pressure exerted by
Agency officials perceived to be too closely aligned with the
pesticide industry and former EPA officials now representing the
pesticide and agricultural community."
Certainly a classic case of influence on
marketing by pseudo science is given in the history of the tobacco
industry. After years of accusations of lies and coverups,
including dubious testimony before Congress by top-ranking company
officials, an article entitled "Tobacco
smoking gun revealed" in the October 19, 2007, Issue of
Dateline UCDavis, reports that "after combing through nearly 50
million pages of previously secret, internal tobacco-industry
documents, UC Davis and UC San Francisco researchers say they have
documented for the first time how the industry funded and used
scientific studies to undermine evidence linking secondhand smoke to
cardiovascular disease." See the full article, "Tobacco
Industry Efforts Undermining Evidence Linking Secondhand Smoke
With Cardiovascular Disease," in "Circulation," a Journal of
the American Heart Association.
Is the pesticide industry now where the tobacco
industry was years ago?
After years of dealing with studies of varying
quality about safety of pesticides, in a handout from his advanced
Biology 273 (page 80 of the catalog), Professor LeStourgeon
refutes the major arguments
of the industrial conservatives. And, in a careful piece
containing some concentration
analogies he candidly asks if "these 'conservative' groups
care about my health or 'conserving' their profit margin." We
have previously noted Dr.
Trochet's connections to the chemical and pesticide
industries. Also, David Brown is the 2008 president of the
Mosquito and Vector Control Association of California (MVCAC), which lists "effective
legislative advocacy" as part of its mission and lists a collection
of 14 associated "vendor sites" on its web page.
Finally, there is growing concern in the
scientific community about restoring scientific integrity. See
the discussion on the web page of the Union of
Concerned Scientists, for example, in which they note that
relative to our impressive history of respecting the independence of
scientists " . . . recent actions by political appointees, however,
threaten to undermine this legacy by preventing the best available
science from informing policy decisions that have serious
consequences for our health, safety, and environment." They
discuss the growing problem and give important examples of such
things as interference at the EPA.
Dr. Trochet says that she cannot say "with
certitude" that there is no risk from the spray. Indeed, she
cannot. However, she then says that she can say "with
certitude" that if we don't spray there will be death, neuroinvasive
cases of the disease, and people paralyzed for life. This is
simply false – those rare events are not guaranteed if we don't
spray, and if they are on the horizon the spray certainly will not
stop them. Indeed, with at most only four cases of
neuroinvasive disease in the Sacramento area this year (2008) and no
deaths tens, if not hundreds, of thousands of people were sprayed
with "very potent" chemicals. Officials might try to take
credit for the almost non-existent case count because of the spray
of South Sacramento, but there is no scientific evidence to support
that contention. And, without spray there has been very little sign of
infection at all in Yolo County this summer and zero WNv cases of
any kind. This is not an aberration – it is
completely consistent with the very low infection levels of such a
disease as it naturally moves into what is called chronic endemicity
after a few more active early years in a region.
Any responsible "public health intervention" must
undergo a risk/benefit analysis. Public officials
unfortunately have this one exactly backward. They assume, in
absence of any scientific evidence, that the spray works and there
are thus benefits. There is simply no evidence for that
assumption. They then assume that the risk of the spray is
less than the risks of not spraying. That is not possible – no
benefit from the spray means that there is no risk not to
spray. The facts of the matter are that there are immediate
risks for a certain segment of our population, such as people with
asthma or Parkinson's disease, and there are long-term risks for all
of us in terms of the new mutagens added to our environment and the
mutational load that a number of us will suffer from spraying "very
potent chemicals" over populated areas.
If local officials can put aside the pseudo
science, and if any benefits of the aerial ULV spray are ever
demonstrated scientifically, an accurate risk/benefit analysis can
be done, unless officials have either begun to use other means to
combat the already small and steadily
diminishing threat (see the comparison to Western Equine
Encephalitis in the Summary) or begun to allow the virus to run its course like some other districts do.
We strongly support methods such as effective, risk-free, and
long-lasting biological controls,
for example. With a scientific demonstration of efficacy of
spraying the actual benefits could then be weighed against the very
clear risks of spraying and the rarity and very mild nature of the
disease for the vast majority of people. However, at present the science of the matter
shows that there is no demonstrated benefit, there are distinct
short and long-term risks, and for the safety of our citizens the
aerial ULV spray program of the SYMVCD should therefore be
Further References about Dose:
the Adage 'the Dose Makes the Poison' Can Be Toxic to Corporate
"the dose make the poison?"
all things poison? Rethinking safety standards for low doses of
to Update Environmental Regulations: Should public health
standards for endocrine-disrupting compounds be based upon
sixteenth century dogma or modern endocrinology?
Doesn’t Always Make Poison.