Silent Spring - units.sla.org

Dr. Diana Post
President, Rachel Carson Council
www.RachelCarsonCouncil.org
rccouncil@aol.com
(301)593-7507
June 17, 2009
Assistance provided by
Michael K. Liddel , PhD
1

Introduction
Rachel Carson is considered on the 20 th Century’s greatest
Americans and the fountainhead of modern
environmentalism.
She had a deep respect for both nature and science
Her Fourth book, Silent Spring, brought issues pertaining
to chemical pesticide toxicity fron the level of scientific
society discussions to citizens’ dinner tables and President
Kennedy's press conference.
After 1962, the year of Silent Spring’s publication, the
problems of technology became difficult for the
government to ignore.
Rachel Carson gave voice to those scientists and thinkers
whose concerns about pesticides’ dangers especially to
wildlife had existed since before the end of World War II.
2

Overview: Rachel Carson’s Impact on Science
Presidents Science Advisory Council (PSAC)
Kennedy’s Expert Panel to Review Silent Spring
Rachel Carson’s Impact on Ecology Education
Increasing concern about chemical contamination
Rachel Carson’s Vision of Pesticide Regulation & the EPA.
Risk Assessment & Multiple Pesticide Exposures
The Rachel Carson Council
DDT
Common misconceptions
Toxicity to humans
3

President’s Science Advisory Council
Established by President Kennedy to evaluate Silent Spring
The PSAC recommended that persistent pesticides be
phased out.
Carson concurred, as she stated in her June 4, 1963
testimony
“Statement of Rachel Carson Before the Subcommittee on
Reorganization and International Organizations of the Committee
on Governmental Operations. Environmental Hazards: Control of
Pesticides and Other Chemical Poisons -- June 4, 1963
4

Silent Spring and Ecology Education
Silent Spring increased concern for pesticide
contamination
Documented by Peterson and Peterson (2000) Ecology,
according to Silent Spring’s Vision of Progress in And No
Birds Sing (Waddell ed).
Silent Spring is now required reading in many
university courses in ecology and biology.
5

Silent Spring and Ecology Education
In their essay “Ecology according to Silent Spring’s
Vision of Progress”, the Peterson’s documented the
increasing focus on chemical contamination in three
successive editions of a widely used ecology text
during the 1950 to 1970 period. They also found that
two college level ecology texts published in the mid
1990s emphasized ecological means of pest
management as being more scientific than other
means.
6

Silent Spring and Ecology
Silent Spring added a new
perspective:
Human beings are a part of
nature and what we do to nature,
we do to ourselves
Rachel Carson’ general purpose
in writing Silent Spring was to
highlight this perspective
This view anticipates the 2005
Millennium Ecosystem
Assessment. Jane Lubchenko
(2008)
7

The Millennium Ecosystem Assessment
Published in 2005, it catalogued into 4 areas the
essential services provided by functioning ecosystems:
1) Supporting
Soil formation, nutrient recycling
2) Provisioning
Food, water, fiber
3) Regulating
Climate control and pest control
4) Cultural
Aesthetic , spiritual
8

Rachel Carson’s Vision of Pesticide
Regulation and the EPA
“If we are ever to find our way out of the present
deplorable situation, we must remain vigilant, we must
continue to challenge and to question , we must insist
that the burden of proof is on those who would use
these chemicals to prove their procedures are safe.”
-Rachel Carson : “A New Chapter to Silent Spring”
- Bulletin of the Garden Club of America, May 1963
9

EPA’s Conditions for Pesticide Regulation
EPA’s Pesticide regulation system does not require that
pesticides be proven safe.
Pesticides are registered by EPA under two risk/benefit
decision-making standards. One for human health, the
other for the environment.
Registered pesticides can never be considered “Safe”’.
Companies have been prosecuted and fined for calling their
pesticides safe.
For more see RCC “Issues and Insights”, Oct 2004 and 40CFR:162.10 (a)(5)(ix))
10

EPA Pesticide Regulation
Ecological & wildlife risks are balanced against the
benefits of using the pesticides
The EPA’s evaluation standard for wildlife is that under
the registered conditions of use, the pesticide use will
not pose an unreasonable risk to the environment or
that it represents no unreasonable risk of harm to
wildlife (Merenda 1998)
11

Pesticides’ Impact on Wildlife
“…the EPA’s ecological risk assessments often show
that legal applications of certain pesticides will almost
certainly kill non-target species that happen to be
nesting, feeding, flying or swimming in and around
treated farm fields. In the real world of pesticide
regulation, birds, fish, and bees are expendable.”
Dr. Chuck Benbrook, “Prevention, Not Profit, Should
Drive Pest Management.” 2008 Rachel Carson Memorial
Lecture (Pesticide News Dec 2008)
12

Costs of wildlife fatalities due to
pesticides
72 million bird deaths annually with an estimated cost to
society of $2.1 billion
14 million fish deaths annually with and estimated cost to
society of $56 million
Estimated cost to society from damage to pollinating
insects and insects that are natural predators of pests is
$700 million annually.
Dr. David Pimentel, 1998, RCC’s Wildlife Pesticides and
People Conference
13

Pesticides and Human Health
EPA’s standard for human health risks from registered
pesticides, provides a reasonable certainty of no harm,
especially for the very young. (Merenda, 1998)
Unfortunately, the Agency does not always carry out this
mandate
14

Public Perception of EPA’s Risk Assessment
RCC believes that today the public is largely
unaware of EPA’s risk/benefit standards.
We believe that those who care about protecting wildlife,
would find them unacceptable.
Rachel’s recommendation, that those promoting
the chemicals prove that their procedures are safe,
is closer to how the FDA approves drugs than the
way the EPA registers pesticides.
Perhaps her influence can still have the power to protect
vulnerable wildlife or at least the public can be informed of
the hazards.
15

Multiple Pesticide Exposures
“In water and soil, and in our own bodies,
these chemicals are mingled with
others…There are little understood
interactions and summations of effect.”
Rachel Carson, June 4, 1963 Congressional Testimony
16

Multiple Pesticide Exposures
The 1996 Food Quality Protection act calls for
estimating aggregate and cumulative risks to human
health from pesticides by EPA .
Aggregate risk: Impact of multiple sources of a single
pesticide active ingredient, such as chlorpyrifos.
Cumulative risk: The impact of several active ingredients
with the same mode of action such as
organophosphates, of which chlorpyrifos is an example.
17

Multiple Pesticide Exposures
Pesticide mixtures at environmentally realistic levels
impact wildlife
Pesticide Combinations have been associated with loss
of olfactory sense in migratory fish (Tierney et al 2008)
This leads to problems locating breeding areas, avoiding
predation, finding food, etc.
A pesticide synergist applied with a short-lived
insecticide could remain active in underwater sediments
and combine with a longer lived insecticide already
existing in the sediment, enhancing the latter’s toxicity
for aquatic organisms (Weston 2006)
18

Multiple Pesticide Exposures
RCC’s Perspective:
EPA needs to give greater consideration to pesticides
mixtures’ impacts on humans, pets and wildlife. All risk
assessments should include aggregate and cumulative
assessments.
In addition, assessments should be made for multiple
exposures to chemical pesticides that may not have the
same mode of action but have a common toxic endpoint
such as cancer, liver damage, neurotoxicity, etc.
19

The Rachel Carson Council (RCC)
Rachel Carson Council, a 501(c)(3) non-profit
organization, is one of Rachel’s enduring legacies. It
was founded a year after her death to continue the
efforts started with Silent Spring.
RCC researches pesticides’ impacts, low-risk pest
management alternatives and fosters a sense of
wonder and respect for nature as did Rachel Carson.
20

Rachel Carson Council
RCC’s searchable database
of over 490 pesticide active
ingredients, an update of
the 1992 The Basic Guide to
Pesticides, is being
prepared for distribution.
21

Rachel Carson & DDT :
Common Misconceptions
Rachel Carson did not initiate the call for banning DDT in
Silent Spring.
The PSAC recommended phasing out persistent pesticides,
including DDT.
Rachel concurred with this recommendation.
DDT has never been banned worldwide
It is still permitted to be used and still used for mosquito
control
Special permission to use DDT can be granted under the 2001
Stockholm Convention
The US has signed this treaty but it has not been ratified
22

DDT Common Misconceptions
According to some historians DDT protected crops from
pests and saved millions of people from malaria, and its
hazardous effects on wildlife and human health only
became known to scientists after years of use. An example
of unforeseen consequences?
Professor Edmund Russell (2004, personal communication)
“During World War II (DDT’s developers) anticipated and
tested for, most of the problems that led to DDT being
banned...” DDT was released to the public at the end of the
war not because its developers failed to foresee problems; it
was released because no government agency had authority
after the war to restrict its sale or use.
23

DDT Misconceptions: Unforeseen
Consequences
Government researchers knew that:
DDT accumulated in the milk of lab mammals and passed into
their offspring.
DDT killed fish when sprayed at a wildlife refuge.
DDT killed off the insect predators, that helped to control pest
insects.
“These concerns were taken seriously enough that the US
banned the aerial spraying of DDT inside the US during the war.”
After the war scientists advised industry to hold off the civilian
market until they could develop a way to minimize its hazards,
but the majority of chemical companies decided to sell DDT
regardless.
Edmund Russell (2004 personal communication)
24

DDT Misconceptions: Unforeseen
Consequences
For further information see:
“The Strange Career of DDT: Experts, Federal Capacity
and Environmentalism in World War II.” Edmund
Russell in Technology and Culture 40(1999) 770-796
War and Nature: Fighting Humans and Insects with
Chemicals. By Edmund Russell, 2001
25

DDT Effects on Humans
DDT can act on the nervous, reproductive, endocrine
and immune systems, and on the liver. It has also been
associated with cancer in humans.
EPA generally does not require testing of pesticides for
their effects on the immune system.
26

DDT Effects on Humans
Neurological Effects
A birth cohort study of children of Mexican farm
workers in California found prenatal exposure to DDT
associated with neurodevelopment delays during early
childhood (Eskenazi et al, 2006)
Adverse effects of DDT in humans reported to poison
control centers include “sensory
disturbances…headache, dizziness, nausea, vomiting,
incoordination, mental confusion, and [in more serious
cases] seizures.” (Reigert & Roberts 1999)
27

Effects on Birds and on Humans
Neurological Effects
by Implication
DDT related changes in the robin brain are found to be
significant and related to those structures associated with mating
and song. “Given the magnitude of these changes in the brain
and and the fact that environmental DDT exposure was restricted
to early development, we conclude that both humans and wildlife
that live in DDT contaminated environments may be at risk of
neurological damage.” (Iwaniuk et al 2006)
28

DDT Effects on Humans
Reproductive Effects
Using DDT in Africa against malaria mosquitoes might
kill as many African babies as it could save due to low
birth weight babies, and shortened lactation time for
mothers. If DDT use became widespread, the lactation
period could become 40% shorter (Rogan& Chen 2005 as found
in Karaim 2005)
29

DDT Effects on Humans
Reproductive Effects
A study of semen parameters in Mexico where DDT was
used to control malaria found that exposure was related
to impaired semen quality.
Men with higher DDE levels had a lower percentage of motile
sperm and greater percentage of sperm with tail defects.
(Ayotte et al 2001)
Impaired semen quality was associated with DDT
exposure in young men living in malaria areas of
Limpopo Provence, South Africa. (Aneck-Hahn 2006)
30

DDT Effects on Humans
Endocrine System
The prevalence of diabetes mellitus (sugar diabetes) in
people was found to be between 3 & 5 times higher
depending on their blood serum concentrations of
persistent organic pollutants such as DDE (a breakdown
product of DDT) (Lee et al 2002)
When the sum of 6 persistent organic pollutants are considered there
is a 5-38 times increased likelihood of diabetes developing. (Lee et al
2002)
31

DDT Effects on Humans
Immune System Effects
“…chemotaxis and phagocytosis (immune protective
mechanisms) were found to be markedly depressed in
occupationally DDT-exposed workers. Additionally, the
prevalence of infectious episodes was significantly
higher in these workers than in a control population.”
(Descotes 1988)
32

Immune Effects on Fish
DDT Effects
A brief period of exposure to o,p’-DDE during early
development of Chinook salmon was associated with a
reduced ability for antibody production in the treated
fish one year later. The authors concluded: “Such
immunosuppression may increase susceptibility to
disease.” DDT and DDE have been found to have
estrogen and antiandrogen effects. Receptors for
estrogen have been identified on immune system cells
indicating that endocrine immune interaction can
occur. (Milston et al 2003)
33

DDT Effects: Breast Cancer
A 2007 study (Cohn et al) in the US measured DDT
blood levels in archived samples from women patients
with breast cancer and discovered a significant link
with increased concentrations of this pesticide
Blood samples reflected DDT exposure of patients as
young girls
Highest levels of DDT during critical period of breast
development were found to have a greater than 5 fold
increased risk of developing Breast cancer later in life.
This study calls attention to the increasing vulnerability to
hazardous outcomes that can accompany exposure of
developing individuals to toxic chemicals
34

DDT and Liver Cancer
A 2006 case-control study (McGlynn et al 2006) found
high DDT blood levels to be associated with liver
cancer in Chinese patients. Subjects with the highest
DDT levels were 3.8 times more likely to develop liver
cancer than those with the lowest levels.
DDE a metabolite of DDT was not associated with this
effect
The authors concluded that DDT may be a risk factor for
liver cancer and that the individual patient’s ability to
metabolize DDT may be involved.
35

Global Trends in Malaria
In the 1950s the Global Malaria Eradication program
using DDT was launched.
In 1969 through the 1980s WHO focused on drug
therapy against malaria.
During the 1990s the malaria parasite developed
resistance to the drug of choice, chloroquine, and
deaths increased.
In 2006 Dr. Kochi director of the WHO program
supported the use of bed nets, combination drug
therapy featuring artemisinin and DDT spraying of
interior walls.
36

Global Trends in Malaria Control
A 2008 Report focused on Rwanda and Ethiopia
showed greater then 50% reduction in malaria
mortality nationwide in high burden countries.
“Indoor spraying with DDT and other insecticides–
used in Rwanda at the end of the study period, and
before and during it in Ethiopia – did not appear to be
a factor in the steep, sudden declines. “ (Brown 2008)
37

Conclusions: Rachel & Science
Rachel Carson had an influence on ecology and
toxicology in various ways, including her legacy
organization RCC.
Rachel believed that those who use chemical
pesticides should be required to prove them safe – now
pesticides are registered by the EPA under a
risk/benefit standard and are not even allowed to be
called “safe” by manufacturers or marketers.
Exposure to pesticide mixtures, not single agents
occurs in the real world, as Rachel Carson asserted.
EPA needs to do more assessments of such risks
38

Conclusions (continued)
Based on research DDT has been associated with human
health problems, including: Reduced sperm
production, shorter lactation times, and increasing
number of preterm births in women, learning
disorders in children, immune system damage as
well as primary liver cancer and breast cancer.
In May of this year UNEP (United Nations Enviroment Program) and
WHO (World Health Organization) announced new projects
using sustainable alternatives to DDT such as mosquito
repellant trees, fish that eat mosquito larvae and
elimination of mosquito breeding sites. They aim to
reduce the use of DDT worldwide by 30% in 2014.
39

References
Aneck-Hahn, NH et al (2006) “Impaired semen quality associated with environmental DDT exposure in young men living in a malaria area in
the Limpopo Province, South Africa” Journal of Andrology, Dec 27 2006
Ayotte, P., S Girous, E Dewailly, M Avila Hernandez, P Farias, R Danis, and C Diaz Villanueva. (2001) “ DDT Spraying for Malaria Control and
Reproductive Function in Mexican Men.” Epidemiology 12(5)
Brown, D (2008) “Anti-Malaria Efforts Yield New Success”. The Washington Post. Feb 1, 2008
Cohn, M, MS Wolff, PM Cirillo,and RI Sholtz. (2007) DDT and Breast Cancer in Young Women: New Data on the significance of age at
exposure. Environmental Health Perspectives 115:1406-1414
Descotes J (1988) Immunotoxicology of Drugs and Chemicals, 2 nd updated edition, 1988, Elsevier
Eskenazi, B et al (2006) “In utero Exposure to Dichlorodiphenyltrichloroethane (DDT), Dichlorodiphenyldichloroethylene (DDE) and
Neurodevelopment among young Mexican American Children” Pediatrics 118(1):233-241
Iwaniuk AN, DT Koperski, LK Smith, and DR Wylie (2006) “Effects of Environmental Exposure to DDT on the brain of a songbird: Changes
in structures associated with mating and song.” Behavioral Brain Research July 4, 2006
Lee DK et al (2002) “ A strong dose-response relation between serum concentrations of persistent organic pollutants and diabetes. Results
from the National Health Examination Survey 1999-2002” Diabetes Care 29: 1638-1644
Lubchenko J (2008) “Rachel Carson’s Scientific and Ocean Legacies”, in Rachel Carson Legacy and Challenge, Sideris & Moore eds. 2008
McGlynn, KA (2006) Serum concentrations of 1,1,1-Trichloro-2,2-bis(p-chlorophenyl)ethane (DDT) and 1,1,-Dichloro-2-2-bis(pchlorophenyl)ethylene(DDE)
and Risk of Primary Liver Cancer,” Journal of the National Cancer Institute 98(14) 1005-1010
Merenda J (1998) Presentation at the Wildlife, Pesticides and People Conference
Milston RH, MS Fitzpatrick, AT Vella, S Clements, D Gundersen, G Feist, TL Crippen, J Leong, and CB Schreck. (2003) “Short-Term Exposure
of Chinook Salmon (Oncoryhnchus tshawytscha) to o,p-DDE or DMSO during Early Life-History Stages Causes Long-Term Humoral
Immunosuppression” Environmental Health Perspectives 11(13) October 2003
Reigart JR and JR Roberts (1999) Recognition and Management of Pesticide Poisonings, Fifth Edition. Office of Pesticide Programs,
Environmental Protection Agency
Rogan & Chen (2005) from Reed Karim “Not so fast with the DDT: Rachel Carson’s Warnings Still Apply.” The American Scholar, 74(3),
Summer 2005
Tierney KB, Sampson JL, Ross PS, Sekela MA, and Kennedy CJ (2008) Salmon Olfaction is Impaired by an environmentally Realistic Pesticide
Mixture. Environmental Science and Technology. 42:4996-5001
Weston DP (2006) “Aquatic Effects of Aerial Spraying of Aerial Spraying for Mosquito Control over an Urban Area.” Environmental Science
and Technology 40(18): 5817-5822
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