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Winter 2000    Volume 15, Issue 3

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American
Heritage
April 1974

The Short-Lived Miracle of DDT

DDT was a savior in the 1940s and a curse
by the 1960s. Its story shows how a technology that does
enormous good can also do enormous
harm.

BY
DARWIN H. STAPLETON

EARLIER THIS YEAR A GROUP OF
JOURNALISTS ASSEMBLED BY NEW York University voted Silent Spring (1962), by the
ecologist Rachel Carson, the second most influential
piece of American journalism of the twentieth century.
Drawing on a wide range of scientific studies, Carson
demonstrated to the public that DDT, the miracle
chemical of World War II and the keystone of the World
Health Organization’s global antimalaria program in the
1950s, was less a benefit to humanity than a danger to
the global ecosystem. Within a decade Carson’s book and
the movement it spawned led to the banning of DDT in the
United States and in most other industrial countries.
The meteoric rise and precipitous decline of DDT is at
once an epic of human achievement in war, a dramatic
chapter in the long struggle against malaria, and a
cautionary story about the outcome of unbridled
enthusiasm for new technology.

If not for the frantic search
for an effective insecticide early in World War II,
there might have been no story to tell. When the United
States entered the war, scientists in the Office of
Scientific Research and Development (OSRD) knew that one
of the greatest threats to troops in wartime has always
been disease, especially insect-transmitted diseases
that thrive when thousands of people are thrown together
in close quarters and new environments. Brig. Gen.
Nathanael Greene learned that hard lesson in 1776, when
one-third of his Continental Army was stricken with
louse-borne typhus during the Long Island campaign.
Typhus was also an important factor in the defeat of
Napoleon’s Grand Army when it invaded Russia in
1812.

Typhus was an even greater
problem in World War I. Millions of soldiers on the
Eastern Front were infected, with large numbers dying
from the disease. Even after the war, typhus devastated
refugees and returnees throughout Eastern Europe.
Mosquito-borne malaria was another serious problem in
World War I. During the Salonika campaign the British
had 162,000 soldiers unfit for combat because of
malaria, compared with 28,000 killed or injured in
battle. The French army at Salonika at one time had less
than 20 percent of its troops ready for combat because
of the same disease.

By the close of the War to End
All Wars, it was unmistakably clear that insect-carried
disease could be disastrous for armies. Yet two decades
later none of the combatants entering the next world war
had significantly improved their abilities to cope with
insects. It was therefore no surprise to any informed
observer when, in the first year after the United States
entered World War II, the entire 1st Marine Division had
to be withdrawn from the Pacific front because more than
half its men had contracted malaria. This serious
defeat, which occurred without enemy action, came in the
summer of 1942, soon after the OSRD had begun
collaborating with the Agriculture Department’s Bureau
of Entomology and Plant Quarantine to find a way to
control or eliminate battle-zone insects. The bureau’s
laboratory in Orlando, Florida, became the center for a
program to test every known insecticide and insect
repellent.

In 1942 the laboratory tried
thousands of commercial and noncommercial chemicals and
preparations, focusing mainly on lice, which seemed
likely to be the greatest enemy. A few lice and a
promising chemical would be put on a civilian
volunteer’s arm, in a sleeve firmly taped at each end.
After 24 hours the sleeve was opened. If the lice had
died, new ones were inserted, but no more insecticide
was added. This process was repeated until the lice
survived. Through most of 1942 only one product killed
lice for as long as eight days: pyrethrum, a natural
insecticide derived from tropical plants that is widely
used today in spray insecticides. Unfortunately, the
major sources of pyrethrum were found primarily in
war-threatened areas of equatorial Africa and in other
tropical areas occupied by enemy troops, such as
Indonesia. Moreover, pyrethrum often irritated skin when
it was applied directly.

The laboratory at Orlando kept
trying every new concoction that came to its notice.
Late in 1942 a new insecticide called Gesarol arrived
from J. R. Geigy, a chemical dye company in neutral
Switzerland. Its active ingredient was
dichlorodiphenyltrichloroethane—DDT, for short. The OSRD
laboratory tagged the sample and tested it the same way
it did everything else.

If the laboratory had known
DDT’s recent history, or if it had not already been
jaded by the extravagant claims of some other commercial
products, it might have pounced on DDT immediately.
Geigy, a long-established firm in the city of Basel, had
entered the insecticide field in 1935, when it assigned
a team of chemists headed by Paul Hermann MÜller to find
a product for mothproofing woolens. After testing a wide
variety of chemicals on household flies, MÜller and his
team hit upon DDT, which had first been synthesized by a
German doctoral student nearly 80 years earlier but had
gone unnoticed until it was rediscovered by MÜller’s
chemists. They found that although DDT was not
immediately lethal, it killed everything in a test box
within 24 hours. Most distinctive of its properties was
its uncanny persistence: It remained effective for days,
even weeks, without reapplication.

In the late 1930s MÜller and
his team tried DDT on cockroaches, mosquitoes, and many
agricultural pests. They found that it combined an
excellent “knockdown” characteristic (the ability to
kill insects on contact) with a superior residual effect
(the ability to continue killing insects that landed on
surfaces sprayed with the chemical). In 1940 Geigy began
selling its new product, Gesarol (DDT at 5 percent
strength), as a pesticide. The next year a dust with
just a 1 percent concentration proved extremely
effective in stopping an infestation of potato beetles
in Switzerland. By 1942 a preparation named Neocid was
being marketed as a louse killer. It was used with
excellent results at Italian refugee camps on the Swiss
border.

DDT had an excellent
“knockdown” characteristic (the ability to kill
insects on contact) and a superior residual effect
(the ability to continue
killing).

Because of Switzerland’s
neutrality, information on DDT was freely available to
all the combatants in World War II. The German army made
some use of DDT, spraying it in Greece and Yugoslavia to
control mosquito larvae in an attempt to reduce the
incidence of malaria. However, it was the Americans who
most effectively exploited the new insecticide. In
August 1942 about 100 kilograms of Gesarol (half of it 5
percent DDT spray and half of it 3 percent DDT dust) had
been exported from Switzerland to Geigy’s subsidiary in
New York via a neutral freighter from Portugal. Copies
of some of the scientific reports soon followed.

Victor Froehlicher, the head of
the Geigy office in New York, laboriously translated the
reports into English. They described effects so far
beyond those of any existing insecticide that he found
them hard to believe. On October 16, 1942, he delivered
his translation and a small quantity of Gesarol to an
official at the Department of Agriculture in Washington.
Following government policy on insecticide research,
information about DDT was thereafter treated as a secret
in the United States.

Gesarol passed the sleeve test
with flying colors, killing lice for nearly three weeks
without renewal. Better yet, it did not seem to irritate
the skin, and it had no odor. Next DDT was tried in the
Orlando countryside. In one remarkable instance the
natural conditions of two neighboring ponds were
surveyed, and then one pond was sprayed with DDT to kill
mosquito larvae. A week later the scientists were
puzzled to find that not only were the larvae in the
first pond dead or dying, but those in the second pond
were too. They realized that even the small quantity of
DDT carried from one pond to the other by ducks and
other waterfowl was enough to kill the insects.

The scientists now knew that
they were dealing with an exceptionally powerful
formula, and the OSRD gave the development of DDT-laden
insecticides a high priority. A range of concentrations
were tested for the manufacture of louse powder, and a
variety of solvents were tried for sprays, because by
this time it was clear that the war in the Pacific would
demand a massive malaria-control effort. One American
general called malaria “an enemy more dangerous than the
Japanese.” At first DDT had to be imported from
Switzerland, but as early as May 1943 a Geigy affiliate,
the Cincinnati Chemical Works, started up a pilot plant.
The chemical process for synthesis of DDT was not
complicated, requiring the reaction of monochlorobenzene
(C6H5Cl) and chloral hydrate
(CCl3CH(OH)2) to form DDT (CCl3CH(C6H4Cl)2) and water, with sulfuric acid
as a catalyst. Production was limited mostly by wartime
bottlenecks in the availability of the basic
ingredients.

The OSRD decided to experiment
with widespread field tests before beginning regular
military distribution. It turned to a nonmilitary
organization, the Rockefeller Foundation, to carry out
much of the fieldwork. Since its creation in 1913 by
John D. Rockefeller, with an endowment that eventually
reached $183 million, the foundation had become a global
leader in public health work, particularly with regard
to parasitic and insect-borne diseases. The foundation’s
public health program continued one that had been
initiated by the Rockefeller Sanitary Commission
(1909-12) and the International Health Board (1913-28).
The program had first attacked hookworm infestation, an
insidious “disease of laziness” that predominantly
affected the poor in the rural Southern United States
and workers on plantations and industrial settlements
throughout the world.

In the 1920s and 1930s the
foundation expanded its public health program to include
yellow fever and malaria. One of its greatest efforts
came in Brazil, where in the late 1930s foundation
officers eradicated Anopheles
gambiae, a yellow-fever-carrying mosquito species
that had inadvertently been introduced from Africa. Soon
after the beginning of World War II, but before Pearl
Harbor, the foundation created the Rockefeller
Foundation Health Commission, composed of foundation
staff who had substantial field experience. The
commission formed a team that could be deployed in
war-damaged regions threatened with epidemics or other
public health problems.

When the United States entered
World War II, the OSRD asked the Rockefeller Foundation
to establish a laboratory to study lice. This louse lab
was set up in New York City using staff from the
Rockefeller Institute for Medical Research (now
Rockefeller University). The laboratory started its work
with a few lice scraped from a patient at Bellevue
Hospital. It then began detailed studies of the insects’
biology. In the fall of 1942, after breeding a few
generations of the lice and ascertaining that they
carried no diseases, samples were taken to New Hampshire
to infest volunteers at a conscientious objectors’ camp.
The lab then sent a series of promising concoctions to
the camp, where they were tested both for their
effectiveness in killing the lice and for any problems
they might cause by coming in contact with skin. Testing
there and in Mexico reinforced the finding that
pyrethrum was an effective lousicide. Early tests of DDT
in the summer of 1943 suggested that it was even more
potent. But with Geigy’s Cincinnati plant still working
out its kinks, supplies remained limited. In any case,
DDT’s field effectiveness was yet to be proved.

After testing pyrethrum powder
in two Egyptian villages in the spring of 1943, the
commission moved its North African operations to newly
liberated Algeria and Tunisia, where it worked with a
branch of the Pasteur Institute in Tunis that had
studied epidemic disease in the region since 1893. The
scientific leader of this Rockefeller Commission unit
was Dr. Fred Soper, an energetic, outspoken veteran of
past Rockefeller public health campaigns. He was famous
among malariologists for leading the foundation’s
successful antimosquito campaign in Brazil a few years
earlier. Among the strategies Soper employed there was
the widespread and repeated distribution on water
surfaces of Paris green, a salt containing copper and
arsenic, to kill mosquito larvae. But Paris green is
poisonous to humans and is only briefly effective. When
Soper began to use DDT, he immediately recognized its
superiority over other insecticides. For the next twenty
years he energetically pushed DDT as an answer to
malaria. But his first mission was to demonstrate the
chemical’s effect on lice, a program he drove forward
relentlessly and with disdain for anyone who did not see
the future as clearly as he did.

In June 1943 Soper and his
commission and Pasteur Institute colleagues received
their first supplies of DDT. They held their initial
tests at the Maison Carrée prison in Algiers, where
inmates were dusted with DDT and other insecticides
currently used by the Allied forces. That fall DDT was
given field tests in an Algerian town with a mixed Arab
and European population and at a nearby prisoner-of-war
camp. Among other factors, the studies aimed to find out
whether DDT powder could be effective against lice when
it was dusted into clothing through neck, arm, and leg
openings. The commissioners thought this would be faster
than requiring each person to disrobe, and they also
recognized that in most cultures civilians would be
reluctant to strip naked in front of strangers.

The lessons learned from these
trials were put to dramatic use in December 1943, when
the Allied military command in Italy asked the
commission to stop an incipient typhus epidemic in
Naples. The American 5th Army had captured the city on
October 1 and found public health conditions deplorable;
by one estimate, 90 percent of the citizens had body
lice. In the next month 25 cases of typhus were
identified; 42 were found in November, and 60 in the
first half of December. The Associated Press reported
the crisis in the United States a few days later and
said that a quarter of the cases had resulted in death.
Although the troops had not suffered any typhus
casualties, humanitarian concerns made it imperative for
the Allies to act quickly.

When the Rockefeller Foundation
Health Commission was called in, a large quantity of the
current production of DDT was earmarked for Naples, with
60 tons dispatched immediately. Commission officers set
up five delousing stations in the city, and on New
Year’s Day 5,000 civilians were dusted using a
hand-operated blower that had been developed and
modified in the North Africa trials. By the end of the
month 1.3 million residents of Naples and the
surrounding region had received insecticidal baths with
DDT and pyrethrum. Typhus continued to fester in
January, began to decline in February, and in March
decreased abruptly to a few cases a day. The epidemic
was over.

In wartime conditions,
DDT’s effectiveness made it indispensable. Yet
even in the glow of impending Allied victory,
disturbing evidence began to crop
up.

Nothing like this result had
ever been seen before. From then on the British and
American armies decreed that “DDT marches with the
troops.” It also proved vitally important in liberated
German concentration camps, where by the spring of 1945
typhus had become rampant.

Important as these triumphs
were, the fight against lice and typhus may ultimately
have been less significant than the fight against
mosquitoes and malaria. After the Allies liberated Rome
and central Italy in June 1944, the Rockefeller
Foundation Health Commission was asked to develop a
malaria-control program, in part because the retreating
German army had destroyed so much of the water-control
system that drained low-lying and marshy areas. Some of
the Rockefeller officers had experience with a pre-war
Rockefeller Foundation antimalaria program in Italy and
knew the terrain and the mosquito habitat quite
well.

The commission decided that the
most likely areas to suffer from malaria, and thus to
impede the war effort in Italy, were the delta of the
Tiber River (which included the port of Ostia, a major
landing point for supplies for the Allied armies) and
the Pontine marshes, which had historically been the
source of malaria infestations for nearby Rome. In both
areas the commission carried out massive DDT campaigns,
hand-spraying the insides of houses and farm buildings
and then moving on to swamps and bodies of water. This
effort was the first time that DDT (mixed with kerosene
or fuel oil) was sprayed from the air to distribute it
quickly and widely. Some malaria developed, but there
was no epidemic. As the European campaign continued, DDT
was also used with effect in battle areas, first by
spraying inside barracks and other military structures
and then with aerial spraying of mosquito breeding zones
near bases.

Now DDT, which had done much to
secure victory for the Allies in Europe, had its turn in
the Pacific. At first it was used in areas behind the
lines, dispensed by hand sprayers. Soon, though, it was
laid down in advance of landing forces, sprayed from
airplanes over coastal zones so that the invading
American forces would not have to worry about insects.
With American production of DDT reaching two million
pounds per month by the end of 1944 (it was now being
manufactured by the giant Du Pont chemical company,
among others), malaria was a minor problem in the last
months of the war. Other diseases spread by insects were
significantly affected by DDT as well. On Saipan, for
example, an epidemic of dengue fever broke out soon
after American troops landed in the late summer of 1944.
It ended after a C-47 sprayed 9,000 gallons of a
kerosene solution of DDT over the island.

With all these successes DDT
came to public notice as one of the most important tools
in the Allied arsenal after the official secrecy about
it ended in July 1944, when Victor Froehlicher of
Geigy’s New York office published a thorough article
about it in a chemical-industry magazine. A month later
Britain, where DDT had been received, investigated, and
manufactured at about the same pace as in the United
States (but in smaller quantities), released a statement
about its military uses. Many British civilians first
heard of DDT from Winston Churchill on September 28,
1944, when, in one of his frequent radio messages, he
rhapsodized about “the excellent DDT powder, which has
been fully experimented with and found to yield
astonishing results.”

In the context of World War
II’s devastation, Churchill’s enthusiastic assessment
made perfect sense. Yet even in the glow of impending
Allied victory, disturbing evidence had begun to crop
up. In 1944 a government installation on a New Jersey
island had been sprayed with DDT to rid it of annoying
flies. This had worked, but along with the flies, the
fish population had been drastically reduced. After the
war, when spraying stopped on one Pacific island,
mosquitoes returned in greater numbers than before
because DDT had wiped out their natural predators. And
worse news was on the way.

In 1946 reports from DDT-soaked
Italy said that flies and mosquitoes were demonstrating
resistance to the pesticide. By 1950 enough was known
about DDT’s possible ill effects on humans for the U.S.
Food and Drug Administration to state that it was
“extremely likely that the potential hazard of DDT has
been underestimated.” The FDA had studied DDT and found
that it tended to accumulate in the fatty tissues of all
animals, including humans. When used on dairy farms for
fly control, it quickly showed up in cows’ milk. The FDA
also found that massive doses of DDT caused nerve
damage, but it was impossible to determine the long-term
effects of the low-level exposure most citizens would
have.

By 1960 some 137 insect
species were known to have developed resistance to
DDT. But resistance was only part of the
problem—the lesser part, it turned
out.

These early hints of trouble
scarcely affected the postwar juggernaut of pesticide
production and distribution. In August 1945, just before
the Japanese surrender, restraints on civilian sales of
DDT ended in the United States, and it quickly spread to
household and agricultural uses. Most people chalked up
DDT’s occasional problems to experience and figured that
adjusting the concentration or the method of application
would solve any problems. And even if a few animals
might die, the improvements in the quality of human life
far outweighed any small costs that might arise.

In the first flush of postwar
giddiness, DDT, just like atomic energy and other
wartime inventions, seemed a miracle. It was employed
against the beetles that carried Dutch elm disease, and
in a few years public health authorities were using it
in mosquito-control programs throughout the country.
Throughout the 1950s the use of DDT for malaria control
expanded globally. First the Rockefeller Foundation led
an experimental attempt to eradicate mosquitoes from
Sardinia, and then the Pan-American Health Organization
(led by the insecticide warhorse Fred Soper) and later
the World Health Organization entered the fray. Early
results were dramatic, as malaria infection rates fell
sharply. The age-old scourge was virtually eliminated
from the Southern United States; worldwide, reliable
estimates suggest that DDT had prevented five million
malaria deaths by 1950. In 1948 MÜller was awarded a
Nobel Prize for his work in discovering the wonder
chemical.

As early as the mid-1950s,
though, it became increasingly clear that DDT would not
be the only answer to the problem of insect-carried
disease. Mosquitoes were not being completely
eradicated; in spite of four years of saturation
spraying in Sardinia, they survived there. Moreover,
insects of all types were developing resistance to DDT.
While the common housefly was one of the most resilient,
by 1960 some 137 species of insect pests were known to
have some level of resistance. The World Health
Organization stated in the 1960s that “resistance is at
present the most important problem” in its
insect-control programs.

But resistance was actually
only part of the problem—the lesser part, as it turned
out. More frightening was the steady accumulation of
evidence that DDT was wreaking environmental damage on a
large scale. Early fish kills following spraying raised
concern, but it took some time for scientists to
understand why the fish had died: some by direct
poisoning, but more because the DDT had killed off their
food supply. Rachel Carson wrote about a massive DDT
campaign to control a spruce budworm infestation in a
watershed in the Canadian province of New Brunswick.
Virtually all the young salmon were killed in a few
days, largely because the insects in the water, on which
they fed, were as susceptible to DDT as the winged
insects it was aimed at.

Over the years, environmental
testing revealed that DDT use had an even more insidious
hazard, one that resulted from the very quality that
made it so effective: its persistence. Because it
deteriorated very slowly, DDT was not just killing
insects but was spreading far up the food chain. By the
time Silent Spring appeared,
in 1962, there were signs that some birds of prey,
particularly fish eaters, were seriously affected by
environmental DDT. Bald eagles and ospreys—large,
beautiful, soaring birds whose nests were familiar
landmarks in coastal waters and inland lakes—had been
driven close to extinction.

As early as 1947 observers
found these birds producing few or no young in areas
where a few years before each nest had regularly yielded
one or two fledglings. Eventually scientists found
evidence that DDT accumulation had interfered with the
egg-making process. In some cases none at all were laid;
in others, eggs were produced but were so fragile that
sitting adults crushed them. Public outcry about the
endangerment of the bald eagle, a national symbol, was a
major reason DDT was banned in the United States in
1972. (By then, of course, epidemics of insect-borne
disease were mostly a thing of the past in this
country.) Since the ban, ospreys and other birds of prey
threatened with extinction have managed to restore their
numbers.

In other parts of the world,
DDT is still a primary insecticide, and eliminating it
is less simple. In fighting the scourge of malaria,
which has been resurgent in the last quarter-century,
DDT is far more affordable and effective than anything
else available. About two dozen developing nations
(including China, India, and Mexico), which together
account for nearly half the world’s population, still
use DDT for house-spraying campaigns. A United Nations
organization has been moving to get DDT banned worldwide
within the next decade, but the Malaria Foundation
International, an organization of more than 350 doctors
and scientists, vehemently opposes such a quick
cutoff.

The foundation argues that
since malaria kills 2.7 million people a year, the price
in human life of such a ban would be too high,
especially since the amounts of DDT being used today are
much lower than in the past. (Spraying all the high-risk
houses in a nation the size of Guyana, for example,
requires no more DDT in a year than would once have been
used on a thousand-acre cotton field.) So there may be
unavoidable public health reasons to continue using DDT
for nonagricultural purposes for at least a while
longer.

The pesticide story is not just
a matter of DDT use, however. One billion pounds of
pesticides and herbicides will be used by American
farmers in 1999, and against all the benefits that they
bring must be balanced the serious environmental damage
they will cause. Approximately 67 million wells in the
United States are contaminated by pesticides in some
degree. Worldwide, after a half-century of heavy use of
DDT and its successors, at least 535 insects have
demonstrated resistance to insecticides.

Alternatives to artificial
pesticides are being examined seriously and applied
extensively in agriculture, though the situation in
disease control is less promising. The use of predatory
insects to control pest species has grown rapidly, and
scientists are researching naturally occurring
pesticides. In March 1999, for example, a newspaper
reported that the federal government’s Agricultural
Research Service had found that “the natural oil that
gives peaches their perfume also kills fungus and other
pests in the soil.”

None of these alternatives is
likely to be a safe, all-purpose magic bullet, any more
than DDT was. Insect immunity will continue to crop up,
and for many applications the simplicity and killing
power of artificial pesticides will make them hard to
resist. As choices proliferate, however, and scientists,
farmers, and the general public gain an everdeeper
understanding of the intricate web of life that makes up
the global ecosystem, we can hope that ways will be
found to keep damage to nontarget species to a minimum
and to ensure that there is no cost in human life.

In early 1999 motorists heading
east near Orlando on 1-4 could see a row of tall
power-line towers, each fitted with a platform at the
top to encourage osprey nesting. There were a dozen or
more platforms, and on almost every one was a pair of
ospreys, newly arrived from their Caribbean wintering
grounds. Their presence creates at least a partial
closing of the circle. In the place where DDT was first
introduced into the American environment, one of the
species believed to be most seriously threatened by it
has made a strong comeback. The Jekyll-and-Hyde chemical
that saved soldiers, sailors, marines, and civilians in
World War II and served as a potent weapon against
malaria, is now fading from the global ecosystem that
found it to be an unprecedentedly serious intrusion.

Darwin H. Stapleton is
the director of the Rockefeller Archive Center in Sleepy
Hollow, New York.

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