Legacy of DDT hangs over Mexicans
Promise of ban rekindles debate over '91 toxic fire, effects
By RICARDO SANDOVAL / The Dallas Morning News
CÓRDOBA, Mexico – For the last decade, Dr. Jorge Arturo de León
has methodically recorded the impact of a fire that consumed a pesticide
facility in a
residential neighborhood in this mountain city 150 miles east of Mexico City.
No one died on May 3, 1991, when the Anaversa plant was engulfed in
flames, igniting countless barrels of chemicals. But throughout the day,
plumes of acrid
smoke wafted through the homes of about 10,000 people in a neighborhood with six schools, two day-care centers, a bustling open-air vegetable market and a
health clinic. At least 300 people were hospitalized.
In the years since, Dr. de León has examined 1,500 residents.
He has logged a dozen cases of leukemia, at least eight serious birth defects
and half-dozen cases of reproductive disorders in young women – including an 8-year-old who began menstruating not long after the fire.
The rates and types of illness that have struck Córdoba since
the Anaversa fire are consistent, Dr. de León said, with acute exposure
to organo-chlorines, a group of
chemicals of which DDT – dichloro-diphenyl-trichloroethane – is the best known.
People in the working-class neighborhood have lost count of cancers
in their midst, but they know that four volunteer firefighters from one
station house have died of
cancer. The firefighters had rushed to battle the blaze even though they lacked training in hazardous materials fires, wore no masks and only short-sleeved shirts and
regular pants with their fire helmets.
Sometime before the end of 2002, Mexico has promised to do away with
the last of its official supply of DDT. The promised action has rekindled
debate over the
chemical's legacy in Mexico, where for decades it was the weapon of choice in the war against malaria and crop-killing bugs.
DDT has spawned a whole line of pesticides. The first major substance
to come out of World War II weapons research, DDT spawned a host of chemical
many of them now banned as well because of concerns over their impact on human health.
Some organo-chlorines were burned into the atmosphere in Córdoba
11 years ago, although there is a strong dispute over whether DDT itself
was present. Dr. de
León and neighbors say it was there, based on the words of former plant workers and Dr. de León's tests, which showed high levels of organo-chloride residues in
the community. Anaversa officials, however, strongly denied that DDT was stored in Córdoba.
The Anaversa plant was boarded up after the fire, and the company moved to a rural site an hour's drive from Córdoba.
The Córdoba debate is emblematic of the controversy that's dogged DDT since Rachel Carson's 1962 book Silent Spring exposed its threat to animals.
The United States banned the chemical in 1972. In Mexico, its use on
farms was suspended in the 1980s, although it was routinely sprayed by
workers against mosquitoes up until 1997.
DDT is on an international list of chemicals known as PBTs, or persistent,
bioaccumulative and toxic. And while it is not as immediately poisonous
to humans as other
farm chemicals, traces of the chemical can persist for years, locking themselves into everything from groundwater to human fat tissue.
DDT was first used 57 years ago against mosquitoes in Brazil, where
its effectiveness guaranteed its place on the front lines against malaria.
found it a strong killer of a variety of bugs. But the pesticide soon lost its punch as insects became resistant. Farmers and government health workers responded by
spraying even more DDT.
DDT's health impact
Scientists are divided on DDT's impact on human health. Opinions range from it being a clear and persistent poison, to it being less toxic than a pack of cigarettes.
Today only one plant in India legally makes DDT, as each year it's banned in more developing nations.
A growing amount of the fresh fruits and vegetables sold in the United
States comes from Mexican farmers, especially in winter months when U.S.
declines. In recent years DDT and several other chemicals banned on farms have shown up as residues on imported foods tested by the U.S. Food and Drug
Administration, but in trace amounts well within acceptable U.S. standards, officials have said. Still, enviornmentalists have complained that the FDA tests are flawed
and check less than 3 percent of imported fruits and vegetables.
For anti-pesticide advocates such as Dr. de León, DDT's negative
legacy is easily seen in studies of mother's milk, dating to 1975, which
have shown persistent
levels of the pesticide throughout Mexico.
The most recent study was published in 2000 by a group of Mexico City
obstetricians. They tested the milk of 10 low-income women who had just
given birth and
found DDT in each, at concentrations up to almost three times the level considered acceptable by international standards.
The results don't surprise Dr. de León, a toxicologist with 30
years' experience in medical research and teaching at the National Autonomous
University of Mexico.
He cited government reports that even after the U.S. ban on DDT, Mexico continued its production and farmers sprayed nearly 7,000 tons of the pesticide, while
anti-malaria workers sprayed another 226,000 tons through 1993.
Despite suspicions that DDT and other organo-chlorines are potential
long-term health threats, some scientists dispute its negative effects.
A few even argue for its
return to active duty against malaria, dengue and other diseases.
Used against malaria
"Critics of DDT who never offered an alternative should understand that
for its time, it was the only solution to malaria – which around the world
still kills a person
every two seconds or so," said Jorge Mendez, a physician and chief of Mexico's anti-malaria squad in the Ministry of Health.
Dr. Mendez was a longtime advocate of DDT's use. As late as two years
ago – well after Mexico joined the list of nations that have banned the
Mendez urged the government to preserve its remaining stock of DDT in case of a massive outbreak of malaria.
Dr. Mendez now wants to destroy Mexico's DDT, but not because he thinks it's bad. The pesticide, in hindsight, became obsolete long ago, he said.
"We just did not know any better," Dr. Mendez said. "After the first
three or four years of its use, we never reviewed our strategy against
malaria and just became
comfortable using more and more of the chemical."
Mexico now insists it has developed nonchemical methods to clean rivers where malaria-carrying mosquitoes thrive.
Dr. de León and his patients in Córdoba shudder at the
suggestion that deaths and illnesses in their neighborhood are acceptable
collateral damage in a greater war
against farm pests and disease.
"My daughter is a blessing from God, but careless men and the chemicals
that kill more than just mosquitoes did this to her," said Rita Franco
Velázquez, 36, who is
a lifelong Córdoba resident.
She became pregnant two years after smoke from the fire settled like a thick fog over her house and lingered for most of the day.
Despite a family history free of major disease, María Rita was born in 1994 with a deformed skull and no fingers or toes.
In a telephone interview, an Anaversa manager insisted that government
health experts found no traces of DDT or any other organo-chlorines 11
Managers later acknowledged, however, that two relatives of DDT had been stored at the plant.
"It's a closed matter," said plant manager Luis Javier Quijano. "The
federal and state governments investigated and over 10 years tested the
water, soil and air around
the plant and found no damage and no ill effects."
Dr. de León insists that the government toxicological sampling did not test for organo-chlorines like DDT.
Furthermore, Anaversa neighbors and firefighters who fought the blaze
said official investigators skipped sections of the community, even after
the Mexican Human
Rights Commission urged that they be included.
The issue is being sorted out in a protracted lawsuit now before the
International Commission for Human Rights. Independent human-rights activists
in Mexico await
the results of Dr. de León's study, to be published this spring, in order to press for compensation on behalf of the Córdoba neighborhood.
Mexican government officials say nothing publicly about the Córdoba
fire, except that it taught valuable lessons on preventing future accidents.
The company was
fined about $10,000.
Environmentalists say the Córdoba fire remains the strongest
proof of Mexico's poor history of regulation of pesticides. Their doubts
are supported by a 1997
document – an internal audit of Mexico's pesticide regulatory agencies – that said the government could not properly account for how pesticides were used and
Monitoring has improved since, environmentalists say, but they express concern that Mexico relies too much on industry self-regulation.
In Córdoba, fears of the effects of the Anaversa fire remain.
"Our men were healthy, at the peak of their life," Capt. José
Luís Martínez Arreola said while leafing through a photo
album containing grainy portraits of the
firefighters who have since died. "Four of the 34 men who went there to save others died of cancer.
"How can the experts explain so many deaths from one station? How can
we believe them when they say DDT was not there, or at least some other
chemicals they don't want to admit they had? We are all concerned because we don't know what else these chemicals are going to do to us."