When Monsanto genetically engineered corn and soybeans to make them
immune to its best-selling weedkiller, the company pitched the
technology as a way to reduce overall use of herbicides and usher in an
environmentally friendly era of farming.
Instead of relying on
older, more harmful chemicals, farmers could douse their fields with
Roundup, a product that Monsanto once advertised as less toxic than
table salt.
Two decades later, overuse of Roundup has spawned weeds that can
survive spraying to grow 8 feet tall with stems as thick as baseball
bats. To kill those so-called superweeds, chemical giants are giving the
next wave of genetically modified crops immunity to the weedkillers of
generations past.
The technology that was supposed to make those
older herbicides obsolete soon could make it possible for farmers to use
a lot more.
For use on its new genetically engineered corn and
soybeans, Dow Chemical Co. is reviving 2,4-D, a World War II-era
chemical linked to cancer and other health problems.
If these
crops are widely adopted, the government’s maximum-exposure projections
show that U.S. children ages 1 to 12 could consume levels of 2,4-D that
the World Health Organization, Russia, Australia, South Korea, Canada,
Brazil and China consider unsafe.
The U.S. Environmental Protection Agency
had considered that exposure dangerous for decades as well. But the
Obama administration’s EPA now says it is safe to allow 41 times more
2,4-D into the American diet than before he took office.
To reach
that conclusion, the Tribune found, the agency’s scientists changed
their analysis of a pivotal rat study by Dow, tossing aside signs of
kidney trouble that Dow researchers said were caused by 2,4-D.
The
EPA scientists who revised that crucial document were persuaded by a
Canadian government toxicologist who decided that Dow — a company that
has a $1 billion product at stake — had been overly cautious in flagging
kidney abnormalities that she deemed insignificant.
When Dow
later published this study, the company’s scientists likewise dismissed
their earlier concerns and changed the most important measure of the
chemical’s toxicity so it agreed with the EPA’s less stringent view.
These
decisions paved the way for the EPA to approve Dow’s weedkiller Enlist
Duo last year and reassure the public that a surge in 2,4-D use wouldn’t
hurt anyone.
Girding that reassurance are two calculations: How
much of the herbicide is safe for human health, and how much will
Americans wind up consuming? There are ways to tweak each of those risk
calculations. With 2,4-D, the Tribune found, the EPA’s math favored a
dramatic increase in the weedkiller.
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