US set to endorse human pesticide testing

[Guest guest]

Nature 437, 24-25 (1 September 2005) | doi: 10.1038/437024a

 

 

Meredith Wadman

 

Pesticide manufacturers are pushing hard to ensure that data from

toxicity tests on people can be used in licence applications for

their products.

 

The pesticide industry is keenly awaiting an imminent US ruling.

Within days, the Environmental Protection Agency (EPA) is expected to

publish its proposed policy on the use of human subjects in tests to

assess the safety of pesticides.

 

The $10-billion industry has plenty riding on the details of this

regulation. It wants to use human toxicity data to help it keep at

least a dozen pesticides on the market. These products must pass new

safety hurdles with the EPA by next August or face being banned or

restricted.

 

Perhaps as important, a formal EPA policy governing company-sponsored

human tests would give an unprecedented government seal of approval

to the controversial practice. Critics predict that this will

encourage companies to conduct human toxicity tests on a wide range

of some 1,200 active pesticide ingredients now on the market, with

the aim of loosening their regulation.

 

Pesticide manufacturers say that human data are vital for fair,

science-based regulation of their products. Tests on humans " provide

very valuable insights into exactly what happens when humans are

exposed to low levels of a compound " , argues Ray McAllister, an

agronomist and policy analyst at CropLife America, a Washington-based

lobby group that represents the US pesticide industry. This, he says,

reduces the uncertainty inherent in relying only on animal tests.

 

Independent scientists have backed the industry, with careful

caveats. Most notably, the National Research Council in a 2004 report

concluded that human test data could be used by the EPA, if strict

ethical and scientific standards were met (see Nature 427, 770; 2004).

 

But environmental groups such as the Natural Resources Defense

Council (NRDC) are scathing in their criticism of human experiments.

They say that the industry wants to conduct them not for the public

good, but to keep threatened products on the market. They point out

that the use of human data could allow the industry to neutralize

additional requirements dating from 1996 that govern the allowable

levels of pesticide residues on food. Those rules set the levels ten

times lower than their previous value — the human data could reverse

that change for many products, experts say.

 

Some scientists also argue that there are few circumstances in which

such studies can be ethical, and that the EPA should not accept data

from them.

 

" Human dosing studies have failed to meet widely accepted ethical

standards for the conduct of research, " says Alan Lockwood, a

neurologist at the University at Buffalo, New York, who has closely

examined six of the company-conducted studies. " There is no assurance

that any such study can be completely free of risk. "

 

The human factor

The new EPA rule — which will remain provisional during a 90-day

period of public comment — will mark a key moment in a decade-long

political battle between pesticide makers and their critics. Congress

joined the fray this year, when two Democrat senators blocked the

nomination of Stephen Johnson as EPA administrator until he agreed to

cancel a study on children.

 

Last month, a law came into effect that commands the EPA to finalize

the rule within six months, and forbids it from considering human

data in the interim. That bill was seen as something of a victory for

pesticide makers, as they managed to head off a one-year moratorium

sought by critics.

 

The current debate stems from a 1996 law that made it much harder for

companies to meet EPA safety standards using animal tests alone. The

Food Quality Protection Act was intended to tighten standards to

protect vulnerable people such as children and babies from pesticide

residues on food. But it encouraged pesticide makers to resume some

human tests — which they had largely abandoned — and to resurrect

data from studies dating as far back as the 1960s.

 

Concerned by this turn of events, the EPA launched a de facto

moratorium on the use of human test data in 1998, which was

formalized in 2001. The pesticide makers sued the agency and won, and

since 2003, the EPA has considered human data on a case-by-case basis.

 

As of June this year, 24 human studies had been presented to the EPA

by pesticide companies. Most have not been published, but opponents

have criticized their ethics after the EPA produced them in response

to demands from Congress. Some bioethicists have also criticized what

they see as deficient informed-consent procedures, inadequate

statistical power and financial conflicts of interest.

 

Several of the studies, for example, were done in Britain by Bayer,

the world's largest pesticide manufacturer. In 1998 and 1999, it paid

contractors to conduct three human dosing experiments using its

pesticide azinphos methyl, an organophosphate that is used on 73% of

US apples and more than half of US pears, cherries and blueberries.

In high doses, it can lead to convulsions and death.

 

In a letter to one potential study participant, the pesticide was

described as a " drug " that would be " administered orally " . In a

volunteer information sheet for another of the studies, nausea,

vomiting and stomach cramps were listed as possible side effects, but

weakness, respiratory failure and death were not.

 

Bayer declined to comment on the particulars of its studies, but in

the past it has defended them as meeting international ethics

requirements.

 

The studies have formed an important part of Bayer's pitch to save

azinphos methyl from the axe under the tighter safety rules of 1996.

In 2001, the EPA banned dozens of uses of the pesticide, but allowed

its application to 15 crops to continue. It is those applications

that the company is now fighting to retain.

 

Last November, in a key battle in this struggle, a dozen Bayer

officials met with 15 EPA regulators at the company's request.

Bayer's officials used the British studies to argue that the

allowable levels for people's exposure to the pesticides' residues

should be 17 times higher than they are at present. The EPA's

decision is due by next August. In the meantime, anti-testing

activists say that the imminent EPA rule accepting human data would

make such meetings commonplace.

 

A leaked draft of the regulations circulated in Washington last

month. It would allow the EPA to consider human data from the

industry provided the tests meet current ethical standards. Earlier

studies would also be admissible as long as they met the ethical

standards of their day.

 

" If the rule stays as this draft has proposed, the floodgates will

open for human testing, " warns Erik Olson, a lawyer for the NRDC.