How many people are killed each year by pesticides
in and on food in the U. S. ?

Peter Montague
Environmental Research Foundation
Phone: (410) 263-1584

This is a difficult question chiefly because the available data are
poor. When the National Academy of Sciences (NAS) broached this question
in 1987, they found "very limited actual data" (NAS, pg. 59) regarding
pesticide residues in food. In other words, no one is paying close
attention to the quantities of pesticides in the American diet.
Furthermore, NAS found that they could estimate the oncogenic potency
(cancer-causing ability) for only about half the pesticides that EPA had
identified as oncogenic. (NAS, pg. 51) For the other half, data were not
available on oncogenic potency, so cancer risks could not be assessed.

The NAS study restricted itself to pesticides in and on food. It
omitted pesticide exposures that occur as a result of drinking
pesticide-contaminated ground water (NAS, pg. 45), a phenomenon that is
common in parts of the U. S.

Herbicides
According to the NAS, about 480 million pounds of herbicides are
used annually in the U. S.; of these, 300 million pounds (62.5%) are
agents that "the EPA [U. S. Environmental Protection Agency] presumes to
be oncogenic or for which positive oncogenicity data are currently under
review by the agency." (NAS, pg. 46). This estimate omits two
large-volume herbicides, atrazine and 2,4-D, because EPA (and NAS)
received data indicating oncogenicity of these chemicals after the NAS
study was completed. (NAS, pg. 47)

Insecticides
Quantities of oncogenic insecticides are not described in detail in
the NAS study. Insecticides are described in terms of acre treatments; one
acre-treatment is defined as one acre to which one pesticide has been
applied one time. NAS says that presumed oncogens make up between 35% and
50% of all insecticidal acre-treatments. (NAS, pgs. 47-48)

Fungicides
About 90% of all fungicides show positive results in oncogenicity
assays. These oncogenic fungicides represent from 70 million to 75 million
of the 80 million pounds of all fungicides applied annually in the U. S.
(NAS, pg. 48)

The NAS committee worked with a 1985 list of 53 pesticides that EPA
considered oncogenic. (NAS, pg. 50) Of these 53, an estimate of
oncogenic potency was only available for 28 of the 53, or 53%. (NAS, pg.
51) In other words, NAS found that it could not estimate the risks for 47%
of the pesticides that EPA identified as oncogenic because necessary data
on oncogenic potency were not available. The NAS restricted its analysis
to the 28 pesticides for which data existed. NAS used EPA's data and EPA's
risk assessment methods (NAS, pg. 46)

NAS says that, in doing risk assessments, EPA "tries to make
necessary assumptions in a way that minimizes the chance of underestimating
risks." (NAS, pg. 50) "The result is that these [NAS] risk
assessments probably overstate true oncogenic risk," NAS said. (NAS, pg.
50)

Risk refers to incidence of cancer cases, not death. (NAS, pg.
65)

The NAS said there are 4 reasons why its risk estimates may
overstate the risk, and four reasons why its estimates may understate the
risk.

Reasons why NAS estimates may overstate the risk:

** In extrapolating from high-dose tumor incidence data to
low-dose estimates, conservative assumptions have been made;

** NAS assumed that all acres of all crops are treated with the
pesticides which are registered for use on those crops;

** NAS assumed that residues are always present at the legally
allowable level, when in fact they are usually present at lower levels;

**NAS assumes that daily exposure occurs during a 70-year lifetime.
(NAS pg. 65)

Reasons why NAS estimates may underestimate the risk:

** NAS lacked toxicological data for some active ingredients and
for most "inert" ingredients, degradation products, and metabolites;

** The models used for extrapolating from animal data to humans
may have been insufficiently conservative in some respects;

** Certain routes of exposure were omitted.

** Possible synergistic (multiplier) effects of pesticides and
metabolites were omitted from consideration. (NAS, pgs. 65-66)

In Table 3-9 (NAS, pg. 68), NAS gives the lifetime cancer
risks for each of the 28 pesticides. Totaling these risks yields a
combined risk estimate of 5.8 per thousand (5.84 X 10-3). This total
risk is given again in Table 3-16 on NAS pg. 74.

Because this is a total lifetime risk (premised on a 70-year
lifetime--see NAS pg. 64), it must be divided by 70 to yield an annual
risk. Thus the annual risk is 8.34 X 10-5 (or 0.0000834). Multiplying
this times the total U. S. population (roughly 250 million people) yields
an annual rate of pesticide-related cancers of 20,800.

The National Cancer Institute (NCI) estimates that in 1990,
1,040,000 new cases of cancer occurred among Americans, and 505,295
Americans died of cancer; thus, according to NCI, roughly 48.6% of those
who get cancer die of it. (NCI, Table I-3, pg. I. 27.) Applying that
percentage to the estimated 20,800 pesticide-related cancers yields an
estimate of 10,100 pesticide-related cancer deaths in the U. S. per year.

This is the best estimate that we know of today.

This estimate needs to be tempered by certain other facts, such as:
Some of the pesticides considered by the NAS are no longer in use. On
the other hand, some oncogenic pesticides used today in large volume
(e.g., atrazine, and 2, 4-D) were not included in the NAS evaluation.

Pimentel presents an estimate that 10,000 cancer cases are caused
each year in the U. S. by exposure to pesticides. (PIMENTEL, pg. 49)
This estimate appears to consider exposure of farm workers as well as
consumers of pesticide-treated food, but this is not entirely clear from
the way the information is presented. If 48.6% of these people died of
their disease, this would put Pimentel's estimate of annual
pesticide-related deaths in the U. S. at 4,860.

Pimentel points out that actual residue levels in food may be
higher than presently estimated because "U. S. analytical methods now
employed detect only about one-third of the more than 600 pesticides in
use." (PIMENTEL, pg. 49)


REFERENCES


NAS: Richard Wiles and others, "Regulating Pesticides in Food; The
Delaney Paradox" (Washington, D. C. : National Academy Press, 1987).
This study is limited oncogenic risks from residues of currently-registered
pesticides in or on food. (NAS, pg. 45)

NCI: Barry A. Miller and others, editors, "Cancer Statistics Review
1973-1990" [National Institutes of Health Publication No. 93-2789]
(Bethesda, Md.: National Cancer Institute, 1993).

PIMENTEL: David Pimental and Hugh Lehman, editors, "The Pesticide
Question; Environment, Economics and Ethics" New York and London:
Chapman & Hall, 1993)

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