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filter applied and care taken not to induce hysteria since the results may be
more dangerous than the cure.
A separate indication of exposure is the assessment of the actual usage of
pesticides in agriculture in the 1990s. This will give us a different view on the
kinds of chemicals being used and provide a basis for comparison to earlier
times, like those of Rachel Carson, when usage patterns were different. This
approach is necessary since random monitoring programs, such as the FDA
project discussed above, were not instituted in earlier years and, therefore, no
basis exists for comparisons across time. Analytical methods were different,
and that alone would preclude a fair comparison. Table 3.2 is a tabulation of
the top pesticides used in agriculture in 1974 versus 1993 as compiled by the
EPA s Office of Pesticide Programs. Very similar to the situation above, these
numbers reflect total agricultural usage and include some nonfood crops. In
fact, 75% of all pesticides targeted against insect pests are used on corn and
cotton crops. Note that corn is one vegetable with a 0% incidence of violative
residues as tabulated in Table 3.1.
A close examination of this usage table shows that the herbicide atrazine
has held the number one spot for the last 20 years. This compound is often
used in nonfood crops such as cotton. However, some compounds are notably
absent from the 1993 tabulation, including toxaphene, methyl-parathion, car-
baryl, propachlor, DSMA, linuron, aldrin, carbofuran, chloramben, maneb,
sodium chlorate, propanil, DBCP, malathion, dinoseb, and chlordane. It
should also be noted that DDT, the pesticide on which Silent Spring was
focused and which continues to be used as the example of man s folly with
chemicals, is not on either list. The one generalization that can be made con-
cerning this list of deletions is that most of these pesticides are more persist-
ent than the compounds that replaced them and a significant number of them
are chlorinated hydrocarbons. It is important to keep these compounds in
mind since popular press accounts of pesticide contamination often quote
incidences of exposure to unnamed pesticides and then focus most discussion
50 CHAPTER 3
TABLE 3.2. Top 25 Pesticides Used in 1974 and 1993.
Rank 1974 1993
01 Atrazine Atrazine
02 Toxaphene Metolachlor
03 Methyl Parathion Sulfur
04 Sulphur Alachlor
05 Alachlor Methyl-bromide
06 Petroleum Oil Cyanazine
07 Dichloropropane/ene Dichloropropane/ene
08 2,4-D 2,4-D
09 Butylate Metam sodium
10 Trifluralin Trifluralin
11 Carbaryl Petroleum Oil
12 Propachlor Pendimethalin
13 DSMA/MSMA Glycophosphate
14 Parathion EPTC
15 Linuron Chlorpyrifos
16 Aldrin Chlorothalonil
17 Carbofuran Propanil
18 Chloramben Dicamba
19 Maneb/Mancozeb Terbufos
20 Sodium chlorate Bentazone
21 Propanil Mancozeb
22 DBCP Copper hydroxide
23 Malathion Parathion
24 Dinoseb Simazine
25 Chlordane Butylate
on chemicals that are no longer used in agriculture, many of which are in the
deleted list above.
Table 3.3 is a tabulation of insecticide usage according to chemical class in
the sixties,  the dawn of environmental awareness, versus the eighties. This
tabulation, coupled with the ranking in Table 3.2, gives us an appreciation
that we are using different pesticides now than we were two to three decades
ago. This was when pesticide debates first occurred and when the majority of
today s population was exposed. The use of organochlorines has plummeted
while use of their nonpersistent replacements (organophosphates, car-
bametes, pyrethroids) has increased. So as not to burden the text of this book
with a mountain of technical details, I have put a brief description of the tox-
icology of pesticides in Appendix A for reference. I would urge the reader to
consult it for a more complete review of these compounds, both past and
present.
It is difficult, based on production and sale figures alone, to get a feel for
THE PESTICIDE THREAT 51
TABLE 3.3. Evolution of insecticide usage by chemical class from
1964 to 1982.
Year Organochlorines Organophosphates Carbamates Pyrethroids Other
1964 70 20 080 2
1966 70 22 070 1
1971 45 39 14 0 2
1976 29 49 19 0 3
1982 0667 18 4 5
Data tabulated as % of total usage.
how much chemical is being used on our farms and whether this has
decreased because of these societal pressures. The impact of these processes
and mindset can be appreciated by examining Figure 3.1, which shows a con-
tinuous reduction in the rate of pesticide application (kilograms per hectare)
from 1940 through 1980, a trend that has continued into the present decade.
Pesticides that were once applied in pounds per acre quantities now are used
effectively in grams per acre. We all experience this when we use the potent
herbicide glycophosphate (Roundup®) in our yards. We are using less pounds
per unit of area and significantly different ones than we did only a few
decades ago.
Silent Spring had a significant effect on decreasing the use of chlorinated
hydrocarbons and, whether right or wrong, it singled out this one class of
chemicals as essentially evil. Agricultural practices have significantly changed
with the introduction of Integrated Pest Management (IPM) techniques that [ Pobierz całość w formacie PDF ]