The End of Doom (16 page)

After the war, American consumers and farmers quickly adopted the wonder insecticide, replacing the old-fashioned arsenic-based pesticides, which were truly nasty. Testing by the US Public Health Service and the Food and Drug Administration's Division of Pharmacology found no serious human toxicity problems with DDT. M
ü
ller, DDT's inventor, was awarded the Nobel Prize in 1948.

DDT was soon widely deployed by public health officials, who banished malaria from the southern United States with its help. The World Health Organization credits DDT with saving 50 million to 100 million lives by preventing malaria. In 1943 Venezuela had 8,171,115 cases of malaria; by 1958, after the use of DDT, the number was down to 800. India, which had over 10 million cases of malaria in 1935, had 285,962 in 1969. In Italy the number of malaria cases dropped from 411,602 in 1945 to only 37 in 1968. In 1970, a report by the National Academy of Sciences stated that “to only a few chemicals does man owe as great a debt as to DDT.”

Chemical Agriculture

The tone of a
Scientific American
article by Francis Joseph Weiss celebrating the advent of “Chemical Agriculture” was typical of much of the reporting in the early 1950s. While “[i]n 1820 about 72 per cent of the population worked in agriculture, the proportion in 1950 was only about 15 per cent,” reported Weiss. “Chemical agriculture, still in its infancy, should eventually advance our agricultural efficiency at least as much as machines have in the past 150 years.” This improvement in agricultural efficiency would happen because “farming is being revolutionized by new fertilizers, insecticides, fungicides, weed killers, leaf removers, soil conditioners, plant hormones, trace minerals, antibiotics and synthetic milk for pigs.”

In 1952 insects, weeds, and disease cost farmers $13 billion ($115 billion in today's dollars) in crops annually. Since gross annual agricultural output at that time totaled $31 billion ($276 billion in today's dollars), it was estimated that preventing this damage by using pesticides would boost food and fiber production by 42 percent. Agricultural productivity in the United States, spurred by improvements in farming practices and technologies, has continued its exponential increase. In the second decade of the twenty-first century, US crop yield was 360 percent higher and farmers produced 262 percent more food using 2 percent less inputs like labor, seeds, fertilizer, and feed than they did in 1950. As a result, the percentage of Americans living and working on farms has dropped from 15 percent in 1950 to under 2 percent today.

But DDT and other pesticides had a dark side. They not only killed the pests at which they were aimed but sometimes killed beneficial creatures as well. The scientific controversy over the effects of DDT on wildlife, especially birds, still vexes researchers. In the late 1960s, some researchers concluded that exposure to DDT caused eggshell thinning in some bird species, especially raptors such as eagles and peregrine falcons. Thinner shells meant fewer hatchlings and declining numbers. But researchers also found that other bird species, such as quail, pheasants, and chickens, were unaffected even by large doses of DDT. Carson, the passionate defender of wildlife, was determined to spotlight these harms. Memorably, she painted a scenario in which birds had all been poisoned by insecticides, resulting in a “silent spring” in which “no birds sing.”

First, let's acknowledge that Carson was right about some of the harms that extensive modern pesticide use could and did cause. Carson was correct that the popular pesticide DDT did disrupt reproduction in some raptor species. It is also the case that insect pests over time do develop resistance to pesticides, making them eventually less useful in preventing the spread of insect-borne diseases and protecting crops. In fact, the first cases of evolving insect resistance were identified in California orchards at the beginning of the twentieth century, when species of scale insects became resistant to the primitive insecticides lime sulfur and hydrogen cyanide. By 1960, 137 species of insects had developed resistance to DDT. To preserve their usefulness, pesticides clearly needed to be more judiciously deployed.

To her discredit, however, Carson largely ignored the great good modern pesticides had done, especially in protecting human health by controlling insect-borne scourges such as typhus and malaria. Barely ten years before the publication of
Silent Spring
the then-new Centers for Disease Control had finally eradicated malaria in the southeastern region of the United States in 1951. Spraying with DDT to control mosquitoes has been central to the CDC's success. Unfortunately, Carson's unwillingness to fairly balance the costs and benefits of new technologies would become a hallmark of the modern environmental movement.

Rachel Carson: Cancer Scaremonger

As a polemicist, Carson realized that tales of empty birds' nests and warnings about pesticide-resistant bugs and weeds were not enough to spur most people to fear the chemicals she opposed. The 1958 passage by Congress of the Delaney Clause, which forbade the addition of any amount of chemicals suspected of causing cancer to food, likely focused Carson's attention on that disease.

For the previous half century some researchers had been trying to prove that cancer was caused by chemical contaminants in the environment. Wilhelm Hueper, chief of environmental cancer research at the National Cancer Institute and one of the leading researchers in this area, became the major source for Carson. “Dr. Hueper now gives DDT a definite rating as a ‘chemical carcinogen,'” according to Carson. After reviewing the extensive epidemiological and experimental literature, the highly precautionary International Agency for Research on Cancer has now determined that DDT is as carcinogenic as coffee. Oddly, Hueper was so blinkered by his belief that trace exposures to synthetic chemicals were a major cause of cancer in humans that he largely dismissed the notion that smoking cigarettes increased the risk of cancer.

The assertion that pesticides were dangerous human carcinogens was a stroke of public relations genius. Even people who do not care much about wildlife care a lot about their own health and the health of their children.

In 1955 the American Cancer Society (ACS) predicted that “cancer will strike one in every four Americans rather than the present estimate of one in five.” The ACS straightforwardly attributed the increase to “the growing number of older persons in the population.” The ACS did note that the incidence of lung cancer was increasing very rapidly, rising in the previous two decades by more than 200 percent for women and by 600 percent for men. But the ACS also noted that lung cancer “is the only form of cancer which shows so definite a tendency.” Seven years later, Rachel Carson would cannily entitle her chapter on cancer “One in Four.”

William Souder, author of a new biography of Carson,
On a Farther Shore,
also notes that Carson's fight against pesticides became personal. “In 1960, at the halfway point in writing
Silent Spring,
just as she was exploring the connection between pesticide exposure and human cancer, Carson was herself stricken with breast cancer.” Given the relatively primitive state of medicine in the 1950s, few diseases were scarier than cancer. And deaths from cancer had been rising steeply. Carson cited government statistics showing that cancer deaths had dramatically increased from 4 percent of all deaths in 1900 to 15 percent in 1958.

“The problem that concerns us here is whether any of the chemicals we are using in our attempts to control nature play a direct or indirect role as causes of cancer,” wrote Carson. Her conclusion was that “the evidence is circumstantial” but “nonetheless impressive.” She added the claim that in contrast with disease germs, “man
has
put the vast majority of carcinogens into the environment.” She noted that the first human exposures to DDT and other pesticides were barely more than a decade in the past. It takes time for cancer to fester, so she ominously warned, “The full maturing of whatever seeds of malignancy have been sown by these chemicals is yet to come.” She further warned that we were “living in a sea of carcinogens.”

Even though Carson vaguely acknowledged the paucity of evidence that man-made chemicals like pesticides were actually causing cancer, she was clearly urging policymakers and the public to take what would now be called precautionary action.

Before the decade of the 1960s was over, activists like population doomster Paul Ehrlich would imaginatively transform and heighten the fears of synthetic chemicals initially spawned by Carson. In his luridly dystopian 1969 “Eco-Catastrophe” article, Ehrlich posited that by 1973 US federal government health officials would estimate “that Americans born since 1946 (when DDT usage began) now had a life expectancy of only 49 years, and predicted that if current patterns continued, this expectancy would reach 42 years by 1980, when it might level out.”

In any case, hinting at cancer doom decades away was not frightening enough. Carson cherry-picked cases in an effort to show that pesticides could wreak their carcinogenic havoc much sooner rather than later. For evidence she cited various anecdotes, including one about a woman “who abhorred spiders” and who sprayed her basement with DDT in mid-August. The woman died of acute leukemia a couple of months later. In another passage, Carson cites a man embarrassed by his roach-infested office who again sprayed DDT and who “within a short time … began to bruise and bleed.” He was within a month of spraying diagnosed with aplastic anemia. Today cancer specialists would dismiss out of hand the implied claims that these patients' cancers could be traced to such specific pesticide exposures.

To bolster these frightening anecdotes, Carson cited data that deaths from leukemia had increased from 11.1 per 100,000 in 1950 to 14.1 in 1960. Leukemia mortality rose with pesticide use; very suspicious, no? “What does it mean? To what lethal agent or agents, new to our environment, are people now exposed with increasing frequency?” asked Carson. Fifty years later the death rate from leukemia is 7.1 per 100,000—half of what Carson cited in
Silent Spring
. In fact, the incidence rate is now 13 per 100,000.

Carson surely must have known that cancer is a disease in which the risk goes up as people age. And thanks to vaccines and new antibiotics, Americans in the 1950s were living much longer, long enough to get and die of cancer. In 1900 average life expectancy was forty-seven, and the annual death rate was 1,700 out of 100,000 Americans. By 1960, life expectancy had risen to nearly seventy years, and the annual death rate had fallen to 950 per 100,000 people. Currently, life expectancy is more than seventy-eight years, and the annual death rate is 790 per 100,000 people. Today, although only about 13 percent of Americans are over age sixty-five, they account for 53 percent of new cancer diagnoses and 69 percent of cancer deaths. Another way to think about the relationship of cancer incidence to increasing age is to note that the incidence per 100,000 men is 60 for men between ages twenty and thirty-nine, 552 for men between ages forty and sixty-four, and 2,893 for men over age sixty-five. The incidence figures per 100,000 women are 89 for women whose age is between twenty and thirty-nine, 555 for those aged between forty and sixty-four, and 1,707 for women over age sixty-five.

Carson realized that even if people didn't worry much about their own health, they did really care about that of their kids. So to ratchet up the fear factor even more, she asserted that children were especially vulnerable to the carcinogenic effects of synthetic chemicals. “The situation with respect to children is even more deeply disturbing,” she wrote. “A quarter century ago, cancer in children was considered a medical rarity.
Today, more American school children die of cancer than from any other disease
[her emphasis].” In support of this claim, Carson reported that “twelve per cent of all deaths in children between the ages of one and fourteen are caused by cancer.”

Although it sounds alarming, Carson's statistic is essentially meaningless unless it's given some context, which she failed to supply. It turns out that the percentage of children dying of cancer was rising because other causes of death, such as infectious diseases, were drastically declining. The American Cancer Society reports that about 10,450 children in the United States will be diagnosed with cancer in 2014 and that childhood cancers make up less than 1 percent of all cancers diagnosed each year. Childhood cancer incidence has been rising slowly over the past couple of decades at a rate of 0.6 percent per year. Consequently, the incidence rate increased from 13 per 100,000 in the 1970s to 16 per 100,000 now. There is no known cause for this slight increase. The good news is that 80 percent of kids with cancer now survive five years or more, up from 50 percent in the 1970s.

Cancer Incidence Rates Are Falling

Did cancer doom ever arrive? No. In fact, cancer incidence rate fell. According to the Centers for Disease Control and Prevention, age-adjusted incidence rates have been dropping for nearly two decades. Why? Largely because fewer Americans are smoking, more are having colonoscopies in which polyps that might become cancerous are removed, and in the early 2000s many women stopped hormone replacement therapy. With regard to hormone replacement therapy, researchers have now concluded it moderately increases the risk of breast cancer.

Back in the early 1990s, based on sketchy research, environmentalists began pushing the hypothesis that past exposure to organochlorine pesticides, such as DDT, was fueling a breast cancer epidemic. However, after years of research a major review article in 2002 in the journal
CA: A Cancer Journal for Clinicians
reported that exposure of organochlorine compounds “is not believed to be causally related to breast cancer.”

With regard to overall cancer risks posed by synthetic chemicals, the American Cancer Society in its 2014
Cancer Facts and Figures
report on cancer trends concludes: “Exposure to carcinogenic agents in occupational, community, and other settings is thought to account for a relatively small percentage of cancer deaths—about 4 percent from occupational exposures and 2 percent from environmental pollutants (man-made and naturally occurring).”