争议在继续，警告仍有效

梅·贝伦鲍姆著

或许今天很少人还会记得1962年的非小说类最畅销书，尽管围绕它曾经丑闻纷纷扬扬。那是一本饮食指南，名为《卡路里无关紧要》（Calories Don’t Count），当时的销售量达两百多万本。该书作者赫尔曼·特勒（Herman Taller）五年后锒铛入狱，因无根据地宣称红花油胶囊可减少随意摄入无碳水化合物卡路里的作用而被判邮件欺诈、违反药物规定和阴谋罪。

而同年出版的另一本非小说类书虽然在销售量上望尘莫及，但其影响力却持久得多，至今仍为众人所知。这本书是：《寂静的春天》。该书作者在1962年已是一位畅销科普作家，去世43年后，她的名字仍然家喻户晓。这本书的不朽影响之一是，它引起公众对滥用杀虫剂的环境后果产生极大关注，增强了对氯代烃滴滴涕的抵制，而且在宏观上使环境运动得到振兴和更强大。

这本书传递的核心信息­——过度依赖控制害虫的某一策略可产生不利的环境影响——并不新奇。当时的昆虫学刊物对这一点其实已经有详细论述。然而，是卡森这位有灵感和天赋的作家以普通大众能够理解——更重要的是，能够体会——的语言，对这个问题作出解释。她告诉人们，在喷洒杀虫剂消灭昆虫或其他物种的同时，也杀死了鸟类和其他无辜生物，可与此同时，杀虫剂所要消灭的物种已经对这些化学物品产生了抗药性。虽然杀虫剂的目标是农作物害虫，但它也会殃及蚯蚓，而知更鸟吃了一定数量的有毒蚯蚓也会死亡。没有鸟儿的歌声，寂静的春天随之降临。

她的话深入人心。在《寂静的春天》首次以连载形式在《纽约客》杂志上发表不到一年，美国各地的州立法机构共提出了40多个控制使用滴滴涕和其他合成有机杀虫剂的议案。1972年，在卡森去世八年后，新成立的环境保护署宣布禁止在国内使用滴滴涕。

被误会的信息

《寂静的春天》很快成为一本极具争议性的书。杀虫剂行业和其他支持对害虫进行化学控制的势力迅速作出反击。他们指称卡森是一个不负责任的歇斯底里者，她的极端主义观点和对科学证据有选择的引用威胁国家的健康和福祉。

奇怪的是，争论双方的许多人仍然没有十分理解《寂静的春天》一书的中心思想。卡森并不是蚊子或一般昆虫的爱好者，而且事实上从未提倡放弃化学控制方法。在《寂静的春天》的第12页，她清清楚楚地写道：“我的意图并不是要绝对不使用化学杀虫剂。我确要指出的是，我们把有毒的和对生物影响力极大的化学物质不加区分地交到对其危害性基本或完全无知的人手中。”

实际上，针对控制疟疾她提出，应该让使用滴滴涕的人 “尽量少喷”而不是“尽量喷”。

《寂静的春天》所主张的绝不是要建立无化学自然天堂的极端主义，而是有说服力地请求人们“少量、有选择和明智地使用化学物质”；1963年她在《奥杜邦》（Audubon）杂志上发表的一篇不广为人知的文章中表明了这一观点。

这种“知情使用”的方法其实是今天普遍采用的对各类害虫的控制方法——“害虫综合防治法”（IPM）———的基础。害虫综合防治法，顾名思义，是综合调动多重有效策略——化学的、文化的和生物的，从而形成一个生态有保障、社会可接受、经济上可行的方案。

卡森的主题思想是要有节制。这完全算不上激进——实际上它可追根溯源到古希腊时期，但它应与今天任何一种关于环境技术的讨论产生共鸣。就此而言，它同样可以很好地适用于当前进行的仍具争议的关于卡路里和控制体重的讨论。

研究在继续

自《寂静的春天》初次问世后的半个世纪以来，人们对合成有机杀虫剂的毒性及其对环境的影响有了更多认识，其中很多来自在卡森和与她观点相同的人的启发下所展开的研究。滴滴涕，第一种，也是名声最昭著的氯代烃类农药，今天仍然富于新闻性和争议性。

Decades ago DDT was used indiscriminately, including in aerosol cans for spraying against houseflies. (© AP Images)

(The following article is taken from the U.S. Department of State publication, Rachel Carson.)

A Persistent Controversy, a Still Valid Warning
By May Berenbaum

Probably few people today remember the best-selling nonfiction book of 1962 despite the scandal that surrounded it. The book, a diet guide titled Calories Don't Count, sold more than two million copies. Its author, Herman Taller, was spectacularly convicted of mail fraud, drug violations, and conspiracy charges five years later over unsubstantiated claims regarding the efficacy of safflower-oil capsules in mitigating the effects of unfettered carbohydrate-free calorie intake.

Although it didn't sell nearly as well, another nonfiction book published that year has had a much more lasting impact; its title, Silent Spring, is recognizable today, and its author, already in 1962 a best-selling popular science writer, remains a household name 43 years after her death. Among the book's legacies are heightened public concern about the environmental consequences of pesticide abuse, including strengthened opposition to one pesticide in particular, the chlorinated hydrocarbon DDT, and more broadly a revitalized and empowered environmental movement.

The book's core message – that over-reliance on a particular pest-control strategy could have adverse environmental effects – was hardly novel. Indeed, it was well documented in the entomological journals of the time. But Carson, an inspired and gifted writer, explained this idea in terms the general public could comprehend and, more importantly, feel. Spraying to eliminate insects or other target species, she explained, also kills birds and other nontarget organisms, even as the target species evolves resistance to the chemicals. Although aimed at a crop pest, a pesticide can inadvertently contaminate earthworms, which in turn if eaten in sufficient quantity can kill robins. Without birdsong, a Silent Spring ensues.

The public took her words to heart. Less than a year after Silent Spring first appeared serialized in the New Yorker magazine, more than 40 bills aimed at controlling use of DDT and other synthetic organic insecticides had been introduced in state legislatures across the United States. In 1972, eight years after Carson's death, the newly established Environmental Protection Agency banned the domestic use of DDT.

Message Misunderstood

Silent Spring quickly proved a controversial book. The pesticide industry and other supporters of chemical controls of pests reacted swiftly and negatively to its publication. They branded Carson an irresponsible hysteric whose extremist views and selective presentation of scientific evidence threatened the health and welfare of the nation.

Even today Rachel Carson's name is a lightning rod for chemical pesticide supporters. Recent efforts to reintroduce DDT to control disease-carrying mosquitoes in malaria-ravaged parts of Africa have returned Silent Spring to center stage. The resulting often intemperate debate eerily mirrors the controversies of a half-century ago.

Oddly enough, many people on both sides of the debate still don't quite understand the central message of Silent Spring. Carson was no lover of mosquitoes, or of insects in general, and in fact never advocated abandoning chemical control methods. On page 12 of Silent Spring she unambiguously writes, “It is not my contention that chemical insecticides must never be used. I do contend that we have put poisonous and biologically potent chemicals indiscriminately into the hands of persons largely or wholly ignorant of their potential for harm.”

Silent Spring was no extremist tract arguing for a chemical-free natural paradise; it was a compelling plea for “sparing, selective and intelligent use of chemicals,” as she wrote less famously in a 1963 article in Audubon magazine.

This “informed use” approach today underlies “integrated pest management” (IPM), the prevailing approach for controlling pests of all descriptions. IPM, as the name suggests, integrates a number of useful strategies – chemical, cultural, and biological – into an ecologically sound, socially acceptable, and economically viable program.

Carson's message was one of moderation. It was hardly radical – indeed its origins date back to ancient Greece – but it should resonate today in any discussion of environmental technology. For that matter, it applies equally well to ongoing and still controversial discussions of calories and weight control.

Research Continues

In the half-century since Silent Spring first appeared, knowledge of the toxicological and environmental effects of synthetic organic insecticides has grown, much of it acquired in studies inspired by Carson and those who embraced her message. DDT, the first and by far the most infamous of the chlorinated hydrocarbons, remains both newsworthy and controversial.

As it turns out, the causative links between DDT and cancer asserted by Carson have proved difficult to confirm, but cancers for which a causative factor has been definitively documented, such as lung cancer and smoking, remain the exception. As for ecosystem effects, epidemiological and animal studies have confirmed links between DDT exposure and reproductive disorders, although DDT is hardly alone in this attribute; new, more sophisticated analyses have revealed that many synthetic compounds and naturally occurring compounds disrupt human endocrine function.

Insect resistance to DDT, a major problem pointed out by Carson, and often forgotten in reexaminations of her central thesis, remains a problem a half-century later, even where DDT has not been used in years. This resistance can render DDT use ineffectual, as it already did in Carson's era for many different insect species. But then again, insects have evolved similar resistance against just about every other form of pest control, including crop rotation. And some new findings about DDT have even softened its image as the ultimate environmental pollutant; it degrades much more rapidly than expected, for example, in the warm, moist tropical environments where its use to combat malaria is most needed.

One thing about DDT that hasn't changed in the past half-century is its price; it remains one of the cheapest insecticides available. Its relatively low threat of acute toxicity to mammals and its affordability make DDT an appealing alternative for controlling insects that carry human diseases in desperately impoverished and disease-plagued regions of the world.

It's impossible to know what Rachel Carson would say today about the wisdom of re-deploying DDT in areas where other pest control measures have failed miserably, either due to cost, improper use, or resistance. It's likely, though, that whatever she advocated would be based on a careful examination of all of the evidence published since Silent Spring, consistent with her plea for “intelligent use of chemicals.” Whatever her position, it likely would be presented in the same elegant, compelling prose that changed history.

[May Berenbaum is head of the entomology department at University of Illinois, Urbana-Champaign.]