On the 50^th Anniversary of Silent Spring

Silent Spring was written by Rachel Carson and published by Houghton Mifflin on September 27, 1962. The book is widely credited with helping launch the contemporary American environmental movement and subsequently the concern about environmental effects globally. The 33rd annual meeting of the Society of Environmental Toxicology and Chemistry-North America included a well-attended special symposium commemorating the 50th anniversary of its publication. Presentation topics included persistent organic pollutants (Keith Solomon, University of Guelph), organophosphorus and carbamate pesticides (Anne Fairbrother, Exponent, Inc.) and phenyl pyrazole insecticides (Dan Schlenk, University of California). Solomon, Fairbrother and Schlenk demonstrated the great strides that have been made in environmental chemistry and the shift away from persistent compounds that biomagnify in food webs, probably as a result of the warnings given in the book. Michelle Boone (Miami University) explained that Carson argued that we should not ban pesticides, but we should consider more thoughtfully their use and weigh whether or not the benefits of such use justify any ecological costs. A central point was reviewed: pesticides are not applied in isolation of ecologically relevant stressors (like predators, competitors), or as single active ingredients. Many target and non-target organisms are exposed to chemical mixtures and these are generally less predictable in their effects and are much harder to regulate. It has been argued that some pesticides and pesticide mixtures may have longer-term consequences than those which are measured. These effects may appear much later in life cycles or even in subsequent generations. Reed Johnson (Ohio State University) observed how rarely Carson mentions honey bees in Silent Spring. One reason is that DDT is not very active against honey bees. Today we are just beginning to recognize that there are claims that a few contemporary pesticides may be highly toxic to these pollinators. Currently, it is not clear what role, if any, pesticide exposure plays in honey bee health declines in the United States and around the world. Mortensen (BASF Corp) explained how agriculture has been revolutionized in the decades following the publication of Silent Spring through the application of innovative chemistry in combination with the use of fertilizer, seed breeding and transgenic crops. Dire predictions of wide-spread famine have been averted by this unprecedented growth in agricultural production capacity.

Much of that for which Rachel Carson campaigned has become common regulatory practice and forms part of the diverse components of all chemical discovery programmes. Today, consideration of the risk to the environment is a primary consideration of crop protection product development, with vetting through rigorous regulatory review processes. Both Spencer and Leighanne Hahn (Indiana State Chemist Office) explained that today's crop protection products are targeted and are often used at reduced rates in integrated pest management (IPM) programs – although not always with the recommendation of the manufacturer. More recently much effort has been spent in attempts to facilitate more effective communication between speciality crop growers, pesticide applicators and those who steward the surrounding habitat that might be at risk in attempts, usually successful, to minimize the possible effects of aerial spray drift. Rachel Carson would indeed be impressed with how her vision has taken root and with the accomplishments made since her book was released. It continues to be a reminder of how we need to strive to improve environmental quality and sustainability consistently.