Environmental Problems, Their Causes, and Sustainability 1

approximately 165 of the active ingredients approvedfor use in U.S. pesticide products are known or suspectedhuman carcinogens. By 2004, only 43 of thesepesticide chemicals had been banned by the EPA ordiscontinued voluntarily by manufacturers.A study of Missouri children revealed a statisticallysignificant correlation between childhood braincancer and use of various pesticides in the home,including flea and tick collars, no-pest strips, andchemicals used to control pests such as roaches, ants,spiders, mosquitoes, and termites. Also, EPA scientistspublished a report in 2000 indicating that atrazine(widely used as a weed killer by farmers) could causeuterine, prostate, and breast cancer in humans and disruptreproductive development.Also, according to studies by the National Academyof Sciences, federal laws regulating pesticide usein the United States are inadequate and poorly enforcedby the EPA, Food and Drug Administration(FDA), and USDA. Another study by the NationalAcademy of Sciences found that up to 98% of the potentialrisk of developing cancer from pesticideresidues on food grown in the United States would beeliminated if EPA standards were as strict for pre-1972pesticides as they are for later ones.The pesticide industry disputes these findings andsays that eating food grown by using pesticides for thepast 50 years has never harmed anyone in the UnitedStates. The industry also claims that the benefits ofpesticides far outweigh their disadvantages.Environmentalists and a number of health officialscall for strengthening U.S. pesticide laws to helpprevent contamination of groundwater by pesticides,improve the safety of farm workers who are exposedto high levels of pesticides, and allow citizens to suethe EPA for not enforcing the law. Pesticide manufacturersstrongly oppose such changes and lobby electedofficials to weaken FIFRA.Pesticide control laws in the United States couldbe improved. But most other countries (especiallydeveloping countries) have not made nearly asmuch progress as the United States has in regulatingpesticides.Case Study: Revisiting DDT— from Richesto RagsSince 1972 DDT has been banned in developedcountries, and there is controversy over itscontinuing use in some developing countries tocombat malaria.After its discovery in 1939, DDT quickly became theworld’s most widely used pesticide. It was a cheapand effective weapon to kill crop-devouring insectsand mosquitoes and other insects that transmitted infectiousdiseases such as malaria. There is little doubtthat single-handedly this chemical has saved manymillions of lives from infectious diseases.DDT’s role as a “chemical hero” began changingin 1962 when Rachel Carson published her book SilentSpring, which warned of the dangers of DDT and otherbroad-spectrum and persistent pesticides (IndividualsMatter, p. 27). This led to much closer scrutiny of suchpesticides and public pressure to ban DDT and its persistentchlorinated hydrocarbon chemical cousins thatwere also widely used as pesticides (Table 23-1).In 1970, the U.S. Environmental Protection Agencywas established. In 1972, the earlier Federal Insecticide,Fungicide, and Rodenticide Act (FIFRA) wasamended to give the EPA control over the registrationand regulation of pesticides in the United States.In that same year, the EPA banned the use of DDT(and later the use of its similar chemical cousins) in theUnited States. The EPA banned DDT for several reasons.First, it is a broad-spectrum chemical that killsmany beneficial insects along with its target species.Second, it is a persistent chemical that remains in onechemical form or another in the environment for up to15 years and can be biologically magnified in foodwebs (Figure 19-4, p. 411). Third, it reduced populationsof many birds and other species, especially thosefeeding at high trophic levels in food webs, such as eaglesand peregrine falcons. Fourth, there was some preliminarybut not conclusive evidence that it couldcause cancer in humans. Fifth, it was becoming less effectivebecause a growing number of insect pests thatconsume crops and transmit diseases had developedgenetic resistance to DDT and other chlorinated hydrocarbonpesticides. Some contend political pressurefrom the public and a growing environmental movementalso played a role in the ban of this chemical.Pesticide manufacturers opposed the ban butwere more than happy to supply more expensive alternatives.Debate over the DDT ban in the United Statescontinues today. There was considerable evidence forits ecological harm and more evidence has accumulated.But pesticide industry scientists say there wasnot enough evidence then (and today) that DDT cancause cancer in humans—one of the key reasons usedto ban the chemical under the FIFRA pesticide law.Critics of the ban try to separate the possibleharmful effects of DDT on humans from its effects onother species and ecosystems. They pose such questionsas, Do we want to protect penguins or people?Scientists say this is too simplistic because we cannotseparate harm to the environment from harm topeople. This is especially true for widely used andlong-lived chemicals such as DDT that can build up infood webs and are now found in even the most remoteparts of the world.This was the heart of Rachel Carson’s warning.Traces of these chemicals are everywhere, including526 CHAPTER 23 Pest Management