Environmental Problems, Their Causes, and Sustainability 1

PreventionPhase out leadedgasoline worldwidePhase out wasteincinerationResearch indicates that childrenunder age 6 and unborn fetuseswith even fairly low bloodlevels of lead are especially vulnerableto nervous system impairment,lowered IQ (by anaverage of 7.4 points), shortenedattention span, hyperactivity,hearing damage, and various behaviordisorders.Good news. Between 1976 and2000, the percentage of U.S. childrenages 1 to 5 with blood leadlevels above the current safetystandard dropped from 85% to2.2%, preventing at least 9 millionchildhood lead poisonings. Theprimary reason was that governmentregulations banned leadedgasoline in 1976 (with completephaseout by 1986) and leadbasedpaints in 1970 (but illegaluse continued until about 1978)—an excellent example of thepower of pollution prevention.Bad news. Even with the encouragingdrop in average bloodlevels of lead, the U.S. Centers forDisease Control and Preventionestimates that at least 400,000 U.S.children still have unsafe bloodlevels of lead, caused by exposurefrom a number of sources. A majorsource is inhalation or ingestion of lead particlesfrom peeling lead-based paint found in about 38 millionhouses built before 1960. Lead can also leach fromwater lines and pipes and faucets containing lead. Inaddition, a 1993 study by the U.S. National Academy ofSciences and numerous other studies indicate there is nosafe level of lead in children’s blood.Health scientists have proposed a number of waysto help protect children from lead poisoning, as listedin Figure 24-25. Taking most of these actions will costan estimated $50 billion in the United States. Buthealth officials say the alternative is to keep poisoningand mentally handicapping millions of children.Although the threat from lead has been reduced inthe United States, this is not the case in many developingcountries. About 80% of the gasoline sold in theworld today is unleaded, but about 100 countries stilluse leaded gasoline. The World Health Organization(WHO) estimates that 130–200 million children aroundthe world are at risk from lead poisoning, and 15–18million children in developing countries have permanentbrain damage because of lead poisoning—mostlyTest blood for lead by age 1Ban lead solder inplumbing pipes, fixtures,and food cansBan lead glazing forceramicware used toserve foodBan candles withlead coresSolutionsLead PoisoningControlSharply reduce leademissions from old andnew incineratorsReplace lead pipes andplumbing fixturescontaining lead solderRemove leaded paintand lead dust from olderhouses and apartmentsRemove lead from TVsets and computermonitors beforeincineration or landdisposalTest for lead in existingceramicware used toserve foodTest existing candlesfor leadWash fresh fruits andvegetablesFigure 24-25 Solutions: ways to help protect children from lead poisoning. Which two of the solutionsdo you believe are the most important?from use of leaded gasoline. Good news. China recentlyphased out leaded gasoline in less than three years.What Is the Threat from Mercury? Some FishMay Come With a Side of Toxic MercuryMercury is released into the environment mostly byburning coal and incinerating wastes and can build tohigh levels in some types of fish consumed by humans.Mercury—the only metal that is liquid at room temperature—isused in thermometers, dental fillings,fluorescent lights, mercury light switches, and otherelectrical equipment and is released into the atmospherefrom burning coal and incinerating municipaland industrial wastes. Mercury compounds are alsoused as paint pigments, fungicides, insecticides, and indry-cell batteries.Once released into the atmosphere from naturalor human sources, elemental mercury often is convertedto more toxic inorganic and organic mercurycompounds, as shown in Figure 24-26. Trace the pathsin this diagram.http://biology.brookscole.com/miller14555