Opposition from the United Stateshas blocked a European proposal tobegin negotiations on an interna-tional protocol to limit mercury

emissions, but the internationalcommunity did agree on an actionplan to provide technical assistanceand advice on ways to reducesources of the toxic element to de-veloping nations. At the GoverningCouncil of the United NationsEnvironment Programme (UNEP)meeting in Nairobi in February, theU.S. delegation argued that an inter-national agreement to limit emis-sions would take too long and costtoo much to negotiate and insteadsupported only “technical assistanceand capacity-building activities.”

The council did agree with UNEPexperts (Environ. Sci. Technol. 2002,36, 441A–442A) that “there is suffi-

Mercury action and inaction

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U.S. fulfillingenvironmental treaties For the most part, the UnitedStates is following through oncommitments made under five keyinternational environmentaltreaties relating to climate change,ozone depletion, and trade in en-dangered species, concludes theU.S. General Accounting Office(GAO) in a recent report. Theagency finds that actions to datehave had a positive effect on theenvironment. The United States fellshort, however, on pledges of fi-nancial assistance to developingcountries and in efforts to reducegreenhouse gas emissions to the1990 level by 2000. InternationalEnvironment: U.S. Actions To FulfillCommitments under Five KeyAgreements (Report No. GAO-03-249) can be accessed at www.gao.gov.

Hazardous playgroundsChildren playing on wooden struc-tures treated with chromated cop-per arsenate (CCA), a widely usedwood preservative, face an in-creased risk ofdeveloping lungor bladder cancer,finds the U.S.ConsumerProduct SafetyCommission(CPSC). This newresearch seems to contradictEPA’s position that CCA-treatedwood does not pose unreasonablerisks to the public or the environ-ment (Environ. Sci. Technol. 2003,37, 89A). To minimize exposure,CPSC now recommends that chil-dren’s hands be washed immedi-ately following play on woodenplay equipment. CPSC and EPAare studying ways to reduce theamount of arsenic leached fromCCA-treated wood. For more infor-mation, go to www.cpsc.gov/phth/ccastatement.html.

News Briefsat Wake Forest University School ofMedicine, in Wake Forest, N.C., wholed this aspect of the peer review.“There is no dose–response rela-tionship, no consistency, there’s justa zig-zag.” In addition, two studiesdone in 1998 and 2001 “are not re-producible; there’s absolutely noconsistency between the two, ” saysAschner.

But EPA toxicologist Kevin Croftonargues that the overall data are con-vincing. “There is variability be-tween studies, and some of thisreflects the difference between labsand the difficulty of the studies. Buteverybody who has ever looked atthyroid hormones sees these ef-fects, so they must be real,” he says.

In addition to concerns aboutthe crucial animal studies, someof the reviewers recommendedthat EPA give more considerationto studies with human volunteers.This is also what the military wants,according to the Air Force’s writtencomments on the toxicologicalreview.

EPA had asked NAS two yearsago to consider the acceptability ofhuman volunteer studies conduct-ed by nongovernmental organiza-tions. The agency’s interim policyis to refuse to accept such studiesuntil it receives NAS recommen-dations and revises its policy.However, the NAS committee ex-amining the issue was still holding

hearings on March 19. Studies already conducted in-

volving healthy human adult volun-teers suggest that it takes muchhigher doses of perchlorate to harmhumans, according to the scientistswho did the studies. Oregon Healthand Science University professorMonte Greer and colleagues esti-mated that 5.2−6.4 micrograms perkilogram per day would have no ef-fect on iodine uptake. This is ap-proximately the adult dose fromdrinking water containing perchlo-rate at 180 or 220 ppb, well abovethe draft standard.

The conflict between the animaland human studies is a red herring,according to Grant Anderson, whostudies thyroid hormones and braindevelopment at the University ofMinnesota Department of Medicinein Minneapolis. This is becauseadults are not the most vulnerablepopulation. In humans, it is widelyacknowledged that thyroid hor-mones exert their greatest effect onbrain development when the devel-oping child is making its own thy-roid hormones—late in pregnancyand after a baby is born, he says.This means that the effects of per-chlorate on an adult’s iodine uptakeor thyroid hormone status are notthe most relevant data for assessinghow perchlorate exposure affectsthe developing brain. —REBECCARENNER

UNEP will provide technical advice onlimiting mercury emissions from varioussources, including dental fillings.

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Environmental▼News

Signifying “a quantum leap forward”on understanding environmentalchemicals and how much is beingabsorbed by humans, officials withthe U.S. Centers for Disease Controland Prevention (CDC) released theirSecond National Report on HumanExposure to Environmental Chem-icals. It contains good news aboutdeclining children’s blood lead levelsand exposures to tobacco smoke fornonsmokers, but some say it raisesconcerns about mercury levels.

We are “pretty excited,” saysDavid Fleming, CDC’s deputy direc-tor for science. “It is almost the mostextensive study ever made of expo-sures to environmental chemicals.”

The report is four times largerthan CDC’s first 2001 document andrelies on blood and urine specimenstaken in 1999 and 2000. It includesdata on 116 chemicals, 89 of whichhave never been measured in theU.S. population, such as polycyclilcaromatic hydrocarbons and carba-mate insecticides. The first reportmeasured levels of four groups of

chemicals: metals, tobacco smoke,organophosphate pesticides, and ph-thalates. The second expands onthese and reports on 12 groups ofchemicals, including dioxins, furansand PCBs, herbicides, pest repellents,disinfectants, and phytoestrogens.

The report establishes exposurebaselines, or reference ranges, that

public health investigators canrefer to when deciding whether anacute exposure, such as an acci-dental factory release, has harmednearby residents. Regulators, too,can refer to the baselines to evalu-ate the effectiveness of controls.A more difficult but potential usewould be to evaluate multiple ex-posures, suggests George Lucier,former director of the NationalToxicology Program.

Released in January, the datasupport government efforts to con-trol substances suspected of ahuman health link, the authorsmaintain, especially with respectto bans on tobacco smoke. For ex-ample, levels of cotinine, a metabo-lite of nicotine, have decreased 58%for children, 55% for adolescents,and 75% for adults when comparedwith levels measured in 1991–1994.At the same time, recent data showthat cotinine levels in kids weremore than twice the levels of adults,and levels in African Americanswere more than twice the levelsof Mexican Americans or whites.“Continued efforts to reduce expo-

CDC pegs human exposures to chemicals

The CDC’s second report on human expo-sures to environmental chemicals findsthat levels of the metabolite 2-ethylhexylphthalate, which tracks exposure to di-2-ethylhexyl phthalate commonly found insoft plastic products, were higher in kids.Yet no generally recognized guidelinesthat indicate values for adverse healtheffects for these levels are available.

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cient evidence of significant globaladverse impacts to warrant interna-tional action to reduce the risks tohuman health and the environmentarising from the release of mercuryinto the environment.” It also sup-ported the action plan to providetechnical assistance and advice toall countries—particularly develop-ing nations and transition coun-tries, such as those in the formerSoviet Union—on ways to cut mer-cury emissions from major sources,such as coal-fired power stationsand incinerators. UNEP will alsoadvise countries on introducingclean coal technologies, improvingpower station efficiency, switchingto other forms of electricity genera-tion, and reducing other sources ofmercury pollution, such as thosefrom contaminated waste sites anddental amalgams. It will also helpcountries develop public awarenessprograms on the risks of mercuryexposure, particularly for vulnera-ble groups such as pregnantwomen.

Everyone agreed that most ofUNEP’s work should focus on as-sisting developing countries imme-diately, explains Jim Willis ofUNEP’s chemicals unit. This wasmainly because most developingcountries are not ready to negoti-ate a treaty without better under-standing the issues in their owncountries, he says. “I believe thateveryone, even the U.S., was satis-fied with taking immediate actionnow, and looking at other op-tions—including treaty options—at the next Governing Council.”

The European Commissionmaintains that it is “not unhappy”with the meeting’s conclusion,according to a spokesperson. Al-though it wanted a binding treaty,it recognizes that this outcome stillleaves the door open for all policyoptions in the future. However, dis-cussions on a binding treaty couldbe deferred to 2005, which is theUNEP Governing Council’s nextmeeting.

In a letter to President Bush in

February, several members of theU.S. Congress expressed their dis-appointment with the U.S. position.They cite a leaked State Depart-ment document that directed theU.S. negotiators to block any at-tempts to move forward on a bind-ing convention and to oppose evenvoluntary targets or any timetablesfor action. The letter’s signatoriessay they are concerned that theBush administration’s stance isweakening the United State’s credi-bility on environmental mattersand spurring resentment in theinternational community.

Environmental groups were alsodisappointed. “No single countrycan resolve the mercury problemon its own; there needs to be abinding global solution,” saysMichael Bender of the Ban MercuryWorking Group, a coalition of envi-ronmental and human health orga-nizations. “There are alternativesfor mercury uses, but there is noalternative to global cooperation.” —MARIA BURKE