The worldwide problem of lead in petrolPhilip J. Landrigan1

The use of lead as a petrol additive hasbeen a catastrophe for public health.Leaded petrol has caused more exposureto lead than any other source worldwide.By contaminating air, dust, soil, drinking-water and food crops, it has causedharmfully high human blood lead levelsaround the world, especially in children (1).

Tetraethyllead was first added topetrol in 1922, to improve engine perfor-mance. Soon after production began inBayway, New Jersey, USA, an outbreak ofacute neuropsychiatric disease appearedamong workers, 80% of whom developedconvulsions and five died (2). A briefmoratorium was imposed, while plantconditions were improved. Then, despitestrong public health warnings, productionresumed. By the 1970s, almost all petrolproduced around the world containedlead. In the United States alone, annualpetrol consumption included almost200 000 tonnes of lead (3).

Lead is toxic to multiple organsystems; even at low levels previouslyconsidered safe, it has been shown througha series of prospective epidemiologicalstudies to produce adverse effects (4).Some of these are clinically evident, whileothers are discerned only through specialtesting and are thus defined as subclinical.

The nervous system of the fetus andinfant is especially susceptible to lead,which can cross the placenta and penetratethe blood-brain barrier. Lead interfereswith neuronal migration, cell proliferationand synapse formation during criticalperiods of early vulnerability. The con-sequences are loss of intelligence anddisruption of behaviour. Because the brainhas little capacity for repair, these effectsare permanent and untreatable. The mostrecent research indicates that lead candamage the infant brain even at bloodlevels as low as 5 m/dl (5).

These findings, together with datashowing that lead can damage the catalyticconverters of cars, have triggered stronggovernmental action. Nations around theworld have begun to ban lead in petrol.Sharp declines in average blood lead levelsand in the number of personswith elevatedlevels have resulted. In the USA, theremoval of lead from petrol between 1976and 1995 resulted in a 90% reduction in

mean blood lead level (6). Similar effectswere recorded in Western Europe,Australia, Canada, New Zealand andSouth Africa (7). In a number of devel-oping countries too, including China,El Salvador, India, Mexico and Thailand,declines in blood lead levels have followedthe removal of lead from petrol (8).Nearly 50 nations have now renouncedthe use of lead in petrol, and more areplanning such action in the next five years.Worldwide, unleaded petrol nowaccounts for 80% of total sales (1). This isa triumph for public health.

The elegant report from Pakistan inthis issue of the Bulletin (pp. 769–775)describes the current situation in thatcountry. On the negative side, the averageblood lead level among children inKarachi is significantly higher than thatseen today among children in industria-lized countries. This exposure derivesfrom multiple sources, and the authorshave done a superb job of tracing them.Their work will guide future prevention.On the positive side, the authors demon-strate that a decline in the use of leadedpetrol in Pakistan has resulted in declinesin children’s blood lead levels. This successis cause for hope.

The technology exists to complete thetransition from leaded to unleaded petrol.The success already achieved attests tothe feasibility of this changeover (1).Previously, concerns had been raised thatlead must be replaced with benzene, aproven cause of leukaemia. Now, however,it has been established that benzene isnot necessary (9). Previously too, it hadbeen suggested that leaded petrol wasneeded for the proper operation of certaincars, especially older ones. But anengineering analysis has shown that thisclaim is not true (10). Moreover, aneconomic analysis has found that the costsof removing lead are generally low —less than US$ 0.02 per litre for mostcountries (1). And there are economicbenefits associated with the protectionof both engines and children against lead.

WHO has been a leader in the globaleffort to remove lead from petrol. TheBangkok Declaration (11), unanimouslyadopted at an international meeting onchildren’s environmental health convened

earlier this year, called specifically for theremoval of lead from petrol. This callresonates with the theme of World HealthDay 2003, which is healthy environmentsfor children.

Precaution is the lesson to be learntfrom the history of lead in petrol. Theworldwide dissemination of tetraethyl-lead is a classic example of our excessivewillingness to adopt a promising butunproven new technology without heedto its possible consequences. We madethe same error with chlorofluorocarbon(CFCs), and we are at risk of making itagain if we adopt fuel additives containingmanganese, a known neurotoxin. For ourchildren’s future, we must do better. n

1. Organisation for Economic Cooperation & Devel-opment / United Nations Environment Programme.Phasing lead out of gasoline: an examinationof policy approaches in different countries. Paris:OECD; 1999.

2. Rosner D, Markowitz G. A ‘gift of God’? The publichealth controversy over leaded gasoline duringthe 1920s. American Journal of Public Health1985;75:344-52.

3. National Academy of Sciences. Lead: airborne leadin perspective. Washington: National AcademiesPress; 1972.

4. National Academy of Sciences / National ResearchCouncil. Measuring lead exposure in infants,children, and other sensitive populations.Washington: National Academy Press; 1993.

5. Lanphear BP, Dietrich K, Auinger P, Cox C.Cognitive deficits associated with blood leadconcentrations <10 mg/dl in US children andadolescents. Public Health Report 2000;115:521-9.

6. US Department of Health and Human Services.Update: blood lead levels — United States, 1991–1994. Morbidity and Mortality Weekly Report1997;46:141-5.

7. Thomas VM. The elimination of lead in gasoline.Annual Review of Energy and the Environment1995;20:301-24.

8. Ruangkanchanasetr S, Suepiantham J. Prevalenceand risk factors of high lead level in Bangkokchildren. International Conference on Environmen-tal Threats to the Health of Children: Hazardsand Vulnerability, Bangkok, Thailand, 2002(in conference programme book, unpublished).

9. Global dimensions of lead poisoning: an initialanalysis. Washington DC: Alliance to EndChildhood Lead Poisoning; 1994.

10. The case for banning lead in gasoline. Washington,DC: Manufacturers of Emission Controls Associa-tion; 1998.

11. SukWA. Beyond The Bangkok Statement: Researchneeds to address environmental threats to chil-dren’s health. Environmental Health Perspectives2002;110:A284-6.

1 Mount Sinai School of Medicine, One Gustave L. Levy Place, Box 1057, New York, NY 10029, USA (email: phil.landrigan@mssm.edu).

Ref. No. 02-0404

Editorials

768 Bulletin of the World Health Organization 2002, 80 (10)