Lead: Assessing the environmental burden of disease at

1,24

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national and local levels

73

stron

2472

ID

World Health Organization

2004

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TABLE OF CONTENTS

Preface . v

Affiliations and acknowledgements vi

Summary vii

1. Background. 1

1.1 Summary of the method. 1

2. Sources of lead and exposure pathways . 3

3. Lead toxicity . 5

3.1 Nervous system effects and intelligence 5

3.2 Systemic effects . 6

3.3 Effects of lead on reproduction 7

4. Exposure-risk relationships 8

4.1 Anaemia and gastrointestinal effects . 9

4.2 Loss of IQ points and estimation of mild mental retardation 10

4.3 Increase in blood pressure and cardiovascular disease 13

5. Exposure assessment 16

5.1 Assessing levels of lead in blood. 16

5.2 Overall output 19

6. Estimating the disease burden. 21

6.1 An example problem: assessing the disease burden effects of a programme to reduce lead in

gasoline . 21

6.2 Adjusting blood lead levels for the effects of the programme to reduce lead in gasoline. 22

6.3 Calculating weighted means 22

6.4 Combining standard deviations . 23

6.5 Calculating the population at risk 24

6.6 Estimating disease rates in children. 28

6.7 Estimating the disease burden due to increased blood pressure 29

6.8 Summary of steps for estimating the disease burden. 30

7. Uncertainties . 31

7.1 Blood lead measurements 31

7.2 Are the data representative?. 31

7.3 Adequacy of adjustment factors 31

7.4 Ranges of reported exposure-response relationships. 32

7.5 Quantitative estimation of uncertainty. 32

8. Research needs and recommendations . 33

9. Disease burden and policy 34

References 35

Annex 1 Country groupings for global assessment 39

Annex 2 Measuring blood lead. 40

Annex 3 Using exposure scenarios to inform policy actions . 43

Annex 4 Estimating the global disease burden of environmental lead exposure 50

Annex 5 Calculation spreadsheet for lead . 65