Prevalence of and factors associated with childhood lead poisoning in Zamfara State, Nigeria, 2012

Transcription

1 Prevalence of and factors associated with childhood lead poisoning in Zamfara State, Nigeria, 2012 Muhammad B. Abdullahi 1,2, N. Umar-Tsafe 1,2, K. Getso 1, I. Kaita 1, B. Bako 1, M. Kachalla 1, A. Gubio 1, H. Muhammad 1, A. Baaba 1, A. Jafiya 1, P. Nguku 1, N. Gwarzo 3, L. Devis 1, A. Nasidi 4, M. Brown 5 1. Nigeria Field Epidemiology and Laboratory Training Program, Abuja, 2. Zamfara Ministry of Health, Gusau, Nigeria, 3. Federal Ministry of Health, Abuja, Nigeria, 4. Nigerian Centre for Disease Control, Abuja, 5. Division of Emergency and Environmental Health Services, National Center for Environmental Health, CDC, Atlanta, USA

2 Overview of lead poisoning Lead poisoning is one of the most common employment related diseases Globally: About 55 countries engaged in artisanal small-scale mining (ASM) million miners 100 million people living on ASM Children are adversely affected Encephalopathy, mental retardation, and death WHO reference level of concern (blood lead level [BLL] = 10µg/dL) and threshold for chelation (BLL = 45µg/dL) 2

3 Lead poisoning in Zamfara In 2010, Zamfara State reported unprecedented lead poisoning in some mining communities unregulated gold processing activities thousands of children became exposed to lead poisoning Hundreds of children died Gold mining activities became widespread gold-rich ores transported and processed all over the State 3

4 Objectives We conducted the study to assess The prevalence of gold mining activities in Zamfara State Prevalence of lead poisoning in under 5 children Factors associated with lead poisoning 4

5 Methods 5

6 Study location Gusau LGA Figure 1: Nigerian map highlighting Zamfara State Source: Health Mapper (WHO software) Zamfara State Zamfara State Headquarters Figure 2: Zamfara State map showing with 14 Local Government Area (LGAs) Landmass of 37,931 sq km 6

7 Advocacy visits All Emirs (traditional leaders) and LGA chairmen Introduce study Highlight our ultimate goals Seek their permission and gain informed consent to visit villages A 7

8 Materials and methods Study setting: Cross-sectional, cluster designed survey, May July 2012 Study population: Children under 5 years and their parents/guardians Inclusion criteria: Children resident of Zamfara for at least 6 weeks 8

9 Sample Size Calculations Prevalence of 50% was used, margin of error around the estimated prevalence of ±10%, assuming a 95% confidence interval and also accounting for clustering 1 village was selected randomly from each cluster (5km cell) Design Effect = 1 + (b -1)ρ = 1 + [(1-1)*0.15] = 1 Sample Size = (z-score) 2 (prevalence estimate)(1-prevalence estimate) = (1.96) 2 (.5) (1-0.5) (margin of error) 2 (0.1) 2 = 97 Inflated by 15%, to 112 villages, to account for potential nonresponse 9

10 5km 2 grids/cells across the 14 LGAs of Zamfara, using LandScan LandScan imagery data (Oak Ridge National Laboratory, Oak Ridge, TN, USA) produce 1km 2 resolution population estimates Each LGA was divided into five-by-five km 2 grids, 10

11 56 Grids selected by SAS statistical software Selected grids across 14 LGAs Sample grid AB36 Selected village coordinates were tracked using GIS 11

12 Sampling techniques 112 villages/settlements surveyed at village level across the State (2 villages per grid) 56 villages/settlements selected for full compound level survey PPS* of 14 LGAs (1 village per grid) 392 compounds selected (7 compounds per each 56 villages/ settlements) 392 children selected (one child per each 392 compounds) for full details blood sample 383 children with adequate blood samples were included in the analyses 9 children had inadequate blood samples *proportionate to population size 12

13 Study instrument, Laboratory procedures and data analysis Study instrument: Semi-structured questionnaires: Head of compound, mother/care giver to record sociodemographics and history of mining activities Laboratory: Collected 383 blood samples Analyzed at CDC DLS (Atlanta, GA) using an inductively coupled plasma mass spectrometer for BLL Data analyses: Epi Info software version 7 (CDC, Atlanta, USA) and Microsoft excel

14 Results 14

15 Socio-demographics of Children (n=383) Variable Frequency n (%) Percent (%) Age group (month) Sex < Male Female Median age (months) = 36 (IQR: 23-48) 15

16 Distribution of BLL among Children BLL (µg/dl) Frequency Percent (%) 95% CI < Median BLL (µg/dl) = 6.5 (Range: ) 16

17 Prevalence of lead poisoning and mining activities Variable Frequency Percent (%) 95% CI BLL (µg/dl) < Mining participated by family member Yes No

18 Prevalence of Gold mining activities and Lead poisoning across 14 LGAs Gold mining activities (11 LGAs) Childhood lead poisoning (14 LGAs) Maru 27.5 Gusau 26.1 Anka Bukkuyum Maru Anka Kaura Namoda Maradun 11.6 Zurmi 6.8 Gusau 7.3 Tsafe 3.4 LGAs Bungudu 7.3 LGAs Talata Mafara Gummi Tsafe 4.4 Bukkuyum 3.4 Gummi 4.4 Maradun 2.3 Kaura Namoda Talata Mafara Bungudu Birnin Magaji Shinkafi Birnin Magaji 1.5 Bakura Percent (%) Percent (%) 18

19 Factors associated with Lead Poisoning Variable BLL : 10µg/dL BLL: <10µg/dL P-value Age group (month) Sex <12 6 (6.8) 20 (6.8) (27.3) 44 (14.9) (19.3) 44 (14.9) (22.7) 61 (20.7) (23.9) 126 (42.7) 0.01 Male 53 (60.2) 147 (49.8) Female 35 (39.8) 148 (50.2)

20 Factors associated with lead poisoning Variable BLL : 10µg/dL BLL: <10µg/dL P-value Family member participated in mining Family member recycled battery Yes 26 (29.6) 43 (14.6) No 62 (70.4) 252 (85.4) Yes 1 (1.1) 10 (3.4) 0.27 No 87 (98.9) 285 (96.6) Child exposed to eye liner cosmetic Yes 80 (90.9) 257 (87.1) 0.34 No 8 (9.1) 38 (12.9) 20

21 Limitations Some selected grids/settlements were not accessible and were replaced with the nearby ones 21

22 Conclusion There was high prevalence of mining activities in the state and lead poisoning among under fives Age and family member participation in gold mining activities were possible factors associated with lead poisoning 22

23 Public health actions We referred children that required treatment to chelation centre Communicated our findings to stakeholders on lead poisoning control Publications Bashir, M., Umar-Tsafe, N., Getso, K., Kaita, I. M., Nasidi, A., Sani-Gwarzo, N., Nguku, P., Davis, L., & Brown, M. J. (2014). Assessment of blood lead levels among children aged 5 years--zamfara State, Nigeria, June-July MMWR Morb Mortal Wkly Rep, 63(15), (in press) Umar-Tsafe, N., Bashir, M., Getso, K., Kaita, I. M., BS Bako 1, M Kachalla 1, AB Gubio 1, HI Muhammad 1, A Baaba 1, A Jafiya 1, Sani-Gwarzo, N., Nguku, P., Davis, L., Nasidi, A., Brown, M. J. Prevalence and Risk Factors of Elevated Blood Lead in Children in Mining and Non-Mining Communities, Zamfara, Nigeria,

24 Recommendations Zamfara SMOH should continue BLL surveillance so as to identify lead poisoned children for treatment Sensitize and create awareness of people on the dangers of lead poisoning Zamfara SMESM to promote safer mining practices and regulate mining activities FMOH, FMEnv, FMinMSD, NESREA and partners to synergize their roles in lead poisoning control 24

25 Acknowledgements Zamfara State Ministries of Health and Environment Federal Ministry of Health, Abuja Nigerian Centre for Disease Control (NCDC) Nigeria Field Epidemiology and Laboratory Training Program (NFELTP), Abuja African Epidemiology Network (AFENET) Centers for Disease Control and Prevention (CDC), Atlanta, USA Dr. Mary Jean Brown, US CDC Dr. Lora Devis, US CDC Dr. Patrick Nguku, NFELTP, Abuja Dr. Nasiru Sani-Gwarzo Prof. Abdulsalami Nasidi 25

26 Thank you For your attention