Academia.eduAcademia.edu

© 2007 Academic Journals

2007

The pervasiveness of human health impacts and ecosystem effects of lead (Pb) is not controversial, but there are serious arguments about the pace at which Pb should be eliminated from consumer products. Presumably, these arguments can be resolved by converting costs and benefits of Pb use to similar units, a notorious methodological challenge for health impacts in developing countries. To estimate the costs of Pb poisoning attributable to petrochemicals in Nigeria, we conducted a meta-analysis of measured blood lead levels (BLL) and we used published Relative Risk values for disease categories to estimate the proportion of overall disease burden attributable to Pb. We modeled the health costs of Pb exposure and we compared this to the cost of banning Pb. We estimate that Pb exposure accounts for 7- 25 % of the disease burden among Nigerian children, costing the health and education sectors $0.38 – 1.15 billion year-1 for every 1 µg/dL increase in BLL. In comparison, we estimate that...

African Journal of Environmental Science and Technology Vol. 1 (2), pp. 027-036, September 2007 Available online at http://www.academicjournals.org/AJest © 2007 Academic Journals Full Length Research Paper The cost of environmental lead (Pb) poisoning in Nigeria Oladele A. Ogunseitan* and Timothy R. Smith Program in Public Health, College of Health Sciences, University of California, Irvine, CA 92697-7070 USA. Accepted 7 August, 2007 The pervasiveness of human health impacts and ecosystem effects of lead (Pb) is not controversial, but there are serious arguments about the pace at which Pb should be eliminated from consumer products. Presumably, these arguments can be resolved by converting costs and benefits of Pb use to similar units, a notorious methodological challenge for health impacts in developing countries. To estimate the costs of Pb poisoning attributable to petrochemicals in Nigeria, we conducted a meta-analysis of measured blood lead levels (BLL) and we used published Relative Risk values for disease categories to estimate the proportion of overall disease burden attributable to Pb. We modeled the health costs of Pb exposure and we compared this to the cost of banning Pb. We estimate that Pb exposure accounts for 7 - 25% of the disease burden among Nigerian children, costing the health and education sectors $0.38 – -1 1.15 billion year for every 1 µg/dL increase in BLL. In comparison, we estimate that a Pb abatement -1 program in Nigeria will cost $0.076 – 0.23 billion year . If a Pb phase-out program is instituted now to lower the national BLL to 1 µg/dL by 2020, a savings of $2.7-8.0 billion would be realized. Key words: Lead (Pb) poisoning, Cost-benefit analysis, Diseases, Petrochemicals Africa. INTRODUCTION Exposure to Pb is widely recognized as a major risk factor for several human diseases, and the structure of industrial ecological systems have made exposure to Pb unavoidable for most people alive today (Needleman, 1999; Pruss-Ustun et al., 2004; WHO, 2000). In affluent countries, sizable investments in the implementation of environmental policies prohibiting the addition of Pb to many consumer products have resulted in rapid decline of human exposures, demonstrable by observed reductions in the human blood content of Pb (USEPA, 1985; Grosse et al., 2002). Unfortunately, the public health gains from extensive research on the adverse effects of Pb and the remarkable successes of effective policies in these industrialized countries have not yet enveloped developing countries, and the course of gasoline-fueled industrialization remains hazardous to public health (OECD, 1999). *Corresponding author. E-mail: [email protected]. Phone: 949-824-6350 Fax: 949-824-2056. Children throughout Africa are particularly vulnerable to Pb exposure because of unabated use of leaded gasoline and lead-acid batteries in automobiles (Nriagu et al., 1996 and 1997; Omokhodion, 1994), and recently, unregulated cottage industries associated electronic waste recycling (Lincoln et al., 2007). Particular socio-ecological and climatic factors also contribute to high levels of inhalation and ingestion of Pb-laden aerosol and dust (Laidlaw et al., 2005; Ogunfowokan et al., 2004; Ogunsola et al., 1994; Rankin et al., 2005). Despite the initiation of phase-out programs in a few countries, the gasoline sold in most African countries contains 0.5 - 0.8 g/l lead, the highest levels in the world (Thomas, 1995). -1 In Nigeria, gasoline with average Pb content of 0.66 g L remains in use (Fakayode and Olu-Owolabi, 2003). In Nigeria’s largest city of Lagos, specific emissions of lead -2 exceed 164 kg km representing approximately 20% of the 2.46 Gg of lead emissions nationwide (Obioh et al., 1988), and ambient air concentration of Pb ranges up to 3 9.58 µg m , exceeding WHO recommended annual ave3 rage of 0.5 µg m at all locations (Obioh et al., 2005). Furthermore, mean blood lead levels (BPb) measured at 028 Afr. J. Environ. Sci. Technol. various times and urban locations in Nigeria have ranged -1 -1 from 11.4 – 25 µg dL ; far exceeding the 10 µg dL action dose recommended for the U.S. population (Adebamowo et al., 2006; Ademuyiwa et al., 2005; Nriagu et al., 1997). In addition to automotive and industrial sources, elevated blood lead levels in children have been attributed to paint, household dust, overcrowding and low parental income (Charney, 1982; Kapu et al., 1989; Kristensen et al., 1993; Landrigan et al., 1976; Nriagu and Pacnya, 1988). Previous studies in Africa have also shown that one of the strongest indicators of childhood BPb was the family either owning a car or living in a house located on a tarred road (Nriagu et al., 1996). These factors are typically only encountered in urban centers. However, the geochemical behavior of Pb and its association with suspended particulates suggests that children in remote suburban or rural regions may also suffer from Pb exposure, in which case, the adverse affects of Pb should be widespread. This hypothesis has not been rigorously tested within the African continent. Also, it has been relatively simple to quantify the financial costs associated with Pb-phase out programs, but the economic costs of health effects attributable to lead exposure are typically externalized. This has made it difficult for policymakers to comprehend cost-benefit scenarios used to justify lead abatement programs. The goal of this research is to provide cost-benefit information to environmental policy makers in Nigeria by employing a quantitative comparison of the health cost of lead-related disease burden to the cost of a national lead abatement program. There are three research objectives: (1) the determination of the representative blood-lead content of Nigerian children (ages 1 - 6 yrs.) and subsequent contribution of environmental lead exposure to the burden of disease in Nigeria; (2) the estimation of the health costs of environmental lead exposure in Nigeria; (3) and the estimation of the cost of a national leadabatement program. METHODS Assessment of lead exposure Children (ages 1 – 6 years; N = 306) were recruited for this study through the scheduled immunization clinic in the semi-rural region of Otukpo, Nigeria (total population of approximately 136,800 people, of which 45% are younger than 14 years for the study period (Population Reference Bureau, 2006). Blood lead concentrations were determined by means of an automatic blood lead analyzer with a sensitivity range of 1.4 - 65 µg dL-1 based on blood sample volume of 50 µl (LeadCare, ESA Inc., Chelmsford, MA and AndCare Inc., Durham, NC. The equipment was kindly provided by the U.S. Centers for Disease Control and Prevention, Atlanta, Georgia). The necessary size of the population sample was estimated within the desired margin of error for predicting the population mean according to Moore and McCabe (2005): 2 n= Z ×s 2.96 × 3.8 = m .65 2 = 300 where: Z = z-score (2.96, 99% CI) ; s = standard deviation (3.8 µg dL-1; Nriagu et al., 1996); m = desired margin of error (± 0.65 µg dL-1) Informed consent was obtained for all human subjects according to standard research ethics, and as approved by the Institutional Review Board. Exclusion categories included those previously treated for Pb poisoning, those who had not been living in the same residence for at least the past 6 months, those who are being treated for severe illness, and those not accompanied by a legal guardian. In addition to the determination of BPb concentrations, a questionnaire was completed by each child subject with the legal guardian to record demographic and socioeconomic statistics and to assess predictors of Pb exposure and the predominant pathways for such exposures. The questionnaire survey was modified from the standard instrument used by U.S. Center for Disease Control and Prevention to better capture the social, economic, and cultural environment of Nigeria. With written consent, the nurse/phlebotomist administered the survey and offered the subject a fact sheet containing health information on lead exposure in children. Association of lead exposure and disease burden Lead exposure is implicated in several disease burden categories including systemic effects such as hypertension, gastrointestinal effects, anemia, nephropathy, and nervous system effects such as Intelligence Quotient (IQ) defects and encephalopathy (ATSDR, 1999; Schwartz, 1991, 1993, 1994; Schwartz et al., 1986). We estimated the contribution of Pb exposure to the following disease categories in Nigeria: genito-urinary disease, prematurity, dental caries, nervous system cancers, congenital anomalies, hypertension, cerebrovascular disease, low birth weight, and mild mental retardation (MMR; IQ levels 50-69). Nine of the 106 disease categories included in the World Health Organization’s Global Burden of Disease study were included in this study (Murray and Lopez, 1996; but see Cooper et al., 1998). A population-adjusted, disease burden for Nigeria was estimated from the regional burdens for relative risk analysis. The numerical model DISMOD® was used to estimate disease burden for two disease categories that were not included in the GBD, prematurity and mild mental retardation (http://www.hsph.harvard.edu/organizations/bdu/DisMod.html). Our estimate of Pb-associated MMR presented a special challenge. Pruss-Ustun et al. (2004) estimated the prevalence of mental retardation and cognitive impairment from known, non-congenital causes (those mentioned above), compared values of developed and developing countries, and estimated a rate accounting for the increase of risk of mental retardation in developing countries, as follows: AR = PR − Pbaseline + PMR standard PMR standard Where: MR = mental retardation; PR = region-specific prevalence of MR from known causes; Pbaseline = prevalence of MR from known, non-congenital causes in developed countries; PMR standard = prevalence of MR according to the standard distribution of IQ score; AR = adjustment ratio That lead exposure contributes to IQ deficit is universally accepted, but there is no consensus on the dose response relationship (Lanphear et al., 2000; Moore et al., 1977; Pocock et al., 1994; Ogunseitan and Smith Table 1. Variables for the cost of lead abatement in Nigeria. Cost ($/liter) Abatement Factors Unleaded Gasoline Non-Pb Additive Refinery Retooling Tetraethyl Lead (TEL) Gasoline Source Domestic Gasoline Foreign Gasoline Total Gasoline *6,837 0.01 6,837 0.006 1,408 0.002 6,837 0.16 1,408 0.16 5,429 0.16 6,837 *(U.S. DoE, 2000) Lynn and Vanhanen, 2002; Stouthard et al., 1997). Based on the meta-analysis conducted by Popcock et al. (1994) and by Schwartz (1994), we relied on the following categories defined by three levels of exposure to Pb measured by blood Pb content. Children with relatively low BLLs (5 - 8 µg/dL) suffer a 1.0 IQ deficit; those with medium BLL (9 - 15 µg/dL) suffer 2.0 IQ deficits, and children in the high Pb exposure category (> 16 µg/dL) suffer 3.0 IQ deficit. Pruss-Ustun et al. (2004) estimated lead-induced MMR to be 0.385/1000 for Sub-Saharan Africa (SSA) populations, compared to 0.256 per 100 people in Europe. We judged this estimate to be inadequate for Nigeria based on the assumption of global average IQ score of 100. Instead, we relied on the baseline IQ estimates of Lynn and Vanhanen (2002) that are more localized in perspective, providing average IQ scores for SSA and Nigeria as 70 and 67, respectively. The present study also departs from the Pruss-Ustun et al. (2004) assessment in the following way. Instead of extracting the fraction of lead-induced MMR from an overall MMR rate in Nigeria, an estimation of the IQ drop due exclusively to lead exposure was assessed on the basis of the range of measured BLLs and the IQ decrements attributed to those ranges in the clinical literature. To estimate the burden attributable to MMR, we adopted the approach used in a Dutch Burden of Disease Study where a severity weight of 0.06 was assigned for deficits in IQ between 1 - 4 points (Stouthard et al., 1997). The proportion of disease cases attributable to Pb exposure to an environmental risk factor (Attributable Faction) was based on Miettenen’s approach (1974): AF j = Table 2. Summary of blood lead levels in children, ages 1-6, Otukpo. Consumption 0.01 P( RR j − 1) P ( RR j − 1) + 1 where: AF j = the fraction of burden from some cause j (lead exposure); RR j = the relative risk of disease for cause j in the exposed to unexposed group; P = Prevalence of exposure. The attributable fraction was used to derive an estimate of the Lead Attributable Burden (LABD) for low, medium, and high Pb exposures given Relative Risks (or Odds Ratios) for each cause of death and disability related to the exposure, levels of exposure (pre 029 Sex Female Male Total n 138 168 306 Mean [BPb] 8.9 9.8 9.4 Range (2.1,23.8) (2.2,31.8) (2.1,31.8) SD 4.2 4.8 4.2 % > 10 ug/dL 32.5 35.0 34.3 valence), and burden of disease due to each cause of death and disability in a given population: AB = AFj B j where: AB = Attributable Burden for a risk factor; AFj = Fraction of Burden from cause j Bj = population level burden of cause j Economic cost of lead exposure The U.S. EPA estimated the cost of a lead abatement program to be approximately 500 million dollars per year in 1985 (USEPA 1985). Estimates for the cost of a lead additive (Tetraethyl lead (TEL), $0.002/liter), refinery overhaul ($0.006/liter), and non-lead additive (Methy tert butyl ether (MTBE), $0.01/liter) were derived from Thomas and Kwong (2000). The average cost of gasoline in Nigeria was estimated to be approximately $.16/liter (Obioh et al., 2005). The annual consumption of domestic and imported gasoline in Nigeria is 24,260 and 93,550 barrels per day, respectively (US DoE, 2000). Thus, the total consumption of leaded gasoline in Nigeria is 117,810 barrels per day (Table 1). Schwartz (1993) estimated that $17.2 billion dollars per year would be saved by a 1 µg/dL reduction in blood levels per year across the U.S. population. We used a similar approach to estimate the economic cost of lead exposure in Nigeria, but with modifications that capture issues specific to Nigeria and time differentials, including adjustments according to the consumer price index (CPI), and gross national income in purchasing power parity (GNI-PPP) of 2.3% for the study period (Population Reference Bureau, 2006). RESULTS AND DISCUSSION Blood lead levels Blood lead levels measured in children of Otukpo are summarized in Table 2. The mean for all children was 9.4 µg/dL (SD = 4.2, n = 306). The mean value for males (55% of the sample; Table 3) was not significantly higher than for females. The highest BLL measured was 31.8 µg/dL, which is below the U.S. standard of 45 µg/dL for lead poisoning treatment with chelation therapy. The proportion of children having BLL above the USEPA action level of 10 µg/dL is more than one third. Figure 1 shows a comparison of BLL distribution among children residing in Otukpo with previous reports of blood lead levels for children in the more urbanized city of Kaduna and other distantly located cities (Nriagu et al., 030 Afr. J. Environ. Sci. Technol. Table 3. Contd. 30 % Population 25 20 Otukpo Kaduna 15 10 5 0 5 7 9 11 13 15 17 19 21 Blood Lead Concentration (ug/dL) Figure 1. Blood lead levels measured in Nigerian children. Table 3. Summary of demographic characteristics in children, ages 1 - 6, Otukpo. Characteristics Percentage Gender Male 54.9 Female 45.1 Age of Child 1 Year 19.9 2 Years 18.3 3 Years 15.0 4 Years 13.7 5 Years 15.4 6 Years 17.6 Born in Otukpo Child 87.9 Mother 42.8 Father 34.6 Average Household Size 6.8 People Maternal Literacy 64.7 Education Level Mother Father 0-4 Years 61.5 55.6 5-8 Years 17.9 21.6 9-12 Years 18.2 15.0 >12 Years 2.3 7.8 Occupation Mother Father Self-Employed 54.6 30.9 Professional 10.1 15.4 Factory Worker 1.0 4.9 Homemaker 14.1 0.0 Farmer 13.4 27.8 Other 13.1 18.6 Years Child has Lived in Current Residence 1 Year 28.1 2 Years 20.9 3 Years 15.0 4 Years 12.4 5 Years 10.1 6 Years 12.1 Type of Housing Detached 21.2 Attached 62.4 Apartment 15.4 Other 1.0 Housing Construction Material Brick/Block 98.0 Wood 0.7 Other 0.7 Unknown 0.7 Source of Drinking Water Pipes 29.7 Public Faucet 1.6 Well 61.8 Barrels 2.3 Bottled 1.6 Combination 3.0 Time Spent Away From Home by Child 0 Hours 84.3 1 Hour 0.3 2 Hours 0.7 3 Hours 2.9 4 Hours 2.6 >4 Hours 9.4 Children That Wash Hands 40.8 Mothers that Cook/Store 36.0 Food/Water in Clay Pots 1997; Adeniyi and Anetor, 1999). The population of Kaduna is approximately 1.5 million people in 2002. The mean BLL in Kaduna children ages 1 - 6 years old is 10.6 -1 µg dL (± 3.8); with total atmospheric emissions of Pb in the region being 150 tons annually, and 97% of that exposure coming from leaded gasoline (Nriagu et al., 1996; Obioh et al., 1988). Table 3 shows a summary of the Socio-Demographic data that was collected through the epidemiological survey. Almost 90% of the children were born in Otukpo, but less than half of the parents were indigenous. The average household size was approximately 7 individuals and most lived in attached compound houses constructed of cement bricks with groundwater wells being the source of drinking water. Mean BLL was significantly associated with household size, maternal literacy, parental occupation, home floor type, time spent outside the home, residential proximity to a ceramics shop, and by parental employment in a print shop (p<.05), but not with age, parental education, housing construction type or detachment status, drinking water, and frequency of hand-to- Ogunseitan and Smith 031 Table 4. Deaths (x1000) and DALYs (x1000) from all Pb-linked diseases for males and females, ages 0-14. Deaths, 0-14 Pb-Disease Category male Genito-Urinary Disease Prematurity* Dental Caries Nervous System Cancers Congenital Anomalies Hypertension** Cerebrovascular Disease Pb-Mild Mental Retardation (MMR) Low Birth Weight*** Sub-Saharan Africa (SSA) SSA, M & F Nigeria Nigeria, M & F female 16 384 0 7 32 2 9 0 262 712 13 384 0 6 33 2 9 0 234 681 1,393 121 116 237 DALYs, 0-14 male female 710 541 2,295 2,295 129 127 270 210 2,455 2,628 66 69 313 298 2,463 2,414 9,827 8,873 18,528 17,455 35,983 3,150 2,967 6,117 *DALYs calculated using DISMOD with incidence rates from (Antilla et al., 1995). **DALY data from Type I Diabetes, ***Low Birth Weight is the largest category within Perinatal Conditions Table 5. Pb-linked burden of disease percentages (BDPb%). Deaths PbBD% of SSA PbBD% of SSA, 0-14 PbBD% of SSA, 0-14, m/f PbBD% of Nigeria PbBD% of Nigeria, 0-14 PbBD% of Nigeria, 0-14, m/f DALYs male female male female 2.42 4.57 2.75 5.31 1.82 2.97 2.04 3.34 4.90 14.25 26.86 mouth behavior (Ogunseitan and Smith, submitted). Lead-associated burden of disease estimates Table 4 shows the results for overall Deaths and DALYs by gender for children, ages 0-14, of Sub-Saharan Africa (SSA) and Nigeria. Table 5 shows the results by gender for lead-linked disease burden for children in Nigeria. The data are shown as a percentage of SSA burden, SSA childhood burden, Nigerian burden, and Nigerian childhood burden. Table 6 shows the medium estimate for DALYs of all nine disease burden categories by gender for children, ages 0-14, for both SSA and Nigeria. Also, the ORs that were found in the literature are shown. The three exposure categories are classified as low exposure (5-8 µg/dL), medium exposure (9-15 µg/dL), and high exposure (>16 µg/dL). There is no OR for lead-attributed mild mental retardation (MMRPb) required, because by definition, 100% of MMRPb is due to lead exposure. Table 16.18 31.25 29.06 3.14 10.71 17.48 11.99 19.67 18.58 7 shows the medium estimate of both the attributable risk and attributable burden for lead exposure across all three exposure categories for children, ages 0 - 14, in SSA and Nigeria. Also, the Pb-attributed burden of disease (BDPb) is shown as a percentage of the total Nigerian BD, and the total Nigerian childhood BD. Nigerian childhood BLLs of 5 - 8 µg/dL account for approximately 2.18% of the total Nigerian childhood burden, BLLs of 9 - 15 µg/dL account for 7.50%, and BLLs >16 µg/dL account for 5.07%. Combined all lead exposure accounts for approximately 14.74% of the total Nigerian childhood disease burden. Health costs of lead (Pb) exposure The estimates of childhood health costs of lead exposure are outlined in Table 8. The total costs are presented in millions of dollars. While all of the sub-categories (medical, compensatory education, lost earnings, IMR, and neonatal care) show significant health costs of Pb expos- 032 Afr. J. Environ. Sci. Technol. Table 6. Dalys and odds ratios for 9 Pb-linked diseases (Medium estimate). Pb-Disease Category Genito-Urinary Disease Prematurity Dental Caries Nervous System Cancers Congenital Anomalies Hypertension Cerebrovascular Disease Pb-Mild Mental Retardation Low Birth Weight Total SSA Total Nigeria DALYs, 0-14 OR @ 3 PbB Levels* male female total 5-8 9-15 >16 710 2295 129 270 2455 66 313 2463 9827 18528 3150 541 2295 127 210 2628 69 298 2414 8873 17455 2967 1251 4590 256 480 5083 135 611 4877 18700 35983 6117 1.0 2.2 6.8 2 1.0 1.0 8 2.2 N/A 1.2 1.9 4.3 4 9.6 5 5.5 1.6 7 1.5 8 4.5 N/A 2.4 3.8 2,3 8.6 4 13.5 5 11.0 6 3.2 3 8 6.8 N/A 9 4.7 1 *BLLs are presented in ug/dL. Not all the Odds ratios were available for all three blood lead levels in every disease category. Estimates were used in those cases. 1(Antilla et al., 1995) 2(Asien et al., 2000); 3(Khera et al., 1980); (Gemmel et al., 2002); 5(Landrigan et al., 1976) 6(Kristensen et al., 1993) 7(Factor-Litvak et al., 1996) 8(Gomaa et al., 2002) 9(Kristensen et al., 1993). 4 Table 7. Attributable risks and attributable Burden for 9 Pb-linked diseases (Medium estimate) AR for PbB Levels Pb-Disease Category Genito-Urinary Disease Prematurity Dental Caries Nervous System Cancers Congenital Anomalies Hypertension Cerebrovascular Disease Pb-Mild Mental Retardation Low Birth Weight 5-8 0.0 29.0 6.8 25.4 0.0 0.0 29.0 100.0 6.4 9-15 >16 33.5 21.9 64.9 43.2 9.6 13.5 71.6 50.0 25.1 18.0 21.9 16.7 66.2 36.7 100.0 100.0 43.9 27.0 Total SSA Total Nigeria % Nigeria BOD Attributable to Pb % Nigeria BOD, Attributable to Pb (0-14) *AB for PbB Levels 5-8 0 1,330 17 122 0 0 177 1,609 1,191 9-15 419 2,978 25 344 1,278 30 405 1,609 8,218 >16 274 1,982 35 240 917 23 224 1,609 5,050 4,446 15,306 10,353 756 2,602 1,760 1.40 4.80 3.25 2.18 7.50 5.07 *Attributable Burden is presented in DALYs (x1000) ure, lost earnings and increased IMR appear to have the largest impact on overall cost. The total childhood health cost was estimated to be $10.3 billion ($238 million GNIPPP adjusted), or 29.8 billion naira annually for a 1 µg/dL increase in BLL. Considering that the average BLL in Nigerian children is approximately 10 µg/dL, the cost of lead exposure could be ten times higher than what is reported here. Thus, if Nigeria is able to decrease national BLL average by 5 µg/dL, the country could gain more than $1 billion in savings annually from childhood health costs. Table 9 shows the results for the adult health costs of lead exposure. The total health costs are presented in millions of dollars. Mortality costs of hypertension–related deaths provide the driving force behind the bulk of the adult health costs, accounting for $6.6 billion out of $7 billion (94%) estimated for total adult health costs. Table 10 shows the estimates for the total health cost annually for the entire population. It also provides the annual per capita health cost of lead exposure, the annual health cost as a percentage of GNI-PPP, and the annual health cost as a percentage of the average per capita health ex- Ogunseitan and Smith 033 Table 8. Childhood health costs of lead exposure. Children Medical Costs Variable $(M) Average blood lead concentration Number of children requiring chelation therapy 9.8 ug/dL 160,909 Cost of chelation therapy Total Medical Costs Compensatory Education Number of children who receive education Cost of education Total Compensatory Education Cost Number children, age 6 Earnings Increase in earnings of a 1 ug/dL reduction in BLL Total Earnings Lost IMR Infant Mortality 1 ug/dL reduced maternal blood – IMR Value of statistical life Number of live births in Nigeria, 2002 Number of reduced deaths Total IMR Cost # of NICU admissions Reduced NICU admissions Neonatal Care Number of fewer NICU admissions Cost of NICU Total Neonatal Cost Total Childhood Cost expenditure. All of these health cost figures are for a 1 µg/dL change in BLL. The total health cost is presented as a low, medium, and high value. The low value was calculated by subtracting the cost of compensatory education and NICU from the total. It is hypothesized that Nigeria could have significantly less compensatory education than the United States for children who are academically challenged. Likewise, the frequency of children admitted into NICU in Nigeria could be much lower than the US. Based upon these assumptions, the low estimate for the health costs due to lead exposure is estimated to be approximately $377 million. The high value for health costs due to lead exposure was taken from Landrigan et al. (2002) who estimated that the health costs due to lead exposure for the cohort of children born in 2000 is approximately $43.4 billion (USD, 1997). This estimate was adjusted using both the Consumer Price Index (CPI) and the GNI-PPP ratio between the US and Nigeria (2.3%). The resultant health cost estimate after allowing for these adjustments is approximately $1.15 billion. GNI-PPP Adjusted Million Naira 1,920 309 162,231 7 888 18 2,286 155 19,406 52.88 6,609.88 202.79 4.66 583.01 10,356.03 238.19 29,773.58 4,902 795 3,515,600 1,920 6,750 75/1000 74.9/1000 4,429,840 5,192,000 519 2,299.09 1,752,300 1,749,960 2,340 86,661 Cost of lead abatement Table 11 illustrates the cost of a lead abatement program in Nigeria. The cost is a combination of four subcategories: the cost the refinery upgrades, the cost of a non-lead additive, the cost of unleaded gasoline, and the cost of TEL. These sub-category costs are presented in $/Liter. To calculate the overall cost of the abatement program, the cost of TEL is subtracted from the summed costs of refinery upgrades, non-lead additive, and unleaded gasoline. Using the national gasoline consumption provided by the Department of Energy (DOE), the medium overall estimated cost of a lead abatement program for Nigeria is approximately $194 million for the first year. This is approximately 48.5% of the health cost of a 1 µg/dL increase in BLL per year µg/dL. The low estimate, using the low estimate cost of $0.01 /L reported by the Organization for Economic Development (OCED) for lead phase out is $76 million per year (11). The high estimate, using the high estimate cost of 034 Afr. J. Environ. Sci. Technol. Table 9. Adult health costs of lead exposure. Adults Variable $(M) GNI-PPP Adjusted Million Naira Medical costs Hypertension Heart attacks Strokes Number of cases of hypertension Annual medical costs 288,712 812 Total Medical Cost 234.43 5.39 674.00 Number of cases of heart attacks Medical costs Total Medical Cost 1,454 33,960 49.38 1.14 141.96 Number of cases of stroke Annual medical costs 591 26,574 Total Medical Cost 15.71 0.36 45.15 Number of cases of hypertension Annual lost earnings Total Earnings Lost 288,712 115.0 33.20 0.76 95.46 Number of cases of heart attacks Annual lost earnings 1,454 31,000 Total Earnings Lost 45.07 1.04 129.59 Number of cases of stroke Annual lost earnings 591 17,716 Total Earnings Lost 10.47 0.24 30.10 Number of deaths Value of statistical life 1,500 4,429,840 Total Mortality Cost 6,644.76 152.83 19,103.69 7,033.02 161.76 20,219.94 Lost wages Hypertension Heart Attacks Strokes Mortality Total Adult Cost Table 10. Total health costs of lead exposure. Low Estimate $M (2003) GNI-PPP Adj. $M † Million Naira Total annual health cost to Nigeria of 1 µg/dL BPb Annual per capita cost Annual cost as percentage of GNI-PPP Annual cost as percentage of per capita health expenditures Medium Estimate *16,391 377 47,124 126 0.36% 14% 2.90 0.36% 14% 362 0.38% 14% Total annual health cost to Nigeria of 1 µg/dL BPb Annual per capita cost Annual cost as percentage of GNI-PPP Annual cost as percentage of per capita health expenditures High Estimate 17,389 400 49,993 134 0.38% 15% 3.08 0.38% 15% 385 0.38% 15% **49,810 1,145 143,203 383 8.81 1,102 1.10% 1.10% 0.38% 44% 44% 44% Total annual health cost to Nigeria of 1 µg/dL BPb Annual per capita cost Annual cost as percentage of GNI-PPP Annual cost as percentage of per capita health expenditures *Low estimate = Total health costs – cost of compensatory education and NICU. **High estimate = ($43.4 billion) (CPI, 2003), (49). †Million Naira. Ogunseitan and Smith 035 Table 11. Cost of lead abatement in Nigeria. Cost ($/liter) Unleaded Gasoline 0.01 Abatement factors Non-Pb Additive 0.01 Refinery Retooling 0.006 Tetraethyl Lead (TEL) 0.002 Domestic Gasoline 0.16 Gasoline source Foreign Gasoline 0.16 Total Gasoline 0.16 Low estimate Total annual cost of abatement Pb abatement cost / Pb health cost Abatement as % of health cost Medium estimate Total annual cost of abatement Pb abatement cost / Pb health cost Abatement as % of health cost ‡ Cons. (10 l/year) 6 6,837 6,837 6,495 6,837 6,495 342 6,837 Cost Cost (M$/yr Cost (M$/yr † ( MN/yr, 2003) 1995) 2003) 68 82 10,250 68 82 10,250 39 47 5,875 14 17 2,125 1,039 271 33,821 55 66 8,250 1,094 1,313 164,148 *75.6 0.189 18.9% 24,250 0.189 18.9% 194 0.485 48.5% 24,250 0.485 48.5% *227 0.567 56.7% 24,250 0.567 56.7% High estimate Total annual cost of abatement Pb abatement cost / Pb health cost Abatement as % of health cost *Low estimate = ($.01/L) (Liters consumed/year) (11). **High Estimate = ($.03/L) (Liters consumed/year) (11). ‡Consumption, †Million Naira. $0.03/L reported by OECD, is $227 million per year (OECD, 1999). In conclusion, we have shown that lead exposure remains a major health risk factor in all Nigeria communities, both rural and urban. The most important – and controllable – source of exposure is leaded automobile fuels. Arguments based on the enormous costs to society of switching to unleaded fuels are weak in the face of counterarguments based on the even more astounding health care and special educational costs associated with lead exposure. In the presence of alternative renewable fuels such as ethanol (Thomas and Kwong, 2000), the removal of lead from all fuels in Nigeria – and all countries in sub-Saharan Africa – should not be delayed a single day further. ACKNOWLEDGMENTS This study was supported in part by funding and resources provided by the Global Forum for Health Research, Switzerland; by the U.S. Centers for Disease Control and Prevention; and by the U.S. National Science Foundation (CMS-0524903). Additional support was provided by the Program in Industrial Ecology at UC-Irvine. We are grateful for the kind support provided by Dr. Sunday Ochenjele at Mount Zion hospital, Otukpo; and by Shime-nenge Imadu, Secretary of the Ethical Committee of the Ministry of Health and Human Services, Benue State, Nigeria. REFERENCES Adebamowo EO, Agbede OA, Sridhar MKC, Adebamowo CA (2006). An examination of knowledge, attitudes and practices related to lead exposure in South Western Nigeria. BMC Public Health 6 (82): 1–7. Ademuyiwa O, Ugbaja RN, Idumebor F, Adebawo O (2005). Plasma lipid profiles and risk of cardiovascular disease in occupational lead exposure in Abeokuta, Nigeria. BMC Lipids in Health and Disease, 4(19): 1–7. Adeniyi FAA, Anetor JI (1999). Lead poisoning in two distant states of Nigeria: an indication of the real size of the problem. Afr. J. Med and Med. Sci. 28: 107-112. Agency for Toxic Substances and Disease Registry (1999). Toxicological profile for lead (update). US Department of Health and Human Services, Atlanta, Georgia. Anttila A, Heikkila P, Pukkala E, Nykyri E, Kauppinen T, Hernberg S, Hemminki K (1995). Excess lung cancer among workers exposed to lead. Scan J Wrk Environ. Health, 21(6): 460-469. Asien AO, Olarewaju RS, Imade GE (2000). Twins in Jos, Nigeria: a seven year retrospective study. Med. Sci. Monit. 6(5): 945-950. Charney, E. (1982). Lead poisoning in children: The case against household lead dust. In: Chisolm J.J. and O'Hara D.M. (eds.), Lead Absorption in Children. Urban & Schwarzenberg, Baltimore-Munich, pp. 35-42. Cooper R.S., Osotimehin B., Kaufman J.S., Forrester T. (1998). Disease burden in SSA: what should we conclude in the absence of data? Lancet 351: 208-210. Factor-Litvak P., Kline J., Slavkovich V., Graziano J. (1996). Blood lead and blood pressure in young children. Epidemiol. 7: 633-637. Fakayode, S.O, Olu-Owolabi, B.I. (2003) Heavy metal contami-nation of roadside topsoil in Osogbo, Nigeria: its relationship to traffic density and proximity to highways. Environ. Geol. 44: 150-157. Gemmel A, Tavares M, Alperin S, Soncini J, Daniel D, Dunn J, Crawford S, Braveman N, Clarkson TW, McKinlay S, Bellinger DC. (2002). Blood lead level and dental caries in school-age children. 036 Afr. J. Environ. Sci. Technol. Environ. Health Perspect, 110: 625-630. Gomaa A, Hu H, Bellinger D, Schwartz J, Schnaas L, Gonzalez-Cossio T, Peterson K, Aro A, Hernandez-Avila M (2002). Maternal bone lead as an independent risk factor for fetal neurotoxicity: a prospective study. Ped, 110(1): 110-118. Grosse SD, Thomas DM, Schwartz J, Jackson RJ (2002). Economic gains resulting from the reduction in children’s exposure to lead in the Unites States. Environ. Health Perspect. 110: 563-569. Kapu M.M., Basak B., Job A., Umara I.O., Kalla S.M., Mohammad B.Y., Harun B.A., Schaeffer D.J. (1989). Studies in human exposure to environmental lead in Zaria, Nigeria. Trace Elements Med. 6: 178181. Khera AK, Wibberley DG, Dathan JG (1980). Placental and stillbirth tissue lead concentrations in occupationally exposed women. Br. J. Ind. Med. 37: 394-396. Kristensen P, Irgens LM, Dalveit AK, Anderson A (1993). Perinatal outcome among children of men exposed to lead and organic solvents in the printing industry. Am. J. Epidemiol. 137(2): 134-144. Laidlaw MAS, Mielke HW, Filippelli GM, Johnson DL, Gonzales CR (2005). Seasonality and children’s blood lead levels: Developing a predictive model using climatic variables and blood lead data from Indianapolis, Indian, Syracuse, New York, and New Orleans, Louisiana (USA). Environ. Health Perspect. 113: 793–800. Landrigan PJ, Baker EL, Jr, Feldman RG, Cox DH, Eden KV (1976). Increased lead absorption with anemia and slowed nerve conduction in children near a lead smelter. J. Pediatr. 89: 904-910. Landrigan PJ, Schechter CB, Lipton JM, Fahs MC, Schwartz J (2002). Environmental pollutants and disease in American children: estimates of morbidity, mortality, and costs for Lead poisoning, asthma, cancer, and developmental disabilities. Environ. Health Perspect, 110: 721728. Lanphear BP, Dietrich K, Auinger P, Cox C (2000). Cognitive deficits associated with blood lead concentrations < 10 µg/dL in United States children and adolescents. Pub Hlth Rep, 115: 521-529. Lincoln JD, Ogunseitan OA, Saphores J-D, Shapiro A.A (2007). Leaching Assessments of Hazardous Materials in Cellular Telephones. Environ. Sci. Technol., 41: 2572 -2578. Lynn R, Vanhanen T (2002). IQ and the Wealth of Nations. Westport, CT: Praeger. Miettenen OS (1974). Proportion of disease caused or prevented by a given exposure, trail or intervention. Am. J. Epidemiol. 99:325-332. Moore MR, Meredith PA, Goldberg A (1977). A retrospective analysis of blood lead in mentally retarded children. Lancet, 520: 717-719. Moore MR., McCabe L.M. (2005). Introduction to Practice of Statistics, 5th Edition, W. H. Freeman and Co. and Sumanas, Inc. p. 896. Murray C., Lopez A, (1996) eds. The Global Burden of Disease: Volume 1 (World Health Organization, Harvard School of Public Health, and The World Bank, Washington, D.C. p. 1022. Needleman HL (1980). Lead and neuro psychological deficit. In: Needleman HL (ed.) Low Level Lead Exposure: the clinical implications and current research. New York: Raven Press, pp. 43-51. Needleman HL (1983). Low level lead exposure and neuropsychological performance. In: Rutter M, Jones RR (eds.), Lead Versus Wealth, John Wiley and Sons Ltd., pp. 229-242. Needleman HL (1999). History of lead poisoning in the world. In: Lead poisoning prevention and treatment: implementing a national program in developing countries. George AM (ed.). The George Foundation, Bangalore, India. Needleman HL, Gunnoe C, Leviton A, Reed R, Peresie H (1979). Deficits in psychologic and classroom performance of children with elevated dentine lead levels. N Eng. J. Med, 300: 689-732. Needleman HL, Landrigan PJ (1981). The health effects of low level exposure to lead. Ann Rev. Public Wealth, 2: 277-298. Needleman H.L., Schell A., Bellinger D. (1990). The long-term effects of low dose exposure to lead in childhood: an 11 year follow-up report. N Eng. J. Med. 322: 83-88. Nriagu JO, Pacnya JM (1988). Quantitative assessment of worldwide contamination of air, water and soils by trace metals. Nature, 333: 134-139. Nriagu JO, Blankson ML, Ocran K (1996). Childhood lead poisoning in Africa: a growing public health problem. Sci. Total Environ. 181: 93100. Nriagu J, Oleru NT, Cudjoe C, Chine A (1997). Lead poisoning of children in Africa, III. Kaduna, Nigeria. Sci. Tot. Environ. 197: 13-19. Obioh IB, Akeredolu FA, Asubiojo OI (1988). National inventory of air pollutants in Nigeria. Report of the Environmental Research Laboratory, Obafemi Awolowo University. Obioh, I.B., Olise, F.S., Owoade, O.K., and Olaniyi, H.B. (2005) Chemical characterization of suspended particulates along air corridors of motorways in two Nigerian cities. J. Appl. Sci. 5: 347-350. Ogunfowokan AO, Asubiojo OI, Adeniyi AA, Oluyemi EA. (2004) Trace lead, zinc, and copper levels in Barbula labarenensis as a monitor of local atmospheric pollution in Ile-Ife, Nigeria. J. Appl. Sci. 4: 380-383. Ogunsola O.J., Oluwole A.F., Asuobiojo O.I., Olaniyi H.B., Akeredolu F.A., Akanle O.A., Spyrou N.M., Ward N.I., Ruck W. (1994). Traffic pollution: preliminary elemental characterization of roadside dust in Lagos, Nigeria. Sci. Total Environ. 147: 175-184. Omokhodion F.O. (1994). Blood lead and tap water lead in Ibadan, Nigeria. Sci. Total Environ. 151:187-190. Organization for Economic Cooperation and Development/United Nations Environment Program. (1999). Phasing lead out of gasoline: an examination of policy approaches in different countries. Paris: OECD. Pocock SJ, Smith M, Baghurst PA (1994). Environmental lead and children’s intelligence: a systematic review of the epidemiological evidence. Br. Med. J. 309: 1189-1197. Population Reference Bureau (2006). World Population Data Sheet. Internet Communications: http://www.prb.org/. Accessed on 6 August, 2007. Pruss-Ustun A, Fewtrell L, Landrigan PJ, Ayuso-Mateos JL (2004). Lead Exposure, pages 1495 – 1552 In: Ezzati, M., A.D. Lopez, A. Rodgers, and C.J.L. Murray. Comparative Quantification of Health Risks: Global and Regional Burden of Disease Attributable to Selected Major Risk Factors. World Health Organization, Geneva. Rankin CW, Nriagu JO, Aggarwal JK, Arowolo TA, Adebayo K, Flegal RA (2005). Lead contamination in cocoa and cocoa products: isotopic evidence of global contamination. Environ. Health Perspect. 113: 1344–1348. Schwartz J (1994). Low level lead exposure and children’s IQ: a meta analysis and search for a threshold. Environ. Res. 56: 42-55. Schwartz J. (1993). Societal benefits of reducing lead exposure. Environ. Res. 66: 105-124. Schwartz J (1991). Lead, blood pressure, and cardiovascular disease in men and women. Environ. Health Perspect., 91: 71-75. Schwartz J, Anglo C, Pitcher MS (1986). Relationship between childhood blood lead levels and stature. Pediatrics, 77: 281-288. Stouthard MEA, Essink_Bot ML, Bonsel GJ (1997). Disability weights for diseases in the Netherlands. Erasmus University, Department of Public Health, Rotterdam. Vos T. Thomas VM (1995). The elimination of lead in gasoline. An Rev. Ener Environ., 20: 301-324. Thomas VM, Kwong A (2000). Ethanol as a lead replacement: phasing out leaded gasoline in Africa. Energy Policy, 10: 1-11. United States Environmental Protection Agency (1985). Costs and benefits of reducing lead in gasoline, final regulatory impact analysis. EPA-230-05-85-006, Washington, D.C. United States Department of Energy (2000). Country energy data report. Internet communications: http://www.eia.doe.gov/emeu/world/country/cntry_NI.html. Accessed on 6 August 2007. World Health Organization (2000). Environmental lead exposure: a public health problem of global dimensions. WHO Bulletin, Tong S, Yasmin E,Von S, Prapamontol T, (eds.) Geneva, Switzerland.