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Blood Lead Levels in Andean Infants and Young Children in Ecuador: An International Comparison ab

S. Allen Counter , Leo H. Buchanan

cd

e

& Fernando Ortega

a

Department of Neurology, Harvard Medical School/The Biological Laboratories, Cambridge, Massachusetts, USA b

Department of Neurophysiology, Massachusetts General Hospital, Boston, Massachusetts, USA c

Department of Pediatrics, University of Massachusetts Medical School/Eunice Kennedy Shriver Center, Worcester, Massachusetts, USA d

Click for updates

Department of Otolaryngology, Harvard University Health Services, Cambridge, Massachusetts, USA e

Colegio Ciencias de la Salud, Escuela de Medicina, Escuela de Salud Pública, Colegio de Artes Liberales y Galapagos Institute of Arts and Sciences–GAIAS, Universidad San Francisco de Quito, Quito, Ecuador Published online: 19 Jun 2015.

To cite this article: S. Allen Counter, Leo H. Buchanan & Fernando Ortega (2015) Blood Lead Levels in Andean Infants and Young Children in Ecuador: An International Comparison, Journal of Toxicology and Environmental Health, Part A: Current Issues, 78:12, 778-787, DOI: 10.1080/15287394.2015.1031050 To link to this article: http://dx.doi.org/10.1080/15287394.2015.1031050

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Journal of Toxicology and Environmental Health, Part A, 78:778–787, 2015 Copyright © Taylor & Francis Group, LLC ISSN: 1528-7394 print / 1087-2620 online DOI: 10.1080/15287394.2015.1031050

BLOOD LEAD LEVELS IN ANDEAN INFANTS AND YOUNG CHILDREN IN ECUADOR: AN INTERNATIONAL COMPARISON S. Allen Counter1,2, Leo H. Buchanan3,4, Fernando Ortega5

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1

Department of Neurology, Harvard Medical School/The Biological Laboratories, Cambridge, Massachusetts, USA 2 Department of Neurophysiology, Massachusetts General Hospital, Boston, Massachusetts, USA 3 Department of Pediatrics, University of Massachusetts Medical School/Eunice Kennedy Shriver Center, Worcester, Massachusetts, USA 4 Department of Otolaryngology, Harvard University Health Services, Cambridge, Massachusetts, USA 5 Colegio Ciencias de la Salud, Escuela de Medicina, Escuela de Salud Pública, Colegio de Artes Liberales y Galapagos Institute of Arts and Sciences–GAIAS, Universidad San Francisco de Quito, Quito, Ecuador Lead (Pb) exposure in infants and children remains an international health concern. Blood lead (PbB) levels of a cohort of 130 Ecuadorian infants and young children aged 0.33 to 5.8 yr were compared to values reported for similar age groups in Africa, Asia, Europe, Latin America, and the United States. The mean PbB level for the total group of 130 Ecuadorian infants and young children in this study was 29.4 µg/dl (SD: 24.3; range: 3.0–128.2; median: 21.7; geometric mean: 20.7 µg/dl). The mean PbB level for the 0–2 yr age group (infants) was 33.6 µg/dl (SD: 28.9; median: 22.0; range: 3.9–119.7; geometric mean: 23.6 µg/dl), while the average PbB level for the 3–5 yr age group (young children) was 27.9 µg/dl (SD: 22.5: median: 22; range: 3–128.2; geometric mean: 19.8 µg/dl). The difference between the mean PbB levels for the infants and young children was not statistically significant. The average PbB level of 32.6 µg/dl for males was not statistically different from the mean PbB level of 26.3 µg/dl for females. The PbB levels observed in Ecuadorian infants and young children in this investigation were elevated above the World Health Organization (WHO) level of concern of 10 µg/dl and Centers for Disease Control and Prevention (CDC) current reference value of 5 µg/dl. Values were comparable to concentrations found in Pakistan, where occupational use of Pb is prevalent. These findings further indicate that infants and young children exposed to Pb from Pb glazing of ceramics in Andean Ecuadorian villages exhibit greater potential metal-mediated poisoning than children of similar ages in Asia, Europe, other Latin American countries, and the United States.

to intellectual disability and immune system dysfunction (Fewtrell et al., 2004; WHO, 2010; Garcia-Leston et al., 2012). Infants and young children are vulnerable populations that require protection from exposure to Pb and other toxic substances. Although blood lead (PbB) levels in infants and young children have declined globally following removal of Pb from petroleum products and introduction of gov-

Although pediatric lead (Pb) poisoning and prevention have received extensive research and clinical attention over several decades, Pb exposure in infants and children remains an international health concern (Ranft et al., 2008; Nacano et al., 2014). According to the World Health Organization (WHO), Pb exposure accounts for approximately 0.6% of the global burden of disease and contributes significantly

Received 22 February 2015; accepted 15 March 2015. Address correspondence to Dr. S. Allen Counter, Jr., DMSc, PhD, Department of Neurology, Harvard Medical School, The Biological Laboratories, 16 Divinity Avenue, Cambridge, MA 02138, USA. E-mail: [email protected] 778

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COMPARISON OF INTERNATIONAL BLOOD LEAD LEVELS

ernmental regulations, pediatric Pb intoxication persists in some countries from environmental exposure where widespread Pb contamination exists. Recent reports of widespread lethal pediatric Pb-mediated poisoning associated with gold mining operations in Nigeria offer further evidence of current severe hazards of Pb exposure (Dooyema et al., 2012; Bashir et al., 2014). Many nations have laws that ban the use of Pb in paint, which has been a significant contributor to Pb poisoning in infants and young children (Clark et al., 2009). In addition, Pb poisoning in children may derive from cultural practices that use cosmetics, folk remedies, and magico-religious materials that are contaminated with Pb (Muzi et al., 2005; Centers for Disease Control and Prevention [CDC], 2013b; Lopes et al., 2015). Recent reports indicate that toys and jewelry that contain Pb-based paint are sources of Pb exposure in children (CDC, 2011; Guney and Zagury, 2012; Mateus-Garcia and RamosBonilla, 2014). Current major sources of Pb exposure globally, particularly in developing countries, are acid battery recycling, dietary sources, exposure from petroleum refineries, exposure from gold mining, and Pb poisoning from glazing of ceramics (Counter et al., 2000; Buchanan et al., 2011; van der Kuijp et al., 2013; Bashir et al., 2014; Nacano et al., 2014). Pica and the ingestion of Pb-contaminated food, soil, dust, or Pb-based paint are the primary vectors of Pb poisoning in young children (Agency for Toxic Substances and Disease Registry [ATSDR], 2007; Ranft et al., 2008; Nacano et al., 2014). However, Pb poisoning may occur during pregnancy as a result of fetal exposure to Pb mobilized from the mother’s bone stores, or during the neonatal and infant stages from Pb-contaminated breast milk of the mother (Gulson et al., 2003; Ettinger et al., 2006; Lamadrid-Figueroa et al., 2006; Ferguson et al., 2013; Counter et al., 2014). Children younger than 6 yr of age are most vulnerable to the harmful health effects of Pb exposure, which may result in adverse physiological health consequences and neurodevelopmental disabilities, including deficits in IQ, attention, visual–motor integration, fine motor

779

coordination, and neurobehavioral development (Koller et al., 2004; Lanphear et al., 2005; Binns et al., 2007; Counter et al., 2009a, 2009b). Neurocognitive deficits associated with Pb exposure have been associated with neuronal damage in the prefrontal cortex (Finkelstein et al., 1998). Lanphear et al. (2000, 2005) showed that PbB levels below the CDC’s previous “level of concern” of 10 µg/dl may induce neurocognitive impairment in children, suggesting that there is no threshold for the neurotoxic effects of Pb exposure in children. Consequently, the CDC has changed its level of concern from 10 µg/dl to an “upper reference interval value,” which currently is 5 µg/dl (CDC, 2013a). Previously, Counter et al. (2004, 2014) noted Pb exposure in infants and young children living in remote communities in the Andes Mountains of Ecuador where Pb was extracted from discarded Pb–acid automobile batteries and was also widely used in ceramic tile production. Data demonstrated elevated PbB levels in nursing infants and young children, and in the blood and milk of lactating mothers. In this same cohort and study area, Counter et al. (1998, 2005) observed neurodevelopmental disorders and neurocognitive deficits in Pb-exposed infants and young children. The objective of the present study was to (1) examine the PbB levels of infants and young children in Ecuadorian Andean cohorts living in highly Pb-contaminated communities and (2) compare these findings with pediatric PbB levels for similar age groups in other countries. The overarching aim of this study was to investigate the prevalence of Andean Ecuadorian Pb exposure in relation to the global health burden of Pb.

METHODS AND MATERIALS Participants and Location The participants in this study consisted of 130 infants and young children (63 males and 67 females) aged 4 mo to 5.8 yr (mean: 3.8; SD: 1.6; median: 4.6 yr). The number of infants (aged 0.33- 2.0 yr) was 33, and the number of young children (aged 2.08 to 5.8 yr) was

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97. The mean age of the males was 3.8 yr (range: 0.42–5.8; median: 4.9 yr), and the mean age of the females was 3.8 yr (range: 0.33–5.5; median: 4.4 yr). The participants resided in the ceramic production and Pb glazing Ecuadorian villages of La Victoria and Racar, Ecuador, South America. The study areas are located in Cotopaxi Province at an altitude of approximately 2850 m and Azuay Province at an altitude of approximately 2500 m. Most families in the study area engage in several aspect of a Pb glazing cottage industry, including manual extraction of Pb oxide/sulfate from automobile storage batteries, mixing of the Pb glazing slurry, application of the Pb mixture onto ceramic roof tiles, vases, urns, and other objects, and the baking of Pb-coated ceramics in family backyard kilns. Various types of utility batteries are also stripped for Pb extraction by adults and children in the study area. Informed consent was obtained from the parent or guardian of each child prior to testing. This study was approved by the Human Studies Committee (Comité de Bioética) of Universidad San Francisco de Quito. The study was conducted under the auspices of Universidad San Francisco de Quito Colegio Ciencias de la Salud, Escuela de Medicina in Quito, Ecuador. The results of this investigation were provided to the parents/guardians of the participants in the study, who were counseled regarding their children’s Pb exposure levels and referred to local health officials for medical intervention as needed. Pb Concentrations in Blood For assessment of PbB, 4 ml whole blood was drawn from the antecubital vein of each infant and young child included in the study following thorough cleaning of the skin with 2–3 swabs containing isopropanol using Liheparin Vacutainer sets. All blood samples were stored in a refrigerated container and later analyzed for Pb concentrations by graphite furnace atomic absorption spectroscopy with Zeeman background correction at the Department of Laboratory Medicine, Boston Children’s Hospital.

Statistical Analysis The arithmetic mean, standard deviation, range, median and geometric mean were calculated for PbB concentrations obtained from the participants in the study. Differences between group means were analyzed by the Mann–Whitney U-test. An alpha level of ≤.05 was accepted as an indication of statistical significance. RESULTS Blood Pb Concentrations The mean PbB level for the total cohort of 130 infants and children was 29.4 µg/dl (SD: 24.3; range: 3–128.2; median: 21.7; geometric mean: 20.7 µg/dL). The average PbB level for males was 32.6 µg/dl (SD: 25.2; range: 3–119.7; median: 21.7; geometric mean: 23.8 µg/dl). The mean PbB level for females was 26.3 µg/dl (SD: 23.2; range: 3–128.2; median: 21.7; geometric mean: 18.2 µg/dl). The difference between the mean PbB levels for males and females was not significant. The average PbB level for the 0–2 yr age group (infants) was 33.6 µg/dl (SD: 28.9; median: 22; range: 3.9–119.7; geometric mean: 23.6 µg/dl), while the mean PbB level for the 3–5 yr age group (young children) was 27.9 µg/dl (SD: 22.5; median: 22; range: 3–128.2; geometric mean: 19.8 µg/dl). The difference between mean PbB levels for infants and young children was not significant. The box plots of Figure 1 compare PbB levels of an earlier cohort (1996–1999) of Ecuadorian Andean children younger than 6 yr of age (median age: 5 yr) with a more recent cohort (2003–2013) of Ecuadorian Andean children of comparable age (median age: 4.4 yr) living in the same communities. The mean PbB level for the 1996–1999 cohort was 34.7 µg/dl (SD: 24.9, range 4.4–128.2, median: 29; geometric mean: 27 µg/dl). The mean PbB level for the 2003–2013 cohort was 24 µg/dl (SD: 22.5; range: 3–107; median: 16; geometric mean: 15.9 µg/dl). The average PbB concentration for the 2003–2013 cohort was significantly lower than the PbB level for

COMPARISON OF INTERNATIONAL BLOOD LEAD LEVELS

781

140

120

PbB µg/dL

100

80

60

40

n = 65 n = 65

20

0

1996–1999

2003–2013

FIGURE 1. Box plots comparing the blood lead (PbB) levels of an earlier (1996–1999) cohort of Ecuadorian Andean children younger than 6 yr of age living in lead (Pb)-contaminated communities with a more recent (2003–2013) cohort of Ecuadorian Andean children of comparable age living in the same communities.

the 1996–1999 cohort, indicating a decline in pediatric PbB levels in the study area over the years. Figure 2 presents a bar graph comparing the PbB levels of Ecuadorian Andean children younger than 6 yr of age with PbB levels of children of comparable age in other Latin American countries. It can be seen from this PbB (µg/dL) 0

5

10

15

20

25

30

PbB (µg/dL)

Ecuador (4 mos-5 yrs.) *Ecuador (4 mos-5 yrs.)

0

5

10

15

20

25

30

Ecuador (4 mos-5 yrs.)

*Argentina (6 mos-5 yrs.)

*Ecuador (4 mos-5 yrs.)

*Argentina (1 mo-1 yr.)

Australia (1– 4 yrs.)

*Argentina (2-3 yrs.)

Bangladesh (< 5 yrs.)

*Argentina (4-5 yrs.)

China (0-6 yrs.)

** Brazil (0-5 yrs.)

*France 6 mos-6 yrs.)

Chile (1 yr.) *Mexico (1-6 yrs.) *Peru Amazon (0-3 yrs.) *Peru Amazon (4-6 yrs.) Peru Urban (6 mos-9 yrs.)

Country

Country

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Years

figure that Ecuadorian infants and young children have PbB levels that are higher than those reported for children in other Latin American countries. The geometric mean of 20.7 µg/dl for Ecuadorian infants and young children is approximately 16-fold higher than the geometric mean PbB level of 1.3 µg/dl for a national population survey of U.S. children aged 1–5 yr, and about 3.5-fold higher than the geometric mean of 6 µg/dl in a cohort of Mexican children of comparable age (Figure 3). Similarly, the geometric mean PbB level of 20.7 µg/dL for Ecuadorian Andean children younger than 6 yr of age is approximately 4-fold higher than medium PbB level of 5.2 µg/dl reported for a cohort of children of comparable age in Brazil. Table 1 lists PbB levels observed in various countries throughout the world that have been reported for infants and young children of comparable age. As Table 1 illustrates, PbB levels reported for European nations, such as France, with a geometric mean of 1.49 µg/dl, and the United States, with a geometric mean PbB level of 1.3 µg/dl, tended to be lower than values reported for Latin American countries. However, the geometric mean PbB level of 6.3 µg/dl reported for an earlier cohort in the industrialized area of Silesia, Poland, is more

*India (0-11 yrs.) *Nigeria, Dust Ore Process (< 5 yrs.) *Nigeria, Non-Dust Ore Process (< 5 yrs.) *Nigeria, No Ore Process (< 5 yrs.) Pakistan (6 mos-5 yrs.) Philippines (6 mos-5 yrs.) Poland (2-7 yrs.)

Uruguay (5 mos-3.75 yrs.) *USA (1-5 yrs.)

FIGURE 2. Bar graph comparing the PbB levels of Ecuadorian Andean children younger than 6 yr of age with the PbB levels of children of comparable age in other Latin American countries. Asterisk denotes geometric mean PbB values; double asterisk indicates median PbB values; and the absence of an asterisk denotes arithmetic mean PbB values.

*Russia (2-6 yrs.) * USA (1-5 yrs.)

FIGURE 3. Bar graph comparing the PbB levels of Ecuadorian Andean children younger than 6 yr of age with the PbB levels of children of comparable age in European, Asian, and African countries. Asterisk denotes geometric mean PbB values; double asterisk indicates median PbB values; and the absence of an asterisk denotes arithmetic mean PbB values.

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TABLE 1. Blood lead (PbB) Levels in Infants and Children in Different Countries

Country

Exposure Source/ Population Description

Cordoba, Argentina

Background Exposure

La Plata, Argentina

Background Exposure National Survey Urban/Rural Areas 1 km of Inactive Pb Foundry Waste Recycling Near Pb Storage Site Away from Pb Storage Site Urban/ Low SES Population Survey National Survey Urban/ Industrialized Smelting Area Gold Ore Processing

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Australia Dhaka, Bangladesh Santo Amaro da Purificação, Brazil Porto Alegre, Brazil Antofagasta, Chile Antofagasta, Chile Santiago, Chile China (15 cities) France Bombay, India Torreón, Mexico Northwestern Nigeria Village A Village B Zamfara State, Nigeria Zamfara State, Nigeria Zamfara State, Nigeria Karachi, Pakistan Visayas, Philippines Peruanito & Santa Isabel, Peru Peruanito & Santa Isabel, Peru Lima & Callao, Peru Silesia, Poland Krasnouralsk, Ekaterinburg, & Volgograd, Russia United States Montevideo, Uruguay a Year

Dust Ore Processing Non-Dust Ore Processing No Ore Processing Urban/ Low SES Rural Peruvian Amazon

Date of Survey

Sample Size

Age Range

Arithmetic Mean PbB (µg/dL)

Geometric Mean PbB (µg/dL)

Reference

1 mo-1 yr. 2-3 yrs. 4-5 yrs. 0.5-5 yrs.

— — — —

3.30 2.96 1.83 4.26

Martinez et al., 2013 Martinez et al., 2013 Martinez et al., 2013 Disalvo et al., 2009

2009-10 2009-10 2009-10 2006

38 30 14 93

1995 2007-09 1998

1575 95 47

1-4 yrs. < 5 yrs. 1-4 yrs.

5.72 12.09 17.10

5.05 — —

Donovan, 1996 Mitra et al., 2012 Carvalho et al., 2003

2006 1997-98

97 486

0-5 yrs. 0-7 yrs.

— —

5.20b 8.70

Ferron et al., 2012 Sepulveda, et al. 2000

1997-98

75

0-7 yrs.



4.22

Sepulveda, et al. 2000

1995-97 2005a 2008-09 2002-03

422 17,141 3,831 754

— 5.95 — —

6.6 — 1.49 8.36

Pino et al., 2004 Zhang et al., 2005 Etchevers et al., 2014 Nichani et al., 2006



6.00

Albalak et al., 2003

2001

367

1 yr. 0-6 yrs. 0.5-6 yrs. 0-11.9 yrs. 1-6 yrs.

2010 2010 2012

44 42 383

< 5 yrs. < 5 yrs. < 5 yrs.

153.3 107.5 —

— — 8.5

Dooyema et al., 2012 Dooyema et al., 2012 Bashir et al., 2014

2012

383

< 5 yrs.



6.4

Bashir et al., 2014

< 5 yrs. 0.5-5 yrs. 0.5-5 yrs. 0-3 yrs.

— 22.00 6.90 —

3.40 — — 7.60

Bashir et al., 2014 Rahman et al., 2012 Riddell et al., 2007 Anticona et al., 2012

47

4-6 yrs.



8.00

Anticona et al., 2012

0.5-11 yrs. 2-7 yrs. 2-6 yrs.

9.9



Espinoza et al., 2003

— —

6.30 7.2

Jarosi´ nska et al., 2004 Rubin et al., 2002

1-5 yrs. 5-45 mos.

— —

1.30 9.00

CDC, 2013a Queirolo et al., 2010

2012 2006-08 2003-04 2009

383 269 2861 52

Peruvian Amazon/

2009

Urban & Mineral Storage Areas Industrial Area Industrial Areas

1998-99

2,510

1993-98 1997

11,877 1101

National Survey Urban Area

2007-10 2007

1,653 222

study was published; b Median PbB level; SES: socioeconomic status.

comparable to that of the Pb-contaminated areas of Latin America.

DISCUSSION This study analyzed data on PbB levels of Ecuadorian Andean infants and young children living in a highly Pb-contaminated environment

where the primary occupation of the parents is Pb acid battery use in the glazing of ceramics, and compared the Ecuadorian children’s PbB levels with PbB levels reported for children of similar ages in other countries. The Ecuadorian infants and young children were exposed to Pb from the ingestion of Pb-contaminated food and dust as a result of living in close proximity to Pb production activities and an associated

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COMPARISON OF INTERNATIONAL BLOOD LEAD LEVELS

Pb-contaminated milieu. Lead exposure in the Ecuadorian cohort can be traced directly to the occupational practice of battery stripping and Pb glazing (Counter et al., 2000), with attendant PbB levels that are similar to those detected in countries where Pb acid battery recycling is common (Matte et al., 1989; Mañay et al., 2008). In some Latin American countries, such as Uruguay and Brazil, the sources of Pb poisoning in infants and young children are reported to be from metal foundries, battery manufacturing/recycling, and Pb mining (Paoliello et al., 2002; Mañay et al., 2008). However, little or no metal ore mining is conducted in the Ecuadorian study area; therefore, these common sources of Pb exposure did not contribute to the high PbB levels observed in the Ecuadorian Andean infants and young children. Although the concentration of Pb in enamel paints used in Ecuadorian households has in the past been found to be extremely high (Clark et al., 2009), the infants and children in the present Ecuadorian study were exposed exclusively to Pb from production of Pb glazed ceramic roof tiles and other ceramic items. This has been verified by findings of a Pb isotope analysis that revealed a common Pb fingerprint in the children’s blood, in the soil collected in the milieu, and in the foods consumed by the children (Counter et al., 2000). For many years, the major contributing source of Pb exposure in children was leaded gasoline used in automobiles. However, as countries developed regulations for phasing out leaded gasoline, PbB levels in children showed an associated significant decline (Annest et al., 1983; U.S. EPA, 1986; Bridbord and Hanson, 2009). Most countries today use unleaded gasoline in automobiles. Therefore, the primary current source of Pb exposure in children in most countries is that of Pb-based paint in older dwellings that were painted before modern regulations. However, in some developing countries, the most prevalent sources of Pb exposure are cottage industries, such as Pb acid battery recycling, Pb glazing of ceramics, and in some instances petroleum refineries and gold mining. The PbB levels observed in the Ecuadorian infants and young children are the results of

783

community Pb glazing of ceramics, and were considerably higher than those reported for other Latin American countries. As shown in Figure 1, the PbB levels of the Ecuadorian infants and young children have declined significantly over the years. This decline in PbB levels is consistent with the reduction in PbB concentrations observed recently in older Ecuadorian children, in Ecuadorian adults, and in the milk of breast-feeding mothers living in the same Pbcontaminated study area (Ortega et al., 2013a, 2013b; Counter et al., 2014). This downward trend in PbB levels is encouraging, but it should be noted that the Ecuadorian infants and young children in the 2003–2013 cohort still exhibit elevated PbB levels, with a geometric mean of 15.9 µg/dl, which is threefold higher than the current CDC reference value. Data in this study indicate that infants and young children, who are more susceptible to clinical and neurodevelopmental effects of Pb poisoning, should be monitored closely by health professionals for Pb exposure. In conclusion, the findings of this study indicated that infants and young children exposed to Pb from Pb production and glazing of ceramics in Andean Ecuadorian communities exhibited greater Pb poisoning than children of similar ages in Asia, Europe, the United States, and the rest of Latin America. Although Pb levels in the Ecuadorian communities are declining, the children’s Pb exposure should continue to be monitored since many of them show PbB levels above international reference values of 5–10 µg/dL and continue to be at risk for health effects of Pb poisoning.

ACKNOWLEDGMENTS The authors thank Universidad San Francisco de Quito Colegio Ciencias de la Salud, Escuela de Medicina in Quito, Ecuador for continued support of the Ecuadorian Lead and Mercury Exposure project. We thank Dr. Gonzalo Mantilla, Dean, Colegio Ciencias de la Salud, Escuela de Medicina, Universidad San Francisco de Quito, for ongoing support and advice. We thank Anthony B. Jacobs

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for excellent technical assistance. We appreciate the support of the physicians and nurses of the Subcentro de Salud, including Roberto Chiriboga, Rommy Correa, María Angela Collaguaso, Rosa Mercedes Cruz, Fabiola Herrera, Erika Herrera, and Jenny Bonifaz. The authors are grateful to the David Rockefeller Center for Latin American Studies at Harvard University for funds to support this project. We thank Dr. Jeremy Bloxham, Dean of Science at Harvard University. We also thank Harvard Biological Laboratories, Harvard University Health Services, and the Eunice Kennedy Shriver Center/University of Massachusetts Medical School for support. L. H. Buchanan is supported in part by National Institutes of Health (NIH) grant P30 HD04147.

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Blood Lead Levels in Andean Infants and Young Children in Ecuador: An International Comparison.

Lead (Pb) exposure in infants and children remains an international health concern. Blood lead (PbB) levels of a cohort of 130 Ecuadorian infants and ...
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