Abstract
BackgroundBlood lead levels have decreased in Mexico since leaded fuel was banned in 1997, but other sources remain, including the use of lead-glazed ceramics for food storage and preparation. Zinc deficiency is present in almost 30 % of children aged 1–2 years. Previous studies have documented negative associations of both lead exposure and zinc deficiency with stature, but have not considered the joint effects. Given that the prevalence of stunting in pre-school aged children was 13.6 % in 2012, the aim of this study was to evaluate if the relationship between blood lead and child stature was modified by zinc status.MethodsAnthropometry, dietary energy intake, serum zinc and blood lead were measured in 291 children aged 24 months from an ongoing birth cohort study in Mexico City. Child stature was represented by recumbent length as appropriate for this age group. The association between blood lead (BPb) and length-for-age Z score (LAZ) was evaluated using a model stratified by zinc status measured by standard criteria and adjusted for: birth length, breastfeeding practices, energy intake, maternal height and education.ResultsMedian (IQR) BPb was: 0.17 (0.12–0.26) μmol/L and 17 % of the sample had zinc deficiency (<9.9 μmol/L). BPb was inversely associated with LAZ in the overall sample (β = −0.19, p = 0.02). In stratified models, this negative association was more than three times higher and statistically significant only in the zinc deficient group (β = −0.43, p = 0.04) compared to the zinc replete group (β = −0.12, p = 0.22) (BPb*zinc status, p-for-interaction = 0.04).ConclusionsZinc adequacy is a key factor that may attenuate the negative association of lead on stature in young children.
Highlights
Blood lead levels have decreased in Mexico since leaded fuel was banned in 1997, but other sources remain, including the use of lead-glazed ceramics for food storage and preparation
A recent report estimated that the geometric mean Blood Lead (BPb) in Mexican children is 0.31 μmol/L (6.5 μg/dL) [5] which is higher than the U.S Centers for Disease Control and Prevention (CDC) reference level of 0.24 μmol/L (5 μg/dL) [6]
The aim of this study was to assess the association between blood lead and child stature for age and sex (using length-for-age Z score (LAZ)) and to investigate if this association differed by zinc status in a cohort of Mexican children at 24 months of age
Summary
Blood lead levels have decreased in Mexico since leaded fuel was banned in 1997, but other sources remain, including the use of lead-glazed ceramics for food storage and preparation. Zinc deficiency is present in almost 30 % of children aged 1–2 years. Previous studies have documented negative associations of both lead exposure and zinc deficiency with stature, but have not considered the joint effects. Given that the prevalence of stunting in pre-school aged children was 13.6 % in 2012, the aim of this study was to evaluate if the relationship between blood lead and child stature was modified by zinc status. Other sources of lead exposure remain including lead-glazed ceramics used for food storage and preparation which is a main source of exposure in the population [3, 4]. While lead and zinc interactions in humans are Cantoral et al Environmental Health (2015) 14:95 not as well defined as those between lead and calcium or iron, it has been shown experimentally that lead increases zinc excretion [12]
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