Prenatal exposure to metals and concentration thereof in umbilical cord blood in a Mexico City cohort

BACKGROUND

In Mexico, there is a paucity of evidence on the magnitude of prenatal exposure to metals.

OBJECTIVE

To estimate the concentration of arsenic, cadmium, manganese and lead in umbilical cord blood (UCB) and its association with maternal blood concentrations during pregnancy and delivery.

MATERIAL AND METHODS

Metal concentration in maternal blood was analyzed during pregnancy (n = 901), delivery (n = 732) and in UCB (n = 512) from participants of the PROGRESS cohort residing in Mexico City. The association between concentrations in UCB and maternal biomarkers was analyzed using generalized linear models, adjusted for relevant covariates.

RESULTS

Mean concentrations (μg/L) of lead, arsenic and manganese in UCB were 27.14 (25.28-29.14), 0.77 (0.71-0.84) and 42.60 (40.45-44.83), respectively. Cadmium concentration could not be estimated because 86.2% of measurements were below the detection limit. Lead and manganese concentrations in UCB were significantly associated with maternal biomarkers during pregnancy and delivery; at delivery, association was only observed with arsenic.

CONCLUSIONS

Prenatal exposure to toxic metals in sensitive periods of organogenesis shows a neglected public health problem. Biomonitoring of the population and establishment of regulations aimed at providing care to vulnerable populations is required.

Reporte nacional de niveles de plomo en sangre y uso de barro vidriado en población infantil vulnerable

Objetivo. Estimar la prevalencia de niveles elevados (≥5.0μg/ dL) de plomo en sangre (PbS) y su asociación con el uso de loza de barro vidriado con plomo (LBVPb). Material y méto­dos. En 2018 se midió PbS capilar en una muestra represen­tativa de niños de 1 a 4 años de edad residentes en localidades de México menores de 100 000 habitantes (Ensanut 100k). Se indagó sobre uso de LBVPb para consumo de alimentos. Para estimar su asociación con PbS, se generaron modelos logit multinomial estratificados por región. Resultados. La prevalencia de niveles elevados de PbS fue de 21.8%. En las regiones Norte, Centro y Sur las prevalencias fueron 9.8, 20.7 y 25.8%, respectivamente. La asociación con uso y frecuencia de LBVPb fue altamente significativa y diferencial por región. Conclusiones. La exposición a plomo permanece como un problema de salud pública en México, particularmente en el Centro y Sur, y está fuertemente asociada con el uso de LBVPb.

Children's Blood Lead Concentrations from 1988 to 2015 in Mexico City: The Contribution of Lead in Air and Traditional Lead-Glazed Ceramics

Despite the removal of lead from gasoline in 1997, elevated blood lead levels (BLLs) > 5 µg/dL are still detectable in children living in Mexico City. The use of lead-glazed ceramics may explain these persistent exposure levels. Mexico lacks a national surveillance program for BLL, but temporal trends can be derived from epidemiological studies. With this approach, we leveraged a series of birth cohorts to report BLL trends from 1987 to 2002 and expanded our analysis to 2015. Data were from 1⁻5-year-old children from five Mexico City cohorts followed between 1988 and 2015. BLLs are reported on 1963 children, who contributed 4975 BLLs. We estimated the trend of mean BLL, which decreased from 15.7 µg/dL in 1988, to 7.8 µg/dL in 1998 (a year after the total ban of lead in gasoline), to 1.96 µg/dL in 2015. The proportion of BLL ≥ 5 µg/dL decreased from 92% (1988⁻1998) to 8% (2008⁻2015). The use of lead-glazed ceramics was associated with an 11% increase in BLLs throughout the study period. Replacing lead-based glazes in traditional ceramics may be the key to further reducing exposure, but this presents challenges, as it involves a cultural tradition deeply rooted in Mexico. In addition, the creation of a rigorous, standardized, and on-going surveillance program of BLL is necessary for identifying vulnerable populations.