Researchers at the University of Seville have carried out a study to determine the relationship between prenatal and early childhood exposure to environmental pollutants with the neurodevelopment of children born in the province of Seville. Their results highlight the presence of a mixture of metals in 100% of the subjects analysed. Each hair sample contained between 2 and 10 metals simultaneously, with an average of 8.37 elements per child.
The researchers highlight that 7 of the 10 elements studied (copper, zinc, chromium, lead, manganese, aluminium and selenium) were detected in more than 90% of samples. In addition, they found that concentrations of neurotoxic elements (lead, aluminium, manganese, nickel and arsenic) tend to be higher at 6 months of age and decrease progressively towards 24 months, thus suggesting a higher body burden or vulnerability in the earliest postnatal window.
The PID2019-106442RB-C21 project, funded by the State Research Agency, has followed the development of 100 children born between 2020 and 2022 in the province of Seville. Specifically, children born at the Virgen del Rocío and Valme hospitals were analysed in order to include inhabitants from two geographical areas with different characteristics.
With regard to the impact of this exposure on neurodevelopment, the study highlights that arsenic is the element with the highest neurotoxic consistency as it is negatively associated with all areas of development (cognitive, motor, language, social and adaptive).
Lead, in contrast, exhibits a specific and gender-differentiated impact. Thus, in the general population, it affects language development, but in boys, its presence has also been correlated with deficits in cognitive and motor development.
Finally, aluminium and manganese show generalised negative correlations, significantly affecting multiple domains of development, with a statistically more marked impact on the subgroup of girls.
For all these reasons, the authors of the study emphasise that, even in a cohort of healthy children in a non-industrial urban area, silent environmental exposure to metal mixtures is detectable and has a measurable effect on early psychomotor development. They therefore stress the need to consider exposure to complex mixtures (and not just isolated toxins) as a public health determinant to be monitored through routine biomonitoring programmes from childhood onwards.
Research development
The researchers worked with a cohort of 100 children born between July 2020 and 2022. These children were monitored periodically, with samples taken and evaluations carried out at 6, 12, 18 and 24 months of age. The participants came from two health areas in Seville with different environmental characteristics: the Virgen del Rocío University Hospital, with a predominantly urban profile, greater potential exposure to road traffic and geographical proximity to areas with a history of mining (towns near Huelva); and Virgen de Valme University Hospital, with a more rural/agricultural profile (intensive farming), relevant due to the possible use of plant protection products. To avoid bias, only mothers who had been living in the area for less than 5 years, with single pregnancies (without assisted reproduction) and in good health, were selected. Newborns who were premature (less than 32 weeks), underweight (below 1500g) or had perinatal pathologies that could alter neurodevelopment per se were excluded.
Hair was used as a biomarker of chronic exposure to xenobiotics, thus allowing for the non-invasive assessment of long-term metal accumulation. Ten elements, namely aluminium, arsenic, cadmium, chromium, copper, manganese, nickel, lead, selenium and zinc, were analysed using inductively coupled plasma mass spectrometry (ICP-MS). The Battelle Development Inventory (BDI), which measures skills in the motor, adaptive, personal-social, cognitive, and language domains, was used for neuropsychological assessment.