Tap Water Lead Levels in Madrid (Spain): Degree of Compliance and Health Risk Assessment

Abstract

Lead is one of few substances known to have a direct impact on health through the drinking water supply. Signifcant amounts of lead can be infltrated in tap water as a result of leaching in distribution and plumbing system. This research was conducted to characterize Pb in tap water in the 21 districts of Madrid city over a long period of 12 years (2007–2018) and to assess the children health risks generated by the exposure to lead in the water supply. A total of 2308 frst-fush water samples were collected from various types of buildings and analyzed for Pb using electrothermal atomic absorption spectroscopy. The sampling was carried out considering diferent factors: year, district and type of building. Tap water in most samples (96%) complied with the legislation throughout the study period. More cases of non-compliance were observed in 2014 because the impact of stricter regulations entry in force in December 2013 (10 μg/L). It was also signifcantly higher in the oldest districts located in the central area of Madrid and in households compared to other types of buildings (p<0.001). The children health risks were assessed using the monitoring data collected from households. The end points of critical efects considered are within the normal range: margin of exposure (MOE)>1 and average loss of Intelligent quotient (IQ loss)<1 in 89.9% of the samples, however, the possibility of an adverse efect for infants and young children could not be excluded for a small percentage of samples exceeding 5 µg/L or 10 µg/L respectively corresponding to old households in the central area. The results point to the need of control of water supply including strategies such as the prioritization of inspections in the buildings of that area and the replacement of old pipes.