**5. Conclusions**

The presence of Cd, Pb, Hg, Ni, Sn, Mn, Cr and V in hair of schoolchildren living near the HWI of Constantí (Tarragona County, Catalonia, Spain) was confirmed in this study. Some significant differences according to the sex were noted, while Hg was the only metal with significant differences according to the zone of residence of the schoolchildren. The levels of Cr and Pb decreased since 1998, when the biomonitoring program was started and despite Mn, Ni, Pb and Sn showed higher levels in 2017 when compared to some previous surveys, their concentrations were even lower than those reported in recent literature. The present results indicate that the current emissions of metals by the HWI do not pose direct health risks of immediate concern. The follow-up monitoring program should be continued in order to assure there are no changes in human exposure to trace elements in the vicinity of the HWI.

**Author Contributions:** Conceptualization, M.S. and J.L.D.; methodology, M.M. (Montse Mari) and M.M. (Montse Marquès); software, M.M. (Montse Mari); validation, R.E. and M.N.; formal analysis, R.E. and M.M. (Montse Marquès); investigation, R.E., M.M. (Montse Mari), M.S., J.L.D. and M.N.; resources, M.M. (Montse Mari); data curation, R.E.; writing—original draft preparation, R.E.; writing—review and editing, M.N.; visualization, M.S.; supervision; project administration, M.M. (Montse Marquès) and J.L.D; funding acquisition, J.L.D.

**Funding:** This study was funded by Sarpi Constantí SL, Catalonia, Spain.

**Acknowledgments:** The authors appreciate the technical assistance of Anabel Díez for the sampling and the analytical treatment, as well all the schoolchildren and their families, who provided all the samples.

**Conflicts of Interest:** The authors declare no conflict of interest.
