. 2021 Aug 28;18(17):9080. doi: 10.3390/ijerph18179080
© 2021 by the authors.
Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https://creativecommons.org/licenses/by/4.0/).
Figure 2.
Risk of bias among the selected studies.