Table 2.

Quality assessment

Author and year	Selection				Comparability		Exposure			Total
Baron 2014	●	●	○	●	●	●	○	●	●	7
Chu 2011	○	○	●	●	●	●	○	●	●	6
da Silva 2019	●	○	●	●	●	●	○	○	●	6
Elimelech 2015	●	●	●	●	●	●	○	●	●	8
Iordache 2019	●	●	○	●	●	●	○	●	●	7
Isola 2017	●	○	●	●	●	●	○	●	●	7
Leung 2011	●	○	●	●	●	●	●	●	●	8
Marcucci 2009	●	○	○	●	○	○	○	●	●	4
Mayer 2013	●	●	●	●	●	●	○	●	●	8
Pischon 2016	●	○	●	●	●	●	○	●	●	7
Wood 1988	●	○	●	●	●	●	○	●	●	7