Table 1.

Method of identification and criteria for selection of studies.

Study type	Studies identified by expert panel	Studies identified from country submissions to UNEP or WHO-Europe	Studies identified by electronic search	Sampling year	Minimum sample size
A. National biomonitoring	Yes	Yes	Yes	Any	N/A
B. Longitudinal birth cohort	Yes	Yes	Yes	Any; but a minimum of 2 sampling periods	N/A
C. Cross-sectional studiesa
General populations (HIC)	No	N/A	Yes	2000–present	$>200$
General populations (LMIC)	Yes	N/A	Yes	2000–present	$>100$
Vulnerable populations (HIC)	No	N/A	Yes	2000–present	$>100$
Vulnerable Populations (LMIC)	Yes	N/A	Yes	2000–present	$>50$

Note: All studies provided a point estimate of central tendency (median, geometric mean) and a measure of variation from which an upper bound could be determined. HIC, high-income countries; LMIC, low- and middle-income countries; N/A, not applicable; UNEP, UN Environment Programme; WHO-Europe, World Health Organization Regional Office for Europe.

^aHIC and LMIC were as categorized by the World Bank (Fantom and Serajuddin 2016).