Temporal and spatial variations of urinary phthalate metabolites for adults in China (2005–2020): A synthesis of biomonitoring data

Chinese people are experiencing phthalate exposure risks. However, temporal and regional phthalate internal exposure variations amongst Chinese have not been established. To address this gap, we integrated our 69 adult participants' bio-monitored urinary phthalate metabolite (UPM) concentration data by high-performance liquid chromatography with mass spectrometry in Xi'an and Nanjing and the data from 35 literature (total sample size: 18768). Then, we analyzed China's temporal and spatial variations of adult UPM levels from 2005 to 2020 based on multi statistical methods. The results showed that the sum of eight UPM concentrations (i.e., monomethyl phthalate (MMP), mono-ethyl phthalate (MEP), mono-n-butyl phthalate (MNBP), mono-2-isobutyl phthalate, mono-benzyl phthalate, and three metabolites from di-2-ethylhexyl phthalate (DEHPM3)) had slightly increased in 2013-2020 (median: 230 (5th-95th: 73.7-653) ng/mL) compared with the period 2005-2012, which were about two times higher than the levels in most EU countries. The MNBP concentration between 2013 and 2020 (120 ng/mL, shared 52% of the eight UPM concentrations) has significantly increased to over two times the level between 2005 and 2012, followed by the DEHPM3 with a similar trend. Conversely, MEP and MMP concentrations in the later period decreased from the former period. In China, adults had the highest UPM concentrations in the East and the lowest in the Middle. The adults in the East, the North, the South, and the Northeast had higher adverse phthalate exposure risks than the adults in the West and the Middle, and the Hazard index (HI) values were the highest in the East (1.61 (5th-95th: 1.01-3.07)). The adult exposure risks in the West had large heterogeneities (HIs: 0.46 (0.11-2.37). Regional variations in climate, the economy, industrial technology, and living styles could cause phthalate exposure differences. China needs to enhance tight regulation and enforcement of di-n-butyl phthalate (DNBP) (the parent of MNBP) and DEHP to protect public health.