Acute endocrine disrupting effect of fine particulate constituents on thyroid homeostasis: A multicenter cross-sectional study in China

New evidence has revealed ambient fine particulate matter < 2.5 μm (PM_2.5) may have endocrine disrupting effect, such as thyroid hormone disorder, while which PM_2.5 constituents contributed to the effect was debatable. The study aimed to identify the specific PM_2.5 constituents regarding to acute endocrine disrupting effect. 2043 individuals aged over 40 years were included in Beijing-Tianjin-Hebei (BTH) region and surrounding areas. Data on air pollutant concentrations and PM_2.5 constituents' concentration were collected by fixed monitoring stations, and serum triiodothyronine (T3) and thyroxine (T4) were determined by chemiluminescence immunoassay (CLIA). Multiple linear regression models were used to analyze impacts of PM_2.5 and its constituents on T3 and T4. PM_2.5 had strongest effect on thyroid hormone level at a lag 0-day period, and its specific components interfere with thyroid hormones' homeostasis were NO₃^- and heavy metals such as Ag, As, Cd, K, Mn, Pb, Sn, and Zn, which were positively associated with T3 and T4. OC and Sb significantly increased T3 level, and similar associations of constituents, such as SO₄^2-, Fe, Ga, with T4 levels were found. Pb, NO₃^- and Zn exhibited primary positive weight in association with increasing thyroid hormone levels, and each IQR increase corresponded to 3.43 (95 % CI: 2.40-4.46) nmol/L, 4.19 (95 % CI: 2.47-5.92) nmol/L, and 3.35 (95 % CI: 2.33-4.37) nmol/L changed in T4. It suggests that PM_2.5 and its specific constituents were associated with thyroid hormone levels, NO₃^- and heavy metals may be key contributors in the acute endocrine disrupting effect.