Table 1.
The main characteristics of included studies.
| Study | Country | Exposure sources | Exposure variables | Age, yr (exposed/unexposed) | Sample size (exposed/unexposed) | Outcomes | Detection method | |
|---|---|---|---|---|---|---|---|---|
| Biswas 2008[16] | India | Environment exposure | Drinking water, urine, nail, hair | 41.05 | 46.05 | 38 (20/18) | ①②④⑦ | CBA |
| Ji 2011[23] | China | Environment exposure | Drinking water | 49.92 ± 9.06 | 53.33 ± 8.28 | 90 (58/32) | ③ | Nephelometry |
| Das 2012[27] | India | Environment exposure | Drinking water, urine | 40.13 ± 13.36 | 40.03 ± 13.01 | 65 (32/33) | ⑤⑥ | ELISA |
| Karim 2013[28] | Bangladesh | Environment exposure | Drinking water, nail, hair | 37.55 ± 11.71 | 35.04 ± 10.93 | 313 (207/106) | ③ | ELISA |
| Ning 2014[25] | China | Environment exposure | Not mentioned | 55.7 ± 6.2 | 53.8 ± 4.9 | 58 (28/30) | ① | ELISA |
| Dutta 2015[29] | India | Environment exposure | Drinking water | 38 ± 6 | 39 ± 4 | 273 (142/131) | ①⑤⑥⑦⑧ | ELISA |
| Wang 2016[26] | China | Environment exposure | Drinking water, urine | 28.92 ± 3.86 | 28.28 ± 5.05 | 168 (120/48) | ④ | ELISA |
| Prasad 2017[17] | India | Environment exposure | Drinking water | 38 ± 7 | 39 ± 5 | 233 (123/110) | ①③⑤⑥⑧ | ELISA |
| Gao 2018[30] | China | Occupational exposure | Urine | 26.43 ± 5.76 | 25.76 ± 6.57 | 394 (114/280) | ③ | Not mentioned |
| Xu 2020[31] | China | Environment exposure | Urine | 49.07 ± 10.04 | 50.52 ± 9.97 | 246 (201/45) | ①④⑤ | ELISA |
| Fang 2019[24] | China | Environment exposure | Urine | 50.69 ± 6.14 | 45.76 ± 7.88 | 190 (149/41) | ④ | ELISA |
| Tutkun 2019[18] | Turkey | Occupational exposure | Serum | Not mentioned (>18) | 135 (62/73) | ①③⑤⑦ | ELISA | |
| Rahman 2021[19] | Bangladesh | Environment exposure | Drinking water | 37.5 ± 11.3 | 35.9 ± 11.2 | 553 (409/144) | ①② | ELISA |
CBA = cytometric bead array, ELISA = enzyme linked immunosorbent assay.
①: TNF-α ②: IFN-γ ③: CRP ④: IL-2 ⑤: IL-6 ⑥: IL-8 ⑦: IL-10 ⑧: IL-12.