2012 7 3 285-291 Asian Journal of Ecotoxicology Vol. 7 2012 No. 3 285-291 # * 100871 USI 8 ~ 10 31 8 ~ 10 5% benchmark dose BMD 168. 17 2. 24 μg L - 1 4. 00% 150 μg L - 1 29. 62 mg kg - 1 150 μg L - 1 USI 1673-5897 2012 3-285-07 R18 A Health Risk Assessment of Iodine Status in Chinese Residents Hu Xindi Gao Fei # Hu Jianying * Key Laboratory for Earth Surface Processes of Ministry of Education College of Urban and Environmental Sciences Peking University Beijing 100871 China Received 11 October 2011 accepted 27 December 2011 Abstract Due to great variation in the natural background levels of iodine found across China the universal salt iodization USI policy which lacks sufficient consideration on this regional variation is not the most proper strategy for preventing and controlling iodine deficiency disease and even may increase potential health risk caused by excessive iodine intake. Recently the Ministry of Health MOH of China has amended the USI policy. However it is still in urgent needs to evaluate and analyze this policy from a perspective of health risk assessment. In this paper the iodine status of Chinese residents was assessed and potential morbidity of subclinical hypothyroidism caused by excessive iodine intake in China was determined by integrating the distribution of urinary iodine concentrations of Chinese 8-10 year-old children dose-response curves and threshold levels. Then the region-specific recommended iodine upper limits in edible salt were calculated based on the 5 % benchmark dose combined with the results of national dietary survey. Results showed that urinary iodine concentrations of national 8-10 year-old children varied greatly in different regions. The geo- 2011-10-11 2011-12-27 2009ZX07419-001 1990- E-mail 00826085@ pku. edu. cn # 1991- E-mail rita-gaofei@ 163. com * Corresponding author E-mail hujy@ urban. pku. edu. cn
286 7 metric mean value and geometric standard deviation were 168. 17 and 2. 24 μg L - 1 respectively. The morbidity of subclinical hypothyroidism induced by excessive iodine intake reached 4. 00%. Recommended iodine upper limit in edible salt for regions with water iodine concentrations below 150 μg L - 1 was 29. 62 mg kg - 1. However for regions with water iodine concentrations above 150 μg L - 1 adequate iodine status has been achieved through intake pathways other than iodized salt and thus there is no need to consume iodized salt for residents in those regions. These conclusions stay in support of the current salt iodization policy that region-specific iodine content in edible salt should be established according to iodine status of local residents. Keywords universal salt iodization policy urinary iodine levels subclinical hypothyroidism health risk assessment regional salt iodization 0 ~ 2 1 2005 6 2 20 90 Szabolcs 9 1997 7. 2 3 8 ~ 10 31 20. 4% 4 13. 5 5 1995 USI 2005 5% 8 ~ 10 12% 6 USI 10 1 Materials and methods 1. 1 1 TDI 5 2005 31 1 500 7 8 ~ 10 2005 TDI 6 16 World Health Organization WHO 100 ~ 199 μg L - 1 8 5 31 8 ~ 10 300 μg L - 1 9 100 ~ 199 μg L - 1 1 Fig. 1 Framework for calculation of recommended iodine contents added in edible salt
3 287 11 ~ 14 14 ~ 18 18 1. 2 1. 6 WHO 8 ~ 10 3 2005 TDI 6 31 8 ~ 10 TDI - = 1. 3 3 = BMD 95% BMDL 10 1-4 dichotomous logistic 11 300 μg L - 1 5% 95% 30. 0% ~ BMDS V2. 0 38. 6% 1. 4 150 ~ 300 μg L - 1 1 12 43. 0% ~ 52. 5% 150 μg L - 1 Risk Risk = 0 f x G x dx 1 82. 3% ~ 86. 1% 3 f x G x 10 2002 1. 3 15 2 ~ 4 4 ~ 7 7 ~ 11 11 ~ 14 Crystal Ball 7 1. 5 TDI TDI = BMDL V 92% 2 V 0 ~ 2 2 ~ 4 4 ~ 7 7 ~ 11 0. 30 0. 52 0. 79 1. 17 1. 47 1. 50 1. 50 L 14 Excel 2007 14 ~ 18 18 6. 2 7. 5 8. 9 10. 35 11. 45 12. 01 g Institute of Medicine 15 2001 13 92% TDI 2 Results μg L - 1 BMDL 2. 1 31 8 ~ 10 1 168. 17 2. 24 μg L - 1 31
288 7 78. 32 ~ d - 1 0. 8% 1 /119 1. 5% 326. 9 μg L - 1 18 2 /135 7. 6% 7 /92 200 μg L - 1 1 8 ~ 10 p m x Table 1 Distribution of urinary iodine x μg L - 1 concentrations of 8-10 year-old children in China P m x = 1 / 1 + e 4. 83-0. 0046x 5 / / μg L - 1 / μg L - 1 400 221. 79 1. 75 359 215. 82 1. 89 362 173. 15 2. 02 370 222. 06 1. 76 360 221. 67 1. 78 374 165. 27 1. 96 360 259. 77 2. 24 360 151. 95 2. 06 437 147. 23 2. 13 358 222. 64 1. 90 360 149. 63 2. 03 361 272. 56 1. 90 351 145. 07 2. 02 359 205. 60 2. 02 360 217. 19 2. 04 358 239. 57 2. 30 360 326. 93 2. 30 362 240. 35 1. 69 360 125. 85 2. 12 360 212. 86 2. 29 424 90. 36 2. 21 386 225. 56 2. 40 360 200. 98 2. 21 360 267. 92 1. 71 374 231. 61 2. 04 381 80. 94 2. 73 359 254. 97 1. 77 356 174. 76 2. 77 359 135. 54 2. 10 354 146. 83 1. 78 360 78. 32 2. 60 11 404 168. 17 2. 24 χ 2 = 0. 13 d. f. = 1 P = 0. 7148 5% 95% BMDL 351. 9 μg L - 1 16-17 BMDL 2. 3 2 8 ~ 10 2. 2 2 8 ~ 10 Fig. 2 Probability distribution of urinary iodine concentrations ATSDR of 8-10 year-old children in China and dose-response 2 Szabolcs 9 curve between urinary iodine concentration and 1997 subclinical hypothyroidism risk 1 5 1 71. 76 99. 97 511. 5 μg L - 1 31 8 ~ 10 0. 0017 0. 0023 0. 012 mg kg - 1 2
3 289 2 Table 2 Health risk evaluation of excessive iodine intake of residents in China 90% % % 3. 46 2. 89 3. 96 4. 23 3. 25 2. 65 3. 51 6. 09 3. 59 2. 51 2. 83 4. 30 8. 22 4. 84 2. 80 7. 61 12. 6 5. 42 3. 66 2. 31 2. 31 4. 52 6. 20 6. 93 1. 72 2. 49 7. 57 2. 03 5. 18 2. 01 4. 55 4. 00 2. 4 2. 4. 1 TDI TDI 2 TDI BMDL 351. 9 μg L - 1 31 8 ~ 10 TDI 0 ~ 2 1. 72% ~ 2 ~ 4 4 ~ 7 7 ~ 11 11 ~ 14 14 ~ 18 12. 6% 4. 00% 9 18 TDI 114. 8 198. 1 302. 4 5. 00% 448. 3 563. 3 573. 8 573. 8 μg d - 1 10. 0% 2. 4. 2 3 4 3 TDI / / μg d - 1 Table 3 3 Age specific recommended iodine upper limits in edible salt for regions with different water iodine concentrations / μg d - 1 / μg d - 1 / mg kg - 1 / μg d - 1 / μg d - 1 / mg kg - 1 / μg d - 1 / μg d - 1 / mg kg - 1 2 ~ 4 198. 1 81. 4 14. 4 29. 62 428. 0 243. 7 N /A 591. 7 413. 9 N /A 4 ~ 7 302. 4 125. 0 22. 2 37. 36 531. 5 302. 7 N /A 715. 7 500. 6 N /A 7 ~ 11 448. 3 129. 7 23. 0 47. 79 597. 7 340. 4 12. 13 802. 4 561. 2 N /A 11 ~ 14 563. 3 126. 2 22. 4 52. 26 684. 8 390. 0 16. 75 930. 5 650. 8 N /A 14 ~ 18 573. 8 150. 6 26. 7 47. 78 735. 7 419. 0 13. 52 976. 9 683. 3 N /A 18 573. 8 179. 5 31. 9 45. 12 794. 1 452. 2 10. 12 1 039. 8 727. 3 N /A TDI N /A TDI
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