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Fluoride IQ Studies: # of participants

The Fluoride IQ studies

There are now 78 out of 87 IQ studies reporting lowered IQ from exposure to elevated levels of fluoride. Since 2017 we learned that the fluoride level of 0.7 mg/L, the "optimal" level used in U.S. and Canadian drinking water fluoridation projects, can create neurodevelopmental harm to the fetus, bottle-fed infant, and child. The fetus and bottle-fed infant were never considered in any risk assessment for water fluoridation by any regulatory agency in any fluoridating country.

Fluoride IQ Studies: # of participants

The following are two Tables that contain the number of participants in the fluoride IQ studies.

Table 1 contains the information from the 78 studies that found an association of fluoride exposure with the lowering of IQ. Participants included: 29,130 children and 689 adults.

Table 2 contains the information from the 9 studies that found no association of fluoride exposure and the lowering of IQ. Particpants included 4,363 children and 1,037 adults.

NOTE: The IQ study #67 by Xu 2020 was retracted by the publisher on Nov 8, 2022. We have adjusted the number of each study to reflect that change. On Nov 9, 2022, another IQ study by Saeed et al. was published, for a total of 77 studies. (EC)

TABLE 1: Number of participants in 77 studies reporting an association of fluoride exposure and the lowering of IQ
Year IQ Study # Lead Author # of Children Ages of Children Sub-total
CHILDREN		 # and Ages of Adults Sub-total
ADULTS
2023 78 Xia 721 8-12 29,721
2023 77 Hall 601 3-4 28,419
2022 76 Saeed 148 5 to 16 27,719
2022 75 Goodman 336 3-4 27,571
2022 74 Feng 694 8-12 27,235

2020

Study
available
Jan 2022 on PubMed

 67 Prabhakar 120 8-10 26,541
2021 73 Yani 100 6 – 12 26,421
2021 72 Ren 444 adults over 60 years of age 689
2021 71 Wang 709 6.7 – 13 26,321
2021 70 Cantoral 103 12 -24 months 25,612
2021 69 Yu 952 7-13 25,509
2021 68 Zhao 567 6-11 24,557
2020

The IQ study #67 Xu 2020 was retracted by the publisher on November 8, 2022

We have adjusted the number of each study to reflect that change. (EC)
2020 66 Lou 99 8-12 23,990
2019 65 Till 398 3 – 4 23,891
2019 64 Wang 571 7 – 13 23,493
2019 63 Green 512 3 – 4 22,922
2018 62 Cui 323 7 – 16 22,410
2018 61 El Sehmawy 1,000 4.6 – 11 22,087
2018 60 Induswe 269 13 – 15 21,087
2018 59 Mustafa 775 Primary school students 20,818
2018 58 Pang 268 8 – 12 20,043
2017 57 Chang 118 up to 12 months 19,775
2017 56 Jin 284 8 – 12 19,657
2017 54 Razdan 219 12 – 14 19,373
2018 54 Yu 2,886 7 – 13 19,154
2017 53 Bashash 299 4 and 6 – 12 16,268
2107 52 Valdez Jiménez 65 3 – 15 months 15,969
2016 51 Das 149 6 – 18 15,904
2016 50 Aravind 288 10-12 15,755
2016 49 Mondal 40 10-14 15,467
2015 48 Khan 429 6 – 12 15,427
2015 47 Sebastian 405 10 – 12 14,998
2015 46 Kundu 200 8 – 12 14,593
2015 45 Choi 51 7.1 = Average age 14,393
2015 44 Zhang 180 11 = Average age 14,342
2014 43 Bai 303 8 – 12 14,162
2014 42 Wei 741 8 – 12 13,859
2013 41 Nagarajappa 100 8 – 10 13,118
2013 40 Singh 42 9 – 14 13,018
2014 39 Karimzade 39 9 – 12 12,976
2012 38 Trivedi 84 6th – 7th graders 12,937
2012 37 Seraj 293 6 – 11 12,853
2012 36 Saxena 173 5th – 6th graders 12,560
2011 35 Ding 331 7 – 14 12,387
2011 34 Poureslami 120 7 – 9 12,056
2011 33 Eswar 133 12 – 14 11,936
2011 32 Shivaprakash 160 7 – 11 11,803
2009 31 Sudhir 1,000 13 – 15 11,643
2009 30 Li 80 8 – 12 10,643
2007 29 Rocha-Amador 132 6 – 10 10,563
2007 28 Wang 720 8 – 12 10,431
2007 27 Trivedi 190 12 – 13 9,711
2007 26 Fan 79 7 – 14 9,521
2006 25 Seraj 126 “children”
Ages not provided in English abstract		 9,442
2005 24 Wang 226 7 – 12 9,316
2003 23 Xiang 512 8 – 13 9,090
2003 22 Li 936 6 – 13 8,578
2003 21 Shao # Adults: 88
Ages:
30 – 50		 245
2001 20 Wang 513 8 – 12 7,642
2001 19 Hong 205 8 – 14 7,129
2000 18 Lu 118 10 – 12 6,924
1998 17 Zhang 164 4 – 10 6,806
1997 16 Yao 823 7 – 14 6,642
1996 15 Yao 536 8 – 12 5,819
1996 14 Zhao 320 7 – 14 5,283
1996 13 Wang 230 4 – 7 4,963
1995 12 Duan # Adults: 157
Ages:
35 – 62		 157
1995 11 Li 907 8 – 13 4,733
1994 10 Xu 330 9 – 14 3,496
1994 9 Li 158 12 – 13 3,166
1994 8 Yang 60 8 – 14 3,008
1992 7 An 242 7 – 16 2,948
1991 6 Lin 749 7 – 14 2,706
1991 5 Guo 121 7 – 13 1,957
1991 4 Chen 640 7 – 14 1,836
1991 3 Sun 420 6.5 – 12 1,196
1990 2 Qin 447 9 – 10.5 776
1989 1 Ren 329 8 – 14 329

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TABLE 2: Number of participants in 9 studies reporting NO association of fluoride exposure and the lowering of IQ
Year IQ Study # Lead Author # of Children Ages of Children Sub-total
CHILDREN		 # and Ages of Adults
2021 #9 Ibarluzea 316 to 248 mother-child pairs 1 – 4 4,363 – 4295
2019 #8 Soto-Barreras 161 9 – 10 4,047
2015 #7 Broadbent 1,037 7 – 13 3,886 # 1,037
Age: 38
2011 #6 Kang 268 Not available 2,849
2010 #5 Li 676 7 – 10 2,581
2010 #4 He 200 8 – 12 1,905
2000 #3 Calderon 61 6 – 8 1,705
1998 #2 Spittle 1,265 8 – 9 1,644
1989 #1 Hu 379 Not available 379  # and Ages are not available