IQ studies that do not demonstrate fluoridation reduces IQ

The references below were sent as part of my critique of a 2019 Draft National Toxicology Program Review of Fluoride Exposure & Health Effects "initiated in response to a nomination from the Fluoride Action Network.” The draft review made a completely disingenuous conclusion that "fluoride is presumed to be a cognitive neurodevelopmental hazard to humans" without any reference to exposure context or significant limitations of reviewed studies. In fact, a sentence following the conclusion stated, "However, the consistency is based primarily on higher levels of fluoride exposure (i.e., >1.5 ppm in drinking water). When focusing on studies with exposures in ranges typically found in the water distribution systems in the United States that can be evaluated for dose response, effects on cognitive neurodevelopment are inconsistent, and therefore unclear." If the effects of drinking optimally fluoridated water are inconsistent and unclear, how can a blanket conclusion, "fluoride is presumed to be a cognitive neurodevelopmental hazard to humans" be published by legitimate scientists?

~> August 2019, Fluorinated water consumption in pregnancy and neuropsychological development of children at 14 months and 4 years of age: (Santa-Marina, et al., Environmental Epidemiology: October 2019)
“Prenatal exposure at the levels found in fluorinated drinking water may exert a beneficial effect on the development at 4 years of age. At low doses, fluoride could present a dose-response pattern with a beneficial effect.” This study was not part of the NTP review.

~> From the 2019 NTP Draft Review, P 54: “Surprisingly, three of the studies (Xu et al. 1994, Qin et al. 2008, Aravind et al. 2016) found that the lowest IQ scores were in areas with the lowest and the highest fluoride concentrations”

~> 2014 dissertation, Fluoride exposure during pregnancy and its effects on childhood neurobehavior: a study among mother-child pairs from Mexico City, Mexico, by Deena B. Thomas used data from the Mexican ELEMENT study which also provided data for the Bashash, et al. 2017 and 2018 IQ and ADHD studies. Four of the five members of her Doctoral Committee and Thomas were coauthors of the published Bashash, et al. studies. Thomas’ dissertation concluded: “Overall, this investigation found no evidence of a detectable adverse outcome on offspring neurobehavioral development associated with maternal fluoride exposure during pregnancy.” P 75
“Overall, this investigation found a significant positive impact on neurobehavioral development due to ingestion of fluoride in male children but no association was detected in female children. Fluoride measured in urine was significantly associated with total WASI score in male children ages 6 to 15 years old” P 77

~> 2018 study, "An Evaluation of Neurotoxicity Following Fluoride Exposure from Gestational Through Adult Ages in Long-Evans Hooded Rats", lead by the Neurotoxicology Group of the NTP concluded, “The findings of this well-controlled animal study directly address previous concerns regarding potential biological plausibility of fluoride as a neurotoxin. The findings provide valuable information and assurance that low-level fluoride exposures from water and diet that are equivalent to the levels allowed in the US does not result in clinically adverse neurobehavioral function or pathological effects in various organs.”
Reviewers at Fluoride Science concluded, “The findings of this well-controlled animal study directly address previous concerns regarding potential biological plausibility of fluoride as a neurotoxin. The findings provide valuable information and assurance that low-level fluoride exposures from water and diet that are equivalent to the levels allowed in the US does not result in clinically adverse neurobehavioral function or pathological effects in various organs.”

~> October 2019, Fluorinated water consumption in pregnancy and neuropsychological development of children at 14 months and 4 years of age: (L, Santa-Marina, et al., Environmental Epidemiology: October 2019) “Conclusions: Prenatal exposure at the levels found in fluorinated drinking water may exert a beneficial effect on the development at 4 years of age. At low doses, fluoride could present a dose-response pattern with a beneficial effect.”

~> January 2015, Community Water Fluoridation and Intelligence: Prospective Study in New Zealand, (Broadbent, et al., Am J Public Health. 2015) “Conclusions. These findings do not support the assertion that fluoride in the context of CWF programs is neurotoxic. Associations between very high fluoride exposure and low IQ reported in previous studies may have been affected by confounding, particularly by urban or rural status.”

~> June 2016, The Effects of Fluoride in the Drinking Water (2016 paper, Aggeborn & Öhman) “We use a rich Swedish register dataset for the cohorts born 1985-1992, together with drinking water ﬂuoride data. To estimate the eﬀect we exploit intra-municipality variation of ﬂuoride, stemming from an exogenous variation in the bedrock. First, we investigate and conﬁrm the long-established positive relationship between ﬂuoride and dental health. Second, we ﬁnd precisely estimated zero eﬀects on cognitive ability, non-cognitive ability and education. We do not ﬁnd any evidence that ﬂuoride levels below 1.5 mg/l have negative eﬀects. Third, we ﬁnd evidence that ﬂuoride improves labor market outcome later in life, which conﬁrms that good dental health is a positive factor on the labor market.”