Morteza Bashash1, Maelle Marchand2, Howard Hu3, Christine Till4, E Angeles Martinez-Mier5, Brisa N Sanchez6, Niladri Basu7, Karen E Peterson8, Rivka Green4, Lourdes Schnaas9, Adriana Mercado-García10, Mauricio Hernández-Avila10, Martha María Téllez-Rojo10. 1. Dalla Lana School of Public Health, University of Toronto, Toronto, ON, Canada. Electronic address: m.bashash@utoronto.ca. 2. Dalla Lana School of Public Health, University of Toronto, Toronto, ON, Canada. 3. Dalla Lana School of Public Health, University of Toronto, Toronto, ON, Canada. Electronic address: howard.hu@utoronto.ca. 4. Faculty of Health - Department of Psychology, York University, ON, Canada. 5. Indiana University School of Dentistry, Indianapolis, IN, United States of America. 6. University of Michigan School of Public Health, Ann Arbor, MI, United States of America. 7. Faculty of Agricultural and Environmental Sciences, McGill University, Montreal, QC, Canada. 8. University of Michigan School of Public Health, Ann Arbor, MI, United States of America; Center for Human Growth and Development, University of Michigan, Ann Arbor, MI, United States of America; Harvard W.T. Chan School of Public Health, Boston, MA, United States of America. 9. Instituto Nacional de Perinatología, Mexico City, Mexico. 10. Instituto Nacional de Salud Pública, Cuernavaca, Morelos, Mexico.
Abstract
BACKGROUND: Epidemiologic and animal-based studies have raised concern over the potential impact of fluoride exposure on neurobehavioral development as manifested by lower IQ and deficits in attention. To date, no prospective epidemiologic studies have examined the effects of prenatal fluoride exposure on behavioral outcomes using fluoride biomarkers and sensitive measures of attention. OBJECTIVE: We aimed to examine the association between prenatal fluoride exposure and symptoms associated with attention-deficit/hyperactivity disorder (ADHD). METHOD: 213 Mexican mother-children pairs of the Early Life Exposures to Environmental Toxicants (ELEMENT) birth cohort study had available maternal urinary samples during pregnancy and child assessments of ADHD-like behaviors at age 6-12. We measured urinary fluoride levels adjusted for creatinine (MUFcr) in spot urine samples collected during pregnancy. The Conners' Rating Scales-Revised (CRS-R) was completed by mothers, and the Conners' Continuous Performance Test (CPT-II) was administered to the children. RESULTS: Mean MUFcr was 0.85 mg/L (SD = 0.33) and the Interquartile Range (IQR) was 0.46 mg/L. In multivariable adjusted models using gamma regression, a 0.5 mg/L higher MUFcr (approximately one IQR higher) corresponded with significantly higher scores on the CRS-R for DSM-IV Inattention (2.84 points, 95% CI: 0.84, 4.84) and DSM-IV ADHD Total Index (2.38 points, 95% CI: 0.42, 4.34), as well as the following symptom scales: Cognitive Problems and Inattention (2.54 points, 95% CI: 0.44, 4.63) and ADHD Index (2.47 points; 95% CI: 0.43, 4.50). The shape of the associations suggested a possible celling effect of the exposure. No significant associations were found with outcomes on the CPT-II or on symptom scales assessing hyperactivity. CONCLUSION: Higher levels of fluoride exposure during pregnancy were associated with global measures of ADHD and more symptoms of inattention as measured by the CRS-R in the offspring.
BACKGROUND: Epidemiologic and animal-based studies have raised concern over the potential impact of fluoride exposure on neurobehavioral development as manifested by lower IQ and deficits in attention. To date, no prospective epidemiologic studies have examined the effects of prenatal fluoride exposure on behavioral outcomes using fluoride biomarkers and sensitive measures of attention. OBJECTIVE: We aimed to examine the association between prenatal fluoride exposure and symptoms associated with attention-deficit/hyperactivity disorder (ADHD). METHOD: 213 Mexican mother-children pairs of the Early Life Exposures to Environmental Toxicants (ELEMENT) birth cohort study had available maternal urinary samples during pregnancy and child assessments of ADHD-like behaviors at age 6-12. We measured urinary fluoride levels adjusted for creatinine (MUFcr) in spot urine samples collected during pregnancy. The Conners' Rating Scales-Revised (CRS-R) was completed by mothers, and the Conners' Continuous Performance Test (CPT-II) was administered to the children. RESULTS: Mean MUFcr was 0.85 mg/L (SD = 0.33) and the Interquartile Range (IQR) was 0.46 mg/L. In multivariable adjusted models using gamma regression, a 0.5 mg/L higher MUFcr (approximately one IQR higher) corresponded with significantly higher scores on the CRS-R for DSM-IV Inattention (2.84 points, 95% CI: 0.84, 4.84) and DSM-IV ADHD Total Index (2.38 points, 95% CI: 0.42, 4.34), as well as the following symptom scales: Cognitive Problems and Inattention (2.54 points, 95% CI: 0.44, 4.63) and ADHD Index (2.47 points; 95% CI: 0.43, 4.50). The shape of the associations suggested a possible celling effect of the exposure. No significant associations were found with outcomes on the CPT-II or on symptom scales assessing hyperactivity. CONCLUSION: Higher levels of fluoride exposure during pregnancy were associated with global measures of ADHD and more symptoms of inattention as measured by the CRS-R in the offspring.
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