Fluoride concentration of bottled water, tap water, and fluoridated salt from two communities in Mexico

Dietary fluoride intake over the course of pregnancy in Mexican women

OBJECTIVE

To estimate dietary fluoride intake (F) over the course of pregnancy and the overall adjusted difference in dietary F intake by pregnancy stages and levels of compliance with dietary recommendations.

DESIGN

Secondary data analysis from a longitudinal pregnancy cohort study in a population exposed to fluoridated salt. Women were followed during the early, middle and late stages of their pregnancy (n 568). The dietary intake of recommended prenatal nutrients according to Mexican dietary guidelines and F intake (mg/d) was estimated with a validated FFQ. Data were summarised with descriptive statistics. Levels of F intake were compared with the USA's Institute of Medicine adequate intake (AI) of 3 mg/d for pregnancy. Adjusted differences in F intake by pregnancy stages and levels of compliance with recommendations were estimated using random effects models.

SETTING

Mexico City.

PARTICIPANTS

Women participating in the Early Life Exposures in Mexico to ENvironmental Toxicants (ELEMENT) project, from 2001 to 2003.

RESULTS

Median dietary F intake throughout pregnancy ranged from 0·64 (interquartile range (IQR) 0·38) in the early to 0·70 (IQR 0·42) in the middle, and 0·72 (IQR 0·44) mg/d in the late stage (0·01 mg F/kg per d). Corresponding adjusted intakes of F were 0·72 (95 % CI 0·70, 0·74), 0·76 (95 % CI 0·74, 0·77) and 0·80 (95 % CI 0·78, 0·82) mg/d. Women who were moderately and highly compliant with Mexican dietary recommendations ingested, on average, 0·04 and 0·14 mg F/d more than non-compliant women (P < 0·005).

CONCLUSIONS

Dietary F intake was below current AI, was greater with the progression of pregnancy and in women who were moderately and highly compliant with dietary recommendations.

Blood levels of lead and dental caries in permanent teeth

OBJECTIVES

The purpose of this study was to determine whether there is an association between lead exposure within the ages of 1-4 years and dental caries in the permanent dentition between ages 9-17 among Mexican youth.

METHODS

Data were collected for the Early Life Exposures in Mexico to Environmental Toxicants (ELEMENT) cohort from a group of 490 children born and reared in Mexico City. Among ages 1-4 years, blood lead levels were measured in micrograms of lead per deciliter of blood (μg/dL) and the presence of caries in adolescence was determined using the International Caries and Detection and Assessment System (ICDAS). The relationship between blood levels of lead and decayed, missing, or filled surfaces (DMFS) was examined using negative binomial regression. Covariates were selected based on previous studies and included age, gender, socioeconomic status, oral hygiene, body mass index, and diet. The nonlinear relationship between lead and DMFS was examined using smoothing splines.

RESULTS

The mean overall blood lead level (BLL) was 4.83 μg/dL (S.D. of 2.2). The mean overall caries level (DMFS) was 4.1. No statistically significant association was found between early childhood blood lead levels and dental caries in adolescence.

CONCLUSION

This study shows a lack of association between exposure to lead between the ages of 1-4 years of age and dental caries in permanent dentition later in life. Other covariates, such as age and sugar consumption, appeared to play a more prominent role in caries development.

Review of Fluoride Intake and Appropriateness of Current Guidelines

Since the classical epidemiological studies by Dean, it has been known that there should be an optimum level of exposure to fluoride that would be able to provide the maximum protection against caries, with minimum dental fluorosis. The "optimal" daily intake of fluoride for children (0.05-0.07 mg per kilogram bodyweight) that is still accepted worldwide was empirically determined. In the present review, we discuss the appropriateness of the current guidance for fluoride intake, in light of the windows of susceptibility to caries and fluorosis, the modern trends of fluoride intake from multiple sources, individual variations in fluoride metabolism, and recent epidemiological data. The main conclusion is that it is very difficult to think about a strict recommendation for an "optimal" range of fluoride intake at the individual level in light of existing knowledge of 1) the mechanisms of action of fluoride to control caries, 2) the mechanisms involved in dental fluorosis development, 3) the distinct factors that interfere in the metabolism of fluoride, and 4) the windows of susceptibility to both dental caries and fluorosis development. An "optimal" range of fluoride intake is, however, desirable at the population level to guide programs of community fluoridation, but further research is necessary to provide additional support for future decisions on guidance in this area. This list includes the effect of factors affecting fluoride metabolism, clinical trials on the effectiveness of low-fluoride dentifrices to prevent caries in the primary dentition, and validation of biomarkers of exposure to fluoride.

Prenatal fluoride exposure and attention deficit hyperactivity disorder (ADHD) symptoms in children at 6-12 years of age in Mexico City

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 (MUF_cr) 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 MUF_cr 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 MUF_cr (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.

Effect of body weight and behavioural factors on caries severity in Mexican rural and urban adolescents

OBJECTIVES

To investigate if, in Mexican adolescents, body weight and caries severity are associated, and if this association differs between rural and urban populations.

METHODS

Adolescents from the rural area of Tepancan and the city of Veracruz were enrolled. Caries was recorded using the International Caries Detection and Assessment System and the body mass index (BMI) was calculated. Oral habits (toothbrushing, flossing, dental check-ups) and dietary patterns (sweets intake) were assessed. A dummy variable between BMI and living area (BMI/Area) was generated. Data were analysed using STATA and a multinomial logistic regression model was run, using caries severity as the dependent variable.

RESULTS

Four-hundred and sixty-four subjects, 12-15 years of age, participated (rural = 240; urban = 224). The BMI and area of residence were significantly associated (χ² = 12.59, P < 0.01). Area was also associated with caries severity (χ² = 24.23, P < 0.01), with the highest number of caries in dentine recorded in participants from the rural area. The dummy variable BMI/Area was related to caries severity (χ² = 27.47, P < 0.01): overweight adolescents with caries in dentine were most frequently found in the rural area. A higher prevalence of caries in enamel and a lower prevalence of caries in dentine (P < 0.01) were recorded in adolescents from the urban area, where better oral habits, but higher sweets intake (P = 0.04), were encountered. According to the multinomial logistic regression model, BMI/Area was significantly associated with caries severity (P < 0.01).

CONCLUSIONS

Overweight was not associated with caries severity in the overall population, but it became a statistically significant risk indicator in adolescents living in the rural area.

Prenatal Fluoride Exposure and Cognitive Outcomes in Children at 4 and 6-12 Years of Age in Mexico

BACKGROUND

Some evidence suggests that fluoride may be neurotoxic to children. Few of the epidemiologic studies have been longitudinal, had individual measures of fluoride exposure, addressed the impact of prenatal exposures or involved more than 100 participants.

OBJECTIVE

Our aim was to estimate the association of prenatal exposure to fluoride with offspring neurocognitive development.

METHODS

We studied participants from the Early Life Exposures in Mexico to Environmental Toxicants (ELEMENT) project. An ion-selective electrode technique was used to measure fluoride in archived urine samples taken from mothers during pregnancy and from their children when 6-12 y old, adjusted for urinary creatinine and specific gravity, respectively. Child intelligence was measured by the General Cognitive Index (GCI) of the McCarthy Scales of Children's Abilities at age 4 and full scale intelligence quotient (IQ) from the Wechsler Abbreviated Scale of Intelligence (WASI) at age 6-12.

RESULTS

We had complete data on 299 mother-child pairs, of whom 287 and 211 had data for the GCI and IQ analyses, respectively. Mean (SD) values for urinary fluoride in all of the mothers (n=299) and children with available urine samples (n=211) were 0.90 (0.35) mg/L and 0.82 (0.38) mg/L, respectively. In multivariate models we found that an increase in maternal urine fluoride of 0.5mg/L (approximately the IQR) predicted 3.15 (95% CI: -5.42, -0.87) and 2.50 (95% CI -4.12, -0.59) lower offspring GCI and IQ scores, respectively.

CONCLUSIONS

In this study, higher prenatal fluoride exposure, in the general range of exposures reported for other general population samples of pregnant women and nonpregnant adults, was associated with lower scores on tests of cognitive function in the offspring at age 4 and 6-12 y. https://doi.org/10.1289/EHP655.

Fluoride Content of Bottled Drinking Waters in Qatar

Fluoridation of drinking water has been recognized as one of the most effective ways of achieving community-wide exposure to the caries prevention effects of fluoride (F). A vast majority of people in Qatar use bottled water for drinking. Use of bottled water without knowing the F level may expose children to dental caries risk if the F level is lower than optimal or to dental fluorosis if the F level is too high. The aim of this study was to determine the F concentration of bottled water available in Qatar. A total of 32 brands of bottled water were evaluated. The F concentrations displayed on the labels were recorded. The F ion-selective electrode method was used to measure the F concentration in water samples, and three measurements were taken for every sample to ensure reproducibility. The p value was set at 0.05. The F concentration ranged from 0.06 to 3.0 ppm with a mean value of 0.8 ppm (±0.88). The F levels were provided by the manufacturers on the labels of 60 % of the samples, but this was significantly lower than the measured F levels (p < 0.0001). Moreover, bottled water that was produced in Saudi Arabia had significantly higher levels of F when compared to those produced in other countries (p < 0.05). There was a wide variation in the F levels in the different brands of bottled water. Furthermore, there was a significant disparity between the F levels which were measured and those that were provided on the labels.

Distance from source and fluoride concentrations in municipal water supply

AIM

The purpose of this study was to evaluate the concentrations of fluoride in community water at the point of source, compared to the concentration delivered to various locations within the Las Vegas Valley, to determine if the levels of fluoride change over distance.

METHODS

Ten samples per week over an 8-week period were taken from four locations, totaling 320 samples. The first location included the water treatment facility where fluoride is added to the municipal water to bring the concentrations to the desired amount. The other locations included three residences at an increasing distance from the source of fluoridation. The 320 samples were submitted for fluoride analysis. Repeated-measure anova was used to compare the means between the four data points.

RESULTS

The fluoride concentration data for the four test locations ranged from 0.73 to 0.89 mg/L. Mauchly's test of sphericity revealed no significant difference in the fluoride concentrations in Las Vegas from the point of source to distant locations.

CONCLUSIONS

The analysis of the collected data revealed that there was no statistical difference in the fluoride concentration in the Las Vegas municipal water supply from the source to the remote locations, and that distance does not affect fluoride concentration in the Las Vegas Valley municipal water supply.

Caries prevalence and its association with brushing habits, water availability, and the intake of sugared beverages

BACKGROUND. With Dental Caries being the most common disease amongst children in the world today, there is a need to fully understand risk factors that may be related to caries prevalence and how they could be best addressed. AIM. The aim of this study was to evaluate soda, juice, sugared-beverage intake, brushing habits, and community water source availability as they relate to the prevalence of both noncavitated and cavitated caries lesions in small rural villages in Mexico. DESIGN. The International Caries Detection and Assessment System (ICDAS) was used in children from small, isolated, villages in Mexico. Risk factors were assessed via questionnaires. RESULTS. Caries prevalence in the villages was very high, ranging from 94.7% to 100% of the children studied. The mean number of surfaces with lesions per child (D1MFS + d1mfs) having scores ≥1 (noncavitated and cavitated) ranged from 15.4 ± 11.1 to 26.6 ± 15.2. Many of the children reported drinking beverages containing sugar. CONCLUSIONS. Drinking sugared beverages, poor oral hygiene habits, and lack of access to tap water were identified as risk factor for caries in this sample of residents of rural Mexico.

Fluoride content of water used to reconstitute infant formula

OBJECTIVE

To assess the fluoride content of water used to reconstitute infant formula by a Latino population living in the Indianapolis, Indiana, area.

BACKGROUND

Negligible as well as excessive fluoride can be detrimental to oral health. Estimates of fluoride intake and exposure for individuals may aid in the determination of their risk for developing dental fluorosis or caries.

METHODS

Interviews were conducted to determine brands of bottled water used to reconstitute infant formula. Identified brands were analyzed for fluoride concentration.

RESULTS

Of the 458 samples tested (from 20 brands), fluoride concentration ranged from 0.006 to 0.740 μg/mL. All brands but one had fluoride concentration less than 0.7 μg/mL, with 16 brands having less than 0.22 μg/mL. Most bottled waters analyzed in the study comply with the American Dental Association recommendation to prevent fluorosis. Comparisons made demonstrated that only waters targeted for infants and that are fluoridated do not comply with recent American Dental Association recommendations.