Open access Research BMJ Open: first published as 10.1136/bmjopen-2018-024189 on 5 February 2019. Downloaded from Cross-sectional study of the association between serum perfluorinated alkyl acid concentrations and dental caries among US adolescents (NHANES 1999–2012) Nithya Puttige Ramesh,1 Manish Arora,2 Joseph M Braun1 To cite: Puttige Ramesh N, ABSTRACT Strengths and limitations of this study Arora M, Braun JM. Cross- Study objectives Perfluoroalkyl acids (PFAAs) are a class sectional study of the of anthropogenic and persistent compounds that may ► Our study contributes to a gap in the literature by association between serum impact some biological pathways related to oral health. perfluorinated alkyl acid examining the relationship between perfluoroalkyl The objective of our study was to estimate the relationship concentrations and dental caries acid exposure and dental caries prevalence among between dental caries prevalence and exposure to four among US adolescents (NHANES adolescents, which, to the best of our knowledge, PFAA: perfluorooctanoic acid (PFOA), perfluorononanoic 1999–2012). BMJ Open has not been examined before. 2019;9:e024189. doi:10.1136/ acid (PFNA), perfluorohexane sulfonic acid (PFHxS) and ► The strengths of our study include the large sample perfluorooctane sulfonic acid (PFOS) in a nationally bmjopen-2018-024189 size (2869 participants) and the nationally repre- representative sample of US adolescents. Prepublication history and sentative nature of the National Health and Nutrition ► Setting/Design We analysed cross-sectional data from additional material for this Examination Survey (NHANES). the National Health and Nutrition Examination Survey from paper are available online. To ► Although we adjusted for potential confounders, 1999 to 2012 for 12–19-year-old US adolescents. view these files, please visit misclassified or unmeasured covariates, such den- Participants Of 10 856 adolescents aged 12 to 19 years the journal online (http:// dx. doi. tal hygiene, are a weakness of our study; these data who had a dental examination, we included 2869 with org/ 10. 1136/ bmjopen- 2018- were not collected in the NHANES data cycles we 024189). laboratory measurements for serum PFAA concentrations used. and complete covariate data in our study. Received 14 May 2018 Primary and secondary outcome measures Dental Revised 13 November 2018 caries prevalence was defined as the presence of decay Accepted 18 December 2018 or a restoration on any tooth surface, or the loss of a Of the diseases that affect the oral cavity, http://bmjopen.bmj.com/ tooth due to tooth decay. We used multivariable logistic dental caries and periodontal infections are regression to estimate the covariate-adjusted association the most prevalent.2 More than 91% of adults between serum PFAA concentrations and dental caries and 58% of adolescents in the USA had a prevalence, accounting for the complex National Health 3 and Nutrition Examination Survey design. caries experience in 2012. Dental caries also Results Of 2869 adolescents, 59% had one or more disproportionately affects adolescents from 4 dental caries. We observed no associations between the low socioeconomic backgrounds. Children prevalence of dental caries and serum concentrations of affected by dental caries have poor growth, PFOA, PFOS or PFHxS. The adjusted odds of caries were behavioural problems and poor learning on September 28, 2021 by guest. Protected copyright. 21% (OR 0.79; 95% CI 0.63 to 1.01), 15% (OR 0.85; 95% abilities, thus making it imperative to focus CI 0.67 to 1.08) and 30% (OR 0.7; 95% CI 0.55 to 0.90) preventative efforts towards reducing the risk © Author(s) (or their lower among adolescents in the 2nd, 3rd and 4th serum of dental caries.5 employer(s)) 2019. Re-use PFNA concentration quartiles compared to adolescents Dental caries is known to be caused by a permitted under CC BY-NC. No in the first quartile, respectively. The linear trend for this dynamic relationship between microbiota commercial re-use. See rights association was not statistically significant. and permissions. Published by Conclusion PFOA, PFOS and PFHxS were not associated in dental plaque, dietary carbohydrates, the BMJ. acidity and consistency of saliva and the cario- 1 with prevalence of dental caries. The prevalence of caries Department of Epidemiology, was reduced with increasing serum PFNA concentrations; genic potential of dental plaque. A shift in Brown University, Providence, however, these results should be interpreted cautiously the plaque concentrations of mutans strep- Rhode Island, USA 2 tococci and lactobacilli is one of the primary Department of Environmental given that we were unable to adjust for several factors Medicine and Public Health, related to oral health. aetiological factors behind the occurrence of 6 Icahn School of Medicine, Mount dental caries. Although tooth decay occurs Sinai, New York, USA due to biochemical process caused by the INTRODUCTIon demineralisation of tooth substance by these Correspondence to Dr Nithya Puttige Ramesh; Poor oral health severely impacts an individ- bacteria, environmental factors have also 7 nithya_ ramesh@ alumni. brown. ual’s quality of life by altering the ability to been linked to dental caries. Several studies edu perform basic tasks such as eating or talking.1 have observed associations of paediatric Puttige Ramesh N, et al. BMJ Open 2019;9:e024189. doi:10.1136/bmjopen-2018-024189 1 Open access BMJ Open: first published as 10.1136/bmjopen-2018-024189 on 5 February 2019. Downloaded from dental caries with lead and passive tobacco smoking.8 9 Based on this evidence, we hypothesised that PFAA However, the role of other environmental pollutants on exposures would be associated with tooth demineralisa- oral health has not been adequately studied and is rela- tion. Our objective was to identify the presence of any tively unexplored. Children and adolescents may be more relationship between PFAA exposure and the preva- sensitive to the effects of environmental toxicants on their lence of dental caries in adolescents given their poten- dental health than adults due to their increased exposure tial heightened susceptibility to environmental chemical to some toxicants, reduced detoxification capacity or exposures. heightened susceptibility to environmental agents.10 Perfluoroalkyl acids (PFAAs) are a group of compounds that have been in use for over 60 years and are predomi- METHODS nantly used as industrial surfactants, stain repellants and Study participants 11 firefighting foams. Contaminated drinking water and We used a nationally representative sample of US adoles- food are the major routes of exposure and, to a lesser cents aged 12 to 19 years. Data for this study came from extent, house dust is also a minor source of PFAA expo- the National Health and Nutrition Examination Survey 12 13 sure. Some PFAAs have biological half-lives on the (NHANES), which recruits non-institutionalised Amer- order of years in humans, and 95% of the US population ican civilians.33 NHANES is a cross-sectional study which from 1999 to 2008 had detectable serum PFAA concentra- combines interviews and physical examinations of chil- 14–16 tions. Due to efforts by the US Environmental Protec- dren and adults living in the USA to assess their health tion agency (EPA) and PFAA manufacturers, a steady and nutritional status. Data are collected using a complex, decline in serum PFAA concentrations has been observed multistage probability design with oversampling of chil- 17 in the past decade. However, those who reside near dren below the age of 5, Mexican-Americans and non-His- industrial sites that use PFAAs in manufacturing or mili- panic blacks. Information regarding interview processes, tary or commercial airports that use aqueous film forming examination protocols and sample collection can be foam may have elevated PFAA exposures compared with found elsewhere.34 35 17–20 the general population. Prior studies also report that NHANES data sets are released every 2 years in cycles PFAA levels are higher in men than women and those of and we used data collected between 1999 and 2012 for our 21 higher socioeconomic status. primary analysis. The 2013–2014 cycle data were used for Although there is no direct evidence available for the sensitivity analyses. There were 9756–10 537 participants effect of PFAA on dental caries, some indirect evidence in each cycle. We excluded the 2001–2002 cycle because supports the possibility of an association. In rodent studies, PFAAs were not analysed in individual serum samples. For prenatal PFAA exposure has been linked to adverse skel- our study, 10 856 adolescents aged 12 to 19 years under- 22 etal deformities. Moreover, serum perfluorooctanoic went a dental examination in six cycles and we restricted acid (PFOA) levels have been associated with a decrease in our analysis to 2869 who had laboratory measurements http://bmjopen.bmj.com/ 23 spinal bone mineral density in premenopausal women. for serum PFAA concentrations and complete covariate However, inconsistencies in results were observed when data. Approximately equal proportions of adolescents different bone sites (such as lumbar spine) were assessed from each cycle contributed to our analysis. and by menopausal status in women.24 PFAA are also potential endocrine-disrupting chemicals (EDCs), and Dental caries assessment have been associated with reduced levels of thyroid A detailed report on the dental examination component hormones, which are necessary for stimulating