Polyfluoroalkyl chemicals in the U.S. population: data from the National Health and Nutrition Examination Survey (NHANES) 2003-2004 and comparisons with NHANES 1999-2000

BACKGROUND: Polyfluoroalkyl chemicals (PFCs) have been used since the 1950s in numerous commercial applications. Exposure of the general U.S. population to PFCs is widespread. Since 2002, the manufacturing practices for PFCs in the United States have changed considerably. OBJECTIVES: We aimed to assess exposure to perfluorooctane sulfonic acid (PFOS), perfluorooctanoic acid (PFOA), perfluorohexane sulfonic acid (PFHxS), perfluorononanoic acid (PFNA), and eight other PFCs in a representative 2003-2004 sample of the general U.S. population >or= 12 years of age and to determine whether serum concentrations have changed since the 1999-2000 National Health and Nutrition Examination Survey (NHANES). METHODS: By using automated solid-phase extraction coupled to isotope dilution-high-performance liquid chromatography-tandem mass spectrometry, we analyzed 2,094 serum samples collected from NHANES 2003-2004 participants. RESULTS: We detected PFOS, PFOA, PFHxS, and PFNA in > 98% of the samples. Concentrations differed by race/ethnicity and sex. Geometric mean concentrations were significantly lower (approximately 32% for PFOS, 25% for PFOA, 10% for PFHxS) and higher (100%, PFNA) than the concentrations reported in NHANES 1999-2000 (p < 0.001). CONCLUSIONS: In the general U.S. population in 2003-2004, PFOS, PFOA, PFHxS, and PFNA serum concentrations were measurable in each demographic population group studied. Geometric mean concentrations of PFOS, PFOA, and PFHxS in 2003-2004 were lower than in 1999-2000. The apparent reductions in concentrations of PFOS, PFOA, and PFHxS most likely are related to discontinuation in 2002 of industrial production by electrochemical fluorination of PFOS and related perfluorooctanesulfonyl fluoride compounds.     

Urinary phthalate metabolites and metabolic syndrome in U.S. adolescents: Cross-sectional results from the National Health and Nutrition Examination Survey (2003–2014) data

Objective

There is limited research on the association between phthalates and metabolic syndrome (MetS). Among adolescents, phthalate exposure, which can occur from multiple sources, has been linked to several risk factors for MetS. The objective was to investigate the association between urinary phthalate metabolite concentrations (i.e., mono-ethyl phthalate (MEP), mono-n-butyl phthalate (MnBP), mono-isobutyl phthalate (MiBP), mono-benzyl phthalate (MBzP), mono-(3-carboxylpropyl) phthalate (MCPP), and di(2-ethylhexyl phthalate (DEHP)) and MetS in adolescents aged 12–19 years using the National Health and Nutrition Examination Survey (NHANES) data (2003–2014). A secondary aim was to assess if observed associations varied by a measure of socioeconomic status, economic adversity, which was defined using parental income and educational attainment as well as household food security.

Cadmium exposure and hypertension in the 1999-2004 National Health and Nutrition Examination Survey (NHANES)

INTRODUCTION: Cadmium induces hypertension in animal models. Epidemiologic studies of cadmium exposure and hypertension, however, have been inconsistent. OBJECTIVE: We aimed to investigate the association of blood and urine cadmium with blood pressure levels and with the prevalence of hypertension in U.S. adults who participated in the 1999-2004 National Health and Nutrition Examination Survey (NHANES). METHODS: We studied participants > or = 20 years of age with determinations of cadmium in blood (n = 10,991) and urine (n = 3,496). Blood and urine cadmium were measured by atomic absorption spectrometry and inductively coupled plasma-mass spectrometry, respectively. Systolic and diastolic blood pressure levels were measured using a standardized protocol. RESULTS: The geometric means of blood and urine cadmium were 3.77 nmol/L and 2.46 nmol/L, respectively. After multivariable adjustment, the average differences in systolic and diastolic blood pressure comparing participants in the 90th vs. 10th percentile of the blood cadmium distribution were 1.36 mmHg [95% confidence interval (CI), -0.28 to 3.00] and 1.68 mmHg (95% CI, 0.57-2.78), respectively. The corresponding differences were 2.35 mmHg and 3.27 mmHg among never smokers, 1.69 mmHg and 1.55 mmHg among former smokers, and 0.02 mmHg and 0.69 mmHg among current smokers. No association was observed for urine cadmium with blood pressure levels, or for blood and urine cadmium with the prevalence of hypertension. CONCLUSIONS: Cadmium levels in blood, but not in urine, were associated with a modest elevation in blood pressure levels. The association was stronger among never smokers, intermediate among former smokers, and small or null among current smokers. Our findings add to the concern of renal and cardiovascular cadmium toxicity at chronic low levels of exposure in the general population.     

Bowel Health in U.S. Vegetarians: A 4-Year Data Report from the National Health and Nutrition Examination Survey (NHANES)

Dietary fiber is of paramount importance in the prevention of large-bowel diseases, yet fiber intake in many high income countries is well below daily recommendations. Vegetarian diets high in fiber-rich plant-foods have been associated with a higher frequency of bowel movements and softer stools. Thus, vegetarians appear to suffer less frequently from constipation and other bowel disorders. The number of studies investigating these associations, however, is limited. The present study sought to investigate bowel health and constipation prevalence in a self-identified vegetarian population from the U.S. National Health and Nutrition Examination Survey (2007–2010). Bowel health assessment included Bristol Stool Scale (BSS), Bowel Movement (BM) frequency and Fecal Incontinence Severity Index (FISI). The present study included 9531 non-vegetarians and 212 vegetarians. We found no associations between vegetarian status and all examined bowel health items (BM frequency, BSS and FISI). Vegetarians consumed significantly more fiber than omnivores (21.33 vs. 16.43 g/d, p < 0.001) but had a lower moisture intake (2811.15 vs. 3042.78 g/d, p = 0.045). The lack of an association of vegetarian status and bowel health is surprising, and may be a result of the relatively low fiber intake in this particular vegetarian cohort, which did not meet the daily fiber recommendations.     

Urinary phytoestrogen concentrations in the U.S. population (1999-2000)

We report population-based urinary concentrations of phytoestrogens stratified by age, sex, and composite racial/ethnic variables. We measured the isoflavones - genistein, daidzein, equol, and O-desmethylangolensin (O-DMA) - and the lignans - enterolactone and enterodiol - in approximately 2500 urine samples from individuals aged 6 years and older who participated in the National Health and Nutrition Examination Survey (NHANES) in 1999 and 2000. We detected all phytoestrogens in over 70% of the samples analyzed; enterolactone was detected in the highest concentrations, and daidzein was detected with the highest frequency. The geometric means for each phytoestrogen were as follows: genistein, 22.3 microg/g; daidzein, 68.6 microg/g; equol, 7.65 microg/g; O-DMA, 3.95 microg/g; enterolactone, 217 microg/g; and enterodiol, 24.3 microg/g creatinine. The 95th percentiles for each phytoestrogen were as follows: genistein, 380 microg/g; daidzein, 944 microg/g; equol, 50.3 microg/g; O-DMA, 217 microg/g; enterolactone, 2240 microg/g; and enterodiol, 240 microg/g creatinine. Multivariate analyses showed statistically significant differences among many of the demographic subgroups. Adolescents had higher concentrations of genistein and equol than adults. Non-Hispanic whites had higher concentrations of enterodiol and equol than Mexican Americans or non-Hispanic blacks. Non-Hispanic whites also had higher concentrations of enterolactone and O-DMA than Mexican Americans. Mexican Americans had higher concentrations of genistein than non-Hispanic blacks; however, the opposite was found for O-DMA. Determination of phytoestrogen exposure in the US population will help us to better understand phytoestrogen consumption in the US and will assist us in elucidating the potential role of phytoestrogens in protecting against cancer and heart disease.     

Urinary concentrations of dialkylphosphate metabolites of organophosphorus pesticides: National Health and Nutrition Examination Survey 1999-2004

Organophosphorus (OP) insecticides were among the first pesticides that EPA reevaluated as part of the Food Quality Protection Act of 1996. Our goal was to assess exposure to OP insecticides in the U.S. general population over a six-year period. We analyzed 7,456 urine samples collected as part of three two-year cycles of the National Health and Nutrition Examination Survey (NHANES) from 1999-2004. We measured six dialkylphosphate metabolites of OP pesticides to assess OP pesticide exposure. In NHANES 2003-2004, dimethylthiophosphate was detected most frequently with median and 95th percentile concentrations of 2.03 and 35.3 μg/L, respectively. Adolescents were two to three times more likely to have diethylphosphate concentrations above the 95th percentile estimate of 15.5 μg/L than adults and senior adults. Conversely, for dimethyldithiophosphate, senior adults were 3.8 times and 1.8 times more likely to be above the 95th percentile than adults and adolescents, respectively, while adults were 2.1 times more likely to be above the 95th percentile than the adolescents. Our data indicate that the most vulnerable segments of our population-children and older adults-have higher exposures to OP pesticides than other population segments. However, according to DAP urinary metabolite data, exposures to OP pesticides have declined during the last six years at both the median and 95th percentile levels.     

Relationship between urinary phthalate and bisphenol A concentrations and serum thyroid measures in U.S. adults and adolescents from the National Health and Nutrition Examination Survey (NHANES) 2007-2008

Background: Limited animal, in vitro, and human studies have reported that exposure to phthalates or bisphenol A (BPA) may affect thyroid signaling.Objective: We explored the cross-sectional relationship between urinary concentrations of metabolites of di(2-ethylhexyl) phthalate (DEHP), dibutyl phthalate (DBP), and BPA with a panel of serum thyroid measures among a representative sample of U.S. adults and adolescents.Methods: We analyzed data on urinary biomarkers of exposure to phthalates and BPA, serum thyroid measures, and important covariates from 1,346 adults (ages ≥ 20 years) and 329 adolescents (ages 12–19 years) from the National Health and Nutrition Examination Survey (NHANES) 2007–2008 using multivariable linear regression.Results: Among adults, we observed significant inverse relationships between urinary DEHP metabolites and total thyroxine (T₄), free T₄, total triiodothyronine (T₃), and thyroglobulin, and positive relationships with thyroid-stimulating hormone (TSH). The strongest and most consistent relationships involved total T₄, where adjusted regression coefficients for quintiles of oxidative DEHP metabolites displayed monotonic dose-dependent decreases in total T₄ (p-value for trend < 0.0001). Suggestive inverse relationships between urinary BPA and total T₄ and TSH were also observed. Conversely, among adolescents, we observed significant positive relationships between DEHP metabolites and total T₃. Mono(3-carboxypropyl) phthalate, a secondary metabolite of both DBP and di-n-octyl phthalate, was associated with several thyroid measures in both age groups, whereas other DBP metabolites were not associated with thyroid measures.Conclusions: These results support previous reports of associations between phthalates—and possibly BPA—and altered thyroid hormones. More detailed studies are needed to determine the temporal relationships and potential clinical and public health implications of these associations.     

Urinary Phthalate Metabolite Concentrations and Diabetes among Women in the National Health and Nutrition Examination Survey (NHANES) 2001-2008

Background: Previous studies have shown that women have higher urinary concentrations of several phthalate metabolites than do men, possibly because of a higher use of personal care products. Few studies have evaluated the association between phthalate metabolites, diabetes, and diabetes-related risk factors among women.Objective: We explored the association between urinary phthalate metabolite concentrations and diabetes among women who participated in a cross-sectional study.Methods: We used urinary concentrations of phthalate metabolites, analyzed by the Centers for Disease Control and Prevention, and self-reported diabetes of 2,350 women between 20 and 79 years of age who participated in the NHANES (2001-2008). We used multiple logistic regression to estimate odds ratios (ORs) and 95% confidence intervals (CIs) and adjusted for urinary creatinine, sociodemographic characteristics, dietary factors, and body size. A secondary analysis was conducted for women who did not have diabetes to evaluate the association between phthalate metabolite concentrations and fasting blood glucose (FBG), homeostasis model assessment-estimated insulin resistance, and glycosylated hemoglobin A1c.Results: After adjusting for potential confounders, women with higher levels of mono-n-butyl phthalate (MnBP), mono-isobutyl phthalate (MiBP), monobenzyl phthalate (MBzP), mono-(3-carboxypropyl) phthalate (MCPP), and three di-(2-ethylhexyl) phthalate metabolites (ΣDEHP) had an increased odds of diabetes compared with women with the lowest levels of these phthalates. Women in the highest quartile for MBzP and MiBP had almost twice the odds of diabetes [OR = 1.96 (95% CI: 1.11, 3.47) and OR = 1.95 (95% CI: 0.99, 3.85), respectively] compared with women in the lowest quartile. Nonmonotonic, positive associations were found for MnBP and ΣDEHP, whereas MCPP appeared to have a threshold effect. Certain phthalate metabolites were positively associated with FBG and insulin resistance.Discussion: Urinary levels of several phthalates were associated with prevalent diabetes. Future prospective studies are needed to further explore these associations to determine whether phthalate exposure can alter glucose metabolism and increase the risk of insulin resistance and diabetes.     

Lead and cadmium levels and balance and vestibular dysfunction among adult participants in the National Health and Nutrition Examination Survey (NHANES) 1999-2004

Background: Few studies have been conducted to identify risk factors for balance and vestibular dysfunction in general populations, but previous studies have reported evidence of adverse effects of lead and cadmium on balance control in high-risk groups.Objective: We evaluated the relationship between blood lead and cadmium levels and balance and vestibular dysfunction in a general population study.Methods: We analyzed data from the 1999–2004 National Health and Nutrition Examination Survey (NHANES) of 5,574 adults ≥ 40 years of age. Balance dysfunction was evaluated by the Romberg Test of Standing Balance on Firm and Compliant Support Surfaces, which examines the ability to stand unassisted using four test conditions to evaluate vestibular system, vision, and proprioception inputs that contribute to balance. Blood levels of lead and cadmium were measured by atomic absorption spectrometry. Associations were estimated using logistic regression models adjusted for potential confounders. Associations with time to loss of balance were estimated using adjusted Cox proportional hazard models.Results: The adjusted odds ratio (OR) for balance dysfunction in association with the highest quintile (3.3–48 µg/dL) versus the lowest quintile (< 1.2 µg/dL) of lead was 1.42 [95% confidence interval (CI): 1.07, 1.89]. The corresponding OR for cadmium (0.9–7.4 µg/L vs. < 0.2 µg/L) was 1.27 (95% CI: 1.01, 1.60). The adjusted hazard ratio for time to failure for the most physiologically challenging balance test among subjects with the highest vs. lowest quintiles of blood lead was 1.24 (95% CI: 1.04, 1.48). Cadmium levels were not associated with time to failure.Conclusions: Our findings suggest that blood lead and cadmium levels may be associated with balance and vestibular dysfunction in a general sample of U.S. adults.     

Nutrition assessment in the National Health And Nutrition Examination Survey 1999-2002

The objective of this study is to describe the components of nutrition assessment in the National Health and Nutrition Examination Survey (NHANES) 1999-2002. The study design was a cross-sectional survey with a nationally representative sample of the US population. The survey participants were interviewed and completed a physical examination. From 1999 to 2002, a total of 25,316 people were included in the eligible sample, 21,004 people (83%) were interviewed, and 19,759 people (78% of the eligible sample) were examined. Dietary assessment consisted of a 24-hour dietary recall interview and questions on supplement use, food security, food-program participation, and other behaviors. Nutrition assessment included anthropometric measurements and body-composition assessment. A number of nutrition biochemistries were measured in blood and urine specimens. In addition, an assessment of cardiovascular fitness and questions on physical activity were included. Data are used to estimate population reference distributions and to monitor trends over time. Data have been used to evaluate the adequacy of nutrient intake using the Dietary Reference Intakes, to assist in development of nutrition policies related to obesity, and to evaluate policies such as folic acid fortification. The NHANES contributes to the knowledge and understanding of nutrition and health status in the US population through public-use microdata files for use by researchers in academia, in the private sector, and in government agencies. Continuous data collection will allow the NHANES to provide more timely information for policy development and evaluation.     

Has Age at Menarche Changed? Results from the National Health and Nutrition Examination Survey (NHANES) 1999–2004

PurposeTo examine self-reported age at menarche in U.S. adults and the associations between age at menarche and race/ethnicity.MethodsData from 1999–2004 National Health and Nutrition Examination Survey (NHANES) for 6788 females 20 years and over were analyzed. Self-reported age at first menses (in years) by birth year groups is reported overall and for Mexican Americans, non-Hispanic whites, and non-Hispanic blacks.ResultsMean age at menarche in the United States declined over time from 13.3 years (95% CI: 13.2–13.5) in the oldest age group, those born prior to 1920, to 12.4 years (95% C.I. 12.2–12.5 years) in the youngest group, born between 1980 and 1984. Declines in age at menarche were observed for all race/ethnicity groups. Non-Hispanic black females had the largest decline in mean age at menarche from 13.6 years (95% CI: 13.1–14.1) in women born prior to 1920, to 12.2 years (95% CI: 11.8–12.6) in the 1980–84 birth cohort. Mean age at menarche among non-Hispanic white females declined from 13.3 years (13.1–13.6) in the pre-1920 birth cohort to 12.5 years (12.3–12.8) in the 1980–84 birth cohort.ConclusionsSignificant declines in the mean age of menarche for U.S. females occurred overall and for all race/ethnic groups examined. Mean age of menarche declined by .9 year overall in women born before 1920 compared to women born in 1980–84; the declines in the mean age at menarche ranged from .7 to 1.4 years depending on the race/ethnicity group.     

Analysis of factors influencing the comparison of homocysteine values between the Third National Health and Nutrition Examination Survey (NHANES) and NHANES 1999+

Two important changes occurred in the time between the Third National Health and Nutrition Examination Survey (NHANES III) (1991-1994) and the later survey (NHANES 1999+) regarding total homocysteine (tHcy), i.e., a change in matrix from serum to plasma and a change in analytical methods. The goals of this study were to determine the magnitude of potential differences between plasma and serum with regard to tHcy concentrations, and between the two analytical methods used in these surveys. Optimally prepared plasma, serum allowed to clot for 30 and 60 min at room temperature and serum allowed to clot for 30 and 60 min and subjected to four freeze-thaw cycles, prepared from blood samples collected from 30 healthy people, were analyzed by both methods. Serum samples had significantly higher tHcy concentrations than plasma samples, and the difference increased with longer clotting time. Freeze-thaw cycles had little or no effect on the variability or bias in the serum sample results. The tHcy results produced by the two analytical methods were significantly different, but consistent across sample types. On average, the results of the method used in NHANES III were lower by 0.64 micromol/L; however, the relative bias varied with tHcy concentration. The tHcy results determined in surplus serum from NHANES III overestimated tHcy concentrations by approximately 10% compared with optimally prepared plasma. The average method bias was 6% between the two analytical methods. On the basis of changes in matrix and methodology, direct comparison of tHcy results between the two surveys is inappropriate.     

Alcohol drinking patterns and diet quality: the 1999-2000 National Health and Nutrition Examination Survey

Associations between alcohol drinking and cardiovascular disease mortality could be confounded by diet if alcohol drinking and diet are related. Depending on the alcohol measure, alcohol-diet relations may or may not be observed. The authors examined associations between alcohol and diet quality (Healthy Eating Index (HEI) scores) using cross-sectional, nationally representative data from the 1999-2000 National Health and Nutrition Examination Survey. Weighted analyses included 3,729 participants aged > or =20 years. In adjusted analyses among current alcohol drinkers, as quantity increased from 1 to > or =3 drinks/drinking day, the mean HEI score decreased from 65.3 (95% confidence interval (CI): 63.4, 67.1) to 61.9 (95% CI: 60.5, 63.2). As frequency increased from the lowest quartile to the highest, the mean HEI score increased from 60.9 (95% CI: 58.7, 63.2) to 64.9 (95% CI: 63.4, 66.4). As average volume ((quantity x frequency)/365.25) increased from <1 drink/day to > or =3 drinks/day, the mean HEI score increased from 62.9 (95% CI: 61.2, 64.5) to 65.2 (95% CI: 62.7, 67.8). In stratified analyses, the lowest HEI score, 58.5 (95% CI: 55.5, 61.5), occurred among drinkers who consumed the highest quantity at the lowest frequency. Average volume of alcohol consumed is driven by and masks the contributions of its components. These results suggest the importance of measuring drinking patterns (quantity, frequency, and stratified combinations) in epidemiologic alcohol-diet studies.     

Prevalence, treatment, and control of diagnosed diabetes in the U.S. National Health and Nutrition Examination Survey 1999-2004

PURPOSE: This study aimed to examine the trends in prevalence, treatment, and control of diagnosed diabetes in United States adults 20 years of age or older. METHODS: Data from the National Health and Nutrition Examination Survey 1999-2004 were used. Glycemic, blood pressure, and total cholesterol target levels were defined as having glycosylated hemoglobin <7.0%, blood pressure <130/80 mm Hg, and total cholesterol <200 mg/dL, respectively. RESULTS: The prevalence of diagnosed diabetes was 7.8% in 2003-2004 and increased significantly in people aged 40-59 years, women, non-Hispanic whites, and obese people in the period 1999-2004. Although there was no significant change in the pattern of antidiabetic treatment, the age-adjusted percentage of people with diagnosed diabetes achieving glycemic and blood pressure target levels increased from 35.8% to 57.1% (p = 0.002) and from 35.7% to 48.3% (p = 0.04), respectively. However, there were only insignificant increases in percentages of those persons achieving total cholesterol target level (from 48.8% to 50.4%) and those achieving all 3 target levels (from 7.5% to 13.2%). CONCLUSIONS: In 1999-2004, the prevalence of diagnosed diabetes increased significantly in some subgroups of the population. However, the increases in percentages of people with diabetes achieving glycemic and blood pressure targets are encouraging, although there is room for improvement.     

Serum ascorbic acid and cardiovascular disease prevalence in U.S. adults: the Third National Health and Nutrition Examination Survey (NHANES III).

PURPOSE: To examine the relation between serum ascorbic acid concentration, which reflects dietary and supplement intake, and the prevalence of cardiovascular disease. METHODS: We analyzed data from 7658 men and women enrolled in the Third National Health and Nutrition Examination Survey (NHANES III). We calculated odds ratios and 95% confidence intervals (CI) to estimate the relative prevalence of cardiovascular disease, defined as self-reported angina, myocardial infarction, or stroke. Because we detected an interaction between serum ascorbic acid concentration and alcohol intake, we performed analyses stratified by drinking status. RESULTS: Among participants who reported no alcohol consumption, serum ascorbic acid concentrations were not independently associated with cardiovascular disease prevalence. Among participants who consumed alcohol, serum ascorbic acid concentrations consistent with tissue saturation (1.0-3.0 mg/dl) were associated with a decreased prevalence of angina (multivariate odds ratio (OR): 0.48; 95% CI: 0.23% to 1.03; p for trend = 0.06), but were not significantly associated with myocardial infarction or stroke prevalence. CONCLUSIONS: These results suggest the possibility of a biologic interaction between ascorbic acid and alcohol and that higher intakes of ascorbic acid may be associated with a decreased risk of angina among drinkers.