Vern Hartz

Contribution of diet to aggregate arsenic exposures—An analysis across populations

The relative contribution of dietary arsenic (As) to aggregate daily exposure has not been well-characterized, especially in relation to the current EPA maximum contaminant level (MCL) of 10 p.p.b. for As in drinking water. Our objectives were to: (1) model exposure to inorganic and total As among non-seafood eaters using subject-specific data, (2) compare the contribution of food, drinking and cooking water to estimated aggregate exposure in households with variable background tap water As levels, and (3) describe the upper distribution of potential dose at different thresholds of tap water As. Dietary As intake was modeled in regional study populations and NHANES 2003–2004 using dietary records in conjunction with published food As residue data. Water As was measured in the regional studies. Among subjects exposed to tap water As >10 p.p.b., aggregate inorganic exposure was 24.5–26.1 μg/day, with approximately 30% of intake from food. Among subjects living in homes with tap water As ≤10, 5 or 3 p.p.b., aggregate inorganic As exposure was 8.6–11.8 μg/day, with 54–85% of intake from food. Median inorganic As potential dose was 0.42–0.50 μg/kg BW/day in subjects exposed to tap water As >10 p.p.b. and less than half that among subjects exposed to tap water As ≤10 p.p.b. The majority of inorganic and total As exposure is attributable to diet in subjects with tap water As <MCL. Further research is needed to determine the potential toxicity and need for regulation of As in foods.

Measured versus modeled dietary arsenic and relation to urinary arsenic excretion and total exposure

Chronic exposure to arsenic (As) in food and water is a significant public health problem. Person-specific aggregate exposure is difficult to collect and modeling based on limited food As residue databases is of uncertain reliability. Two cross-sectional population exposure studies, the National Human Exposure Assessment Survey-Arizona and Arizona Border Survey, had a combined total of 252 subjects with diet, water, and urinary As data. Total As was measured in 24-h duplicate diet samples and modeled using 24-h diet diaries in conjunction with several published food surveys of As. Two-stage regression was used to assess the effects of dietary As on urinary total As (uAs): (1) generalized linear mixed models of uAs above versus below the limit of detection (LOD); and (2) restricted models limited to those subjects with uAs>LOD, using bootstrap sampling and mixed models adjusted for age, sex, body mass index, ethnicity, current smoking, and As intake from drinking and cooking water. In restricted models, measured and modeled estimates were significant predictors of uAs. Modeled dietary As based on Total Diet Study mean residues greatly underestimated the dietary intake. In households with tap water As ≤10 p.p.b., over 93% of total arsenic exposure was attributable to diet.

Development of a questionnaire and a database for assessing dietary D-limonene intake

OBJECTIVE Increasing recognition of the potential importance of phytochemicals in the aetiology of cancer and heart diseases has highlighted the need for methods to measure individual phytochemical consumption that are sufficiently simple to be used in large epidemiological studies and whose reproducibility and accuracy have been quantified. d-Limonene is a natural component of a variety of foods and beverages and is found mainly in citrus fruits. However, d-limonene is not assessed by any nationally available analysis database. DESIGN We designed our study to assess the d-limonene content of different citrus juices and beverages and to develop a dietary assessment instrument to measure consumption of citrus foods (fruit, juice and peel) and d-limonene intake and test it for reliability. SUBJECTS AND METHODS A total of 120 citrus juice samples were analysed and used to develop the preliminary d-limonene database. A self-administered citrus food-frequency questionnaire was developed and administered twice to participants, separated by a 2-month interval. The questionnaire was tested for reproducibility of estimates of citrus food consumption and d-limonene intake among 120 participants. RESULTS Correlation coefficients between the two administrations of the questionnaire ranged from 0.50 for citrus peel use to 0.82 for orange juice. Mean intakes (range) of d-limonene from citrus juices among consumers were 13.0 (0.24-141.9) mg day-1 and 13.2 (0.07-83.9) mg day-1 (r = 0.60, P < 0.001). CONCLUSION The citrus frequency questionnaire developed in this study provided highly reproducible estimates of citrus foods, citrus peel and d-limonene intakes. This instrument may be a useful tool in studies of the associations between citrus peel use, d-limonene intake and risk for chronic disease.

Nutrients in one-carbon metabolism and urinary arsenic methylation in the National Health and Nutrition Examination Survey (NHANES) 2003–2004

Exposure to inorganic arsenic (inAs), a potent toxicant, occurs primarily through ingestion of food and water. The efficiency with which it is methylated to mono and dimethyl arsenicals (MMA and DMA) affects toxicity. Folate, vitamins B12 and B6 are required for 1C metabolism, and studies have found that higher levels of these nutrients increase methylation capacity and are associated with protection against adverse health effects from inAs, especially in undernourished populations. Our aim was to determine whether 1C-related nutrients are associated with greater inAs methylation capacity in a general population sample with overall adequate nutrition and low levels of As exposure. Univariate and multivariable regression models were used to evaluate the relationship of dietary and blood nutrients to urinary As methylation in the National Health and Nutrition Examination Survey (NHANES) 2003-2004. Outcome variables were the percent of the sum of inAs and methylated As species (inAs+MMA+DMA) excreted as inAs, MMA, and DMA, and the ratio of MMA:DMA. In univariate models, dietary folate, vitamin B6 and protein intake were associated with lower urinary inAs% and greater DMA% in adults (≥18years), with similar trends in children (6-18). In adjusted models, vitamin B6 intake (p=0.011) and RBC folate (p=0.036) were associated with lower inAs%, while dietary vitamin B12 was associated with higher inAs% (p=0.002) and lower DMA% (p=0.030). Total plasma homocysteine was associated with higher MMA% (p=0.004) and lower DMA% (p=0.003), but not with inAs%; other blood nutrients showed no association with urinary As. Although effect size is small, these findings suggest that 1C nutrients can influence inAs methylation and potentially play an indirect role in reducing toxicity in a general population sample.

Relation of dietary inorganic arsenic to serum matrix metalloproteinase-9 (MMP-9) at different threshold concentrations of tap water arsenic

Arsenic (As) exposure is associated with cancer, lung and cardiovascular disease, yet the mechanisms involved are not clearly understood. Elevated matrix metalloproteinase-9 (MMP-9) levels are also associated with these diseases, as well as with exposure to water As. Our objective was to evaluate the effects of dietary components of inorganic As (iAs) intake on serum MMP-9 concentration at differing levels of tap water As. In a cross-sectional study of 214 adults, dietary iAs intake was estimated from 24-h dietary recall interviews using published iAs residue data; drinking and cooking water As intake from water samples and consumption data. Aggregate iAs intake (food plus water) was associated with elevated serum MMP-9 in mixed model regression, with and without adjustment for covariates. In models stratified by tap water As, aggregate intake was a significant positive predictor of serum MMP-9 in subjects exposed to water As≤10 μg/l. Inorganic As from food alone was associated with serum MMP-9 in subjects exposed to tap water As≤3 μg/l. Exposure to iAs from food and water combined, in areas where tap water As concentration is ≤10 μg/l, may contribute to As-induced changes in a biomarker associated with toxicity.

Need for Specific Sugar-Sweetened Beverage Lessons for Fourth- and Fifth-Graders

OBJECTIVE Consumption of sugar-sweetened beverages (SSB) is linked to obesity. The authors hypothesized that school-based nutrition education would decrease SSB consumption. DESIGN Self-selected interventional cohort with random selection for pre and post measurements. SETTING Arizona Supplemental Nutrition Assistance Program-Education Program-eligible schools. PARTICIPANTS Randomly selected (9%) fourth- and fifth-grade classroom students. INTERVENTION The University of Arizona Nutrition Network provided general nutrition education training and materials to teachers, to be delivered to their students. The University of Arizona Nutrition Network administered behavioral questionnaires to students in both fall and spring. MAIN OUTCOME MEASURE(S) Change in SSB consumption. ANALYSES Descriptive statistics were computed for student demographics and beverage consumption on the day before testing. Paired t tests evaluated change in classroom averages. Linear regression assessed potential correlates of SSB consumption. RESULTS Fall mean SSB consumption was 1.1 (± 0.2) times; mean milk and water intake were 1.6 (± 0.2) and 5.2 (± 0.7) times, respectively. Beverage consumption increased (3.2%) in springtime, with increased SSBs (14.4%) accounting for the majority (P = .006). Change in SSB consumption was negatively associated with baseline SSB and water consumption but positively associated with baseline milk fat (P ≤ .05). CONCLUSIONS AND IMPLICATIONS The results suggest the need for beverage-specific education to encourage children to consume more healthful beverages in warmer weather.