Creatinine corrections for estimating children's and adult's pesticide intake doses in equilibrium with urinary pesticide and creatinine concentrations

A urine contaminant concentration per se has uncertain meaning for human health because of dilution by hydration. However, the estimation of the health-related daily intake dose of pollutant (mg/kg/day) that equilibrates with a spot urinary concentration of a pesticide residue or metabolite, or other analyte, can be made using creatinine-corrected toxicant levels (mg analyte/mg creatinine) multiplied by an estimate of the subjects' expected creatinine excretion rates (mg creatinine/kg/day). The objective was to develop a set of equations predicting a person's expected daily creatinine excretion (mg/kg) as a function of age, gender, race and morphometry, from birth to old age. We review the creatinine excretion literature where infants, children and adults provided 24 h total urine samples for creatinine analysis. Equations are developed for infants (or=18 years) that match at 3 and 18 years. A series of equations that estimate daily creatinine excretion (mg/day) are developed that are piecewise continuous from birth through infancy through adolescence and through adulthood for males and females, and Black and White races. Complicating factors such as diet, health status and obesity are discussed. We propose that these equations, with caveat, can now be used with measured urine concentrations to consistently estimate the corresponding equilibrium intake doses of toxicants at ages from birth to 92 years for the healthy non-obese. We recommend that this system of equations be considered for future development and reporting of applied doses in mg/kg/day of pollutants and toxicants that are measured in urine samples, as in the National Health and Nutrition Examination Survey.     

Prediction of 24-hour urinary creatinine excretion from age, body weight and height of an individual and its application]

Equations to predict 24-hour urinary creatinine excretion (UcrV) from age, body weight (W) and body height (H) were developed based on the data for UcrV determined by collecting 24-hour urine for 3-5 days in 256 male and 231 female clinically healthy subjects, aged from 20 to 84 years. By regression analysis a regression equation was developed. Multiple regression analysis revealed that age, W and H contributed most to the measured value of UcrV. The regression equations to predict UcrV from age, W and H were as follows: Predicted value of UcrV (PRCr) = -12.63 x Age + 15.12 x W + 7.39 x H - 79.90 (male: mg/day) PRCr = -4.72 x Age + 8.58 x W + 5.09 x H - 74.50 (female: mg/day) The multiple correlation coefficients were 0.87 for males and 0.73 for females, respectively. The difference between PRCr and measured UcrV (residual) was +0.81 +/- 154 (SD) mg/day on the average. An analysis of residuals by means of plotting of standardized residuals and predicted standardized dependent variables showed no remarkable deviations in both sexes, suggesting that these equations are applicable to the prediction of UcrV. These equations were applied to 38 Japanese men and women who were asked to collect 24-hour urine for 14 days on average, and also to 47 foreigners (American, Nepalese and Italian). The average residual in the former was +27 +/- 87 mg/day and that in the latter -3 +/- 85 mg/day, suggesting that these equations can be applied not only to the Japanese but also to the foreigners as a useful index in predicting 24-hour urinary creatinine excretion.     

Recruiting Strategy and 24-Hour Biomonitoring of Paraquat in Agricultural Workers

ABSTRACT

The objectives of this study were to recruit agricultural workers in Costa Rica to participate in a 24-hour urine collection for paraquat exposure assessment and to compare the 24-hour sampling to end-of-shift sampling. The authors recruited 187 handlers and 54 nonhandlers from coffee, banana, and palm oil plantations. The completeness of 24-hour urine samples collected (a total of 393 samples) was confirmed by questionnaire and urinary creatinine level. For a subset of 12 samples, the absorbed paraquat level was determined in 24-hours and end-of-shift spot urine samples. The participation rate for handlers was?～90%. The completeness of 24-hour urine collections was verified as the overall average of creatinine levels from 393 urines (1.11?±?0.50 g/L). A total of 92.4%?to 96.7%?of urine samples were considered within the acceptable range of urinary creatinine, whereas 94.7%?of the samples were described as “complete” from the questionnaire. Measured creatinine correlated well to predicted values (r?=?.327, p?=?.0024, 95%?CI .12–.51). Detected paraquat levels in spot urine samples had a sensitivity of 96.9%?at the high specificity of 100%?compared to 24-hour urine samples as the gold standard. There was a significant (p?<?.0001) correlation between spot and 24-hour urine paraquat levels (r?=?.7825, 95%?CI .61–.88). The recruiting strategy was successful in getting 24-hour urine samples from a farm worker population. Comparison between the paraquat levels in spot and 24-hour urine samples demonstrated that for this compound, end-of-shift spot urine samples would be an appropriate substitute for 24-hour collections.     

Formulas developed based on the ratio of urea nitrogen to creatinine concentrations obtained from multiple spot urine samples are acceptable to predict protein intake at group level but not at individual level

In this study, we hypothesized that spot urine can be used to predict protein intake at both group and individual levels. Participants (n = 369) of this study were recruited from all 47 prefectures in Japan. Sex-specific formulas were developed based on the ratio of urea nitrogen to creatinine concentration obtained from 3 spot urine samples. Validity of the formulas was examined against two 24-hour urine collections for 7 combinations of spot urine (single and means of 2 or 3 samples) using t test (mean estimation), Spearman correlation, and Bland-Altman plot (individual bias). Means of measured protein intake based on 24-hour urinary excretions were 87.3 g/d (standard deviation 19.7) for men and 70.5 g/d (standard deviation 14.7) for women. Irrespective of sex, the predicted intakes were not significantly different (within 2.7% of differences) from those measured by urinary excretions. Predicted intakes were moderately correlated with measured intakes (men, 0.45-0.60; women, 0.35-0.53). Even after using the mean of 3 samples, Bland-Altman plots showed a considerably wide limit of agreement (men, −30 to 33 g/d; women, −27 to 24 g/d). Except for using single spot urine samples in women, the formula tended to overestimate intake at a lower and underestimate at a higher level of protein intake (slope: men, −0.47 [P < .0001]; women, −0.38 [P = .002]). In conclusion, predictive formulas developed in this study can be used to predict protein intake at group level or to rank individuals' intake but not to predict absolute intake at individual level.     

Control of Lead Workers by Determination of Urinary δ-Aminolaevulinic Acid

The output of δ-aminolaevulinic acid (ALA) and of creatinine was determined in lead workers. Values from 24-hour specimens were compared with values from specimens voided at the time of examination. Highly significant positive correlations were found between the output of ALA and of creatinine in both sets of specimens. The individual spreads, however, were considerable.

Values for ALA in mg./100 ml. urine and ALA in mg./g. creatinine were strongly correlated in fresh specimens as well as in 24-hour specimens. When values for ALA in mg./100 ml. urine were compared with ALA in mg./g. creatinine, an approximate relationship of 1:5 was found in the range 1.0-3.0 mg. ALA/100 ml. urine, i.e., the mean urinary concentration of creatinine was 0.2 g./100 ml.

It is concluded that the collection of 24-hour specimens is not necessary and also that reference to creatinine appears to have no advantage over the simple expression of ALA in mg./100 ml. urine. This must be due to the fact that the influence of the metabolic activities of lead has a greater effect on the urinary concentration of ALA than has the concentration of urine in the kidneys.

     

Urinary Screening Tests to Detect Excessive Lead Absorption

The biological variation encountered in spot urine samples was assessed by collecting six sets of serial urine specimens from five men. The lead, coproporphyrin, and creatinine contents of each specimen were determined and the specific gravity was measured. It is found that as the mean concentration of the metabolite rises so the variability of the individual values increases. The scatter of the concentrations is not significantly different from that found in the rates of excretion. Adjustment of the figures to either a constant specific gravity or creatinine concentration increased the scatter. The effect of the diurnal cycle on the variability is negligible as the spread of the combined results is uniform over the 24-hour period.

The results of spot urine samples must be considered collectively before they can indicate the mean excretion level.

Twenty-four-hour urine samples were obtained from 23 lead-intoxicated men before and throughout their treatment with chelating agents. The initial excretion of lead during intravenous infusion of disodium calcium ethylenediaminetetra-acetate (first Pb EDTA) and the weight of lead excreted as the complex, before the coproporphyrin excretion falls to a normal level (less than 100 μ.g per day), termed the `excess' lead, are used as objective measures of the lead absorption. These two indices are linearly related to the pretreatment urinary levels of lead and coproporphyrin, regardless of whether the results are expressed in μg. per litre or μg. per day. Due to the environment having an effect on the urinary concentrations it is concluded that in general the weight of metabolite excreted in the 24-hour period possibly provides the more reliable guide to the lead absorption of the individual.

     

Sodium and Potassium Intake of Urban Dwellers: Nothing Changed in Yazd,Iran

To assess the daily salt intake of people aged 20-74 years based on the 24-hour urinary sodium excretion in urban population of Yazd, a population-based cross-sectional study was conducted. This is a substudy of Yazd Healthy Heart Project in Iran. From 2004 to 2005, two thousand people of the urban population of Yazd city, aged 20-74 years, were enrolled in the main study. Overall, 219 volunteer participants of 20-70 years were enrolled in this substudy. Sample frame was the household numbers according to the database of Yazd City Health Services. Calcium, phosphorus, sodium, potassium, and creatinine were measured in the urine samples collected from the participants over a 24-hour period. Sodium content in urine over 24 hours was 171.7±82.9 mmol/day in males and 127.8±56.1 mmol/day in females (p<0.0001) while potassium content was 49.4±23.2 mmol/day in males and 41.5±25.1 mmol/day in females (p=0.2). Estimated average daily salt (NaCl) intake was 10.0±4.8 g/day in males and 7.5±3.3 g/day in females (p<0.0001). Only one participant had the ideal Na/K ratio of less than one. Na/K ratios greater than one and less than two were seen in 11.3% (n=24), and a ratio equal to or greater than 2 was observed in 82.3% (n=118) of the participants. The average Na/K ratio was 3.69±1.58. Unlike many developed countries where sodium intake declined over the past few decades, the daily sodium intake in Yazd is high, and daily potassium intake is low. This is similar to what was observed four decades ago in an area not far from Yazd. Efforts must be directed towards health promotion interventions to increase public awareness to reduce sodium intake and increase potassium intake.Key words: 24-hour urine, Blood pressure, Cardiovascular disease, Hypertension, Policy, Potassium, Prevention, Salt, Sodium, Iran     

Sodium Intake in a Cross-Sectional,Representative Sample of New York City Adults

Objectives. We estimated sodium intake, which is associated with elevated blood pressure, a major risk factor for cardiovascular disease, and assessed its association with related variables among New York City adults.Methods. In 2010 we conducted a cross-sectional, population-based survey of 1656 adults, the Heart Follow-Up Study, that collected self-reported health information, measured blood pressure, and obtained sodium, potassium, and creatinine values from 24-hour urine collections.Results. Mean daily sodium intake was 3239 milligrams per day; 81% of participants exceeded their recommended limit. Sodium intake was higher in non-Hispanic Blacks (3477 mg/d) and Hispanics (3395 mg/d) than in non-Hispanic Whites (3066 mg/d; both P < .05). Higher sodium intake was associated with higher blood pressure in adjusted models, and this association varied by race/ethnicity.Conclusions. Higher sodium intake among non-Hispanic Blacks and Hispanics than among Whites was not previously documented in population surveys relying on self-report. These results demonstrate the feasibility of 24-hour urine collection for the purposes of research, surveillance, and program evaluation.Cardiovascular disease (CVD) is the leading cause of death in the United States,1 and hypertension is a leading risk factor. A positive and continuous relationship between sodium intake and blood pressure (BP) is well established.2 Existing estimates of sodium intake measured by self-report show that US adults consume a daily average of 3400 milligrams, well above the recommended limit (1500–2300 mg/d),2 and public health efforts are aimed at reducing sodium consumption.3–5 In a simulation analysis of risk factor and outcome data from key CVD data sources, researchers estimated that up to 92 000 deaths could be averted annually by lowering the current mean adult intake by 1200 milligrams of sodium, resulting in intake closer to the recommended limit.6 Although reduced sodium intake decreases BP on average in all racial/ethnic groups and in individuals with normal and high BP, the BP-lowering effect of sodium reduction is greater in Blacks than in other racial/ethnic groups.7,8 National estimates of sodium intake derived from self-report do not demonstrate higher intake among Blacks.The gold standard method for assessing sodium intake is measurement of sodium excretion in rigorously collected 24-hour urine samples, although this method has some limitations, such as undercollection.9 This method has been used to assess population intake in the United Kingdom, Finland, Portugal, and Barbados.10–14 In the United States, population intake has been assessed since 1971 through 24-hour dietary recall. Although adequate for understanding general trends and intake, estimates that rely on self-report are subject to reporting error and bias.9 Objective measures would avoid these problems; however, to date no representative assessment of sodium intake derived from 24-hour urine collections has been performed in the United States.In the absence of nationally representative US surveys employing the gold standard method, we measured sodium excretion in urine over 24 hours in a representative sample of adults in New York City. Our objectives were to estimate mean population sodium intake, overall and by subgroup, particularly in different racial/ethnic groups; to understand sodium intake in relation to recommended limits; and to assess the relationship between sodium intake and other variables.     

国内外减盐干预策略和措施研究进展

  目的  比较3种随机点尿计算方法与24 h尿钠法估算安徽省成年居民平均盐摄入量的差异和一致性,为验证3种随机点尿方法估算人群盐摄入量方法的可靠性提供参考依据。  方法  收集2019年安徽省成年居民高血压和钠摄入量监测基线调查中随机尿样合格3329人、24 h尿样合格1500人以及24 h尿样和随机尿样配对1493人的相关数据,采用3种点尿转换24 h尿钠方法估计平均盐摄入量,并与24 h尿钠法估算的盐摄入量进行比较;应用配对样本t检验、组类内相关系数（ICC）分析和Bland-Altman图检验3种随机点尿计算方法与24 h尿钠法的差异和一致性。  结果  基于24 h尿钠法估算的安徽省成年居民平均盐摄入量为9.1（95%CI = 8.9～9.4）g/d,Kawasaki、Tanaka和 INTERSALT 3种随机点尿计算方法估算的安徽省成年居民平均盐摄入量分别为12.7（95%CI = 12.6～12.9）、9.5（95%CI = 9.4～9.6）和 8.6 （95%CI = 8.5～8.7）g/d。配对比较结果显示,Tanaka随机点尿计算方法估算的结果最接近24 h尿钠法,平均差值为0.2（95%CI = 0.0～0.4）g/d;Tanaka随机点尿计算方法估算的ICC值最高（0.34）,INTERSALT随机点尿计算方法估算的ICC值次之（0.33）,Kawasaki随机点尿计算方法估算的ICC值最低（0.23）;3种点尿法的估计值与24 h尿钠法的估计值吻合较好,除Kawasaki外,INTERSALT和Tanaka随机点尿计算方法估算的结果在低水平盐摄入量时可能高估,在高水平摄入时可能低估。  结论  安徽省成年居民盐摄入量的3种点尿估计方法均与24 h尿钠法一致,Tanaka法相对更准确地估计人群盐摄入量。     

Bisphenol A Data in NHANES Suggest Longer than Expected Half-Life,Substantial Nonfood Exposure,or Both

Background

It is commonly stated in the literature on human exposure to bisphenol A (BPA) that food is the predominant BPA exposure source, and that BPA is rapidly and completely cleared from the body. If this is correct, BPA levels in fasting individuals should decrease with increased fasting time.

Objectives

We set out to investigate the relationship between urine BPA concentration and fasting time in a population-based sample.

Methods

We modeled log BPA urine concentration as a function of fasting time, adjusted for urine creatinine and other confounders, in 1,469 adult participants in the 2003–2004 National Health and Nutrition Examination Survey. We estimated the BPA “population-based half-life” (pop½) for a fasting time of 0–24 hr, < 4.5 hr, 4.5–8.5 hr, and > 8.5 hr.

Results

The overall pop½ for the 0- to 24-hr interval was 43 hr [95% confidence interval (CI), 26–119 hr]. Among those reporting fasting times of 4.5–8.5 hr (n = 441), BPA declined significantly with fasting time, with a pop½ of 4.1 hr (95% CI, 2.6–10.6 hr). However, within the fasting time intervals of 0–4.5 hr (n = 129) and 8.5–24 hr (n = 899), we saw no appreciable decline. Fasting time did not significantly predict highest (> 12 ng/mL) or lowest (below limit of detection) BPA levels.

Conclusions

Overall, BPA levels did not decline rapidly with fasting time in this sample. This suggests substantial nonfood exposure, accumulation in body tissues such as fat, or both. Explaining these findings may require experimental pharmacokinetic studies of chronic BPA exposure, further examination of BPA levels and effects in fat, and a search for important nonfood sources.     

Validation of 4 Estimating Methods to Evaluate 24-h Urinary Sodium Excretion: Summer and Winter Seasons for College Students in China

Twenty-four-hour urine sample collection is regarded as the gold standard for sodium intake evaluation, but the implementation can be difficult. The objective was to validate and evaluate the accuracy and feasibility of estimating sodium intake by four methods. A group of 268 healthy volunteers aged 18–25 years was enrolled in this study. Twenty-four-hour urine samples as well as timed (morning, afternoon, evening, and overnight) urine samples were randomly collected in summer and winter. The sodium intake was estimated by four published methods—Kawasaki, INTERSALT, Tanaka, and Sun’s. The consistencies between estimated sodium intake and real measured values of 24-h urinary sodium excretion were compared by Bland–Altman plots in each of the methods. The 24-h urinary sodium analysis result indicated that average daily sodium intake was 3048.4 ± 1225.9 mg in summer and 3564.7 ± 1369.9 mg in winter. At the population level, the bias (estimated value-measured value) was the least with the INTERSALT method with afternoon (−39.7 mg; 95%CI: −164.7, 85.3 mg) and evening (−43.5 mg; 95%CI: −166.4, 79.5 mg) samples in summer. In winter, the Kawasaki method (162.1 mg; 95%CI: 13.5, 310.7 mg) was superior to others. Estimation of sodium intake using the four methods is affected by the time and temperature. In summer, the INTERSALT method provides the best estimation of the population’s mean sodium intake. The Kawasaki method is superior to other methods in winter.     

Sodium Intake and Proteinuria/Albuminuria in the Population—Observational,Cross-Sectional Study

Sodium effects on proteinuria are debated. This observational, cross-sectional, population-based study investigated relationships to proteinuria and albuminuria of sodium intake assessed as urinary sodium/creatinine ratio (NaCR). In 482 men and 454 women aged 35–94 years from the Moli-sani study, data were collected for the following: urinary NaCR (independent variable); urinary total proteins/creatinine ratio (PCR, mg/g), urinary albumin/creatinine ratio (ACR, mg/g), and urinary non-albumin-proteins/creatinine ratio (calculated as PCR minus ACR) (dependent variables). High values were defined as PCR ≥ 150 mg/g, ACR ≥ 30 mg/g, and urinary non-albumin-proteins/creatinine ratio ≥ 120 mg/g. Urinary variables were measured in first-void morning urine. Skewed variables were log-transformed in analyses. The covariates list included sex, age, energy intake, body mass index, waist/hip ratio, estimated urinary creatinine excretion, smoking, systolic pressure, diastolic pressure, diabetes, history of cardiovascular disease, reported treatment with antihypertensive drug, inhibitor or blocker of the renin-angiotensin system, diuretic, and log-transformed data of total physical activity, leisure physical activity, alcohol intake, and urinary ratios of urea nitrogen, potassium, and phosphorus to creatinine. In multivariable linear regression, standardized beta coefficients of urinary NaCR were positive with PCR (women and men = 0.280 and 0.242, 95% confidence interval = 0.17/0.39 and 0.13/0.35, p < 0.001), ACR (0.310 and 0.265, 0.20/0.42 and 0.16/0.38, p < 0.001), and urinary non-albumin-proteins/creatinine ratio (0.247 and 0.209, 0.14/0.36 and 0.09/0.33, p < 0.001). In multivariable logistic regression, higher quintile of urinary NaCR associated with odds ratio of 1.81 for high PCR (1.55/2.12, p < 0.001), 0.51 of 1.62 for high ACR (1.35/1.95, p < 0.001), and of 1.84 for high urinary non-albumin proteins/creatinine ratio (1.58/2.16, p < 0.001). Findings were consistent in subgroups. Data indicate independent positive associations of an index of sodium intake with proteinuria and albuminuria in the population.     

Evaluation of Riboflavin Intakes and Status of 20–64-Year-Old Adults in South Korea

A recent Korea National Health and Nutrition Survey indicated inadequate riboflavin intake in Koreans, but there is limited research regarding riboflavin status in South Korea. The purpose of this study was to determine riboflavin intake and status of Korean adults. Three consecutive 24-h food recalls were collected from 412 (145 men and 267 women) healthy adults, aged 20–64 years, living in South Korea and urine samples were collected from 149 subjects of all subjects. The dietary and total (dietary plus supplemental) riboflavin intake was 1.33 ± 0.34 and 2.87 ± 6.29 mg/day, respectively. Approximately 28% of the subjects consumed total riboflavin less than the Estimated Average Requirement. Urinary riboflavin excretion was 205.1 ± 190.1 μg/g creatinine. Total riboflavin intake was significantly positively correlated to the urinary riboflavin excretion. (r = 0.17171, p = 0.0363). About 11% of the Korean adults had urinary riboflavin <27 μg/g creatinine indicating a riboflavin deficiency and 21% had low status of riboflavin (27 μg/g creatinine ≤ urinary riboflavin < 80 μg/g creatinine). Thus, one-third of Korean adults in this study had inadequate riboflavin status. In some adults in Korea, consumption of riboflavin-rich food sources should be encouraged.     

Validity of Bioelectrical Impedance Analysis to Estimation Fat-Free Mass in the Army Cadets

Background: Bioelectrical Impedance Analysis (BIA) is a fast, practical, non-invasive, and frequently used method for fat-free mass (FFM) estimation. The aims of this study were to validate predictive equations of BIA to FFM estimation in Army cadets and to develop and validate a specific BIA equation for this population. Methods: A total of 396 males, Brazilian Army cadets, aged 17–24 years were included. The study used eight published predictive BIA equations, a specific equation in FFM estimation, and dual-energy X-ray absorptiometry (DXA) as a reference method. Student’s t-test (for paired sample), linear regression analysis, and Bland–Altman method were used to test the validity of the BIA equations. Results: Predictive BIA equations showed significant differences in FFM compared to DXA (p < 0.05) and large limits of agreement by Bland–Altman. Predictive BIA equations explained 68% to 88% of FFM variance. Specific BIA equations showed no significant differences in FFM, compared to DXA values. Conclusion: Published BIA predictive equations showed poor accuracy in this sample. The specific BIA equations, developed in this study, demonstrated validity for this sample, although should be used with caution in samples with a large range of FFM.     

某些水溶性维生素营养状况评定的研究

用任意一次尿中某些水溶性维生素排出量与肌酐排出量的比值来作为评定人群的营养状况最为简便,能解决收集24小时尿量不易完整的困难。本文的人体实验结果证明,任意一次尿中肌酐排出量与全日尿中肌酐排出量有显著的相关,即使一日偶尔增加100—300g的酱牛肉,对全日尿中肌酐的排出量影响不大。任意一次尿中硫胺素、核黄素、N’-甲基尼克酰胺的排出量与肌酐排出量的比值,能够反映出绝大多数受试者这些维生素的营养状况,可作为评定人群营养状况的指标。     

Daily Bisphenol A Excretion and Associations with Sex Hormone Concentrations: Results from the InCHIANTI Adult Population Study

Background

Bisphenol A (BPA) is a high production volume chemical widely used in packaging for food and beverages. Numerous studies have demonstrated that BPA can alter endocrine function in animals, yet human studies remain limited.

Objective

We estimated daily excretion of BPA among adults and examined hypothesized associations with serum estrogen and testosterone concentrations.

Methods

We conducted cross-sectional analyses using data from the InCHIANTI Study, a prospective population-based study of Italian adults. Our study included 715 adults between 20 and 74 years old. BPA concentrations were measured by liquid chromatography–mass spectrometry in 24-hr urine samples. The main outcome measures were serum concentrations of total testosterone and 17β-estradiol.

Results

Geometric mean urinary BPA concentration was 3.59 ng/mL [95% confidence interval (CI), 3.42–3.77 ng/mL], and mean excretion was 5.63 μg/day (5th population percentile, 2.1 μg/day; 95th percentile, 16.4 μg/day). We found higher excretion rates among men, younger respondents, and those with increasing waist circumference (p = 0.013) and weight (p = 0.003). Higher daily BPA excretion was associated with higher total testosterone concentrations in men, in models adjusted for age and study site (p = 0.044), and in models additionally adjusted for smoking, measures of obesity, and urinary creatinine concentrations (β = 0.046; 95% CI, 0.015–0.076; p = 0.004). We found no associations with the other serum measures. We also found no associations with the primary outcomes among women, but we did find an association between BPA and SHBG concentrations in the 60 premenopausal women.

Conclusion

Higher BPA exposure may be associated with endocrine changes in men. The mechanisms involved in the observed cross-sectional association with total testosterone concentrations need to be clarified.     

Iodine Status and Thyroid Function in a Group of Seaweed Consumers in Norway

Seaweeds, or macroalgae, may be a good dietary iodine source but also a source of excessive iodine intake. The main aim in this study was to describe the iodine status and thyroid function in a group of macroalgae consumers. Two urine samples were collected from each participant (n = 44) to measure urinary iodine concentration (UIC) after habitual consumption of seaweed. Serum thyroid stimulating hormone (TSH), free thyroxine (fT₄), free triiodothyronine (fT₃), and peroxidase autoantibody (TPOAb), were measured in a subgroup (n = 19). A food frequency questionnaire and an iodine-specific 24 h recall were used to assess iodine intake and macroalgae consumption. The median (p25–p75) UIC was 1200 (370–2850) μg/L. Median (p25–p75) estimated dietary iodine intake, excluding macroalgae, was 110 (78–680) μg/day, indicating that seaweed was the major contributor to the iodine intake. TSH levels were within the reference values, but higher than in other comparable population groups. One third of the participants used seaweeds daily, and sugar kelp, winged kelp, dulse and laver were the most common species. Labelling of iodine content was lacking for a large share of the products consumed. This study found excessive iodine status in macroalgae consumers after intake of dietary seaweeds. Including macroalgae in the diet may give excessive iodine exposure, and consumers should be made aware of the risk associated with inclusion of macroalgae in their diet.     

The Risk of Cardiovascular Disease According to Chewing Status Could Be Modulated by Healthy Diet in Middle-Aged Koreans

To assess whether a healthy diet could change the risk of cardiovascular disease (CVD)-related chewing difficulty (CD) in relation to age distribution. In a cross-sectional study of 9411 middle-aged Koreans from the KNHANES VII. In this study, the Framingham 10-year general CVD risk prediction equations and the Korean Heathy Eating index (KHEI) were used to assess the 10-year estimated risk of CVD and dietary quality, respectively. CD was experienced by 16.7% of the total subjects. Among subjects with CD, the 10-year estimated CVD risk was 8.71% of the subjects in the 30–49 years age group and 30.38% of those in the 50–64 years age group, which is a difference of approximately 3.5 times. Regardless of age distribution, the total score of the KHEI in subjects who had CD was significantly lower than in those who had no CD (NCD) (p = 0.004 for the 30–49 years age group and p < 0.001 for the 50–64 years age group, respectively). Among the subjects with poor KHEI in the 30–49-year age group, the adjusted odds ratio for the 10-year estimated CVD risk of the subjects with CD was 2.204-fold (95% CI = 1.385–3.506) higher using NCD as a reference. The findings showed that dietary quality could modify the risk for CVD according to chewing status.     

Urinary Concentrations of Metabolites of Pyrethroid Insecticides in the General U.S. Population: National Health and Nutrition Examination Survey 1999–2002

Background

Pyrethroid insecticides are the most commonly used residential insecticides in the United States.

Objectives

Our objective was to assess human exposure via biomonitoring to pyrethroid insecticides in a representative sample of the general U.S. population ≥ 6 years of age.

Methods

By using isotope-dilution high-performance liquid chromatography/electrospray chemical ionization/tandem mass spectrometry, we measured five urinary metabolites of pyrethroid insecticides in 5,046 samples collected as a part of the 1999–2002 National Health and Nutrition Examination Survey (NHANES). Univariate, multivariate, and Pearson correlation analyses were performed using SUDAAN and SAS software, incorporating the appropriate sample weights into the analyses. Multivariate analyses included age, sex, race/ethnicity, creatinine, fasting status, and urine collection time as covariates.

Results

We detected 3-phenoxybenzoic acid (3PBA), a metabolite common to many pyrethroid insecticides, in more than 70% of the samples. The least-squares geometric mean (LSGM) concentration (corrected for covariates) of 3PBA and the frequency of detection increased from 1999–2000 (0.292 ng/mL) to 2001–2002 (0.318 ng/mL) but not significantly. Non-Hispanic blacks had significantly higher LSGM 3PBA concentrations than did non-Hispanic whites and Mexican Americans in the 2001–2002 survey period and in the combined 4-year survey periods but not in the 1999–2000 survey period. Children had significantly higher LSGM concentrations of 3PBA than did adolescents in both NHANES periods and than adults in NHANES 1999–2000. Cis- and trans-(2,2-dichlorovinyl)-2,2-dimethylcyclopropane-1-carboxylic acid were highly correlated with each other and with 3PBA, suggesting that urinary 3PBA was derived primarily from exposure to permethrin, cypermethrin, or their degradates.

Conclusions

Pyrethroid insecticide exposure in the U.S. population is widespread, and the presence of its metabolites in the urine of U.S. residents indicates that children may have higher exposures than adolescents and adults.     

Within-person variability in urinary bisphenol A concentrations: Measurements from specimens after long-term frozen storage

Background

Bisphenol A (BPA) is an estrogenic contaminant of food and water associated with adverse developmental effects in laboratory animals. BPA has recently been linked to morbidity in adult humans, but studies of developmental effects in humans are methodologically more difficult. The ability to measure BPA in urine samples after long-term storage could aid in such studies. Because the half-life of BPA is <6 h, a single measurement would be useful only if the environmental exposure is relatively constant over weeks or months. Our aims were to evaluate the stability of BPA in specimens after 22-24 years of storage and to measure within-person temporal variability in urinary BPA.

Methods

We measured total BPA concentration by mass spectrometry in first-morning urine samples from 60 premenopausal women. We selected from each woman's stored daily collections three urine samples approximately 2 and 4 weeks apart. Samples were selected from both the follicular and luteal phases of the menstrual cycle to assess cycle effects. Temporal variability was assessed with mixed model regression and correlations.

Results

BPA levels had an inter-quartile range from 1.1 to 3.1 ng/mg creatinine, slightly higher than levels in specimens from NHANES collected 3-11 years later. The Spearman correlation was approximately 0.5 for samples 2 weeks apart and 0.3 for samples 4 weeks apart. Menstrual cycle phase did not influence levels. BPA tended to increase during the three-year collection period, but not significantly.

Conclusions

The similar distribution to NHANES samples and correlation of BPA levels taken at 2-week intervals provide indirect evidence that BPA is relatively stable during long-term freezer storage. The correlations indicate generally stable exposures over periods of weeks. These findings suggest that developmental effects of BPA exposure could be investigated with measurements from stored urine.