BPA variability of urinary BPA in Korean infants

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1 BPA variability of urinary BPA in Korean infants
논문초독회 BPA variability of urinary BPA in Korean infants 이 장 우

2 Long term variability and trend of urinary bisphenol A in Korean infants
Highlights BPA is an endocrine disrupting chemicals that can affects the development of infants BPA was a substance with a short half-life and repeatedly exposed in the environment, but no information exists on variability of urinary BPA in infants Urinary BPA was the highest at birth, followed by 9, 12, 15 months and 3 months after birth. The intra-class correlation (ICC) of repeated measurements of BPA was low, ranging from zero (specific gravity and creatinine corrected) to (uncorrected). The within variations mostly contributed in total variations of urinary BPA due to changes in urinary BPA by their growth and related various exposure.

3 Summary - Objectives 영유아의 소변 중 BPA의 시기별 변화와 변동성 확인 - Sample collection

4 Urinary BPA by age - Results Adjusted with gender, weight, height
Corrected specific gravity

5 - Results Intra-class coefficients (ICCs) and variance estimates of log transformed repeated measurements of BPA Variables All Girls Boys N Variable estimate ICC Between- person σ2 Within- Unadjusted 320 0.075 1.611 0.044 150 0.124 1.423 0.080 170 0.054 1.781 0.029 SG adjusted 220 1.763 96 0.289 1.441 0.167 124 1.837 Cr adjusted 238 1.838 104 0.284 1.551 0.155 134 1.879

6 - Disccusion 소변 중 BPA가 출생 시에 가장 높으며 3개월에는 낮아졌다가 9개월 부터는 다시 높아짐
출생 시 에는 엄마로부터 제대혈을 통해 전달 받았기 때문 그리고 양수를 통해 섭취 출생 후 3개월에는 분유, 모유 섭취 그리고 젖병, 장난감 등을 사용 그러나 아기 용품에 BPA 금지 및 대체물질 사용 그러므로 노출 수준이 낮음 9, 12, 15개월은 이유식과 다른 요인에 의해 높아짐 (다른 요인에는 실내환경 또는 아기의 활동 등)

7 - Disccusion ICC 값이 0.044: within person variation이 더 기여함, 출생 시 데이터를 제외하더라도 ICC 값은 낮음 Between person variation이 0이므로 개인 간의 BPA의 수준의 차이를 구별할 수 없음 개인마다 Variation은 있으나 개인 간 차이는 크지 않음 이는 아이들의 사용 물품 또는 식이가 유사하기 때문 반복샘플의 수집 기간의 간격이 길다 (long term variability) 수집 기간의 간격이 클수록 ICC값이 낮아짐

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9 Highlights Characterizing within- and between-individual variability of BPA concentrations is important for characterizing exposure in biomonitoring studies This has been investigated previously in adults, but not in children Concentrations ranged from 0.53 to 74.5 ng/ml, with geometric mean and standard deviation of 2.70 ng/ml and 2.94 ng/ml, respectively The between-individual variability was approximately equal to the within-individual variability (ICC = 0.51), and this ICC is somewhat higher than previously reported literature values Single spot samples obtained from young children provide a reliable characterization of absolute and relative exposure over the short time window studied, but this may not hold true over longer timeframes.

10 - Results Number of repeated samples
Table 2. Results for Spearman's rank correlation coefficient (ρ) between generated mean and observed 4-sample mean (average of 1000 iterations); and fraction correctly ranked by tertile based on ‘true’ 4-sample mean; 95% CI = 95% confidence interval Number of repeated samples ρ to observed 4-sample mean (95% CI) Fraction of subjects ranked in correct tertile based on observed 4-sample mean (95% CI) 1 0.81 (0.64–0.91) 0.68 (0.52–0.84) 2 0.88 (0.77–0.94) 0.76 (0.60–0.92) 3 0.91 (0.83–0.96) 0.80 (0.68–0.92) 4 0.93 (0.86–0.97) 0.84 (0.68–0.92)

11 - Results Fig. 1. Within- and between person variation in urinary total BPA concentrations in 2–4 year old children. Horizontal bars denote 2-day arithmeticmean urinary concentration. Dashed line indicates estimated population 95th percentile for ages 2–4 years calculated based on data from a previous pooled study (see Heffernan et al., 2013); dot-dashed line indicates method limit of reporting.

12 - Disccusion The relatively high ICC in the current study compared to previous Studies The majority of the previously published ICC values have been based on sampling in adults Mouthing behaviours - may increase the potential for buccal absorption Different patterns of food consumption - smaller but more frequent meals, more homogeneous diets Therefore, lower within-individual, within-day variation in BPA exposure and excretion rates and might expect between-day variation to be lower in infants

13 - Disccusion Limitation
The majority of the previously published ICC values have been based on sampling in adults Exposure classification (by goal) Extimating intake levels – within person variation should be considered Categorization of small children – between person variation should be considered Short term exposure - single spot sample may be appropriate Long term exposure - repeated samplingmay be required

14 아이들의 쓰는 용품 및 식이가 크게 다르지 않기 때문에 개인간 변이가 낮음 그리고 개인내 변이는 큼 반감기가 빠르기 때문
차이점 Heffernan에서는 조금씩 자주 섭취하고 어른 보다 동일한 음식을 섭취하기 때문에 within individual, within-day variation이 낮음 아이들의 쓰는 용품 및 식이가 크게 다르지 않기 때문에 개인간 변이가 낮음 그리고 개인내 변이는 큼 반감기가 빠르기 때문

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16 Highlights BPA is relatively stable during long-term freezer storage.
The ability to measure BPA in urine samples after long-term storage could aid in studies of developmental effects in humans 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 BPA levels had an inter-quartile range from 1.1 to 3.1 ng/mg creatinine, slightly higher than levels in specimens from NHANES The Spearman correlation was approximately 0.5 for samples 2 weeks apart and 0.3 for samples 4 weeks apart. BPA is relatively stable during long-term freezer storage. So, developmental effects of BPA exposure could be investigated with measurements from stored urine

17 - Results

18 - Results

19 - Disccusion Our data show a correlation of over 0.5 for samples taken 2 weeks apart, which suggests that day-to-day exposures are similar in the short term. However, for samples taken 4 weeks apart, the correlation dropped to 0.3, suggesting that exposure becomes more variable across longer time intervals. The latter is the only one of these to report correlations between samples taken at various time intervals, and they also found decreased correlations as time between samples increased (maximum interval was 6 months) (Teitelbaum et al., 2008).

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25 Figure 1. Distribution of log-transformed (A) urinary BPA (ng/mL) and (B) creatinine-standardized BPA (μg BPA/g creatinine) concentrations in HOME Study children ages 1−8 years. p-values for child age trend < Increases in urinary creatinine with age resulted in the more pronounced decrease in creatinine-standardized BPA concentrations (see Supporting Information Figure S1)