Dietary exposure to acrylamide in a group of Japanese adults based on 24-hour duplicate diet samples.

Acrylamide is a probable human carcinogen and known human neurotoxin that can be generated in food through heating. Using a mathematical modelling approach, our previous study estimated long-term average dietary exposure to acrylamide in the Japanese people; however, the validity of these estimates remained unknown. Here, we aimed to obtain a more accurate estimate of acrylamide exposure that would reflect the usual practice of heat processing and consumption of foods in the population. We collected duplicate diet samples and dietary records during 24 h from a group of Japanese adults. A total of 110 duplicate diet samples were analysed for acrylamide by LC-MS/MS. Data from individual dietary records were used to examine the association between dietary acrylamide exposure and consumption of selected food groups (e.g., coffee, tea, confectioneries, and vegetables prepared at high temperature [deep-frying, stir-frying, sautéing, and baking]). Of the 110 homogenised diet samples, 108 contained detectable levels of acrylamide. Dietary exposure to acrylamide ranged from 8 to 1582 ng/kg body weight (bw)/day, with the mean value of 215 ng/kg-bw/day and median value of 143 ng/kg-bw/day. This mean value was higher than the value we previously estimated for Japanese adults using a mathematical approach. Multiple linear regression analysis showed log dietary acrylamide exposure was significantly associated with consumption of coffee and vegetables prepared at high temperature during 24-hr of sampling (adj. R2 = 0.250, p < 0.001). We revealed significant difference in dietary acrylamide exposure between participants who had coffee and vegetables prepared at high temperature (median, 169 ng/kg-bw/day; range, 35-1224 ng/kg-bw/day, n = 42) and those who had none of them (median, 75 ng/kg-bw/day; range, 8-311 ng/kg-bw/day, n = 15) (Steel-Dwass test, p < 0.05).

Inter- and intra-individual variation in urinary concentrations of parabens in male and female Japanese subjects.

We evaluated the representativeness of concentrations of parabens in a spot urine sample for the assessment of long-term exposure levels. Urine sample was taken monthly from 10 male Japanese subjects (35.9 ± 6.8 years) and 12 female Japanese university students (21.1 ± 0.4 years) for 5 months and measured for methyl (MP), ethyl (EP), propyl (PP) and butyl (BP) parabens by liquid chromatography-tandem mass spectrometry. Median (min-max) specific-gravity-adjusted urinary concentrations of the male group (n = 10) were 39.7 (2.99-268), 1.69 (< 0.045-75.2), 0.569 (< 0.11-123) and 0.0264 (< 0.020-24.4) ng mL-1 for MP, EP, PP and BP, respectively. Those of the female group (n = 12) were 283 (5.49-1687), 9.30 (0.290-487), 22.9 (< 0.11-307) and 3.76 (< 0.020-135) ng mL-1, respectively, which were significantly higher than those of the male group. Intra-class correlation coefficients (ICCs) were calculated for the four parabens to find 0.56, 0.58, 0.39 and 0.28 for MP, EP, PP and BP, respectively, in the male group, and 0.40, 0.43, 0.41 and 0.37 for MP, EP, PP and BP, respectively, in the female group. The results suggested that four paraben concentrations in a spot urine sample moderately reflected long-term paraben exposure of Japanese subjects. Source of exposure to parabens is also discussed.

Paraben exposure and semen quality of Japanese male partners of subfertile couples.

OBJECTIVES: Possible relationship between semen quality (semen volume, sperm concentration and sperm motility) and parabens exposure was investigated in male partners of couples who visited a gynecology clinic in Tokyo for infertility consultation (n = 42, 36.8 ± 5.4 years). METHODS: Semen parameters were measured according to WHO guideline at the clinic, and urinary methyl- (MP), ethyl- (EP), propyl- (PP) and butyl (BP) paraben concentrations were measured with liquid chromatography-tandem mass spectrometry. RESULTS: Geometric mean urinary concentrations (geometric standard deviation) of the subjects were 48.2 (4.52), 1.88 (4.72), 1.13 (6.75) and 0.184 (11.1) ng/mL for MP, EP, PP and BP, respectively. No significant association was found between semen parameters and urinary paraben concentrations in multiple regression analyses and logistic regression analyses. CONCLUSIONS: Two reasons of the absence of adverse effects on semen quality might be suggested: lower paraben exposure level of the subjects and small sample size. Further investigation of effect of paraben exposure among general male population at environmental levels is warranted.

Association between paraben exposure and menstrual cycle in female university students in Japan.

Parabens have been known to have estrogenic activity in many in vivo and in vitro studies and biomonitoring data indicated ubiquitous exposure in general populations. However, there are few human studies on reproductive effects of parabens. In this study, menstrual cycle length and its intra-individual variation were investigated by bleeding record over the period of 5 months and urinary concentrations of parabens were measured for 128 female Japanese university students. We found significantly negative relationships between menstrual cycle length and urinary estrogen-equivalent total paraben (odds=0.73, 95% CI 0.56-0.96) and butyl paraben concentrations (odds=0.83, 0.70-0.99), which indicated shortened cycle length in women with high urinary paraben concentrations. This study indicated that paraben exposure at not excessive levels is associated with menstrual cycle length or its variability among general female subjects. These results suggest a possibility that parabens exposure is one of the environmental causes of human reproductive problem.