PFAS levels and exposure determinants in sensitive population groups.

BACKGROUND: Per- and polyfluoroalkyl substances (PFAS) are persistent organic pollutants. The first exposure to PFAS occurs in utero, after birth it continues via breast milk, food intake, environment, and consumer products that contain these chemicals. Our aim was to identify determinants of PFAS concentrations in sensitive population subgroups- pregnant women and newborns. METHODS: Nine European birth cohorts provided exposure data on PFAS in pregnant women (INMA-Gipuzkoa, Sabadell, Valencia, ELFE and MoBa; total N = 5897) or newborns (3xG study, FLEHS 2, FLEHS 3 and PRENATAL; total N = 940). PFOS, PFOA, PFHxS and PFNA concentrations were measured in maternal or cord blood, depending on the cohort (FLEHS 2 measured only PFOS and PFOA). PFAS concentrations were analysed according to maternal characteristics (age, BMI, parity, previous breastfeeding, smoking, and food consumption during pregnancy) and parental educational level. The association between potential determinants and PFAS concentrations was evaluated using multiple linear regression models. RESULTS: We observed significant variations in PFAS concentrations among cohorts. Higher PFAS concentrations were associated with higher maternal age, primipara birth, and educational level, both for maternal blood and cord blood. Higher PFAS concentrations in maternal blood were associated with higher consumption of fish and seafood, meat, offal and eggs. In cord blood, higher PFHxS concentrations were associated with daily meat consumption and higher PFNA with offal consumption. Daily milk and dairy consumption were associated with lower concentrations of PFAS in both, pregnant women and newborns. CONCLUSION: High detection rates of the four most abundant PFAS demonstrate ubiquitous exposure of sensitive populations, which is of concern. This study identified several determinants of PFAS exposure in pregnant women and newborns, including dietary factors, and these findings can be used for proposing measures to reduce PFAS exposure, particularly from dietary sources.

Gender differences in cadmium and cotinine levels in prepubertal children.

Susceptibility to environmental stressors has been described for fetal and early childhood development. However, the possible susceptibility of the prepubertal period, characterized by the orchestration of the organism towards sexual maturation and adulthood has been poorly investigated and exposure data are scarce. In the current study levels of cadmium (Cd), cotinine and creatinine in urine were analyzed in a subsample 216 children from 12 European countries within the DEMOCOPHES project. The children were divided into six age-sex groups: boys (6-8 years, 9-10 years and 11 years old), and girls (6-7 years, 8-9 years, 10-11 years). The number of subjects per group was between 23 and 53. The cut off values were set at 0.1 µg/L for Cd, and 0.8 µg/L for cotinine defined according to the highest limit of quantification. The levels of Cd and cotinine were adjusted for creatinine level. In the total subsample group, the median level of Cd was 0.180 µg/L (range 0.10-0.69 µg/L), and for cotinine the median wet weight value was 1.50 µg/L (range 0.80-39.91 µg/L). There was no significant difference in creatinine and cotinine levels between genders and age groups. There was a significant correlation between levels of cadmium and creatinine in all children of both genders. This shows that even at such low levels the possible effect of cadmium on kidney function was present and measurable. An increase in Cd levels was evident with age. Cadmium levels were significantly different between 6-7 year old girls, 11 year old boys and 10-11 year old girls. As there was a balanced distribution in the number of subjects from countries included in the study, bias due to data clustering was not probable. The impact of low Cd levels on kidney function and gender differences in Cd levels needs further investigation.

Interpreting biomarker data from the COPHES/DEMOCOPHES twin projects: Using external exposure data to understand biomarker differences among countries.

In 2011 and 2012, the COPHES/DEMOCOPHES twin projects performed the first ever harmonized human biomonitoring survey in 17 European countries. In more than 1800 mother-child pairs, individual lifestyle data were collected and cadmium, cotinine and certain phthalate metabolites were measured in urine. Total mercury was determined in hair samples. While the main goal of the COPHES/DEMOCOPHES twin projects was to develop and test harmonized protocols and procedures, the goal of the current paper is to investigate whether the observed differences in biomarker values among the countries implementing DEMOCOPHES can be interpreted using information from external databases on environmental quality and lifestyle. In general, 13 countries having implemented DEMOCOPHES provided high-quality data from external sources that were relevant for interpretation purposes. However, some data were not available for reporting or were not in line with predefined specifications. Therefore, only part of the external information could be included in the statistical analyses. Nonetheless, there was a highly significant correlation between national levels of fish consumption and mercury in hair, the strength of antismoking legislation was significantly related to urinary cotinine levels, and we were able to show indications that also urinary cadmium levels were associated with environmental quality and food quality. These results again show the potential of biomonitoring data to provide added value for (the evaluation of) evidence-informed policy making.

Endocrine actions of pesticides measured in the Flemish environment and health studies (FLEHS I and II).

Within the Flemish Environment and Health studies (FLEHS I, 2002-2006, and FLEHS II, 2007-2012), pesticide exposure, hormone levels and degree of sexual maturation were measured in 14-15-year-old adolescents residing in Flanders (Belgium). In FLEHS II, geometric mean concentrations (with 95 % confidence interval (CI)) of 307 (277-341) and 36.5 ng L(-1) (34.0-39.2) were found for p,p'-dichlorophenyldichloroethylene (p,p'-DDE) and hexachlorobenzene (HCB). These values were respectively 26 and 60 % lower than levels in FLEHS I, 5 years earlier. Metabolites of organophosphorus pesticides (OPPs) and of para-dichlorobenzene were measured for the first time in FLEHS II, yielding concentrations of 11.4, 3.27 and 1.57 µg L(-1) for the sum of dimethyl- and diethyl phosphate metabolites and 2,5-dichlorophenol (2,5-DCP), respectively. Data on internal exposure of HCB showed a positive correlation with sexual maturation, testosterone and the aromatase index for boys and with free thyroxine (fT4) and thyroid stimulating hormone (TSH) (both boys and girls). For both p,p'-DDE and HCB, a negative association with sexual development in girls was found. The OPP metabolites were negatively associated with sex hormone levels in the blood of boys and with sexual maturation (both boys and girls). The pesticide metabolite 2,5-DCP was negatively correlated with free T4, while a positive association with TSH was reported (boys and girls). These results show that even exposure to relatively low concentrations of pesticides can have significant influences on hormone levels and the degree of sexual maturation in 14-15-year-old adolescents.

Quantification of PCDD/Fs and dioxin-like PCBs in small amounts of human serum using the sensitive H1L7.5c1 mouse hepatoma cell line: optimization and analysis of human serum samples from adolescents of the Flemish human biomonitoring program FLEHS II.

Since the CALUX (Chemically Activated LUciferase gene eXpression) bioassay is a fast and inexpensive tool for the throughput analysis of dioxin-like compounds in a large number of samples and requires only small sample volumes, the use of this technique in human biomonitoring programs provides a good alternative to GC-HRMS. In this study, a method for the separate analysis of PCDD/Fs and dioxin-like PCBs (dl-PCBs) in human serum with the new sensitive H1L7.5c1 mouse hepatoma cell line was optimized. Sample dilution factors of 5 and 2.4 were selected for routine analysis of respectively the PCDD/Fs and dl-PCBs. The validation studies showed that repeatability and within-lab reproducibility for the quality control (QC) standard were within the in-house criteria. A long-term within-lab reproducibility of 25% for the PCDD/F fraction and 41% for the dl-PCB fraction for the analysis of pooled serum samples, expressed as pg BEQ/g fat, was determined. CALUX recoveries of the spiked procedural blanks were within the acceptable in-house limits of 80-120% for both fractions and the LOQ was 30.3 pg BEQ/g fat for the PCDD/Fs and 14.5 pg BEQ/g fat for the dl-PCBs. The GC-HRMS recovery of a C13-spiked pooled serum sample was between 60 and 90% for all PCDD/F congeners and between 67 and 82% for the non-ortho PCBs. An adequate separation between both fractions was found. The CALUX/GC-HRMS ratio for a pooled serum sample was respectively 2.0 and 1.4 for the PCDD/Fs and the dl-PCBs, indicating the presence of additional AhR active compounds. As expected, a correlation was found between human serum samples analyzed with both the new H1L7.5c1 cell line and the more established H1L6.1c3 cell line. The geometric mean CALUX-BEQ values, reported for the adolescents of the second Flemish Environment and Health Study (FLEHS II) recruited in 2009-2010, were 108 (95% CI: 101-114) pg CALUX-BEQ/g fat for the PCDD/Fs and 32.1 (30.1-34.2) pg CALUX-BEQ/g fat for the dioxin-like PCBs.

Hormone levels and sexual development in Flemish adolescents residing in areas differing in pollution pressure.

In 2002, the Centre for Environment and Health in Flanders, Belgium started a human biomonitoring program. For 1679 adolescents, residing in nine study areas with differing pollution pressure, hormone levels and the degree of sexual maturation were measured. Possible confounding effects of lifestyle and personal characteristics were taken into account. Participants from the nine different study areas had significantly different levels of sex hormones (total and free testosterone, oestradiol, aromatase, luteinizing hormone) and the thyroid hormone free triiodothyronine, after correction for confounders. Significantly higher hormone concentrations were measured in samples from participants residing in the area around the waste incinerators, while significantly lower values were found in participants residing in the Albert Canal zone with chemical industry. Sexual maturation of boys as well as girls tended to be somewhat slower in the industrial city of Antwerp and in the Antwerp harbour compared to the other areas in Flanders. Even within the same study area, significant differences in hormone levels could be observed between sub-areas. Data on the internal exposure of the same adolescents to lead, cadmium, PCBs, p,p'-DDE, HCB, 1-hydroxypyrene and t,t'-muconic acid have already been published. The observed differences in hormone levels and in sexual maturation could however only in part be explained by the measured differences in internal exposure to pollutants, suggesting that also other pollutants and other factors that vary in function of the area of residence could play a role. Nevertheless, our results also suggest that local (environmental) factors, acting within a short distance, might influence the measured hormone levels and degree of sexual maturation.

Internal exposure to pollutants measured in blood and urine of Flemish adolescents in function of area of residence.

The Centre for Environment and Health in Flanders, the Northern part of Belgium, started a biomonitoring program on adolescents in 2003. 1679 adolescents residing in nine areas with different patterns of pollution participated in the study. Possible confounding effects of lifestyle and personal characteristics were taken into account. The geometric mean levels of cadmium and lead in whole blood amounted to 0.36 and 21.7 microg l(-1), those of PCBs, DDE and HCB in serum to 68, 94 and 20.9 ng g(-1) fat, and those of 1-hydroxypyrene and t,t'-muconic acid in urine to 88 ng g(-1) creatinine and 72 microg g(-1) creatinine. Significant regional differences in internal lead, cadmium, PCBs, DDE and HCB exposure were observed in function of area of residence, even after adjustment for age, sex, smoking (and body mass index for the chlorinated compounds). Compared to a reference mean, internal exposure was significantly higher in one or more of the areas: Cd and Pb in the Antwerp agglomeration, Cd in the Antwerp harbour, PCBs in the Ghent agglomeration, PCBs, DDE and HCB in the Ghent harbour, Cd, PCBs, DDE and HCB in the rural area, DDE in Olen and in the Albert canal areas. Adolescents living in an area with intensive fruit cultivation (showing overall the lowest values) and, surprisingly, in areas around household waste incinerators (average of six areas), had no significantly increased internal exposures. Subjects from separate areas around waste incinerators showed significant differences in body load of various environmental contaminants.

In vivo influence of nicotine on human basal and NSAID-induced gut barrier function.

BACKGROUND: Smoking reduces the non-steroidal anti-inflammatory drug (NSAID)-induced small intestinal permeability increase in healthy people. It also affects inflammatory bowel disease that is associated with a disturbed gut barrier function. To assess the role of nicotine on barrier function, its influence on basal and NSAID-induced intestinal permeability was studied in healthy volunteers. METHODS: Thirty-one healthy non-smoker subjects performed permeability tests with 51Cr-EDTA and sugar markers (sucrose, lactulose, mannitol, sucralose) before and during 2 weeks of nicotine patch application, and with and without indomethacin intake, respectively. Since smoking has been described as affecting motility, transit measurements were also done with the sodium[13C]-octanoate and lactose-[13C]-ureide breath tests before and during nicotine exposure. Correlations between permeability markers were checked and the influence of gastrointestinal transit was assessed. RESULTS: Nicotine did not affect barrier function in vivo, nor gastric emptying, small-bowel transit time or orocaecal transit. 51Cr-EDTA and lactulose correlated in basal 0-6 h permeability testing (r = 0.529, P < 0.0001), as did 6-24 h excretion of 51Cr-EDTA and sucralose (r = 0.474, P < 0.001); 97% and 90% of the subjects had a permeability increase after indomethacin intake for 0-6 h and 6-24 h excretion of Cr-EDTA, respectively. This population proportion is 63% for lactulose/mannitol and 83% for sucralose. CONCLUSIONS: Short-term exposure to nicotine does not alter normal basal or NSAID-induced gut barrier function or transit. 51Cr-EDTA and the respective sugar markers correlate well in in vivo permeability testing in healthy humans. The radioactive test detects more NSAID-induced permeability increase than does the lactulose/mannitol ratio permeability test.

Menopause and the characteristics of the large arteries in a population study.

In previous cross-sectional and longitudinal population studies, we found that the slope of systolic pressure on age was steeper in postmenopausal than in premenopausal women. We hypothesised that this observation could be due to a specific effect of menopause on the elasticity of the large arteries. We investigated 315 randomly selected women, aged 30 to 70 years. Based on 5.2 years of follow-up, 166 women were premenopausal and 149 menopausal (44 reaching menopause and 105 postmenopausal). These women were matched on age and body mass index with 315 men. We used a wall-tracking ultrasound system to measure the diameter, compliance and distensibility of the brachial and the common carotid and femoral arteries as well as carotid-femoral pulse wave velocity. Pulse pressure was determined from 24-h blood pressure recordings. Both in menopausal women (r = 0.37; P < 0.001) and in matching male controls (r = 0.16; P = 0.04), pulse pressure widened with increasing age. The slope of the 24-h pulse pressure on age was steeper in menopausal women than in their premenopausal counterparts (0.428 vs -0.066 mm Hg per year; P = 0.003) and than in the male controls (0.428 vs 0.188 mm Hg per year; P = 0.06). After adjustment for age, 24-h mean pressure, body mass index, antihypertensive drug treatment, smoking and the use of oral contraceptives or hormonal replacement therapy, postmenopausal women showed a higher carotid-femoral pulse wave velocity (7.77 vs 6.71 m/s; P = 0.02) and had a slightly greater diameter of the common carotid artery (7.09 vs 6.79 mm; P = 0.07) than their premenopausal counterparts. After similar adjustments, menopausal class was not significantly associated with other vascular measurements in women or with any vascular measurement in control men. In conclusion, menopause per se may increase aortic stiffness. We hypothesise that this phenomenon may contribute to the rise in systolic pressure and pulse pressure in women beyond age 50 and, in turn, may lead to a slight dilatation of the common carotid artery.

The effects of smoking and indomethacin on small intestinal permeability.

BACKGROUND: Smoking modulates inflammatory bowel disease, protecting from ulcerative colitis on the one hand and worsening the course of Crohn's disease on the other. This influence might occur through changes in intestinal permeability, because permeability is increased in most patients with Crohn's disease. AIM: To study the influence of smoking on small intestinal permeability and its increase induced by indomethacin. METHODS: 50 smokers and 50 nonsmokers underwent a 51Cr-EDTA basal permeability test and the same test after challenge with indomethacin 125 mg p.o. RESULTS: Small intestinal permeability was the same in smokers (median 1.22%; IQR 1.00-1.58) and nonsmokers (1.24%; 0.94-1.66). Basal small intestinal permeability was lower in females (1.09%; 0.87-1.33) than in males (1.48%; 1.18-1.88). Indomethacin challenge increased permeability by 110% (71-141) in smokers, vs. 156% (78-220) in the nonsmokers (P=0.04). CONCLUSION: Smoking reduces the effect of NSAID on small intestinal permeability. It is therefore unlikely that the adverse effect of smoking on Crohn's disease is related to its influence on intestinal permeability.

Effect of long-term oral glutamine supplements on small intestinal permeability in patients with Crohn's disease.

BACKGROUND: Glutamine is a major fuel and an important nitrogen source for the small intestinal cell. It plays a key role in maintaining mucosal cell integrity and gut barrier function. Increased permeability may be a factor in the pathogenesis of Crohn's disease and may be an interesting parameter in the follow-up of the disease. Therefore, the aim of this study was to examine whether oral glutamine supplements are able to restore an increased intestinal permeability in patients with Crohn's disease. METHODS: The inclusion criteria for the study were Crohn's disease and a disturbed small intestinal permeability for 51Cr-EDTA. Of 38 patients screened, 18 had an increased permeability (6 hours urinary excretion >1.1% of label recovered in urine). Fourteen patients were included in the study and were randomized to receive either oral glutamine (7 g three times per day; n = 7) or placebo (7 g glycine three times per day; n = 7) in addition to their normal treatment during a 4-week period. The study was performed in a double-blind manner. RESULTS: Baseline permeability (mean +/- SD) was 2.32%+/-0.77% dose in the glutamine group and 2.29%+/-0.67% dose in the placebo group. Permeability did not change significantly after glutamine (3.26%+/-2.15% dose) or after placebo (2.27%+/-1.32% dose). There was no significant effect on plasma glutamine, plasma glutamate, plasma ammonium, Crohn's disease activity index, C-reactive protein, or nutritional status. CONCLUSIONS: Oral glutamine supplements, in the dose administered, do not seem to restore impaired permeability in patients with Crohn's disease.