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.

Internal exposure of Flemish teenagers to environmental pollutants: Results of the Flemish Environment and Health Study 2016-2020 (FLEHS IV)

The Flemish Environment and Health Study (FLEHS) collects information on internal exposure to a broad range of environmental chemicals in the general population in Flanders, the Northern region of Belgium. The aim is to establish biomonitoring exposure distributions for the general population in support of public health and environmental policy, environmental risk assessment and risk management decisions. In 2017-2018, urine and blood samples were collected from 428 teenagers by a stratified clustered two stage randomized design. Samples were analyzed for a broad range of biomarkers related to exposure to chlorinated and newer pesticides, brominated and organophosphate flame retardants (BFR/OPFR), polychlorinated biphenyls (PCBs), bisphenols, phthalates and alternative plasticizers, per-and polyfluoroalkyl substances (PFAS), polycyclic aromatic hydrocarbons (PAHs), benzene, metals and trace elements. The geometric mean levels and percentiles of the distribution were estimated for each biomarker, for the whole study population and following stratification for sex, the household educational attainment and the residence area's urbanicity. Geometric means of biomarkers of lead, dichlorodiphenyltrichloroethane (DDT), PCBs, PAHs, regulated phthalates and bisphenol A (BPA) were lower than in the previous FLEHS cycles. Most biomarker levels were below health-based guidance values (HB-GVs). However, HB-GVs of urinary arsenic, blood lead, blood cadmium, sum of serum perfluorooctane sulfonate (PFOS) and perfluoro-1-hexanesulfonate (PFHxS) and the urinary pyrethroid metabolite (3-PBA) were exceeded in respectively 25%, 12%, 39.5%, 10% and 22% of the teenagers. These results suggest that the levels of exposure in the Flemish population to some environmental chemicals might be of concern. At the same time, we noticed that biomarkers for BPA substitutes, metabolites of OPFRs, an expanded list of PFAS, glyphosate and its metabolite could be measured in substantial proportions of participants. Interpretation of these levels in a health-risk context remains uncertain as HB-GVs are lacking. Household educational attainment and residential urbanicity were significant exposure determinants for many biomarkers and could influence specific biomarker levels up to 70% as shown by multiple regression analysis. The research consortium also took care of the broader external communication of results with participants, policy makers, professional groups and civil society organizations. Our study demonstrated that teenagers are exposed to a wide range of chemicals, it demonstrates the success of public policies to reduce exposure but also points to concern and further priorities and needs for follow up.

Linking a European cohort of children born with congenital anomalies to vital statistics and mortality records: A EUROlinkCAT study

EUROCAT is a European network of population-based congenital anomaly (CA) registries. Twenty-one registries agreed to participate in the EUROlinkCAT study to determine if reliable information on the survival of children born with a major CA between 1995 and 2014 can be obtained through linkage to national vital statistics or mortality records. Live birth children with a CA could be linked using personal identifiers to either their national vital statistics (including birth records, death records, hospital records) or to mortality records only, depending on the data available within each region. In total, 18 of 21 registries with data on 192,862 children born with congenital anomalies participated in the study. One registry was unable to get ethical approval to participate and linkage was not possible for two registries due to local reasons. Eleven registries linked to vital statistics and seven registries linked to mortality records only; one of the latter only had identification numbers for 78% of cases, hence it was excluded from further analysis. For registries linking to vital statistics: six linked over 95% of their cases for all years and five were unable to link at least 85% of all live born CA children in the earlier years of the study. No estimate of linkage success could be calculated for registries linking to mortality records. Irrespective of linkage method, deaths that occurred during the first week of life were over three times less likely to be linked compared to deaths occurring after the first week of life. Linkage to vital statistics can provide accurate estimates of survival of children with CAs in some European countries. Bias arises when linkage is not successful, as early neonatal deaths were less likely to be linked. Linkage to mortality records only cannot be recommended, as linkage quality, and hence bias, cannot be assessed.

Pooled analysis of genotoxicity markers in relation to exposure in the Flemish Environment and Health Studies (FLEHS) between 1999 and 2018

BACKGROUND

The Flemish Environment and Health Studies (FLEHS) are human biomonitoring surveys running in Flanders since 1999. Additionally to biomarkers of exposure, markers of genotoxicity and oxidative stress have been measured, including the alkaline comet and micronucleus assay in peripheral whole blood cells, and urinary concentrations of 8-oxo-2'-deoxyguanosine (8-oxodG).

AIM

Exposure-effect associations were explored in a pooled dataset of nine different cross-sectional FLEHS surveys. Data of adolescents collected in a time frame of about 20 years (1999-2018) were compiled. The aim of the study was to examine whether increased variation in exposure, lifestyle and environmental factors would lead to more powerful and robust exposure-effect associations.

MATERIALS & METHODS

The biomarkers were measured in 2283 adolescents in the age range of 14-18 years. Exposure to polycyclic aromatic hydrocarbons [1-hydroxypyrene (1-OHP)], benzene (tt'-muconic acid), metals (arsenic, cadmium, copper, nickel, thallium, lead, chromium), persistent organochlorines and phthalates were assessed in blood or urine. Furthermore, outdoor air levels of particulate matter (PM₁₀ and PM_2.5) at the residences of the youngsters were calculated. Pooled statistical analysis was done using mixed models. Study-specific differences in the genotoxicity markers and in the strength/direction of the association were accounted for. This was done by incorporating the random factor 'study' and a random study slope (if possible). The exposure markers were centered around the study-specific mean in order to correct for protocol changes over time.

RESULTS

A significant association was observed for the urinary oxidative stress marker 8-oxodG, which was positively associated with 1-OHP (5% increase for doubling of 1-OHP levels, p = 0.001), and with urinary copper (26% increase for doubling of copper levels, p = 0.001), a metal involved in the Fenton reaction in biological systems. 8-oxodG was also associated with the sum of the metabolites of the phthalate di(2-ethylhexyl) phthalate (DEHP) (3% increase for doubling of the DEHP levels, p = 0.02). For those associations, data pooling increased the statistical power. However, some of the associations in the individual surveys, were not confirmed in the pooled analysis (such as comet assay and 8-oxodG vs. atmospheric PM; and 8-oxodG vs. urinary nickel). This may be due to inconsistencies in exposure-effect relations and/or variations in the pollutant mix over time and regions.

CONCLUSION

Pooled analysis including a large population of 2283 Flemish adolescents showed that 8-oxodG, a marker of oxidative DNA damage is a valuable marker to assess impact of daily life pollutants, such as PAHs, Cu and the phthalate DEHP.

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.

A pilot study on the feasibility of European harmonized human biomonitoring: Strategies towards a common approach, challenges and opportunities

In 2004 the European Commission and Member States initiated activities towards a harmonized approach for Human Biomonitoring surveys throughout Europe. The main objective was to sustain environmental health policy by building a coherent and sustainable framework and by increasing the comparability of data across countries. A pilot study to test common guidelines for setting up surveys was considered a key step in this process. Through a bottom-up approach that included all stakeholders, a joint study protocol was elaborated. From September 2011 till February 2012, 17 European countries collected data from 1844 mother-child pairs in the frame of DEMOnstration of a study to COordinate and Perform Human Biomonitoring on a European Scale (DEMOCOPHES).(1) Mercury in hair and urinary cadmium and cotinine were selected as biomarkers of exposure covered by sufficient analytical experience. Phthalate metabolites and Bisphenol A in urine were added to take into account increasing public and political awareness for emerging types of contaminants and to test less advanced markers/markers covered by less analytical experience. Extensive efforts towards chemo-analytical comparability were included. The pilot study showed that common approaches can be found in a context of considerable differences with respect to experience and expertize, socio-cultural background, economic situation and national priorities. It also evidenced that comparable Human Biomonitoring results can be obtained in such context. A European network was built, exchanging information, expertize and experiences, and providing training on all aspects of a survey. A key challenge was finding the right balance between a rigid structure allowing maximal comparability and a flexible approach increasing feasibility and capacity building. Next steps in European harmonization in Human Biomonitoring surveys include the establishment of a joint process for prioritization of substances to cover and biomarkers to develop, linking biomonitoring surveys with health examination surveys and with research, and coping with the diverse implementations of EU regulations and international guidelines with respect to ethics and privacy.

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.

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.

Harmonized European human biomonitoring in small countries: Challenges, opportunities and lessons learned in Cyprus and Luxembourg from the DEMOCOPHES study

Background: To advance human biomonitoring (HBM) for policy support in Europe, a harmonized approach was developed (COPHES project, FP7 2009- 2012) and evaluated in 17 countries (DEMOCOPHES project, Life+, 2010-2012). Cyprus (CY) and Luxembourg (LU) tested the hypothesis that the COPHES European Protocol is applicable to small countries.Materials and methods: In 2011-12, the European Protocol was adopted and tested by CY and LU for the harmonized biomonitoring of 60 children and their mothers for cadmium, phthalates and cotinine in urine and for mercury in scalp hair in two sampling areas (urban, rural). Results: Both small countries achieved the preset goals for recruitment, sample collection and analysis, which allowed for the first time the assessment of children’s and mothers’ exposures to the selected chemicals in comparison with other countries. Capacity building was accomplished and communication actions were particularly effective, with both countries taking advantage of their small size to access participants, policy makers, other stakeholders and the press. Time constrains and requirements for capacity building were limiting factors. Conclusion: The COPHES European Protocol for HBM surveys is attainable in small countries. The following elements are fundamental in the design of a harmonized European HBM program, from the perspective of small countries: (a) consultation with and active involvement of the implementing countries, (b) flexibility for national decisions, while not compromising harmonization, (c) elaboration of standardized methods, procedures and documents (d) quality assurance mechanisms, (e) means of training and support.

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.

Availability and comparability of human biomonitoring data across Europe: a case-study on blood-lead levels

Recently, it has become clear that the complexity of environmental health issues requires an approach that takes into account the complexities, interdependencies and uncertainties of the real world. An urgent issue that has surfaced is the need for accurate tools to better describe exposure characterization to environmental chemicals. By including human biomonitoring (HBM) data, a greater precision in exposure and associated risk estimates and more accurate dose-response relationships may be achieved. A restricting issue still is the availability of reliable and comparable HBM data. The aim of the current study was twofold: (1) to find out whether it is practically feasible to collect raw, individual HBM data across Europe; and (2) to evaluate the comparability and use of these HBM data for environmental health impact assessment at a European scale. Blood-lead (B-Pb) was selected as the chemical of choice because of its long history as an environmental pollutant in HBM programs and its known public health relevance. Through literature search and identification of HBM experts across Europe, HBM programs that measured B-Pb were identified and asked to share individual data on age, gender and B-Pb levels. Following this request, more than 20,000 individual data points from 8 European countries were collected. Analysing these data made clear that it is difficult to use disparate data collections because of the inherent variability with respect to the gender and age of participants and calendar-years sampled. When these confounders were taken however, there was no additional variability in B-Pb distributions among different countries. It was concluded that while it is possible to collect HBM data from different sources across Europe, the need to get data from comparable (sub-)populations is essential for appropriate use and interpretation of HBM data for environmental health impact assessment.

A battery of DNA effect biomarkers to evaluate environmental exposure of Flemish adolescents

The present paper deals with the evaluation of a battery of genotoxicity biomarkers in healthy Flemish adolescents and their relation with common pollutants occurring in their life environment. DNA damage as reflected by the comet assay appeared to be most sensitive to ozone (partial r(2) = 0.102, p < 0.00001), and to a lesser extent to ortho-cresol (partial r(2) = 0.055; p = 0.001) and 1-hydroxy-pyrene (1-OH-pyrene, partial r(2) = 0.031; p = 0.013). 8-hydroxy-deoxyguanosine (8-OHdG) was only related to ortho-cresol (r(2) = 0.069; p < 0.007). Interestingly, the comet assay results and urinary 8-OHdG concentrations were positively correlated with a Pearson r = 0.21 (p = 0.003, N = 200). Logistic regression models revealed significant relations between chromatid breaks and 1-OH-pyrene (relative risk (RR): 1.58; p = 0.008), and t,t-muconic acid (RR: 1.71; p = 0.014). There was no correlation between micronucleus formation or occurrence of chromosomal or chromatid breaks on the one hand and comet or 8-OHdG results on the other hand. Thus, in this study the comet assay on whole blood samples and urine 8-OHdG measurements especially appeared sensitive biomarkers for assessing the genetic effects of environmental pollutants to which adolescents may be exposed.

Endocrine disrupters and human puberty

In this overview of the literature, epidemiological research studying the effect of endocrine disrupters on the onset of puberty is summarized. In girls, earlier age at menarche was reported after exposure to polychlorinated biphenyls (PCBs), polybrominated biphenyls (PBBs), persistent pesticides [dichlorodiphenyltrichloroethane (DDT)] and phthalate esters. However, several other studies found no effect of these compounds on age at menarche or pubertal Tanner stages. One study reported a delaying effect of dioxin-like compounds on breast development. In boys, exposure to PCBs, PCDFs or the pesticide endosulfan was associated with delayed puberty or decreased penile length. Much of the results found in population studies are in accordance with experimental studies in animals. However, the mixture of different components with antagonistic effects (oestrogenic, anti-oestrogenic, anti-androgenic) and the limited knowledge about the most critical window for exposure (prenatal, peri-natal and pubertal) may hamper the interpretation of results.

Influence of the presence of doctors-in-training on the blood pressure of patients: a randomised controlled trial in 22 teaching practices

Until now, no information is available about the effect of the presence of a doctor-in-training on a patient's blood pressure. We tested the hypothesis that the presence of a last year medical student might increase the blood pressure of the patient, in addition to the possible pressor response to the doctor-trainer. Normotensive and hypertensive patients with a minimum age of 25 years, visiting for any reason, were recruited at 22 teaching general practices. Patients were randomised into a 'trainee' group (n=133) and a 'no trainee' (n=129) group. The blood pressure was measured at two subsequent contacts. In the 'trainee' group, a student was present at the first visit only. In the 'no trainee' group, both visits were without student. Both groups had similar anthropometric characteristics at entry. At the first visit, systolic pressure was higher in the 'trainee' group than in the control group (139.5 vs 133.1 mmHg, P=0.004), with a similar trend for diastolic pressure (80.2 vs 77.8 mmHg, P=0.07). From the first contact to the follow-up visit, blood pressure decreased in the trainee group by 4.8 mmHg systolic (P<0.001) and 1.7 mmHg diastolic (P=0.03), whereas the corresponding changes in the control group were -0.1 mmHg (P=0.90) and +1.5 mmHg (P=0.03). Thus, the between group differences in these trends averaging 4.7 mmHg (CI 1.5-7.9, P=0.005) systolic and 3.2 mmHg (CI 1.1-5.3, P=0.003) diastolic were statistically significant. We conclude that in teaching-practices, the presence of a doctor-in-training has a significant pressor effect when an experienced general practitioner measures a patient's blood pressure. If confirmed, our findings imply that doctors should be cautious to initiate or adjust antihypertensive treatment when blood pressure readings are obtained in the presence of a student.

Determinants of white-coat hypertension

BACKGROUND

The prevalence of white-coat hypertension (WCH) is considerable in patients referred with elevated office blood pressure. Failure to recognise this phenomenon can lead to the inappropriate use of antihypertensive medications. We undertook this study to determine the profile of patients with WCH.

METHODS

Baseline clinic and daytime ambulatory blood pressures were available from 5716 patients referred over a 22-year period. Individuals were considered to have WCH if they had an elevated clinic blood pressure measurement greater than 140/90 mmHg and normal daytime mean ambulatory blood pressure. Mean age was 53.6 years and 53.2% were female.

RESULTS

The overall prevalence of white-coat hypertension was 15.4%. A higher prevalence was seen amongst older adults, females, and non-smokers.

CONCLUSION

Multivariate logistic regression analysis confirmed these characteristics as independent predictors of WCH.

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.

The relationship between blood pressure and blood lead in NHANES III. National Health and Nutritional Examination Survey

There is no general agreement as to whether low-level lead exposure increases blood pressure. The present study examined the correlation between blood pressure and blood lead in the NHANES III database (1988-1994). Analyses were performed for all adults (> or =20 years), and reported separately for white males (n = 4685), white females (n= 5138), black males (n = 1761) and black females (n = 2197). Significant covariates of blood pressure were selected by stepwise regression. The change in blood pressure that would be associated with a doubling of blood lead was calculated from the adjusted regression coefficients. Mean systolic/diastolic blood pressure was 123/76 mm Hg in white males, 119/70 mm Hg in white females, 126/77 mm Hg in black males and 121/72 mm Hg in black females. Median blood lead was 174 nmol/L (3.6 microg/dL), 101 nmol/L (2.1 microg/dL), 203 nmol/L (4.2 microg/dL) and 111 nmol/L (2.3 microg/dL), respectively. For a doubling of blood lead, the changes in systolic blood pressure were 0.3 (95% confidence interval: -0.2 to 0.7, P= 0.29), 0.1 (-0.4 to 0.5, P = 0.80), 0.9 (0.04 to 1.8, P = 0.04) and 1.2 (0.4 to 2.0, P = 0.004) mm Hg, respectively and the changes in diastolic blood pressure were -0.6 (-0.9 to -0.3, P = 0.0003), -0.2 (-0.5 to -0.1, P = 0.13), 0.3 (-0.3 to 1.0, P = 0.28) and 0.5 (0.01 to 1.1, P = 0.047) mm Hg, respectively. In conclusion, there is no consistent relationship between blood pressure and blood lead in the NHANES III dataset.

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.

Renal function, cytogenetic measurements, and sexual development in adolescents in relation to environmental pollutants: a feasibility study of biomarkers

BACKGROUND

Human exposure to chemicals is normally monitored by measurement of environmental pollutants in external media. We investigated whether biomarkers in adolescents can show exposure to, and health effects of, common environmental pollutants.

METHODS

We recruited 200 17-year-old adolescents (120 girls) from a rural control area and from two suburbs polluted by a lead smelter and two waste incinerators. We measured biomarkers of exposure and of effect in blood and urine samples, and obtained questionnaire data. School doctors measured testicular volume and staged sexual maturation.

FINDINGS

Internal exposure was mostly within current standards. Concentrations of lead and cadmium in blood, PCBs (polychlorinated biphenyls) and dioxin-like compounds in serum samples, and metabolites of VOCs (volatile organic compounds) in urine were higher in one or both suburbs than in the control area. Children who lived near the waste incinerators matured sexually at an older age than others, and testicular volume was smaller in boys from the suburbs than in controls. Biomarkers of glomerular or tubular renal dysfunction in individuals were positively correlated with blood lead. Biomarkers of DNA damage were positively correlated with urinary metabolites of PAHs (polycyclic aromatic hydrocarbons) and VOCs. Interpretation Biomarkers can be used to detect environmental exposure to pollutants and measure their biological effects before overt disease develops. Our findings suggest that current environmental standards are insufficient to avoid measurable biological effects.

Efficacy of different drug classes used to initiate antihypertensive treatment in black subjects: results of a randomized trial in Johannesburg, South Africa

BACKGROUND

Thiazides are recommended to initiate antihypertensive drug treatment in black subjects.

OBJECTIVE

To test the efficacy of this recommendation in a South African black cohort.

METHODS

Men and women (N = 409), aged 18 to 70 years, with a mean ambulatory daytime diastolic blood pressure between 90 and 114 mm Hg, were randomized to 13 months of open-label treatment starting with the nifedipine gastrointestinal therapeutic system (30 mg/d, n = 233), sustained-release verapamil hydrochloride (240 mg/d, n = 58), hydrochlorothiazide (12.5 mg/d, n = 58), or enalapril maleate (10 mg/d, n = 60). If the target of reducing daytime diastolic blood pressure below 90 mm Hg was not attained, the first-line drugs were titrated up and after 2 months other medications were added to the regimen.

RESULTS

While receiving monotherapy (2 months, n = 366), the patients' systolic and diastolic decreases in daytime blood pressure averaged 22/14 mm Hg for nifedipine, 17/11 mm Hg for verapamil, 12/8 mm Hg for hydrochlorothiazide, and 5/3 mm Hg for enalapril. At 2 months the blood pressure of more patients treated with nifedipine was controlled: 133 (63.3%, P</=.03) vs 20 (39.9%) receiving verapamil, 21 (40.4%) receiving hydrochlorothiazide, and 11 (20.8%) receiving enalapril. At 13 months (n = 257), more patients (P<.001) continued receiving monotherapy with nifedipine (94/154 [61.0%]) or verapamil (22/35 [62.9%]) than hydrochlorothiazide (10/39 [25.6%]) or enalapril (1/29 [3.4%]). A sustained decrease of left ventricular mass (P<.001) with no between-group differences was achieved at 4 and 13 months.

CONCLUSIONS

In contrast to current recommendations, calcium channel blockers are more effective than thiazides as initial treatment in black subjects with hypertension. If treatment is started with thiazides or converting-enzyme inhibitors, combination therapy is more likely to be required to control blood pressure and reduce left ventricular mass.

Anti-Saccharomyces cerevisiae antibodies (ASCA), phenotypes of IBD, and intestinal permeability: a study in IBD families

BACKGROUND

Serologic markers anti-Saccharomyces cerevisiae antibodies (ASCA) and antineutrophil cytoplasmic antibodies with perinuclear staining (pANCA) have been proposed to study the immunopathogenesis of IBD. Their measurement may allow better phenotyping of the disease and the detection of subclinical disease.

AIMS

To test the hypothesis that serological markers identify an immunologic trait related to disease susceptibility. We also wanted to test the hypothesis that ASCA is a marker related to abnormal tissue permeation by common antigens.

METHODS

We studied the prevalence of pANCA and ASCA in a large cohort of sporadic and familial inflammatory bowel diseases and their unaffected relatives and spouses. Kinetics of ASCA was studied and the relationship between ASCA and 51Cr-EDTA intestinal permeation was investigated.

RESULTS

ASCA was associated with sporadic Crohn's disease (CD) (63%), with Crohn's patients belonging to pure CD families (62%) and also with their unaffected family members (21%). pANCA was associated with UC (58%). The prevalence of ASCA in CD patients belonging to mixed families was strikingly low (33%). ASCA was a stable marker throughout the disease and was not related to an increased small intestinal permeability.

CONCLUSION

ASCA is strongly associated with familial CD in Belgium, and 21% of healthy family members also display the marker. The association is much weaker in patients belonging to mixed families. ASCA is a stable marker and is not a secondary phenomenon due to increased intestinal permeability.

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.

Risks of untreated and treated isolated systolic hypertension in the elderly: meta-analysis of outcome trials

BACKGROUND

Previous meta-analysis of outcome trials in hypertension have not specifically focused on isolated systolic hypertension or they have explained treatment benefit mainly in function of the achieved diastolic blood pressure reduction. We therefore undertook a quantitative overview of the trials to further evaluate the risks associated with systolic blood pressure in treated and untreated older patients with isolated systolic hypertension

METHODS

Patients were 60 years old or more. Systolic blood pressure was 160 mm Hg or greater and diastolic blood pressure was less than 95 mm Hg. We used non-parametric methods and Cox regression to model the risks associated with blood pressure and to correct for regression dilution bias. We calculated pooled effects of treatment from stratified 2 x 2 contingency tables after application of Zelen's test of heterogeneity.

FINDINGS

In eight trials 15 693 patients with isolated systolic hypertension were followed up for 3.8 years (median). After correction for regression dilution bias, sex, age, and diastolic blood pressure, the relative hazard rates associated with a 10 mm Hg higher initial systolic blood pressure were 1.26 (p=0.0001) for total mortality, 1.22 (p=0.02) for stroke, but only 1.07 (p=0.37) for coronary events. Independent of systolic blood pressure, diastolic blood pressure was inversely correlated with total mortality, highlighting the role of pulse pressure as risk factor. Active treatment reduced total mortality by 13% (95% CI 2-22, p=0.02), cardiovascular mortality by 18%, all cardiovascular complications by 26%, stroke by 30%, and coronary events by 23%. The number of patients to treat for 5 years to prevent one major cardiovascular event was lower in men (18 vs 38), at or above age 70 (19 vs 39), and in patients with previous cardiovascular complications (16 vs 37).

INTERPRETATION

Drug treatment is justified in older patients with isolated systolic hypertension whose systolic blood pressure is 160 mm Hg or higher. Absolute benefit is larger in men, in patients aged 70 or more and in those with previous cardiovascular complications or wider pulse pressure. Treatment prevented stroke more effectively than coronary events. However, the absence of a relation between coronary events and systolic blood pressure in untreated patients suggests that the coronary protection may have been underestimated.

Effect of glutamine on the intestinal permeability changes induced by indomethacin in humans

BACKGROUND

Long-term non-steroidal anti-inflammatory drug (NSAID) intake may induce increased intestinal permeability, eventually resulting in enteropathy. Because increased permeability might be related to cell damage resulting from energy depletion, it was hypothesized that glutamine--the major energy source of the intestinal mucosal cell--might prevent permeability changes.

METHODS

The 6-h urinary excretion of 51Cr-EDTA after an oral load of 51Cr-EDTA was used in this study as a measure for intestinal permeability. Healthy volunteers underwent a series of permeability tests: (i) basal test; (ii) test following NSAID (indomethacin); (iii) test following NSAID in combination with glutamine and/or misoprostol.

RESULTS

The NSAID induced increased permeability in all volunteers. Pre-treatment with glutamine (3x7 g daily, 1 week before NSAID-dosing) did not prevent the NSAID-induced increase in permeability. Multiple doses of glutamine close in time to NSAID-dosing resulted in significantly lower permeability compared to the NSAID without glutamine. Co-administration of misoprostol with the multiple-dose scheme of glutamine resulted in a further reduction in the NSAID-induced increase in permeability.

CONCLUSIONS

Glutamine decreases the permeability changes caused by NSAID-dosing when it is administered close in time, and misoprostol has a synergistic effect.

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.

In vivo butyrate metabolism and colonic permeability in extensive ulcerative colitis

BACKGROUND & AIMS

Impaired short-chain fatty acid metabolism by the colonocyte has been suggested as a pathogenic factor in ulcerative colitis (UC). The aim of this study was to measure in vivo butyrate metabolism in UC and to correlate butyrate oxidation with colonic permeability.

METHODS

Butyrate oxidation was measured by means of a 14CO2-breath test after rectal instillation of 14C-butyrate. 51Cr-ethylenediaminetetraacetic acid (EDTA) was added to the enema, and the urinary % dose excretion of 51Cr-EDTA after 6 hours was a measure for permeability.

RESULTS

Patients with active extensive UC showed a significantly lower butyrate oxidation and increased colonic permeability in comparison to healthy controls. Butyrate oxidation correlated significantly negative with clinical activity. Oxidation of butyrate was not decreased in most patients with inactive extensive UC. In 3 patients with inactive disease and decreased oxidation, a relapse occurred within a few weeks after the test, whereas all patients with normal oxidation maintained their remission for at least 3 months. A significantly negative correlation existed between butyrate oxidation and colonic permeability.

CONCLUSIONS

Patients with active extensive UC have a decreased colonic butyrate oxidation. However, the fact that remission is associated with normal oxidation suggests that UC mucosa is not intrinsically altered in butyrate oxidation, making this unlikely to be a primary defect in UC.

The Inter-regional Belgian Bank Employee Nutrition Study (IBBENS)

OBJECTIVE

This study compares the dietary intake in different geographical areas in Belgium.

DESIGN

Food habits were examined by the 3-day food record with additional intervieW.

SETTING

The study was performed in the head offices of one bank situated in seven Dutch-speaking cities (spread over two districts) in the north and one French-speaking city in the south of Belgium.

SUBJECTS

371 male and 192 female healthy employees participated in the survey.

RESULTS

The results show a difference in fat consumption between north and south. Men in the French-speaking district consumed on average 18.8 E% (SD = 3.2) of saturated fat, compared to 16.2 (2.8) and 16.7 (2.9) E% for the two Dutch-speaking districts (P < 0.001). For women the respective data are 18.9 (3.2), 16.4 (3.0) and 17.1 (3.1) E% (P < 0.01). The E% of polyunsaturated fat in the three districts equals respectively 5.2 (1.8), 7.2 (2.4) and 6.7 (2.5) (P < 0.001) for men; 4.9 (1.8), 7.2 (2.7) and 6.6 (2.2) (P < 0.001) for women. A significantly lower P/S ratio (P < 0.001, for both sexes) and U/S ratio (P < 0.001, for both sexes) was found in the south. The intake of cholesterol (mg per 4.18 MJ) was significantly higher in the south (P = 0.01, for both sexes). The differences between the Dutch-speaking centres were relatively small. For men significant differences in P/S ratio, 0.48 (0.22) in the east versus 0.43 (0.20) in the west (P < 0.001), and in E% of monounsaturated fat, 15.2 (2.7) versus 16.3 (3.1) (P < 0.01), could be established.

CONCLUSION

Differences in fat intake exist between the north and the south of Belgium. Within the north significant differences exist in P/S ratio and in intake of monounsaturated fat.