Trends of the internal phthalate exposure of young adults in Germany--follow-up of a retrospective human biomonitoring study.

The exposure of the general population to phthalates is of increasing public health concern. Variations in the internal exposure of the population are likely, because the amounts, distribution and application characters of the phthalate use change over time. Estimating the chronological sequences of the phthalate exposure, we performed a retrospective human biomonitoring study by investigating the metabolites of the five most prominent phthalates in urine. Therefore, 24h-urine samples from the German Environmental Specimen Bank (ESB) collected from 240 subjects (predominantly students, age range 19-29 years, 120 females, 120 males) in the years 2002, 2004, 2006 and 2008 (60 individuals each), were analysed for the concentrations of mono-n-butyl phthalate (MnBP) as metabolite of di-n-butyl phthalate (DnBP), mono-iso-butyl phthalate (MiBP) as metabolite of di-iso-butyl phthalate (DiBP), mono-benzyl phthalate (MBzP) as metabolite of butylbenzyl phthalate (BBzP), mono-(2-ethylhexyl) phthalate (MEHP), mono-(2-ethyl-5-hydroxyhexyl) phthalate (5OH-MEHP), mono-(2-ethyl-5-oxohexyl) phthalate (5oxo-MEHP), mono-(2-ethyl-5-carboxypentyl) phthalate (5cx-MEPP) and mono-(2-carboxymethyl hexyl) phthalate (2cx-MMHxP) as metabolites of di(2-ethylhexyl) phthalate (DEHP), monohydroxylated (OH-MiNP), monooxidated (oxo-MiNP) and monocarboxylated (cx-MiNP) mono-iso-nonylphthalates as metabolites of di-iso-nonyl phthalates (DiNP). Based on the urinary metabolite excretion, together with results of a previous study, which covered the years 1988-2003, we investigated the chronological sequences of the phthalate exposure over two decades. In more than 98% of the urine samples metabolites of all five phthalates were detectable indicating a ubiquitous exposure of people living in Germany to all five phthalates throughout the period investigated. The medians in samples from the different years investigated are 65.4 (2002), 38.5 (2004), 29.3 (2006) and 19.6 µg/l (2008) for MnBP, 31.4 (2002), 25.4 (2004), 31.8 (2006) and 25.5 µg/l (2008) for MiBP, 7.8 (2002), 6.3 (2004), 3.6 (2006) and 3.8 µg/l (2008) for MBzP, 7.0 (2002), 5.6 (2004), 4.1 (2006) and 3.3 µg/l (2008) for MEHP, 19.6 (2002), 16.2 (2004), 13.2 (2006) and 9.6 µg/l (2008) for 5OH-MEHP, 13.9 (2002), 11.8 (2004), 8.3 (2006) and 6.4 µg/l (2008) for 5oxo-MEHP, 18.7 (2002), 16.5 (2004), 13.8 (2006) and 10.2 µg/l (2008) for 5cx-MEPP, 7.2 (2002), 6.5 (2004), 5.1 (2006) and 4.6 µg/l (2008) for 2cx-MMHxP, 3.3 (2002), 2.8 (2004), 3.5 (2006) and 3.6 µg/l (2008) for OH-MiNP, 2.1 (2002), 2.1 (2004), 2.2 (2006) and 2.3 µg/l (2008) for oxo-MiNP and 4.1 (2002), 3.2 (2004), 4.1 (2006) and 3.6 µg/l (2008) for cx-MiNP. The investigation of the time series 1988-2008 indicates a decrease of the internal exposure to DnBP by the factor of 7-8 and to DEHP and BzBP by the factor of 2-3. In contrast, an increase of the internal exposure by the factor of 4 was observed for DiNP over the study period. The exposure to DiBP was found to be stable. In summary, we found decreases of the internal human exposure for legally restricted phthalates whereas the exposure to their substitutes increased. Future investigations should verify these trends. This is of increasing importance since the European Commission decided to require ban or authorization from 1.1.2015 for DEHP, DnBP, DiBP and BzBP according to REACh Annex XIV.

The potential of spatial information in human biomonitoring by example of two German environmental epidemiology studies.

This study aimed at statistically investigating the association between the internal exposure of children and young adults to uranium (U) and epidemiologically relevant external determinants of exposure. The investigation was performed with data from two studies within the framework of the German health-related environmental monitoring program: The German Environmental Survey for Children (GerES IV) conducted by the Federal Environment Agency (Umweltbundesamt) with data on 1,780 children 3-14 years of age and their home environment and the German Environmental Specimen Bank (ESB, section: human specimens) with data on 2,253 students 20-29 years of age. Both studies provided data on the U levels in human urine for all probands. GerES IV furthermore provided an extensive environmental and demographic database on, e.g., U levels in drinking water. The data from GerES IV and ESB were linked by GIS to spatially relevant exposure information, including background values of U in stream sediments and in upper and lower soils, U levels in mosses and particulate matter in the lower atmosphere, precipitation and elevation as well as forest density. Bivariate correlation analysis and two decision tree models showed moderate but significant associations between U in human urine and U levels in drinking water, stream sediments and upper and lower soils. Future investigations considering additional epidemiologically relevant data sets may differentiate the results. Furthermore, the sample design of future environmental epidemiology studies should take the spatial evaluation of the data into greater account.

Fetal exposure to phthalates--a pilot study.

The fetus is considered to be the most sensitive stage of life to the potential developmental and reproductive toxicity of the phthalates. But, data on human fetal exposure to phthalates is still scarce. In this pilot study we collected 11 pairs of amniotic fluid (AF) and corresponding maternal urine (MU) samples during Caesarean section and analysed them for several phthalate metabolites by LC-MS/MS. In all AF samples, metabolites of di-n-butyl phthalate (DnBP), diisobutyl phthalate (DiBP), butylbenzyl phthalate (BBzP), di(2-ethylhexyl) phthalate (DEHP) were detectable. For the first time, we were able to detect also oxidative phthalate metabolites in AF, with two carboxy metabolites of DEHP showing the highest abundance. In the MU samples, the concentrations of the phthalate metabolites were generally much higher than in the AF samples. There was a statistically significant linear correlation for the DiBP monoester (MiBP) (r=0.93; p<0.001) in the AF and MU samples. We also found a significant correlation for the DEHP monoester (MEHP) (r=0.91; p<0.001), although there was a most likely external contamination with MEHP in the MU samples. Our results suggest that several phthalates or their metabolites, respectively, reach the human fetus, which might be able to affect fetal health. Further research is needed to elucidate fetal metabolism of phthalates and to evaluate the in utero phthalate exposure and the potential effects on fetal reproductive development. Due to the continuous turn over of AF, urinary levels may be most appropriate for assessing both maternal and fetal phthalate exposure.

Preliminary observations on perfluorinated compounds in plasma samples (1977-2004) of young German adults from an area with perfluorooctanoate-contaminated drinking water.

In May 2006, a serious environmental contamination with perfluorinated compounds (PFCs) became evident in a rural area of North Rhine-Westphalia (NRW) (Region Sauerland), Germany. In autumn 2006, we performed a human biomonitoring study in which a 4-8-fold increase in perfluorooctanoate (PFOA)-plasma concentrations of children, their mothers and men living in Arnsberg (District Hochsauerlandkreis, NRW) was observed compared with a reference population. The exposure was clearly related to the consumption of PFOA-contaminated tap water. However, there is no clear information on the duration of this contamination. The current investigation involves the analysis of PFCs in 30 blood samples of young adults (age 20-31 years) who had ever lived in the affected area. The samples were taken between 1977 and 2004 and stored at the German Environmental Specimen Bank for Human Tissues. Analyses of PFOA, perfluoroctanesulfonate (PFOS), perfluorohexanoate (PFHxA), perfluorohexanesulfonate (PFHxS), perfluoropentanoate (PFPA) and perfluorobutanesulfonate (PFBS) in blood plasma were performed by solid-phase extraction, HPLC and MS/MS detection. PFOA values (median, range) were 6.1, 1.7-40.7 microg/l, PFOS values were 18.8, 8.1-150.7 microg/l and PFHxS values were 1.7, 0.5-4.6 microg/l. The concentrations of PFHxA, PFPA and PFBS in plasma were all below limit of detection. Time-trend analysis showed that between 1977 and 2004 PFOA and PFOS levels remained fairly stable. PFOS and PFOA levels were in the range of current background levels of the general population. In contrast, PFHxS plasma levels have steadily increased since 1977. There was a close association between PFOS and PFOA-plasma levels. From this pilot study there are no indications for an increased exposure to PFCs of residents in Arnsberg in the years 1977-2004 prior to the contamination in 2006.

Rapid evaluation of human biomonitoring data using pattern recognition systems.

Assessing human biomonitoring data often necessitates dealing with fragmentary prior knowledge and a complex set of variables. A procedure for explorative data analysis via decision-tree analysis was undertaken to obtain high-level descriptive summary information on human exposure on a timely basis. This study is based on a subset of monitoring data of the Environmental Specimen Bank for Human Tissues within the German Environmental Specimen Bank (n sigma: 2401: 42/58% males/females; 34/66% born in East/West Germany). Three well-known xenobiotic organochlorines (XOCs) [sum of polychlorinated biphenyls (PCBs) 138 + 153 + 180, pentachlorophenol (PCP), and hexachlorobenzene (HCB)] were used as target variables. Meta-data regarding the samples and individuals were collected via a self-reported questionnaire and used as potential predictor variables. Prior to decision-tree analysis, XOC levels were adjusted (trend, lipids, creatinine, total protein) via stepwise linear regression. Adjusted XOC levels were subsequently utilized to identify relevant predictors of human XOC exposure using Exhaustive CHAID as a common decision-tree algorithm. Although overall tree model quality is generally poor, consistent and plausible predictors for human exposure were identified. Besides time trend and clinical parameters, the predominant predictors for HCB and PCB exposure were birthplace, gender, age, body mass index (BMI), and consumption of milk/dairy products or animal fats. For PCP, predominant predictors were sampling site, gender, and consumption of animal fats. Summing results of decision-tree models and regression models, explained variances for metric scaled XOC are: PCB (34.2%) > HCB (30.3%) > PCP (17.2%). Explorative analysis of human biomonitoring data based on simple decision-tree analysis provides valuable information for planning further investigations and statistical data for analyses to support prediction, consequences, and regulation of XOC.

Internal phthalate exposure over the last two decades--a retrospective human biomonitoring study.

In a retrospective human biomonitoring study we analyzed 24h urine samples taken from the German Environmental Specimen Bank for Human Tissues (ESBHum), which were collected from 634 subjects (predominantly students, age range 20-29 years, 326 females, 308 males) in 9 years between 1988 and 2003 (each n >or= 60), for the concentrations of primary and/or secondary metabolites of di-n-butyl phthalate (DnBP), di-iso-butyl phthalate (DiBP), butylbenzyl phthalate (BBzP), di(2-ethylhexyl) phthalate (DEHP) and di-iso-nonyl phthalate (DiNP). Based on the urinary metabolite excretion we estimated daily intakes of the parent phthalates and investigated the chronological course of the phthalate exposure. In over 98% of the urine samples metabolites of all five phthalates were detectable indicating a ubiquitous exposure of the German population to all five phthalates throughout the last 20 years. The median daily intakes in the subsets between 1988 and 1993 were quite constant for DnBP (approx. 7 microg/kg bw/d) and DEHP (approx. 4 microg/kg bw/d). However, from 1996 the median levels of both phthalates decreased continuously until 2003 (DnBP 1.9 microg/kg bw/d; DEHP 2.4 microg/kg bw/d). By contrast, the daily intake values for DiBP were slightly increasing over the whole time frame investigated (median 1988: 1.1 microg/kg bw/d; median 2003: 1.4 microg/kg bw/d), approximating the levels for DnBP and DEHP. For BBzP we observed slightly decreasing values, even though the medians as of 1998 levelled off at around 0.2 microg/kg bw/d. Regarding daily DiNP exposure we found continuously increasing values, with the lowest median being 0.20 microg/kg bw/d for the subset of 1988 and the highest median for 2003 being twice as high. The trends observed in phthalate exposure may be associated with a change in production and usage pattern. Female subjects exhibited significantly higher daily intakes for the dibutyl phthalates (DnBP p=0.013; DiBP p=0.004). Compared to data from US National Health and Nutrition Examination Surveys (NHANES) exposure levels of the dibutyl phthalates were generally higher in our German study population, while levels of BBzP were somewhat lower. Overall, for a considerable 14% of the subjects we observed daily DnBP intakes above the tolerable daily intake (TDI) value deduced by the European Food Safety Authority (EFSA) (10 microg/kg bw/d). However, the frequency of exceedance decreased during the years and was beneath 2% in the 2003 subset. Even though transgressions of the exposure limit values of the EFSA and the US Environmental Protection Agency (US EPA) occurred only in a relatively small share of the subjects, one has to take into account the cumulative exposure to all phthalates investigated and possible dose-additive endocrine effects of these phthalates.

The Environmental Specimen Bank for Human Tissues as part of the German Environmental Specimen Bank.

The German Environmental Specimen Bank for Human Tissues (ESBHum) as part of the German Environmental Specimen Bank (ESB) focuses on documenting and assessing trends of human exposure via real-time monitoring of body burden and long-term storage of samples under stable deep freezing conditions (-150 degrees C) for later retrospective analyses. Real-time monitoring is performed after completing sampling processes of one year and covers actually 20 inorganic and 5 organic substances. While concentrations of several substances, e.g., arsenic, cadmium and mercury, are remained unchanged over time, other substances, e.g., lead and pentachlorophenol (PCP), show a clearly perceptible decrease. Substances which are not routinely analyzed in real-time monitoring are retrospectively measured by indication in the stored human specimens. Indications of retrospective monitoring are availability of valid analytical methods, e.g., in case of PCDF and PCDD, or assessment of concentration trends of substances with actual interest of toxicology and/or environmental medicine, e.g., polybrominated diphenyl ethers (PBDE), perfluorooctane sulfonate (PFOS) and perfluorooctanoic acid (PFOA). While over time the body burden of dioxins as well as PFOS and PFOA decreased, the PBDE concentrations in human blood increase. The observed decrease of blood lead and PCP levels over time is a consequence of legal prohibition and restriction. The time-dependent concentrations of the aforementioned substances agree with results of other national studies. So it can be concluded that the German ESBHum is an important instrument for health-related environmental observation and protection in Germany.