Discovering time-trends of the German populations exposure to contaminants by analysis of human samples of the German Environmental Specimen Bank (ESB)

The German Environmental Specimen Bank (ESB) is a monitoring instrument of the German Federal Ministry for the Environment, Nature Conservationand Nuclear Safety. The permanent biobank facility is run since 1981 containing environmental and human samples from Germany. All samples are collected according to standard operating procedures (SOP). An annually standardized collection of human samples at four different regional sites of the country has been established since 1997. Routine sampling is done once a year, recruiting healthy non occupationally exposed students aged 20-29 years, in an equal gender distribution. The number of participants recruited is approximately 120 students per site and year. Directly after the annual sampling process, the human samples are analyzed for selected environmental chemicals. The time-trends of lead in blood, mercury and pentachlorophenol in 24 h-urine and polychlorinated biphenyls in plasma demonstrated a decrease of exposure during the last two decades by about 40 – 90 percent. In parallel retrospective studies using cryo-archived samples revealed increasing time trends of emerging chemicals used as substitutes for regulated toxicants. The data demonstrates the great relevance of the ESB for the health related environmental monitoring and shows the importance of human biomonitoring as a tool in information based policy making

Assessing background contamination of sample tubes used in human biomonitoring by non-targeted liquid chromatography–high resolution mass spectrometry

Controlling and minimising background contamination is crucial for maintaining a high quality of samples in human biomonitoring targeting organic chemicals. We assessed the contamination of three previous types and one newly introduced medical-grade type of sample tubes used for storing human body fluids at the German Environmental Specimen Bank. Aqueous extracts from these tubes were analysed by non-targeted liquid chromatography-high resolution mass spectrometry (LC-HRMS) before and after a dedicated cleaning procedure. After peak detection using MZmine, Bayesian hypothesis testing was used to group peaks into those originating either from instrumental and laboratory background contamination, or actual tube contaminants, based on if their peak height was reduced, increased or not affected by the cleaning procedure. For all four tube types 80–90% of the 2475 peaks (1549 in positive and 926 in negative mode) were assigned to laboratory/instrumental background, which we have to consider as potential sample tube contaminants. Among the tube contaminants, results suggest a considerable difference in the contaminant peak inventory and the absolute level of contamination among the different sample tube types. The cleaning procedure did not affect the largest fraction of peaks (50–70%). For the medical grade tubes, the removal of contaminants by the cleaning procedure was strongest compared to the previous tubes, but in all cases a small fraction increased in intensity after cleaning, probably due to a release of oligomers or additives. The identified laboratory background contaminants were mainly semi-volatile polymer additives such as phthalates and phosphate esters. A few compounds could be assigned solely as tube-specific contaminants, such as N,N-dibutylformamide and several constituents of the oligomeric light stabiliser Tinuvin-622. A cleaning procedure before use is an effective way to standardise the used sample tubes and minimises the background contamination, and therefore increases sample quality and therewith analytical results

Trends in characteristics of 24-h urine samples and their relevance for human biomonitoring studies: 20 years of experience in the German Environmental Specimen Bank

To document trends in human exposure to environmental pollutants, the German Environmental Specimen Bank (ESB) has been routinely collecting and archiving 24-h urine samples from young adults at four sampling sites in Germany on an annual basis. For the purpose of normalizing measured analyte concentrations, urinary creatinine (UC), specific gravity (SG), conductivity (CON), and total urine volume (UVtot) of 24-h urine samples have also been recorded. These parameters are however susceptible to variation over time, as well as within/among participants and normalization against them can thus affect the interpretation of data regarding exposure to environmental pollutants. To evaluate the influence of normalization against these parameters, we first sought to determine variations of these parameters with regard to differences between sexes and trends over time. We analysed data from 8619 urine samples collected from 1997 to 2016. We observed an inverse relation between UVtot and UC, SG, and CON. We also found differences between sexes for UC, SG and CON, but not UVtot. UC, SG, and CON showed significant decreasing trends over time in both sexes. In contrast, a significant increase of over 30% in UVtot, independent of participant age and BMI, was revealed. This increase in UVtot and the concomitant sample dilution is likely to have an impact on measured analyte concentrations in 24-h urine samples. Hence, normalization of urinary concentrations is warranted when interpreting time trends of human exposure. Next, urinary calcium (Ca2+) concentrations of ESB participants were used to demonstrate the effects of normalization against each of the four urine parameters. From 1997 to 2016, measured Ca2+ concentrations showed a statistically significant but scientifically implausible decrease. Normalization of Ca2+ concentrations against UVtot (by calculating the total daily excretion), UC, or CON, but not SG, eliminated this decrease. Consistent with previous work, Ca2+ concentrations in urine and total daily Ca2+ excretion were higher for males than females. Normalization against UC, SG, or CON, however, attenuated this difference. Thus, to avoid misinterpretation in trend analysis and sex-specific excretion in 24-h urine samples, the calculation of the total daily excretion is recommended

Distances of mission locations from headquarter (Sulzbach/Saar) and repository (Muenster).

<p>Distances of mission locations from headquarter (Sulzbach/Saar) and repository (Muenster).</p

Mobile epiLab at first mission.

<p>A: The expandable unit. B: View to the examination room. C: BSL-2 area in the mobile epiLab with urine processing area (background) and blood processing area (foreground).</p

Schematic workflow for the processing of urine (yellow), blood (red) and plasma (pink) samples in the mobile epiLab.

<p>Three volunteers per 20 min are assumed for the optimum throughput shown here. The starting delay for the blood processing is caused by the on-site blood draw.</p

Overview of provided instruments.

<p>Overview of provided instruments.</p

Overview of required members of staff and their tasks.

<p>Overview of required members of staff and their tasks.</p

Sample types per Volunteer.

<p>Sample types per Volunteer.</p

General layout and concept of the mobile epidemiologic laboratory (epiLab).

<p>Three motoric driven expansion units provide a reception and counseling area (14.5 m²) and an examination room (21.1 m²). The laboratory block (15.5 m²) has three rooms (personnel lock, BSL-2 lab and sample repository) with individual pressure levels for secure operation.</p