In Europe, the aim is in future to investigate the exposure of people to pollutants in an harmonized manner. The COPHES project developed the guidelines for doing so. From September 2011, the sister project, DEMOCOPHES, carried out human biomonitoring according to these specifications in a pilot study in 17 European countries.
The study tracked the exposure of children and their mothers to certain chemicals which can enter into the human organism through various exposure paths (for example: food or air).
An interview with the mothers, relating, among other things, to the living environment, diet and eyposure-related behaviours, helps to explain the exposure measured by means of the chemical analysis of hair and urine samples from children and their mothers.
DEMOCOPHES is a pilot study: in other words, it is a preliminary study whose essential purpose was to test certain procedures. For this reason, only 120 mother-child pairs were included in this study (children aged 6-11 years and their mothers).
DEMOCOPHES was carried out only in selected regions of the 17 participating countries. In Germany these were Bochum and the Hochsauerland district.
DEMOCOPHES was co-financed by the Life+ financial instrument of the European Commission.
Design of the study
For DEMOCOPHES it was decided that the following groups of people were to be included in the study:
- Children from 6-11 years old (born in the years 2000-2005) and their
- Mothers aged up to 45 years (born in 1966 or later). A mother is deemed to be a person who lives with the child in the same household (biological mother, stepmother, or foster mother).
A requirement for participation was that mother and child had been living in the selected study region for at least 5 years. The child was required to spend most of its time (i.e. more than 16 days in the month) at the address.
Only one child of the family was chosen at random.
If a lack of knowledge of German would significantly hinder the survey, the family could not take part.
The study participants were chosen randomly from the registers of residents in the two selected study sites of Bochum and the Hochsauerland district. Prospective participants were not permitted to apply independently.
Participation in the study included an interview with the mothers and samples of morning urine and head hair from both mother and child.
The sampling and the interviews were carried out in the homes of the participating families. If this was not possible, the visit was conducted in a study centre.
The precise timetable for the study in Germany is described on the information page for participating families.
In each of the 17 countries where the DEMOCOPHES study was carried out there was a management unit responsible for the organisation within the country in question. In Germany this was specialist department II.1.2 for toxicology and health-related environmental monitoring of the Federal Environment Agency (UBA) under the direction of Dr. Marike Kolossa-Gehring. The UBA has many years of experience with the implementation of environment-related population studies (environmental surveys) and is also part of the international COPHES working group, which is responsible for the creation of the implementation guidelines for DEMOCOPHES.
The fieldwork and analysis modules were put out for public tender by the UBA. The field work was conducted by the Ruhr-University Bochum (RUB) (Department of Hygiene, Social and Environmental Medicine). This included the selection and acquisition of participants and the actual implementation of the study at the two selected study sites.
The analysis of chemical substances (determination of cadmium and cotinine, phthalate metabolites and creatinine in the urine; mercury in the hair) was carried out at three different laboratories:
- Department of Hygiene, Social and Environmental Medicine at the Ruhr-University, Bochum.
- Institute for Prevention and Occupational Medicine of the German Social Accident Insurance at the Ruhr-University (IPA), Bochum
- Institute and Outpatient Clinic of Occupational, Social and Environmental Medicine, University of Erlangen-Nuernberg, Erlangen
Data evaluation and the publication of results were carried out by the Federal Environment Agency.
In addition to this national organisational structure, DEMOCOPHES also required a European organisation, which was responsible in particular for the coordinated implementation of all the national DEMOCOPHES projects. The scientists of the COPHES working group formed part of the European organisation. They monitored compliance with the common operating procedures within the DEMOCOPHES project. Any changes which the countries involved wished to make to these common guidelines had to be approved by the COPHES team. It was also responsible for evaluating the data obtained at the European level, reviewing the experiences of all national DEMOCOPHES projects and deriving recommendations from them for future pan-European human biomonitoring studies.
European project partners
DEMOCOPHES was carried out in a total of 17 European countries. Each country had adapted the general implementation guidelines drawn up in the COPHES project to the specific local situation. Adaptations were necessary, for example, if national laws rendered a particular procedure obligatory (for example, provisions regarding approval by a National Ethics Commission) or if particular requirements could not be met (for example, it was not permitted/possible in each country to obtain addresses of study participants from the local registers of residents. In this case the participants were recruited through schools).
In addition to Germany, DEMOCOPHES was carried out in the following countries:
- United Kingdom (incl. Northern Ireland)
- Czech Republic
Privacy and ethics
Like all scientific studies in Germany, DEMOCOPHES was subject to provisions relating to privacy and ethics. Prior to execution the study was approved by the competent Ethics Commission of the Ruhr University Bochum. The data protection officer of the Ruhr-Universität Bochum also had to verify conformity with the data protection provisions.
The Federal Environment Agency and the Ruhr-Universität Bochum assured the participating families that the materials and personal data placed at their disposal would be handled carefully and sensitively. This included, among other things, an undertaking that personal data (names, addresses, telephone numbers) would be kept separate from the study data collected. The collected data are stored and evaluated in pseudonymised form.
Prior to the study the participants and their children had to make a written declaration of their consent to participation. Participation was on a purely voluntary basis. Non-participation or withdrawal from the study were possible at any time without any detriment to the participant or their child.
Information for participating families
The families had the opportunity to find out in advance about the exact course of the study.
Selection of participating families
The children from 6-11 (birth years 2000-2005) envisaged for the study were selected at random from a district of the city of Bochum and a location in the Hochsauerland district. To this end the addresses of children aged 6-11 were extracted from the corresponding registers of residents by using random numbers. Participation by other interested families was not possible.
The families of the randomly selected children were given detailed information about the study and asked to participate. As the study was actually carried out in Germany not by the Federal Environment Agency but by the Ruhr-Universität Bochum (Department of Hygiene, Social and Environmental Medicine), the study centre at the University of Bochum was the sole point of contact.
The ideas was for the families to send back the enclosed reply card to the study centre expressing either interest or lack of interest in taking part in the study.
Those interested in participating received a call from the study centre to check whether mother and child met the conditions for inclusion in the study. The following items were asked:
- Age of mother and child,
- Sex of the child (to achieve an approximately uniform distribution),
- Length of time for which mother and child had been living in the region in question,
- Whether the child lived there for most of the time,
- Whether mother or child were suffering from particular diseases diagnosed by a doctor which might affect the composition of their urine.
As soon as it became clear that mother and child were eligible for enrolment in the study and also wished to take part, an appointment was arranged for a home visit during which the interview was carried out and the samples (hair and urine of mother and child) were taken.
Before the interview and sampling could take place, both mother and child had to grant their consent in writing. To do this they received a pre-printed form which the mothers were required to sign and return to the study centre.
What happens with the hair and urine samples?
The interviewer took receipt of the refrigerated urine samples. In the study centre the samples were separated, frozen and sent to various laboratories for analysis for cadmium, cotinine, creatinine and phthalate metabolites. Residual amounts of urine were retained for later studies in facilities of the Federal Environment Agency.
The hair samples were sent in a paper envelope to the laboratory that was responsible for performing the mercury analysis.
On request, every mother was given her results and those of her child, along with the corresponding assessments of and declarations concerning the values detected. If the values found were unusually high, the mother was informed. Recommendations for reducing exposure were given and a consultation appointment offered.
The pollutant content of the samples taken from all mothers and children was anonymised and then statistically evaluated. The samples help German and European scientists gain further knowledge in relation to the exposure to pollution of mothers and children (see also data analysis and interpretation).
Each participating mother was informed – if she wished so – how high the pollutant concentrations were in the samples analysed, for herself personally and her child. In addition, she was informed whether the measured values exceeded health-related assessment values and which measures are recommended to reduce exposure.
It should be noted that, for substances which have a short half-life in the human body, all that can be offered is a snapshot and that elevated levels can also be brought about by short-term temporary exposure to pollutants.
- There are assessment values, known as HBM values, for cadmium and the phthalate metabolite DEHP which make it possible to assess the values found in the samples analysed.
- If cotinine is found in the urine it can be assumed that the subject has been in contact with tobacco smoke (actively or passively).
- Creatinine is not a pollutant and is measured only as a reference substance; this measurement makes it possible to make a statement on the degree of dilution of the urine.
- There is still no uniform assessment value for the assessment of mercury content in hair; a new international discussion is currently underway. The collection of exposure data from the population is all the more important.
By taking part in DEMOCOPHES, each study participant and her child contributes to the acquisition of important information about the exposure of German women and children to the chemicals under investigation. Moreover, the scientists can gain new insights from the answers given in the interview into the way in which contamination with chemicals arises, i.e. which behaviours and environmental conditions contribute to which forms of exposure.
These data are helpful as a means of helping politicians make decisions concerning the handling, use or prohibition of certain harmful substances.
Information on the pollutants studied in the DEMOCOPHES project can be found in our pollutant information.
For an animated explanation of human biomonitoring, see “Wissenschaftliche Animation zum Human-Biomonitoring der Kinderumwelt gemeinnützige GmbH” (in German).
Data analysis and interpretation
In addition to the task of testing common operating procedures for a European human biomonitoring study, a further function of the pilot study was to define provisional reference values for the chemicals analysed (cadmium, cotinine, phthalate metabolites in urine, mercury in hair) for women and children in the individual countries, with a possible view to doing so jointly for all the countries involved.
To allow this to be done, all participating laboratories in different countries were obliged to take part in interlaboratory tests and to comply with high quality standards.
The data thus collected served in the first instance to provide general statistical key figures (median, geometric mean and 95th percentile) at national level for the individual substances in the different age groups, including the proportion of individuals with unusually high values. Furthermore, the pollution burdens of mother and child were correlated; data from the interview were used to identify sources of exposure and the data were matched with any existing pollution data.
Thereafter, statistical key figures for the participating European countries were jointly identified in a coordinated manner at European level, taking into account all input data. Because only a very small sample of individuals was examined in each country, great care needed to be taken with the interpretation of the key figures. The data are not representative for the country or Europe.
In Germany there are currently no available data on mercury and phthalate metabolites in mother-child pairs, which is why DEMOCOPHES is unable to provide new insights into pollution pathways. The study of cotinine in children and their mothers is offering new insights into the exposure of children to “second-hand” smoke. Also crucial is the comparison of the average exposure identified in Germany with that of other European states - taking into account the previously mentioned uncertainties of data interpretation.
Recording characteristics in respect of which participants may differ from non-participants is important for the interpretation of research results. For this reason, potential participants who had chosen not to take part were asked why they had declined to participate.