A scientific study by the Hessian State Office for Soil Research (today: Hessian State Office for Nature Conservation, Environment and Geology HNLUG) has found natural, so-called geogenic deposits of arsenic and thallium in the soil of the "Bergkirchenviertel" in Wiesbaden.

This is due to thermal springs that have since dried up, which caused the accumulation of these substances in the soil for around 10,000 years. The natural distribution area of the two chemical parameters is essentially limited to the core area of Wiesbaden's Bergkirchen district. The concentrations of arsenic and thallium can vary greatly within a small area. Only chemical soil tests can provide concrete information on a case-by-case basis.

As the ingestion of these substances can lead to health risks in the event of direct contact with the soil and may result in increased disposal costs during construction work, attention is drawn to the arsenic problem in construction projects in Wiesbaden's Bergkirchen district.