Environmental risk of (heavy) metal release from urns into cemetery soils

Cremation of the deceased has become the most common funeral type in many countries in the world, including Germany. The ashes of the cremated human body (cremains) are transferred in an urn and most commonly buried in the soil. However, the possible environmental impacts of cremains on soils and groundwater have been rarely studied. In this context, it is still unclear whether or not the release of (heavy) metals like chromium, zinc, copper, nickel and lead from cremains and urns poses an environmental problem in urn grave soils. The aims of the study were to analyze the (heavy) metal content of two cremains from a 74-year-old male and 70-year-old female, and of soils in 6 cemeteries with urn graves in North and West Germany. Soil samples were taken from below the burial depth of 42 urns (upon expiry of the resting time) and from reference soils without urn burials (same cemetery site and depth). The two cremains differed significantly in their heavy metal content (zinc, nickel, copper, chromium), which originated from metal components of the deceased's clothing or burial objects or may have resulted from contrasting occupational exposure during the deceased's lives. Investigations at the cemetery sites revealed a high variability in (heavy) metal contents in the soil samples from below the buried urns. As expected, the accumulation of some element (e.g., lead and tin) in the soil increased with a higher degradation degree of the urns, but an enrichment in copper, chromium, nickel, and iron was also detected below only slightly corroded but not yet perforated urns, which were often made out of copper-bearing material and other alloying agents. This demonstrated that heavy metal releases into cemetery soils originated from both cremains and urn material. •Different levels in (heavy) metal content in the two analyzed cremains•Increase in pH and heavy metal content in the soil directly below the urns•Heavy metals in cemetery soils are released from cremains and urn material.