Lead, pesticides, brominated flame retardants, plastic additives, polychlorinated biphenyls (PCBs), and heavy metals. This is what researchers at Lund University in Sweden found when they collected dead hedgehogs to investigate the environmental pollutants found in urban environments.

Previous research has investigated the presence of heavy metals in hedgehogs from other urban areas in Europe and found similarly elevated levels of heavy metals. However, the team weren’t expecting so many other pollutants.

“What surprised us was that there were so many different environmental pollutants in the animals, such as PCBs and several different phthalates, and that there were very high concentrations of certain heavy metals, especially lead,” says Maria Hansson, ecotoxicologist at Lund University and the person who initiated the study.

The Lund researchers are, to their knowledge, the first to find evidence of hedgehog exposure to PAHs, phthalates and pesticides through analyses of liver tissue.

Environmental fingerprint

Urban green spaces attract many species of wildlife but also contain a range of unsustainable synthetic materials and chemicals. Because hedgehogs travel long distances – in and out of parks and gardens every night – and eat insects and other invertebrates, they are particularly exposed to high concentrations of environmental pollutants. When researchers in Lund wanted to learn more about the chemicals and pollutants found in urban areas, using the hedgehog as a study subject was therefore a natural choice. The objective was to understand what risk factors the different pollutants pose to animals in urban environments, and also to ourselves.

“Analysing hedgehogs provides us with a kind of environmental fingerprint of what is in an area’s ecosystem. Such knowledge is very difficult to access, but the hedgehogs have enabled us to gain a unique insight into what kind of urban environmental pollution we have directly around us,” explains Maria Hansson.

Roadkill hedgehogs were examined

As part of the project, which was based in Lund and neighbouring areas in Skåne, Sweden, Maria Hansson and her colleagues enlisted the help of the public, who were asked to get in touch if they came across a dead hedgehog. The researchers were also given access to hedgehogs that had been submitted for wildlife rehabilitation but had died. In total, they measured the presence of 11 different elements, including several heavy metals, and 48 organic environmental pollutants in the dead hedgehogs.

The researchers wanted to do a more in-depth analysis than had been previously conducted. Therefore, they looked at both long-term exposure to heavy metals (by examining both spines and teeth) as well as more short-term exposure to a variety of organic environmental chemicals (by examining liver tissue).

The results showed that the hedgehogs had high concentrations of the heavy metal lead and contained several organic environmental chemicals such as phthalates used as plasticisers in plastics and rubber, as well as PCBs – a collective name for toxic substances that have been banned in manufacturing since the 1970s. In addition, the researchers found pesticides, brominated flame retardants, elevated levels of other heavy metals and polycyclic aromatic hydrocarbons (PAHs) in some animals.

More environmental monitoring needed in urban environments

“This shows that urban environments, where the majority of people live today, contain a large amount of environmentally problematic substances that are proven to be harmful to health. These problematic substances come from building materials, plastics, pesticides, air pollution, waste, traffic, vehicles and even contaminated soil,” says Maria Hansson.

She says the study highlights the need for more environmental monitoring of soil and organisms in urban areas, including gardens and parks.

“People should also reduce the use of synthetic materials, chemicals and plastics as they have an impact on nature. Today, we want nature in our cities, so we must also reduce the risk of organisms being exposed to the chemicals in the materials and products we choose to use,” she says.

Indistinct impact

The hedgehog is a red-listed species and Maria Hansson emphasises the importance of using tissue from animal carcasses as far as possible in studies like this.
“Deliberately killing wild animals is unethical and should obviously be avoided,” she says.

How hedgehogs are affected by the substances and environmental pollutants to which they are exposed is not yet known by the researchers. Very little is known about how different species are affected by environmentally hazardous substances and studying wildlife is considered complex.

“However, as hedgehogs are mammals just like us, it is worrying to find substances that we know are endocrine disruptors, carcinogenic or interfere with human reproduction. Of course, other organisms are also affected by our emissions,” concludes Maria Hansson.