By Shereen Siewert

Soil samples collected at a city-owned property targeted for potential redevelopment show high concentrations of metals including thallium, a substance now banned in the U.S. due to its extreme toxicity to humans.

The test results are part of a Phase II environmental study performed by GEI Consultants and released in January that also noted levels of potentially cancer-causing contaminants as much as four times the industrial standard in some areas of the property at 1300 Cleveland Avenue. The roughly 7-acre property is south of Thomas Street and is surrounded largely by residential homes.

The Phase II study collected subsurface soil samples from 22 locations at two different depths per location. Of the 44 soil samples, thallium was detected in 21 locations in concentrations ranging from 0.8 to 1.7 milligrams per kilogram, the report shows. Thallium is found at hazardous waste sites at an average of 1.7 milligrams per kilogram, according to the federal Agency for Toxic Substances and Disease Registry.

Many of the locations where thallium was detected are across the street from neighborhood homes.

Thallium is found naturally in the Earth’s crust, but commercial and consumer use of thallium as a rodenticide or insecticide has been banned since 1975 in the U.S. and in most other countries. Russia and China continue to use thallium commercially as a rat poison, according to the California Poison Control System.

According to an analysis by the Center for Health and Environmental Justice, thallium can be released into the environment by combustion or improper disposal of combustion waste. The Cleveland Avenue property, acquired by the city in 1986, was the former site of Connor Forest Industries, a wood manufacturing plant that was the subject of several Wisconsin Department of Natural Resources investigations. The property later became the site of Wausau’s business incubator.

In a memo to the grassroots environmental group Citizens for a Clean Wausau that was shared with city officials and the DNR, environmental expert Stephen Lester said exposure to thallium by eating contaminated foods, living near waste sites, breathing contaminated dust and by touching or swallowing contaminated soil can have “devastating effects” on many parts of the body.

Short-term exposure can cause dysfunction of the nervous system, heart, kidneys, lungs, and liver and can cause death, Lester wrote. Studies in animals have found that ingesting thallium can cause reproductive and developmental defects.

“Scientific evidence makes it clear that thallium exposure can pose a danger to human health and life,” Lester wrote.

Lester said his organization is recommending cleanup and remediation of thallium before any development occurs on the property, in order to protect the health and life of Wausau residents.

Wisconsin DNR hydrogeologist Matt Thompson said the CHEJ evaluation outlines the causes for thallium to be considered a hazardous substance quite well.

“Plainly put, the levels of thallium and other compounds exceeding state standards, pose a risk to individuals that may come into contact with them at the site,” Thompson told Wausau Pilot & Review. “State standards are calculated using compound specific toxicological data, similar to how the US E.P.A. establishes their cleanup standards.”

Thompson said it is too early to comment on the extent of cleanup that needs to take place but noted that Wausau has been instructed to continue investigating the contamination found at the site.

“The department is working closely with the city of Wausau, its consultant GEI, and concerned members of the community to ensure this site is investigated in accordance with state law,” Thompson said. “Once the investigation is complete, the city will have to opportunity to propose a cleanup which the department will review for compliance with state law.”

Thallium, accidentally discovered in 1861 by Sir William Crookes, has a storied history of applications as a depilatory, syphilis remedy, rodenticide, ant killer, and in the manufacturing of photocells and semiconductors – and as a real-life agent of murder with worldwide homicidal use documented since the 1800s, according to the California Poison Control System. Acute ingestion of as little as one gram of thallium salt may kill an adult, the CPCS states.

The Wisconsin Administrative Code establishes cleanup standards for soil in order to restore the environment and protect human health from direct contact with a contaminant, Lester said. The cleanup standard for thallium dictated by both the state’s administrative code and the EPA is 0.78 mg/kg, which means the thallium concentration at the site would be considered a potential risk to human health by code standards.

Thompson said the DNR will “rigorously enforce” cleanup standards for the site moving forward.

A Committee of the Whole meeting is set for Tuesday at Wausau City Hall to review the report, allow public comment and discuss next steps.