Wood toxin could harm zoo animals

Date: May 20, 2016

Source: University of Florida Institute of Food and Agricultural Sciences

When those cute animals gnaw on wood enclosures at a zoo, they may be risking their health by ingesting toxic levels of arsenic, so zoo managers need to pay attention to the potential risk of the wood on zoo animals, a new University of Florida Institute of Food and Agricultural Sciences study shows.

The wood in question is treated with chromated copper arsenate (CCA), which can be toxic.

After visiting a zoo with her family, Julia Gress, a former post-doctoral researcher in the UF/IFAS soil and water sciences department, recognized that animals living in enclosures made from CCA-treated wood might face health risks.

Gress wanted to assess the impact of CCA-treated wood on arsenic exposures in zoo animals. She measured arsenic concentrations in soil from inside enclosures and on wipe samples of CCA-treated wood. Samples were taken from inside 17 wood enclosures, and also included crocodilian eggs, bird feathers, marmoset hair and porcupine quills.

Researchers found arsenic levels in soil that were higher than the U.S. Environmental Protection Agency's risk-based level for birds and mammals. As well, arsenic levels in some animal tissues were also higher than those in other studies. Those findings should encourage zoo managers to limit animal exposure to arsenic found on the wood surface and in nearby soil, Gress said.

"Zoos care about the animals, which are often worth a lot of money," said Gress, who conducted her search under the guidance of UF/IFAS soil and water sciences professor Lena Ma. Gress now works at the California Department of Toxic Substances Control in the Safer Consumer Products program.

CCA-treated wood is used in many structures. CCA preserves wood and extends its life by 20 to 40 years, but it contains large amounts of arsenic. CCA was withdrawn from use in most residential applications in 2004 because of health concerns over arsenic. Still, CCA-treated poles, fencing and plywood are still commonly used in areas where animals are housed, including barns, feedlots and zoos, according to the study.

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