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Detoxifying American Indian artifacts

Decades of antiquated preservation methods have led to the contamination of American Indian artifacts with toxic metals, potentially damaging the artifacts while posing danger to the conservators working with them.

With a grant from the National Center for Preservation Technology and Training, Timberley Roane, associate professor of biology at the University of Colorado at Denver and Health Sciences Center, has been researching a means to resolve an environmental quandary involving toxic substances and artifacts such as kachina dolls, pipes, pottery, blankets, mounted animals and ceremonial masks.

“Historically, artifacts might have been treated with a variety of different pesticides to preserve the objects from insects and microbial damage,” Roane said. “Two of the most prevalent pesticides that we’re most concerned with now are mercury and arsenic, as the toxicity of these metals to biological systems is under review.”

Roane, a Lumbee tribe member, collaborated with a Navajo friend who works with the Environmental Protection Agency to conceptualize the use of bacteria as a possible means to extract mercury from these artifacts without damaging them. Due to the presence of mercury, for example, and the risk of dermal or inhalation exposure, some of these artifacts could not be put back into cultural use.

Roane is working with bacteria already living on the artifacts that will allow her to change mercury into a gaseous form that can then be disposed of properly. This builds on her past research that uses naturally occurring bacteria for environmental cleanup.

“With funding from the NCPTT, we’ve been able to isolate mercury-resistant bacteria capable of removing mercury from contaminated media,” she said. “We are very excited by the prospect of being able to remove mercury from treated museum materials, in hopes of mitigating the toxicity of these materials for not only repatriation to tribal members but for anyone who comes in contact with them.”

Traditional methods of removing toxic metals include chemicals, ultraviolet light and heat. These methods can damage materials, which led to Roane’s desire to research less invasive methods to clean collections.

“You have to treat them gently and with respect, especially since some of these materials are considered living by their native peoples,” she said. “New methods like those proposed by the grant procedures offer new hope.”

Roane was granted access to Native American collections at the Arizona State Museum for her research. Dozens of samples have been taken and documented. After the bacteria are grown in the lab they are screened for their ability to turn mercury into a gaseous form. Those bacteria are then tested further.

While much is not known about contamination levels in native artifacts, Roane’s research represents a promising step toward dealing with the contamination from the past while preserving these significant cultural artifacts for the future.

“The start to this project shows a lot of potential,” she said. “We plan to continue our efforts in using bacteria to remove mercury from collections and hope to eventually develop an effective mitigation technology.”