Getting the lead out
Student researchers find ways to remove toxins from reusable grocery bags
Feb. 17, 2011
by Michelle Cometa
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Reusable grocery bags are everywhere. With designs as varied as peapods and flowers, the bags are toted around town like status symbols. But unbeknownst to shoppers, they have been toting toxins as well.
When some of the popular reusable bags were found to contain lead, finding the source and solving the problem seemed overwhelming. Today, the supply chain extends around the globe, and regulations can be a long, winding paper trail. But Chen Chen and Lu Gao, graduate students in RIT’s packaging science program, started on the trail and found viable solutions to keep the bags stylish and, most importantly, safe.
Reports of lead found in the bags from brand name stores such as Publix, Walmart and CVS were recently made public. Closer to home, Wegmans also made headlines. Its reusable bags with the green peapods and holiday designs were tested and found to have high levels of the controversial element. Each company acted swiftly to remove the bags from stores and inform consumers of risks.
Chen and Gao seized the opportunity to investigate the problem using quality control theories, Lean Six Sigma techniques and old-fashioned detective work. They reviewed the original test results of the different bags. The data showed some had just over the allowable 100 parts per million of lead; one company had nine times the acceptable levels. Most of the bags tested were imported from China.
Use of lead in products has varied over the years from construction materials to lead-acid car batteries, from equipment to shield individuals from radiation to stained glass windows and, most commonly, inks and paints. It is malleable and non-corrosive and able to stabilize elements like sulfuric acid. With more information about lead leading to learning disabilities in children and fertility problems in adults, some manufacturers have decreased or removed lead entirely from products, while others have not.
Gao began by flow-charting the supply chain, a complex path of resource acquisition, product development, mass production, shipping and distribution, analyzing each step extensively.
“You have to go into the root of the process to do root cause analysis,” says Gao, who was raised in Shanghai. “First we needed to know what is in the ink and where the lead comes from.”
She found that the yellow ink was made from lead chromate and used in making the green-colored bag design. The lead chromate is also part of the solvent carrier used in current printing processes. Additionally, lead was found in the recycled content of the polypropylene bag material. Changing the solvent and substituting yellow lead chromate with a UV-cured ink were two possible solutions that could be implemented. UV-cured ink has no lead in it and requires a different application process to seal the ink onto the bag material.
However, Gao wanted to be accurate; she noted that still more research needed to be done to see if the alternative solvent and UV-cured ink are available in China. She says the most important thing for Chinese manufacturers and American retailers to do is to evaluate if the change to UV-cured ink might mean retrofitting equipment, incurring additional costs. But pressure to conform to consumer concerns might offset barriers to improving equipment.
“If they follow some statistical process control procedures,” Gao says, “the quality of the product can be controlled in acceptable ways even without switching to a different ink or solvent.”
Chen’s exploration took her down a confusing path of governmental regulations. “We checked many toxin-in-packaging laws,” says Chen, originally from Heilongjiang province in China. She did work that most companies hand off to a team of corporate lawyers, finding that regulations vary and some companies provide back up documentation about tests and results, and others do not.
“In America, companies are expected to do the due diligence in assuring the products and materials meet specifications,” says Duane Beck, packaging science faculty and academic advisor to both Gao and Chen. “The regulations say the onus is on the manufacturer, so as a result, some might say, ‘the testing is not our problem, we have the certificate of compliance.’”
Companies may not need in-house versions of the Environmental Protection Agency, but they will need knowledgeable people like Gao and Chen who understand how all the processes come together—from regulations to resources.
During break, Gao traveled with her family to New York City and visited the Museum of Modern Art. With her entry fee she received the museum’s signature reusable bag.
Her first reaction was to note its bright color. “It was so green,” she laughs. Then she checked inside and found it was assembled in China. Through her work with Chen, she said she looks at the reusable bags that have become so much a part of everyday life in a different way. It confirmed for her how important the work is they are doing.
“People think this is a small problem, but we don’t think so,” she says. “It is something that cannot be overlooked. It is not good for the environment or for our health, especially kids. We think our research can help companies, not just the consumers but the manufacturers.”