Are you sure you know what's in your pet's food? A new study by a Denver non-profit has found that some top pet foods actually contain an abundance of toxins.

Denver-based non-profit Clean Label Project is focus on health and transparency in consumer product labeling. They use state-of-the-art laboratory testing to examine what actually goes into various products. Then they rate the best and worst performers on their 5-star rating system, and post all the ratings on their website so consumers can know how their favorites performed. Their latest study focuses on top pet foods. Recently they took 900 of the best-selling pet foods from 74 brands and tested them for more than 130 contaminants and toxins. The results they found are nothing short of shocking. In some pet foods, they found lead at 16 times the concentration of the lead in Flint, Michigan's tainted drinking water. They also found arsenic in concentrations "555 times higher than the maximum contaminant level for human drinking water set by the Environmental Protection Agency."

Companies may be unaware these chemicals are in their products, as many of these tests are not routine or required - but that doesn't make the presence of these toxins any less dangerous... The rapid expansion of manufacturing and outsourcing has made an impact on the purity of not just pet food, but all food - and the only way to fix it is to increase awareness and demand action." -Jackie Bowen, Clean Label Project executive director

For owners that feed their cats tuna, the study also warns that mercury levels in some brands can cause neurological impairments. Bowen also points out that these animals are eating the same thing every day, two to three times a day. That means extended and consistent exposure to these contaminants. All the tested products were evaluated in blind tests by Ellipse Analytics, an independent chemistry lab. Results were then verified by two additional labs through random testing. The blind data was analyzed by Clean Label Project's Technical Advisory Board of veterinarian, statisticians, epidemiologists and food safety scientists before results were published. Some of the tested brands include Blue Buffalo, Cesar, Dick Van Patten's Natural Balance, Greenies, Hill's Science Diet, Iams, Purina, TruDog and Whiskas. You can find a complete list of the tested brands here, and you can access all their results and ratings here.

How did your preferred brand fare in their tests? Are you surprised by what they found? Share your thoughts with us in the comments below!

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