For the past five years, biochemist Zac Hildenbrand has investigated potential links between unconventional drilling and water quality, collecting thousands of samples throughout the major shale plays in Texas.

Some of the results, he said, are worrisome. As part of a collaboration with researchers at the University of Texas at Arlington, Hildenbrand has identified water wells with high levels of chlorinated solvents, alcohols and compounds commonly found in petroleum products.

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