ChemRisk is a Delaware Limited Liability Company, a for-profit scientific consulting firm headquartered in San Francisco, California that is part of Cardno ChemRisk. ChemRisk founder and former president, Dennis Paustenbach, "has long been an expert witness and top consultant" to "scores of companies in the chemical, energy and medical products industries" facing lawsuits over products or environmental practices or product safety. Their clients included San Francisco-based utility Pacific Gas & Electric (PG&E) and BP. ChemRisk uses toxicology and risk assessment to measure the hazards of chemicals in soil, air, water, food, sediments and consumer products.