Murphy, Megan Kate. "The Chemical Industry: Hidden Risks and Value Potential for Strategic Investors." Innovest Strategic Value Advisors, July 1999.

Uses a proprietary environmental assessment model to evaluate 19 S&P 500 chemical companies, and finds that "companies receiving above average ratings outperformed companies with below average ratings by approximately 20% over the past year [1998]." Dupont ranked highest on the proprietary environmental assessment model, while Great Lakes Chemical ranked lowest. No risk-adjustment was attempted, and the evaluation period was short. Innovest, a New York investment advisory firm, reports similar returns to the environmental variable (but over short time periods) in other industries as well.