Through the Investor Environmental Health Network, the Interfaith Center on Corporate Responsibility, Ceres and other organizations, investors have engaged scores of companies in recent years on toxic chemicals in products.

Here are some lessons I hope companies have garnered from these experiences:

1. Investors can be a useful antidote to senior management group-think. Group-think can cause senior management to fool both themselves and their investors, to the detriment of both.

2. Investors can be silo-busters. Chemical issues cut across departments and supply chains; investors can prompt senior management to bring together product designers, marketers and other folks who ought to be talking to one another but aren't.

3. Investors can prompt development of forward-looking, beyond-compliance programs. Like soccer, football, baseball or hockey stars, the most successful companies anticipate and move to where the ball or puck is going to be and get there ahead of the competition.

4. Investors can provide over-the-horizon warnings. In 2005, investors raised concerns about Bisphenol-A (BPA) in polycarbonate plastic bottles, three years ahead of the massive market shift to alternatives. Investors are now suggesting that companies consider exit strategies for triclosan used in soaps and body washes.

5. Providing investors an opportunity to review draft corporate social responsibility (CSR) reports can prevent corporate embarrassment. Not only might they remind corporate staff that in the very first paragraph "data" is a plural, not singular, word, but investors can suggest how companies defending their use of BPA can do so without citing ancient discredited data.