The study of how substances alter gene expression is part of the field of epigenetics. Some chemical exposures appear to turn on and turn off genes in ways that disregulate cell growth and predispose for cancer. From this perspective, our genes are less the command-and-control masters of our cells and more like the keys of piano, with the environment as the hands of the pianist.

Indeed, the quantity of PCBs still in use plus the quantity still languishing in waste dumps exceeds the total amount that has already escaped into the general environment. Without a program to recall and contain them, semivolatile PCBs will continue to insinuate themselves into the food chain for decades.

I have come to believe that extracting natural gas from shale using the newish technique called hydrofracking is the environmental issue of our time. And I think you should, too.

We are all musicians in a great human orchestra, and it is now time to play the Save the World Symphony. You are not required to play a solo, but you are required to know what instrument you hold and play it as well as you can. You are required to find your place in the score. What we love we must protect. That’s what love means. From the right to know and the duty to inquire flows the obligation to act.

Here in the United States, a study of nearly 700 women in California showed an increased risk of fetal death among babies whose mothers lived near crops when certain pesticides were sprayed. The largest risks were found among pregnant women exposed during the critical first trimester and among those who lived in the same square mile where pesticides were used.

In the world outside this glass room, songbirds are feeding and resting in the trees. Some will take off tonight and not land until they reach Venezuela. Sandpipers, plovers, and broad-winged hawks have already left for Patagonia and Panama. Bats are headed for caves in Kentucky and Tennessee. Out in the Atlantic, humpback whales pass by on their way to the Caribbean. Even now, Canada geese are honking toward us from Quebec. It is a good day for the beginnings of journeys.Every time I look at you, I think, Now I cannot die.

The study of how substances alter gene expression is part of the field of epigenetics. Some chemical exposures appear to turn on and turn off genes in ways that disregulate cell growth and predispose for cancer. From this perspective, our genes are less the command-and-control masters of our cells and more like the keys of piano, with the environment as the hands of the pianist.