National Geographic Society

By Catherine Zandonella, M.P.H.

My mother-in-law notes that my two precious darling children are, at times, a bit unruly. I fully accept that the cause of their boisterousness is my parenting style. Nevertheless, I am intrigued by a recent scientific study suggesting that chemicals in our environment can influence the brain development and behavior of future generations.

The study found that pregnant rats exposed to a fungicide called vinclozolin could pass down changes in certain brain genes to their third generation of offspring-their grandchildren. Some of the altered genes are suspected of contributing to conditions such as schizophrenia, depression, post-traumatic stress disorder, anxiety and Alzheimer's.

The researchers, led by Michael Skinner, a molecular and cell biologist at Washington State University, published their findings November 18, 2008 in the journal PLoS ONE. They found that those third-generation rats had altered behaviors, and that the changes in behavior and gene activity differed between males and females. Males became more hyperactive, while females became more anxious.

The chemical vinclozolin is a fungicide used on fruits and vegetables, and is a known endocrine disruptor. You may run into it as an ingredient in Scotts Vorlan EG, which is used to treat flowers and fruit trees. Skinner and his team suspect that the hormone-like action of vinclozolin disrupts the turning on and off of genes in both the reproductive cells of the embryonic rats being exposed and their pregnant mothers. These gene changes are called epigenetic because they involve the molecules that govern the turning on and off of gene activity rather than alterations of the DNA itself.

These changes in gene expression can then be passed on to offspring. Previously Skinner's team found that vinclozolin enhanced susceptibility to disease among members of the third generation, but this was the first study to look at brain gene activity and behavior.

Skinner cautions that the study as it was designed cannot prove that the gene changes directly caused the rats anxiety-like behaviors. The rats' parents were exposed to vinclozolin while in the womb, and may have treated their offspring differently, giving them less affection, for example, than unexposed rats give their young.

Nevertheless, the fact that exposure to synthetic chemical compounds can cause changes in behavior that we might pass on to our children and even grandchildren suggests that we should avoid purchasing or using harmful chemicals in cleaning products, lawn and garden applications, and other products at home and in the workplace. For my part, I hope my children are rowdy because they're young, and not because of any chemicals that their grandmother may have encountered.

I miss daylight. It's hard to get up before the sun rises to exercise, or to leave work in the afternoon darkness. One of my favorite celebrations of the year is of the Winter Solstice, which marks, within a few days of each other, both the earliest sunset and the shortest day of the year.

But I do appreciate the seasonal rhythms of darkness and light, day and night. And I love a night sky, its vastness awash with stars or lit up by a big harvest moon. And so I was moved by Verlyn Klinkenborg's cover story in National Geographic's November issue, "The End of Night." It's not often one reads about light pollution and its effects on living things. Light is a powerful biological force, according to scientists, acting for many species as a magnet, drawing seabirds, for example, to the light from gas flares on marine oil platforms, and prompting swans to migrate earlier than is optimal for nesting. Sadly, nesting sea turtles, which prefer dark beaches, find fewer and fewer of them on which to nest. Their hatchlings, which would normally move themselves toward the brighter sea horizon are confused by artificial lighting beyond the beach and are lost by the hundreds of thousands every year.

"In most cities," Klinkenborg writes, "the sky looks as though it has been emptied of stars." New York City scores a nine on the nine-point Bortle Dark-Sky Scale, according to the International Dark Sky Association, which has pushed for city and state legislation to turn the lights down.

New York has, in fact, begun to dim down. The State Assembly passed legislation in June requiring that new outdoor lighting have shields that reduce glare and waste. Other measures -- to require full streetlight shields and motion detectors in all commercial and government buildings, and to mandate more efficiently lighted billboards - are now under consideration. The business community may be a bit ahead of the politicians on these matters. Several of the city's newest skyscrapers incorporate cutting-edge technologies that appeal to both environmentalists and those eager to keep energy costs down. Landlords have also found that meeting stiffer energy-efficiency standards in their new and refurbished buildings is a selling point with tenants, especially those that pay their own electricity bills.

For our part, Green Guide just moved into a space with just one light switch for the whole floor. It's not that large a floor, but it feels strange to not be able to turn the light off in my office when I leave. Worse still, what an awful waste for me to have to light the whole floor when I am the only one in the office. I have an LED desk lamp, which helps on these late-fall afternoons, as my desk is in a dark corner (LED lamps are particularly energy efficient). And hopefully we'll eventually be able to afford a lighting retrofit that would allow for zone lighting, motion sensors, timers and more.

In the meantime, I'm encouraged to see New York join the many other cities that are taking steps to save energy and cut down on light pollution. It may be a long, long time before we get to see Venus from our rooftops, but perhaps if we've got it in our mind's eye we'll keep working toward reaching that goal some day...or night.