(Re-posted from Huffington Post)

I became an environmental activist in the early 1970s just as I was
completing my doctorate in ecology at the University of British
Columbia. It was the height of the Cold War and the height of the Viet
Nam War and we were compelled to take a very public stand against
activities we thought to be catastrophic both for people and for the
planet.

I joined a small committee that was meeting in the basement of
the Unitarian Church. We organized a protest voyage against U.S.
hydrogen bomb testing in Alaska and had tens of thousands marching in
the streets. When that H-bomb was set off at Amchitka Island in
November 1971, it was the last hydrogen bomb the U.S. ever detonated.

It was the birth of Greenpeace, the organization I co-founded,
spending 15 years in its top committee, helping to lead environmental
campaigns around the world.

But it's ironic in the extreme that, as we mark the 100th
anniversary of drinking water chlorination, my old organization and
other activist groups aligned with it continue to oppose this most
important public health achievement.

Activist organizations like Greenpeace have access to a full century of
observations on the results of water chlorination in the US, all the
way back to September 26, 1908 when Jersey City, NJ became the first US
city to chlorinate its public water supply.

It's true, there were those back then who vehemently opposed the
use of this "poison" in public water supplies. According to one
official at the time, continued chlorination to eradicate typhoid was
akin to being "between the devil and the deep blue sea, for at present
we don't know whether typhoid fever or the (chlorinated) drinking water
is the worst."

Thankfully from the perspective of human health, chlorination
of water supplies spread rapidly. Today, chlorination is the
overwhelming choice for treating public water systems.

The results are clear. This widespread adoption of chlorine
disinfection across the U.S. has had very important results. Waterborne
diseases like typhoid, Hepatitis A and cholera that once killed
thousands of Americans each year have been virtually eliminated.
Typhoid fever cases fell by more than 99 percent between 1900 and 1960.
Related childhood mortality fell dramatically. And average life
expectancy rose from 47 years in 1900 to nearly 78 years in 2006.

Yet, many of my old environmental colleagues continue to vilify
chlorination of water by raising unwarranted fears about health risks
of chlorine and disinfection byproducts. In fact, it was a Greenpeace
decision in 1986 to support a world-wide ban on all chlorine use that
turned out to be a breaking point between my old organization and me.

My strongly held view is that chlorine is essential for our
health. It is that simple. At the time I explained to my fellow
Greenpeace International directors that water chlorination was the
biggest advance in the history of public health, and in addition that
the majority of our pharmaceuticals are based on chlorine chemistry. As
the only board member with an education in science, my words fell on
deaf ears.

In short, my former colleagues ignored science and supported
the ban, giving me no choice but to leave the group as I could not
support such a policy. Despite science concluding no known health risks
- and ample benefits - from water chlorination, Greenpeace and other
environmental groups have continued to oppose its use for more than 20
years.

I believe the opposition to the use of chemicals such as
chlorine is part of a broader hostility to the use of chemicals in
general. I often cite Rachel Carson's 1962 book, Silent Spring, as
having had a significant impact on many pioneers of the green movement.
The book raised some legitimate concerns, many rooted in science, about
the risks and negative environmental impact associated with the
indiscriminate use of chemicals.

But the day-to-day water chlorination that occurs across
America is not in the category of indiscriminate use. For Greenpeace
and groups like it, the healthy skepticism learned from Carson has
hardened over the years, and given way to a mindset that treats
virtually all use of chemicals with suspicion.

After a century of use and the resulting eradication of
waterborne diseases across the US and the world, those activists who
continue, absurdly, to oppose water chlorination only illustrate the
need for an alternative environmental policy based on science and logic
- not misinformation and campaigns of fear.

After all, campaigns based on groundless fears distract the
public from real environmental threats such as air pollution and
tropical deforestation for example.

As we mark one of the key milestones in improving the public
health of Americans right across the country, let's always remember we
all have a responsibility to be environmental stewards. But stewardship
requires that science drive our public policy, just as it did a hundred
years ago in Jersey City.