Taking Water Samples: Lessons from the Field

It is, perhaps, not surprising that a reporter who authored a book called Parts Per Million would have a cursory understanding of how to collect data on environmental toxins. So it is with an equal measure of humility and embarrassment that my final blog for Reporting on Health reflects the utter stupidity I felt when I traveled to California's Central Valley to collect water samples -- and realized I had little idea of what I was actually getting myself into.

No doubt, taking water samples for a story about pesticide contamination is a risky proposition for any journalist.

For one thing, you have to know what you're looking for. Are the pesticides in question water soluble? Do they have half-lives that might elude testing? For another, there's the question of whether the laboratory you're using has the capacity to analyze your samples correctly.

But most important is the final result: if you don't detect pesticides in the water you've collected, will that undermine the premise of your story? Or, conversely, if your lab results come back with detections for multiple herbicides in the same sample of tap water, as happened to me, what are your ethical obligations to the people who have agreed to have their water tested?

Lucky for me, my editor at Sierra agreed that my story about the link between Parkinson's disease and pesticide use in California's Central Valley farming communities would be strengthened if we collected our own data.

My reporting, which looked at the people behind the statistics, was inspired by a series of elegant studies (see the International Journal of Epidemiology, American Journal of Epideiology and European Journal of Epidemiology) by UCLA epidemiologist Beate Ritz and a team of researchers, who found that Central Valley residents under age 60 who lived near fields where the pesticides maneb and paraquat had been sprayed between 1974 and 1999 had a Parkinson's rate five times higher than other residents in the region. The federally-funded research was the first of its kind to actually quantify chemical exposures, rather than rely on residents' recall, by comparing pesticide application records with land-use maps. Of particular concern to the UCLA scientists was the consumption of private well water in farming regions with documented long-term pesticide use. Domestic wells are not regulated by state or federal clean water laws.

Since their work was based on historical information, I was curious to find out whether I'd find evidence of domestic well water contamination now.

Clearly, there is no paucity of data documenting groundwater contamination in California. Federal studies by the U.S. Geological Survey (see an overview of water quality from domestic wells, 1991-2004, data on on ground-water quality in the San Joaquin Valley, and the Pesticide National Synthesis Project) and state tests by both the California Department of Pesticide Regulation (DPR) and State Water Resources Control Board (SWRCB) show a 30-year history of pesticide contamination in the Central Valley. But DPR, citing national security concerns, doesn't reveal the exact location of its tests. And the most recent groundwater assessments by SWRCB are based on data collected three years ago.

So, I set out with an ice cooler and amber glass bottles from a Los Angeles-based environmental monitoring laboratory. And I kept replenishing my supply of ice along the way. What I didn't realize, until after I had driven 200 miles to drop off my water samples to the lab, was that its detection limits were set too low. In other words, I needed a lab that could detect chemical substances at the parts per trillion level but the first lab I relied on used less sensitive assay methods in the parts per billion range – 1,000 times less than what was needed.

"Just because we didn't find it doesn't mean it's not there," the lab chemist explained to me of our initial findings of "non-detects" for pesticides. This, after sinking $1,200 of my own money – for nothing.

Not ready to give up, I explained my predicament to a scientist who works for a federal agency. He offered to cover all costs of analysis, sampling kits and pre-paid shipping labels if I agreed to collect three 1-liter glass bottles of water for each sample sent overnight via Federal Express to the laboratory in exchange for confidentiality. With my editor's approval, we agreed to the arrangement.

The question of whose water I would test and where was another challenge. Thanks to Maria Herrera, community outreach organizer with the Community Water Center in Visalia, I was able to gain access to domestic water wells in Orosi and other farming communities. Also invaluable were members of the Central Valley Parkinson's Disease Support Group in Visalia, who welcomed me and encouraged me to gather water tests. With their help, I was able to gain permission -- and access -- to collect samples. In one case, I agreed to not reveal the identity of a longtime resident.

It took about 90 days to receive the results, given the number of analytes and low levels of pesticides being tested.

This story took 18 months from start to finish, a record for me. One of my greatest frustrations was what did not appear in print. For example, I spent time with some remarkable people, including Teresa DeAnda an activist with Californians for Pesticide Reform, whose work was not included in my article. Space limitations also meant that the work of scientist Annie Esperanza at Sequoia and Kings Canyon National Park was edited out of my story. Her data collection from sediment, streams and snow helped me understand that, through air modeling, it's possible to track how organophosphate pesticides used in agriculture on the valley floor travel high up into the Sierras -- and how research from scientists in our national parks is advancing key public health issues. And Nicole M. Gatto, assistant research professor of epidemiology at UCLA School of Public Health and the lead investigator on "Well Water Consumption and Parkinson's Disease in Rural California" was especially helpful and I regret that her contributions to my story did not meet print.

My fellowship project remains ongoing. Next month, I'll return to Visalia to share our water testing results at the monthly meeting of the local Parkinson's disease support group – and to personally thank the families that made the story possible.

Photo credit: Eliza Peyton via Flickr