The first peer-reviewed analysis of New Orleans' hurricane floodwaters finds the stuff was no more polluted than what normally fills the city's storm drains after heavy rains -- there was just a lot more of it.
The report is based on sampling done in several flooded neighborhoods around the city in early September -- about a week after water driven by Hurricane Katrina from Lake Pontchartrain breached several levees protecting the mostly-below-sea level city.
It shows that concerns of the floodwater being a "toxic soup" of chemicals and dangerous microbes were probably overstated, although the long-term effects of the muck left behind and of the pumped-out water on the ecology of Lake Pontchartrain remains unclear.
Wednesday, October 12, 2005
More on Katrina toxics
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The latest word on Katrina toxics shouldn’t be the last word on the subject because the issue reveals some interesting points about the state of environmental science, risk management, and government’s role. In hindsight, anyone who really took the time to even scribble on the back of a napkin the quantities of chemicals stored in the watershed and the amount of storm water that flushed through would probably not expect a “toxic soup.” One article which summarizes the first peer-reviewed analysis of New Orleans' hurricane floodwaters as “floodwaters less toxic than expected” deflates the issue. Perhaps it was our expectations that were off. But are there contaminants out there? Sure. Do we know what the toxicological impact will be? Not yet.
The source sampling report (http://pubs.acs.org/cgi-bin/sample.cgi/esthag/asap/html/es0518631.html), in fact, puts the results in the context that the contaminants weren’t detected by discussing dilution and evaporation. The report also points to low dissolved oxygen levels which indicate the presence of biological and chemical contaminants. These contaminants react with the dissolved (aqueous) oxygen in the water; this, as opposed to chemical toxicity, typically cause fish kills after a chemical release by essentially suffocating them. Although there have been no reports of fish kills in Lake Pontchartrain, isolated fish kills have been reported on the north shore and tributaries.
The report in itself is good work and the organization that peer-reviewed it and released it, Environmental Science & Technology (ES&T), is beyond reproach. ES&T’s online news release (http://pubs.acs.org/subscribe/journals/esthag-w/2005/oct/science/pt_neworleans.html), in fact, cited criticisms of EPA for not clearly communicating the risks. The scientists did what they are supposed to do – they got out there and sampled; albeit nine days after the hurricane and the concentrated plumes of contamination were dispersed and diffused. Critics who point the finger at EPA for a “bumbling response” may be missing the forest for the trees. The efficacy of any one test or pronouncement should not be the focal point: it’s the overall response that is the cause for concern. This failure to think big is the frustrating aspect of EPA’s leadership; moreover, that appears to be the case of several federal organizations under criticism.
First, environmental regulations weren’t intended for a disaster of this scale. There are detailed response protocols to assess, control, and abate spills – specific scenarios - a storage tank, a processing building, even a freighter. But when a whole city is wiped out, in what context does some storm water sampling fit in? This is analogous to Person A handing Person B a bucket of golf balls to count. And Person B lines them out, takes out a golf club, whacks them all into the woods, and then counts the balls he/she can find. Well, we roughly know the quantity and location of chemicals in the watershed. Wouldn’t it make more sense to perform some hydrological modeling of the contaminate fate and transfer and then use sampling results to validate the model – rather than using a sampling “snapshot” to quantify the risk? Maybe. This is routinely done for ground water contaminants but for storm water this may be a bit outside the box.
Furthermore, toxicology and environmental science are in terms of concentrations and doses – as they scientifically should. But in some ways I can’t necessarily describe, that framework fails to address catastrophes in an understandable way to the general public.
This is complicated by the whole ppm and ppb business. A caveman may have disregarded a found dead animal if it smelled bad enough. His innate senses and instinct communicated risk. Science has allowed us to quantify chemicals and has effectively allowed us to regulate safety and health. But as technology now allows us to detect parts per billion, risk becomes less intuitive. In water that we once thought was pure, we can now find molecules of chemical contaminants. What is risky? We have very little empirical data on human toxicology. Regulatory levels are typically extrapolated from animal testing trials with safety margins built into them. They’re good faith estimates – presumably the best science has to offer.
So, sure, people are frustrated because EPA is not clearly communicating the risk. Risk is a murky thing. The attitudes you see in New Orleans are typical. On one extreme, some people are entering back into New Orleans with little recognition of risk. They smell mold and fecal odors and probably respond accordingly. They don’t see or smell mercury and don’t consider it a hazard. On the other extreme, some people perceive a great risk and demand answers. To address the concerns of local residents, Wilma Subra, president of Subra Co., Inc. is conducting her own tests of the sediments. She advises residents to not enter the city unless they wear a respirator, boots, and gloves. That’s an OSHA level of protection for hazardous waste site workers. She notes that Wal-Marts within 100 miles have sold out of such equipment.
Where is the sane middle ground? Most EPA officials seem to have a lawyer over their shoulder. Ok, maybe they really do and have to select their words carefully. They advise people about potential long-term effects. You can find reasonable guidance in places, assuming we know what reasonable is. If EPA is to be faulted for something, then perhaps it should be for not being the master of their domain and telling people what they need to know to return to their lives:
“We don’t know what the risks are for certain but we’re going to sample the residuals, the drinking water, the produce, the seafood the best we can and give you the best conclusion we can. In the meantime, don’t expose yourself to anything you don’t have to. Drink bottled water and don’t eat local foods. Clean off all surfaces the best you can. Safely dispose of materials you can’t decontaminate. Take particular care keeping children away from anything that could have been contaminated in the flood water. Don’t lick the sidewalk. We’re in this together.”
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