Swimming and eating stuff from the water downstream.

From "This American Life," a show I listen to and like...

The second, Conrad "Dan" Volz, at the University of Pittsburgh, estimated how much toxic crap—chemicals and pollution from gas exploration—might be getting into water supplies. (1)

In my last post, I made the comment that you can't get to the conclusion Dr. Volz presents in his report from his comparison to EPA/ATSDR limits that have been established so that “daily human exposure to a hazardous substance that is not likely to pose an appreciable risk of adverse noncancerous health effects” when the assumption of a "lifetime exposure" will not be met.  In other words, if that water is not going to be consumed at the point where sampling took place, there is also no assumption that someone at 70kg could drink it daily for a 70 year lifetime (MCL).

Comparing the barium concentration in the effluent with an MCL was wrong, and the comment "this is approximately 14 times the [MCL] of Ba in drinking water" is therefore misleading.  But what about Dr. Volz's contention that:

Recreationalists are at high risk of being exposed to outfall contaminants through ingestion, inhalation and through dermal exposure.  [C]hildren wade and swim in the creek during warmer weather... Anglers catching and eating fish from upstream or downstream of the effluent outfall are at risk for exposure to multiple contaminants that were sampled in this study.

What does the term "high risk" convey?  Is it at the level of death?  Should it illicit an OMG! if one comes in contact with the water?  "High risk" of what, exposure?  Dr. Volz reports that I will have a high risk of coming into contact with barium, bromides, strontium, benzene, TSS, and pH if I ingest, inhale or contact the Blacklick Creek Water?  Will that exposure lead to a health effect?  Are we talking about a high risk of exposure to a puppy or a Doberman? (that will make more sense if you read this post).

If we are not going to drink the effluent, will exposure to these chemicals at the concentration found at the point of discharge cause "an appreciable risk of adverse noncancerous health effects?”  Fair question.  What are the concentrations of these chemicals in the water where the children wade and swim?  What are the levels of these contaminants in the fish caught and consumed?  There isn't any of that data presented in Dr. Volz's report.

What the report does is imply that if a chemical - such as barium - is discharged into the creek, it will present an exposure risk to someone who comes in contact with the water downstream "of the effluent outfall ."  In other words, high risk of exposure must translate to "an appreciable risk of adverse noncancerous health effects."

That's not how environmental public health professionals look at a chemical exposure manifesting into a health risk.  You can't get there from here.  You can speculate, imply, assume, insinuate, and wish it to be true, but that's not what an environmental public heath professional is supposed to do.

So once more, with feeling...

To estimate risk we need to know the amount of chemical entering into the receptor (uptake), the length of time the exposure has taken place, the toxicokentics, and compare them to a concentration assumed to present no appreciable risk of adverse noncancerous health effects.

When we know the amount of uptake (how much of the chemical got into the system) from the exposure, we can compare it to a number, such as the MRL.  Keeping with the barium concentration in the effluent reported, Dr. Volz states:

The ATSDR minimum risk levels (MRL) for intermediate and chronic human exposure is .2 mg/L/day; the barium in PBT- Josephine effluent water is approximately 135 times the MRL’s for both intermediate and chronic human exposure.

Lets look at what ASTDR says about barium in it's ToxGuide for Barium:

Notice what Dr. Volz - a DrPH, MPH and (former) Director of the U of Pitt GSPH's Environmental Health Risk Assessment Certificate Program failed to take into account?  That MRL value of 0.2 mg is not per liter, but per kilogram body weight of the receptor.

A 30 kg child would need to consume 0.2 * 30 = 6 mg of barium for 15 - 364 days to potentially have a negative health impact.  To put this in perspective....

If the effluent (discharge end of pipe) contains a maximum of 37 ppm, little Suzy or Billy would have to stand near that pipe and consume about 250 ml of the creek water.  That's the amount of water in the container little Suzy is holding.

Oh, and she would have to do drink that amount for 15 - 364 days.  And even if she did, the ASTDR states:

Exposure to a level above the MRL does not mean that adverse health effects will occur. (2)

The effluent is not 135 times the MRL.  At the end of the pipe - where the samples were collected - it is only 7 times higher than the maximum detected level of barium.  What the barium concentration is downstream where little Suzy and Billy "wade and swim" was not sampled by Dr. Volz.  That's where the sample's should have been taken if risk "of these chemicals in the water where the children wade and swim" was to be evaluated properly.

It is quite possible - as that is the reason for the NPDES permit the treatment facility discharges under - that the water "where the children wade and swim" is below the MRL for barium and all the other chemicals reported.

But heck with the kids!  What about the guys who eat the fish swimming in the "toxic crap?"

Once again we need to know how much barium would be consumed when they eat the fish.  Believe it or not, there is a calculation for that:

http://www.epa.gov/reg3hwmd/risk/human/rb-concentration_table/usersguide.htm

And for barium, the amount in the fish that would create concern for the EPA requiring cleanup would be 270 mg of barium per kg of fish.

http://epa-prgs.ornl.gov/cgi-bin/chemicals/csl_search

This is how we look at risk from exposure to a chemical.  The fact that a chemical is present in the environment and we come in contact with it does not mean we will be subject to an appreciable risk of adverse noncancerous health effects.  There is a proper - agreed upon - method to look at estimating elevated, or high risk, when exposed to a chemical.  Dr. Volz must understand that what he present in his report was not a valid indication of the risk to public health and the environment from the water discharged by this frac water treatment facility.

Choosing to ignore the science and objectivity is what led to Dr. Volz no longer being the director of the University of Pittsburgh's Center for Healthy Environments and Communities at Pitt's Graduate School of Public Health.

I am glad that Dr. Volz believes he has a "calling for advocating for public health."  All I ask is that he and others so inclined present and describe the risk properly and objectively.

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