Perhaps twenty years ago I asked that question of Jeff Merriman (Chemtura) at a public CPAC (Chemtura Public Advisory Committee) meeting. Now most of the time Jeff was a pretty calm fellow but that particular question set him off. He became loud and agitated and behaved as if the question itself was a personal afront and secondly as if I had worded the question more like "You dirty dog are your disgusting Dioxin and DDT contaminants also further disgusting Dense Non Aqueous Phase Liquids (DNAPLS) that only the most slovenly polluters would have on their site.?".
Now his response surprised me because it was a calm and serious question. I did not know the answer then and am still not certain if they could actually be defined as DNAPLS or not. My suspicion then and now is that they could be according to some DNAPL criteria but possibly usually are not for some reason or another. Also just to be perfectly clear I most certainly did not phrase the question with words like ", "slovenly", "disgusting", "dirty dog" etc..
Mr. Merriman strongly answered my question in the negative while somehow implying that the question itself was somehow inappropriate which for Jeff was unusual. Don't get me wrong, he was a company man through and through but still usually he at least attempted to answer questions, even difficult ones, without being unusually defensive. This response of his was strange.
DNAPLS are known as "sinkers" because their density (specific gravity) is greater than 1 . This means that they will literally descend through both surface water as well as unsaturated and saturated soils (i.e. groundwater). Water has a density of 1 . Generally DNAPLS also have a low solubility in water which means that unlike NDMA which readily and fully dissolves in water, DNAPLS have a maximum mathematical solubility in water which can limit the extent of their groundwater contamination. For example chlorobenzene is a recognized DNAPL chemical with a solubility of around 440,000 parts per billion. While 440,000 is a big number it isn't when compared to one billion. In fact as a fraction chlorobenzene can only dissolve in water less than one half part per thousand parts of chlorobenzene. The problem arises with chlorobenzene as with many DNAPLS that their low solubility in water (i.e. 440,000/1,000,000,000) still greatly exceeds their human health drinking water standard of only 80 parts per billion. Both Dioxin and DDT have very low solubilty in water although certainly Dioxins solubility exceeds the drinking water standard which is an extremely low 15 parts per quadrillion or 15/1,000,000,000,000,000). The Ontario Drinking Water Standards (ODWS) does have a health criteria for DDT which makes me believe that DDT under some circumstances can dissolve in water at a rate greater than the ODWS. If not then why have a drinking water standard at all?
There are numerous other DNAPL criteria that I believe Dioxin and DDT have. The real issue may be the difficulty in finding them and other DNAPLS in the subsurface. This is because they are able to migrate under gravity flow versus the usual subsurface groundwater fllow. They can also penetrate both aquifers and aquitards and may or may not end up in depressions where they are capable of slowly dissolving over decades and centuries at concentrations greater than drinking water standards. Despite these difficulties, at least since January 2007 when Drs. Cherry and Parker (then Univ. of Waterloo) advised myself, Susan B., Wilf Ruland and Pat McLean that they should be removed or remediated from the subsurface, this world class professional advice has been ignored at CPAC, RAC, TAG and now TRAC.
I believe that both DDT and Dioxins are now probably in the off-site Elmira Aquifers courtesy of this negligence.