Benzine in the water supply 1

[frankjur]

Has anyone had any experience in methodologies that homeowners can use to remove benzine from their water supply?

Background: From 1993 to 1999 I was an American living the the Russian city of Khabarovsk. It's on the right bank of the Amur River just 30 km. from the Chinese border. I still have a lot of Russinan friends there.

If you recall, last November there was a chemical plant explosion in Harbin, China. Tons of benzine and heavy metal (arsenic, etc.) pollutants were dumped into their river. Unfortunately, the river adjacent to Harbin flows into the Amur. Two weeks after the explosion in China, the pollution plume reached Khabarovsk. At about that time winter came and the river froze over. Now with the approach of spring, the Amur will be thawing. Of course the Russians living there are very worried about the health dangers of their water supply--particularly those with small children--which is the case in one of my friend's family.

Whatever dillution may have occurred over the winter has been negated by yet another chemical plant explosion in Harbin early this month (April, 2006). So another pollution plume is on the way.

Khabarovsk's water supply comes from the Amur. Not only is it used for drinking water (and not too healthy at that during good times), but it's also used for supplying the centralized, hot-water heating for all the buildings in the city. Access to alternate sources is really not an option--even with the unaffected Ussuryiski River nearby. The Russian authorities really don't have the funds to do much about the problem, and they tend to not be too free with information. The Chinese, on the other hand, have to get information dragged out of them and only when they're "outed" by outside agencies.

The residents of Khabraovsk are already experieincing health problems: high blood pressure, etc. So my question is: are there any filters or other methodologies that the individual homeowner can do to make their drining water supply safer? Also does anyone have a handle on what the specific health risks of benzine are? (I'm assuming that the heavy metals have already sunk to the river bed becoming toxic to the fish population and ultimatly to the human food supply.)

Any help would be appreciated.


Frank A. Jur, P.E.
Electrical Engineer

 

[francesca]

Benzene is a carcinogen, so the risk associated with it is of cancer over a protracted exposure period (e.g. 30 years). The high blood pressure is probably a result of the stress from worry about the contamination.

Benzene is also a volatile organic compound (VOC), less dense than water, that has a low soluablility in water. This means that, if it remains in the water (instead of adsorbing onto the soil) it will be on the surface and will evaporate quickly, hopefully before the pollution plume reaches your friends. Unfortunately, if it's still on the water when it reaches them, the benzene will be in the air and inhalation is also an exposure pathway. Fortunately, benzene in the air breaks down within days and a few days exposure isn't enough to cause cancer.

Further, significant doses of benzene can be smelled in the air and tasted in water. Unfortunately, benzene is colorless, so it's not visible on the water like an oil slick would be.

The main risk to your friends is through ground water contamination. I'm not qualified to say how great that risk is from a contaminated river that presumably has significant flow. Common sense says that the benzene will be on the surface of the water and is most likely to adsorb to soil particles on the banks, in low concentrations. However, I reiterate that I'm not qualified to say even that much. (Three graduate environmental engineering courses doesn't an environmental engineer make.)

You're best off with the EPA website and this website looks promising, too.

You asked about ways to remove benzene from drinking water. The EPA site linked above says this:

The following treatment methods have been approved by EPA for removing benzene: Granular activated charcoal in combination with Packed Tower Aeration.

When reading the EPA site you'll notice that there are two concentrations specified for drinking water standards. The MCLG (Maximum Contaminent Level Goal) is always zero for a carcinogen, regardless of whether studies have shown it to be a risk at higher concentrations. The MCL (Maximum Contaminent Level) is the regulated concentration, which takes into account the ability to measure the contaminent. (For instance, you can't regulate 1 part per trillion (ppt) if you can only measure to an accuracy of 1 ppb.) For some contaminents, for instance arsenic, the risk of cancer due to exposure at the MCL is still greater than one in a million (which is the level of risk for which the EPA regulates). In non-carcinogens, this one in a million concentration is the MCLG, but as I said, for carcinogens, the MCLG is always zero.