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The deadly truth of every gallon spilled

(An editorial from On Wings Of Care Founder  Bonny L. Schumaker)
2011 December 10 

We are told that 200 million gallons of "Louisiana sweet crude" oil and 2 million gallons of Corexit dispersant were added to the Gulf of Mexico in the Deepwater Horizon disaster of 2010.1 Leaving aside speculation as to how much those numbers should be increased to reflect reality in the Gulf today, and without going into scientific discussion of the merits of using chemical dispersants or dangers of crude oil pollution, let's consider what these numbers mean.

The US transportation sector consumes about 220 billion gallons of liquid hydrocarbon fuel per year.2 So all the oil that gushed into the Gulf of Mexico last year would have been enough to supply the entire US transportation needs for about -- eight hours.

The Louisiana Superdome -- the world's largest enclosed stadium -- has a volume of about 125 million cubic feet, or about 1 billion gallons.  So all the 200 million gallons of crude that gushed into the Gulf would have fit into just one-fifth of the Superdome.  The Gulf of Mexico is estimated to have a volume of  660 quadrillion gallons --  the equivalent of 660 million Superdomes!  The ratio of those two quantities is a tiny 0.3 to one billion -- 0.3 ppb.

Recall that BP CEO Tony Hayward said "The Gulf of Mexico is a very big ocean.  The amount of volume of oil and dispersant we are putting into it is tiny in relation to the total water volume."  (Tony Hayward, 2010 May 14)  The oil industry is famous for saying that "The solution to pollution is dilution."   Are they right?  Have we over-reacted a bit?


But wait.  Let's not forget that both crude oil and Corexit are toxic to life.  They are known to damage every bodily organ and system -- brain, heart, liver, kidneys, skin, respiratory, circulatory, immune, nervous, reproductive, and endocrine.  They cause cancer and other diseases,  DNA damage, and multi-generational birth defects.3 Our government's National Institute  for Occupational Safety and Health (NIOSH) says that crude oil is carcinogenic in concentrations as small as 80 parts per billion (80 ppb) when inhaled, ingested, or otherwise contacted closely.4 

To dilute something to a concentration of 80 ppb means to mix it with the reciprocal of 80 ppb -- or 12.5 million times -- as much water.   The resulting ratio of the two quantities --  the thing being diluted, and water -- is 80 to one billion (80 ppb). Here's an example to bring this home:  A standard bathtub holds about 50 gallons.  A concentration of 250 ppb of crude oil -- three times larger (more dangerous) than the aforementioned NIOSH safe limit -- would result from putting 0.01 teaspoon -- about one drop -- in a bathtub full of water.5

It is thus dangerous fallacy to refer only to the number of gallons of crude oil spilled in the Gulf of Mexico.  It is as fatally misleading as telling someone not to worry because, after all, you spilled barely a teaspoon of bleach into their large mug of coffee!

Making it worse, humans and large marine mammals such as dolphins and whales are considerably more robust to this kind of poisoning than are the smaller, less complex marine animals -- the animals whose normal lifespans are less than a year or two and who contribute heartily to the food chain of the Gulf.  For them, the unsurvivable concentration of crude oil in sea water is much less than 80 ppb.

What does all this mean, exactly?  If crude oil (or a 100:1 mix of crude and Corexit) is toxic until it  is diluted to a "safe" concentration of 80 ppb, then the effective volume that results from thoroughly mixing 200 million gallons of crude with seawater could be as great as 12.5 million times 200 million gallons -- or 2,500 trillion gallons of toxic water.  That would fill 2.5 million Superdomes and is enough to cover uniformly all five Gulf Coast states6 -- Florida, Alabama, Mississippi, Louisiana, and Texas, with a 25-ft-deep toxic lake where life would be unsustainable. Put another way,  it could cover all of the US Lower 48 states with .046 inches, or 1.2 millimeters, of toxic, carcinogenic rain.7

If we are willing to accept a limit that is 50 times higher than the NIOSH safe limit of 80 ppb, or a concentration of about 4000 ppb (4 ppm), we would now be at a concentration that corresponds to a water quality largely unacceptable even for industrial use, a level of impurity so high that water treatment plants couldn't even bring it up to drinkable quality.  If we take THAT concentration as acceptable for marine life in the Gulf, then 200 million gallons of crude oil, diluted by mixing to 4 ppm, is enough toxic water to cover all five Gulf coast states uniformly with a 6-inch-deep toxic lake.

Think maybe we've done some damage?

1It is also sometimes stated in terms of barrels (bbl).  A barrel of oil is equivalent to 42 US gallons.  200 million gallons is equal to about 4.8 million barrels.


3See, e.g., or EPA warnings about crude oil components such as benzene.

5In metric units, one liter (l) -- or 1000 millileters (ml) -- is equal to 1000 cubic centimeters (cc).  Conversely, 1 cubic  meter (m3) is precisely equal to 1000 liters, or 1,000,000 (one million) ml.  So-called "standard units" have no such convenient relations. One cubic foot is equal to about 7.48 US gallons, or 957.5 fl oz. Since there are approximately 2.54 cm per standard inch, and 12 inches per foot, one cubic foot  is approximately 28.3 liters, and one gallon is approximately 3.8 liters.

Metric units have another advantage when comparing volume to weight of water: For pure water on Earth's surface, 1 cc weighs 1 gram (g), or 1000 milligrams (mg).  Equivalently, 1 liter (l) -- 1000 ml, weighs 1000 gm, or 1 kilogram (kg).   In contrast, one US pound (lb), defined as 16 dry ounces (oz), implies the awkward relation  that 1 gal weighs about 8.3 lb or 133.5 oz.   Using cubic feet instead of gallons is no better:  one cubic foot of water weighs a little over 1,012 oz.  And 1 fl oz of water weighs about 1.06 dry oz!

When comparing units of volume to other units of volume, fractions or percentages are convenient.  One part per million (1 ppm) -- equal to 1000 parts per billion (ppb), is the same as 1 cubic centimeter per cubic meter, or  1 cc/m3.  It is also equal to approximately 0.58 teaspoons per cubic foot (1 fl oz = 6 tsp). For water at Earth's surface, these true fractions (volume compared to volume) are essentially identical to densities (weight compared to volume), because 1 ml of water weighs 1 mg -- equivalently, 1000 l, or 1 cubic meter, of water weighs 1 kg.  This is not true of substances other than water.  For example, 1 ml of Texas crude oil, at 60° F, weighs 0.873 mg.  These details don't change the substance of the arguments in this note, however.

6The area of Texas is 261,232 sq mi, or 7.283 trillion sq ft.  That area, with a height of 1 ft, would have a volume of  55 trillion US gallons.  The area of Louisiana is 51,843 sq mi. Area of Mississippi is  48,434 sq mi.  The area of Alabama is 52,423 sq mi.   The area of Florida is 65,795 sq mi.  1 mi = 5,280 ft.  The combined area of LA, MS, AL, and FL is 218,495 sq mi, or  6.091291 trillion sq ft.  That area, with a height of 1 ft, would have a volume of 45.563 trillion gallons.  The Deepwater Horizon's resulting 2,500 trillion gallons of toxic water was enough to  cover the combined Gulf Coast states of LA, MS, AL, and FL with a 55-ft deep toxic lake, or the state of TX with a 50-ft-deep toxic lake.  Alternatively, it was enough to cover all five Gulf coast states -- including Texas, with a 25-ft deep toxic lake.

7Together, the 48 contiguous states and D.C. occupy a combined area of 3.1 million square miles, or 87 quadrillion square feet.  x 1 ft = 650 quadrillion gallons.  Therefore 2500 trillion gallons of 80 ppb crude would cover the lower 48 and DC with 0.046 inches, or 1.2 mm, of  toxic water.


Copyright © 2011 On Wings Of Care, Inc. and Bonny L. Schumaker, Ph.D.  All Rights Reserved.