How many spots do you think there are on all of the Dalmatians in the Disney movie 101 Dalmatians (the original 1961 cartoon version, not the remake with Glenn Close as Cruella de Vil)?  According to the Internet Movie Database there are 6,469,952 spots.  And just think, in the days before CGI, artists had to draw all of those spots by hand.  But how do we know if this count is accurate?    Well if on a rainy Saturday afternoon your kids are being more hyperactive (or from their own point of view more ebullient) than usual, just plop them down in front of the TV, put on the Dalmatian movie, and set them to counting spots shot by shot and see how far they get.  Little do they know, they will be objectively measuring and verifying something–they will be doing the same thing real scientists do to answer serious scientific conundrums.

Measuring, or what Richard Feynman called “quantitative observation” in his Lectures on Physics, is one of the defining features of science.  Some scientists, most notably Steven Hawking, even believe that science is nothing but measuring – if something can’t be measured it isn’t science.  But measuring is also fraught with surprising practical, philosophical, and political implications – and even important social consequences – as demonstrated by a recent study of the Alberta tar sands.

An Alberta tar sands study by the fresh water ecologist Dr. David Schindler of the University of Alberta and his colleagues initially caused a measure of controversy in Canada, garnering the attention of the Canadian Parliament and press.  This study, published in the Proceedings of the National Academy of Science, was controversial because it contradicted government and industry claims that pollutants were naturally occurring and not the result of mining the tar sands (Schindler, 2009).

What and where are the tar sands?  Tar sands is the common name for oil sands, which are, as the name implies, oil but in a semi-solid state.  They consist of bitumen mixed with quartz sand and other rocks and minerals. Picture the goopy mixture of molasses and mud that Creulla de Vil fell into at the end of the 101 Dalmations.  Oil in this form is highly viscous and needs to be modified or processed to turn it into useful crude. The bitumen is mixed with warm water and other solvents to extract the oil.  There are some tar sands in the United States, mostly in Alabama, California, and Utah.  The U.S. Geological Survey has estimated that  tar sands in the U.S. hold about 11 billion recoverable barrels (the U.S used almost 7 billion barrels last year)..  However they are scattered, remote, and lack the water resources necessary for production at the source.  As such it has not been economically feasible or profitable to develop these tar sands.

Alberta’s tar sands on the other hand, contain an estimated 175 billion barrels of recoverable oil (the largest oil deposits in the world outside of the Middle East), and are concentrated in three locations north of the city of Edmonton, through which the Athabasca and Peace rivers run. Geologists call it the McMurray geological formation.

A government/industry study called RAMP (Regional Aquatic Monitoring Program) was set up to monitor the environmental effects of mining the tar sands. This was a rather ad hoc study that set out to monitor the water and sediment quality in rivers, and the health of the fish and plant populations (Ayles, 2004). It concluded that pollutants near development sites occurred naturally in the tar sands and were not the result of development.   But ecologists like Schindler were sceptical because the statistical sampling techniques used in the RAMP study were inadequate – as if you were to count the number of spots in 101 Dalmatians by watching one scene only and making a rough extrapolation. A review of RAMP study noted: “There is little discussion of each station’s attributes, the quality of data, data limitations, and most importantly what role the station plays in the overall monitoring program.” (Ayles,2004)  Additionally, chemical tests were done with poor levels of detection – as if you were to count Dalmatian spots with one eye closed.   For this reason Schindler decided to carry out his own study to examine the effects of tar sand mining.

What did they do differently? Schindler and his team took samples from more locations than the RAMP study, from areas both upstream and downstream of tar sands mining.  This was an important factor to examine because it allowed Schindler to tease out the effects of natural pollutant seepage from the tar sands (this is what you would see upstream of the mining sites) to the additional effects that result from mining the oil (which you would see downstream).

In his study, Schindler used polyethylene membrane devices (PMDs), which are porous devices that can be placed in water and mimic fish gills so that researchers can measure the amounts of chemicals in said water.  What did the study look for?   Pollutants called polycyclic aromatic compounds (PACs), which are among the ‘priority pollutants’ listed by the U.S. Environmental Protection Agency  -they are known to be toxic to aquatic animal life in low concentrations.

The results from their measurements showed that “…current background PAC concentrations in surface soils, vegetation, snow, and runoff over a broad area of boreal forest may be greater than true background concentrations contributed naturally by oil sands in the region.”   Sites in and along the Athabasca River that were far from the tar sand mines, and with no deforestation or mining development, are “closely comparable with concentrations in remote Canadian arctic rivers.”  In other words, test sites downstream of mining had higher concentrations of pollutants than those either upstream (with naturally occurring pollutants) or in distant locations where the effects of mining would be diminished. By comparison, at locations where the impact of mining the tar sands was heaviest, concentrations of pollutants were “10 – to nearly 50 – fold greater.”  (Schindler, 2009).  Mining clearly caused an increase in the amount of pollutants in the surrounding area, a finding at odds with the previous RAMP study.

Schindler’s findings led the provincial and federal governments, as well as the Royal Society of Canada, to set up panels to review the controversial findings.  In October, Alberta’s Department of the Environment announced that they were setting up a new agency whose work will be peer-reviewed and ‘arms-length’ from government interference. They claim that this new agency will measure the environmental impact of tar sands mining in more locations, with improved methods, and greater public transparency.

Last month, another study was published at the annual meeting of the Society of Environmental Toxicology and Chemistry that independently confirmed the findings of Schindler’s work. These scientists studied sediments that have been collecting in lakes near the tar sands over the past century.  Their work showed that concentrations of the pollutants measured in recent sediments are between 2 and 23 times greater than in pre-1960 sediments, before widespread mining began.

The controversy surrounding Dr.Schindler and colleagues’ study of the ecological impact of the Alberta tar sands serves as a reminder of a couple of important ideas about science.  The first is that what we can learn from science is limited by how experiments or studies are designed, the accuracy and reliability of the methods and tools scientists use to make measurements, and scientists choose to measure. The less stringent government RAMP study gave data that underestimated the effects of mining the tar sands, a conclusion that if left unexamined could have had damaging effects to the environment.  The entire RAMP study was peer-reviewed at 5-year intervals, instead of each finding being reviewed by independent experts and made public.

The second idea is the commonplace one that science can describe the factual world but can’t give us values. It can tell us how many spots there are on 101 Dalmatians but can’t tell us if we should skin them for a new fur coat.   But we also can’t make sound decisions that have social, economic, and environmental impacts, like the ones involving tar sands development, without the best factual measurements that science can provide.  Only through, rigorous, sceptical, replicable, and critically evaluated science can we get an accurate measure of the world around us – whether of pollutants in the tar sands or the number of spots on 101 Dalmatians – and only then can we make logical, informed decisions.

Jeff Betz is a grad student in the science communication program at Laurentian University in Canada, and has been working as an intern at Harvard’s Museum of Comparative Zoology.


Ayles, Burton et al. Oil sands regional aquatic monitoring program (RAMP) scientific peer review of the five year report (1997-2001) Feb.,13,2004. <>

Humphries, Marc.  Report for Congress: North American oil sands.  Congressional research service 17/1/2008. <>

Kirk, Jane, et al. ”Trends in atmospheric deposition of inorganic contaminants to the Alberta oil sands region obtained from snowmelt and lake sediment core measurements”  Paper delivered to the Society of Environmental Toxicology and Chemistry of North America, 33rd annual meeting, 11-15 Nov., 2012.

Schindler, David, et al. “Oil sands development contributes polycyclic aromatic compounds to the Athabasca and its tributaries.”  Proceedings of the national academy of science, December 29, 2009, vol.106 no.52, pp 22346-22351.

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