Guy sez, "I am a cell and molecular biologist located in Montreal, and interested in the environment, history and disease-related issues--among other things.
I published last summer, in the July issue of the International Journal of Tuberculosis and Lung Disease (IJTLD), a peer-reviewed international scientific journal, a paper about the impact of air pollution by coal on the emergence of tuberculosis during industrialization, and nowadays in China, entitled
'Historical Statistics Support a Hypothesis linking Tuberculosis and Air Pollution Caused by Coal.' The figure 4 of the paper is very striking in that it strongly suggests a direct correlation between overall coal consumption in China, and TB disease in the last 25 years. As you know, China is very big on coal consumption -- some analysts say that one coal plant opens per month in Asia."
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What is "direct correlation"? Is a tighter correlation indicative of something more significant that...correlation?
All I see is two things that are probably just a sample of population explosion result metrics. I would wager to say that TB is caused by crowded conditions of increasing population, and coal usage/pollution follows the increase as well. I bet other communicable diseases follow this same pattern.
I thought same as Keneke, brief scan of paper restored confidence in peer-review process. Paper goes beyond just proposing correlation...
Funny that the authors use "coal consumption," because the word "consumption" was considered Tuberculosis during England's industrial revolution.
A direct correlation is a term that describes the nature of a correlation. A correlation may either be direct or indirect (also you can think of it as positive or negative). Direct correlations mean that as one variable increases, another does as well, whereas an indirect correlation means when one variable increases the other decreases.
Hope that clears it up for you.
Also, it also might be helpful to note that in general, the scientific community does not equate correlation with causation. A correlation is still interesting, even if its still ambiguous whether or not the relationship is causal.
What is the compelling reason to believe that these two trends are connected? China has also gotten more crowded over the same time period, especially in urban areas, a trend that could cause both increase demand for coal and increased transmission of TB.
Readers might be interested to learn of another interesting correlation between piracy and global warming. Clearly, the historical data support a hypothesis linking the two.
Well (and diplomatically) put, Marisa.
Well, the US population increased dramatically from 1953 to 2001 while TB cases went down dramatically. So it doesn't seem like population density would correlate (directly, as least) with TB.
(1950 population: 161 million, 2000 population: 291 million.)
MYCOPHAGE: I couldn't put it more bluntly than DCULBERSON did, as for density of population. The decline of TB after World War Two remains somewhat of a mystery. One thing is that electrification seems to have improved a lot the indoor air quality of dwellings, which I believe may also explain why allergies have increased during the last 50 years.
There is also a strong correlation between the use of the word correlation and skepticism, for some reason, as if using the C word was a sin. BTW, in this paper, I used the Pearson partial correlation for my analysis.
That air pollution impacts on tuberculosis is known, and increasingly studied, however up to now nobody specifically investigated the impact of coal I believe. The extent to which air pollution will impact on the emergence of TB remains to be determined. That it is of paramount importance is my opinion based on this analysis.
I posted the full paper on Scribd for those interested:
http://www.scribd.com/doc/179196/Historical-statistics-support-a-hypothesis-linking-tuberculosis-and-air-pollution-caused-by-coal
The decline of TB after World War Two remains somewhat of a mystery.
I guess it has nothing to do with the fact that childhood vaccination against the disease only became widespread after World War Two, then...
Actually the number of coal plants opening is far higher than one in Asia per month. See:
http://www.nytimes.com/2006/06/11/business/worldbusiness/11chinacoal.html?ex=1307678400en=e9ac1f6255a24fd8ei=5088partner=rssnytemc=rss
"Every week to 10 days, another coal-fired power plant opens somewhere in China that is big enough to serve all the households in Dallas or San Diego."
Correlation, rather than causation, is not a word for skeptics but for honest scientists. There is no valid way to derive causal relationships from correlations period. Correlations are interesting only insofar as it tells us that a relationship might be interesting to look at.
In the case of piracy and global warming, we know outside information that make that relationship much less interesting. ;)
Wait, where are all the lunatics? I've just come over from the global warming thread, spoiling for a fight - and all I find here are pleasant, intelligent people having a conversation... Don't the skeptics even want to come over and quibble about every point on the graph? I just don't understand.
Guy:
I know what a correlation is, and I don't think I'm smarter than you. That's probably kind of refreshing right about now.
Others:
Whenever people complain about simplified science writing in in the news? Well, this is why scientists don't take it straight to the people. The people don't understand the methodology but somehow think they are smarter than the people who sit around all day thinking about these things.
This appears in a peer-reviewed journal. Those peers are probably much smarter than you. If you think you spot a hole, you're either smarter than the reviewers or a lot dumber.
One bet is safer than the other.
JY YANG: The BCG vaccine has an efficacy around 50%. So you might as well toss a coin. BCG was not used in the US or Netherlands but the disease decreased in those countries after WWII.
SMMIGB: Well well what can I say loll. There is a cloud of CO over Asia, as can be seen by the UofT MOPITT satellite imaging: http://www.eos.ucar.edu/mopitt/data/plots/mapsv3_mon.html
MARISA: "In the case of piracy and global warming, we know outside information that make that relationship much less interesting." -- What the hell is that supposed to mean? Also, are you trying to suggest that I am dishonest? I believe that the aforementioned data and statistics cannot be discrediting; however, you are entitled to your opinion. BTW, I don't really do blah blah blah.
is there ANY possibility that spores are suviving in the coal itself (and subsequent burning) from way back in the day when it used to be a germ-riddled peat bog? that'd be wild... have any organisms been cultured from coal before? (i ask only because there are bacteria that can survive in nuclear cores...hardy little buggers)
The
Morbidity and Mortality Weekly Report by the
Centers for Disease Control and Prevention Covers the BCG vaccine efficacy in its April 26, 1996 issue:
Which is quoted from reference 39:
Thus the 50% efficacy seems to be overly optimistic (at least for adults).
MIRKO JUNGE: Agreed. Litterature reported efficacy of the BCG vaccine from 0% to 80%. Bottomline it seemed to work a little bit on children.
SEXYROBOT: TB plagues the aliens of planet Mars as well. ;-)
SEXYROBOT: Mycobacterium tuberculosis doesn't form endospores, and a coal fire would be pretty hard on even those ridiculously hardy species that do.
Endospores can apparently last indefinitely.
Viable bacterial endospores have been recovered and from pockets in 250 Million year-old salt crystals.
When things got salty, the bacteria dried up their DNA etc. and waited 250 MILLION years until someone plucked them out and woke them up in a nice warm petri dish.
RodriquezSeeds, right-wing websites haven't furnished their regulars with coal/tuberculosis talking points, so this thread gets to discuss science.
Guy: The comment about the correlation between piracy and global warming was directed to mycophage. He brought it up, and I referred to it because it exemplified the case where strong, direct correlations are found but do not tell us much since we have other information.
Im not saying you're dishonest, but I do disagree with you if you think using the word correlation is only for skeptics (or is that not what you were claiming?)
Guy: Hm. I see your point about population and TB -- though I think there are social reasons why dense populations in China are more likely to be associated with increased disease transmission, e.g. the belief in traditional Chinese medicine that expectoration (spitting out mucus) is healthy.
That made me think, though: Coal use has risen to record">http://www.usatoday.com/money/industries/energy/2007-10-28-coal_N.htm>record levels in the USA, during a time when TB is on the decline in that country. Does that data then mitigate the significance of your conclusion?
Incidentally, whether you use the Pearson is irrelevant to whether you're detecting causation, so I'm not sure why you mention it.
Mycophage: The idea that increased density and transmission go along of course is true. However it does not explain why only 10% of those infected get the disease. Economic status, poverty, however important a factor, seems not to explain the whole picture of TB, as overall poverty decreased in China in the last 20 years whereas TB increased. In fact, there may have been confusion between environmental and socioeconomic factors as poor people live in lesser conditions and with lower grades of fuel.
However that the use of coal has overall increased in the US, the indoor use of coal has nearly disappeared, and the coal is burned in more efficient coal plants than say 50 years ago.
I wanted to say that I did not use the word correlation lightly, and that saying the "C" word ain't no sacrilege. Of course, more experiments need to be done to enforce the link coal/TB so we can speak of clear causation.