Air pollution this, air pollution that. We all know about it
when mentioned in small talks about respiratory problems (Davis, 2002), but hardly anyone goes out of one’s way to do something
about it. What if, some of these air pollutants were found to induce a more profound change - heritable
DNA mutations, for example - that could forever change your generation’s
genome? Freaky.
A study was conducted in Hamilton Harbor and Lake Ontario to
test air pollutants produced from steel mills nearby. A rural reference point
30 km away from the immediate-polluted areas was chosen to serve as a control.
An equal number of fecund male and female mice were picked at random and were
exposed to the three sites (rural-pristine, Hamilton, and Lake Ontario) for 10
weeks (Somers et al. 2002) They were brought into the lab for their own DNA analysis and their
reproducibility, to observe any effects on DNA of future generations.
The results were shocking in the least. They discovered that
the paternal germline was significantly affected by the mutagens closer to the
polluted area, while the maternal germline was not significantly affected. Male
germ cells that have not yet gone through meiosis were shown to be sensitive to
airborne emissions near steel mills. This study was only conducted for 10
weeks, and the significantly elevated mutation rate is in every aspect a reason
for concern. Globally, hundreds of thousands of humans live or work in
industrial areas near steel mills and are incidentally or intentionally exposed
to airborne emissions. Whether workers or innocent bystanders, they might be at
risk of increased heritable mutation through exposed fathers. Of course, there
should be a more thorough investigation of the genetic hazards associated with
exposure (whether incidental or occupational) to contaminated air in urban and
industrial areas, but it is never foolish to take precautions.
References:
Somers, C., Yauk, C., White, P., Parfett, C., Quinn, J. “Air
pollution induces heritable DNA mutations.” PNAS
99(25): 15904-15907. 10 Dec. 2002.
Davis, M. "Recessions and Health: The Impact of Economic Trends on Air Pollution in California." American Journal of Public Health 102:10, 1951-1956. 2002.
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What kind of precautions do you think should be taken to protect one's self from industrial air pollution, excluding simply avoiding areas of industrial emissions as much as possible?
ReplyDeleteIt's difficult to say for sure. Simply avoiding areas of industrial emissions might not be practical for many people living in urban areas any way. I know they have air filtering for indoors, but people will still get exposed if they work near industrial areas anyway. Masks can come in handy. I know in the states, it might look ridiculous wearing those masks that cover up below the eyes, but in several Asian countries, wearing masks is not a problem to avoid urban pollution.
DeleteIt's interesting that only the paternal germline was significantly affected. Is there any study that explains why paternal germline is more vulnerable to mutagens?
ReplyDeleteI'm not sure, I never got a chance to come across that information.
DeleteHow were the paternal germ cell lines affected, exactly? Did the mutation show up in the subsequent offspring, or were the gametes DNA-sequenced?
ReplyDeleteI tried to look more into detail, but I wasn't about to find anything more about the actual effects of paternal germlines by the pollution. But I think the original paper mentioned that the mutation shows up in the subsequent offspring genome. Other than that, I can't be more of help.
DeleteThis study only looked at the effects of steel mill pollution on mice, so I can't help but wonder if there are implications from other types of air pollution. Since we live in Houston, I immediately think of oil refineries.
ReplyDeleteHow about males that work in scientific laboratories handling chemicals? Generally, these men are smarter, so could they be putting future populations at risk? Intelligence is somewhat heritable, so will many future geniuses have physical abnormalities?
ReplyDeleteLike Marisol said, this study is exclusively on steel mills and the byproducts that come out as air pollution. Males that work in scientific laboratories should be avoiding inhaling fumes anyway, and properly attired to avoid any direct contact with chemicals, so I don't think we have much to worry about there.
DeleteLike Martin, I find it really interesting that only the paternal germlines were significantly affected. Were all of the exposed paternal germlines mutated in the same sequence, or were there just all-around higher levels of mutation? If the mutations were in a specific sequence, then maybe it would be interesting to see how this sequence differs in females. Furthermore, were the mutations seen in both male and female offspring, or just the males? Did these mutations decrease fitness?
ReplyDeleteWhen we talk about mutation to DNA, we tend to think first about radiation. What is the pathway of the inhalation of toxic chemical leading to the mutation of genomes?
ReplyDeleteIt is interesting to see studies done showing potential dangers of living near factories and mills, especially since many urban/high density areas are located near factories. I also thought it was interesting to read about heritable changes caused by steel mills because of the text book example of peppered moths changing color due to smoke from the industrial revolution.
ReplyDelete-Jeff Brown
What chemicals were present in these industrial areas? Did scientists pinpoint which of the substances present were the offending mutagens? Because industry is so ubiquitous, especially in developed countries like the US, it would be difficult to impossible to limit our exposure to all industrial processes. I would think the next step would be for scientists to determine what specifically can cause results like these and to extent we can extrapolate to other industries.
ReplyDeleteIt is interesting that people can be so susceptible to steel mills only in the course of 10 days. They should do more research on people who work on the mills and nearby residents to pinpoint the differences the industrial world can have on individuals.
ReplyDeleteI am extremely surprised to hear that in just 10 weeks such a noticeable change was observed! It makes you wonder how urban development over the past two centuries has changed, or even dictated evolution in any organisms. It would be interesting to compare DNA changes in humans, mice, and other organisms that are commonly found in human areas over the past few decades, or beyond if possible, to see how anthropogenic effects really have an influence on evolution.
ReplyDeleteThis was very interesting! What specifically about meiosis do you think gave the maternal germline a longer lifespan?
ReplyDeleteGreat post! Like some others, I am really interested in why it only affected males and not the females and that it caused mutations so quickly. I hope that this study sparked some interest and it will be looked into more closely because it would be extremely hazardous for humans to undergo such mutations.
ReplyDeleteWow this was very interesting, well-written, engaging, and informative!! It is very interesting that the paternal germline was significantly affected by the mutagens closer to the polluted area, while the maternal germline was not. Hopefully a more thorough investigation of the effects of exposure of pollutants can be conducted.
ReplyDelete-Daniel Johnson
First off: well done. I found this post to be extremely interesting. Just like a few others from previous comments, I still have questions about what kind of chemical causes the mutation, and if the mutagen is also present in other byproducts of industry aside from steel mills. Possibly a topic for further researh? I also think it would have been interesting to address if other organisms were affected, besides the obvious mice and humans.
ReplyDelete-Melissa Martinez
The first paragraph was a great way to make the blog post relatable to the reader, thus making it engaging. I found it very interesting that the steel mill pollutants would affect the paternal germline more than they would affect the maternal germline. Perhaps there's a particular gene in the male germ cells that is susceptible to steel mill pollutants, or perhaps there's a particular gene in the female germ cells that make them resistant to the pollutants. Have these findings resulted in more studies on this topic?
ReplyDeleteOn the topic of evolution, why do you think that the maternal germline is unaffected, but the paternal is? Has adaptation already taken place? Perhaps evolutionary forces simply work more efficiently to the maternal germline compared to the paternal. Or, perhaps the pollution that affects the paternal germline is not strong enough to warrant any major changes.
ReplyDelete