Water hardness is an inherent characteristic of water that refers to the amount of minerals, particularly calcium, dissolved within it.3 The mineral content of water is highly dependent on the geology of a location.1 Areas with a more limestone-rich landscape will often have a harder water supply as a result.1,5 As water is undoubtedly used for bathing purposes, it is evident why water quality has been linked to skin conditions. Atopic dermatitis (AD), more commonly known as childhood eczema, is one of the most common skin afflictions found in infants.1 Symptoms include red & cracking rashes accompanied with itchy, dried out skin.4 The article that I have chosen seeks to reveal a potential association between these two occurrences.
The Journal of Allergy and
Clinical Immunology published a paper entitled "Association between
domestic water hardness, chlorine, and atopic dermatitis risk in early life:
A population-based cross-sectional study" in April 2016. This study sought
to determine how water hardness, measured in calcium carbonate concentration,
along with chlorine concentrations could affect the risk of development of
atopic dermatitis in infancy. Researchers enrolled roughly 1,300 babies - all
three months of age - from across the United Kingdom. Over the
course of about two and a half years, data was gathered on severity of AD,
transepidermal water loss (TEWL), and presence of filaggrin (FLG) mutations. TEWL
is a measure of "skin barrier function" and a mutation in FLG can
lead to "skin barrier impairments."1 This information was
then compared to water hardness data as well as a multitude of potentially
confounding factors. Among these factors were home location, sex, FLG mutation
presence, ethnicity, socioeconomic status and water softener ownership.1
A "hybrid variable" was created to make statistical analysis simpler;
a group that encompassed households with low [CaCO3] & low total
chlorine (CaL/ClL) was used as a baseline for comparison against the CaH/ClL,
CaL/ClH and CaH/ClH groups. It was found that each group had a higher incidence
of AD when compared to the baseline.1 After adjusting for some of
the confounding variables mentioned above, it was evident that water hardness'
effect on risk of AD was enhanced for both the CaH/ClL and the CaL/ClH groups. Not
only that, but also, the possession of an FLG mutation showed strong correlation
with AD symptoms.1 Overall, the study concluded that water hardness
plays an important role in determining the risk associated with developing AD
and may be of more concern to parents whose infants carry a filaggrin mutation.
A Huffington Post article authored by
Sarah Bell provides an overview of the results of the research described above.
Bell begins by describing the study's set-up: the researchers looked at [CaCO3]
and chlorine level. She also mentions how they considered the frequency of
bathing along with the use of bath products.2 The author goes on to
say that the babies were inspected to determine AD symptoms & natural skin
barrier integrity as well as "screened for the FLG gene."2
Ultimately, Bell makes the statement that "hard water is linked to an 87
percent increased risk of eczema for babies of three months of age."2
Beyond this, she provides a quote from one of the authors stating that they are
still unsure as to whether or not water hardness leads to skin conditions
directly or if these effects are a result of other water characteristics, like
pH, which is largely affected by the ion content of water. She concludes with
the idea that, hopefully, solutions are on their way due to a study that is to
follow this one wherein a device meant to lower water hardness is installed
into households with infants.
One important issue
that I found within Bell's overview of the study was how she chose to present
the findings. The way her statement reads, it sounds as if our interpretation
of the study should be that if one has hard water, regardless of other factors,
a baby's risk of developing childhood eczema is 87% higher. However, as I
mentioned before, the researchers created a "hybrid variable" for use
in their analysis. These three groups were compared to a baseline group whose
odds ratio was 1. Odds ratios were then calculated for each of the three
groups. After adjustment for the confounding factors I previously stated, an
adjusted odds ratio was calculated. Bell chose only to present the percentage that is represented by the CaH/ClL group's adjusted odds ratio
of 1.87. Not only that, but she failed to mention the majority of the
confounding factors for which this result was adjusted. On a different note,
there were a few places I thought could use some elaboration. One place in
particular is after her quote from one of the authors. It may have been
beneficial to include how pH and water hardness coincide because otherwise it
almost feels as if including that portion of the comment is irrelevant. Finally,
there is one technicality that the author overlooked. Bell stated that "infants
were screened for the FLG gene." In actuality, the babies were screened
for mutations in the FLG gene; a minor flaw but still a critical detail.
While the author
was not entirely factually inaccurate, she failed to provide an appropriate amount
of detail. If Bell had clarified some of the intricacies associated with the
result she presented, it could have made this result more meaningful to
readers - some of whom may be concerned parents. Combing through results to
find the most significant value in order shock readers is doing a disservice to
those who may not delve into the realm of academic reports. The target audience
of popular media should still be able to discover representative facts from
these outlets as opposed to sneaky extrapolations by authors that are meant to trigger
astonishment. While it is true that the
general conclusion of the journal article stated that hard water increases the
risk of developing atopic dermatitis, there are a multitude of factors that can
alter the amount of risk. Failure to mention these confounders does not bode well for
Bell's article. Not only that, but also, by toning down the amount of
scientific language in her article, some points are not explained; there are
statements without elaboration. Including even the slightest expansion on
certain points would have boosted the significance behind the facts that she
chose so selectively. It is for these reasons that
I would give Bell's article a 5 out of 10 in terms of how well her article
represents the findings published by the peer-reviewed journal.
1) Perkin, Michael R., Joanna
Craven, Kirsty Logan, David Strachan, Tom Marrs, Suzana Radulovic, Linda E.
Campbell, Stephanie F. Maccallum, W.h. Irwin Mclean, Gideon Lack, and Carsten
Flohr. "Association between Domestic Water Hardness, Chlorine, and Atopic
Dermatitis Risk in Early Life: A population-based Cross-sectional
Study." Journal of Allergy and Clinical Immunology 138.2
(2016): 509-16. Web.
2) Bell, Sarah Caroline.
"Water Quality Linked to Infant Skin Health." The Huffington
Post. 26 May 2016. Web.
<http://www.huffingtonpost.com/sarah-bell-2/water-quality-linked-to-infant-skin-health_b_10137450.html>
3) Perlman, Howard. "Water
Hardness." Hardness in Water, USGS Water Science School. Web.
<http://water.usgs.gov/edu/hardness.html>
4) "Fast Facts About
Atopic Dermatitis." U.S National Library of Medicine. U.S.
National Library of Medicine. Web.
<http://www.niams.nih.gov/health_info/atopic_dermatitis/atopic_dermatitis_ff.asp>
5) Sengupta, Pallav. “Potential Health Impacts of Hard Water.” International
Journal of Preventive Medicine 4.8 (2013): 866–875. Web. <https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3775162/>
Nice choice, Shannon! I also agree that while Bell's article was an easy and engaging read, it oversimplified the results of the study. This unfortunately led to an inaccurate interpretation of the study's data and an exaggerated depiction of the numbers presented in the original research. On the other hand, I still appreciate how the author introduces a potential solution to this issue, as well as the uncertainties that still haven't been addressed by the current study.
ReplyDeleteThanks Alex! When I first found this article, I didn't think I would be able to find a whole lot to analyze due to its length. But as you said, because it is such an easy read, oversimplification became one of the main issues that I found. And I agree, it was thoughtful of Bell to include the author's thoughts on this research as well as their plans for an upcoming study.
DeleteWhen I read the Huffington Post article the thing that stuck out to me the most was the FLG gene sentence. I think a lot of popular news outlets often don't accurately portray the affect a gene has on a certain disease. In the sense that they will say that if someone has a gene, they have the disease. When in actuality everyone has the gene, it's just mutations in the gene that cause the disease. I think that is really problematic and I'm glad you mentioned it in your post.
ReplyDeleteThanks for the comment Aubrey - I absolutely agree. While the mechanics of genetics can often be confusing to a non-expert, the journal clearly stated that "venous blood samples were screened for the 6 most common FLG mutations..." By overlooking that fact, Bell gave her readers some misinformation. Like you mentioned, and in this case in particular, mutations in the FLG gene are associated with a "compromised skin barrier" whereas the FLG gene itself helps create a strong barrier.
DeleteFor more information on FLG, check out this link: https://ghr.nlm.nih.gov/gene/FLG
Interesting topic! I would like to see the results of Flohr's upcoming study- From a brief search of atopic dermatitis it seems symptoms can range from being fairly short lived to lasting for years. I wonder how quickly/if symptoms will resolve with a water softening device.
ReplyDeleteGreat point Mary. I'd be curious to hear about those results as well. Especially for patients who suffer from long-term symptoms, an effective water softening device that could alleviate even some discomfort has great potential as a solution to their affliction!
DeleteThis actually surprises me. I initially was more concerned about drinking hard water than bathing in it. Did they do any control related to this? Like if a group bathed in CaH/ClH water but drank bottled water that was softened would they still see the effect. Likewise does hard water effect adults in any ways?
ReplyDeleteI also would be concerned about correlation and causation. Hard water can carry other characteristics other than high calcium or chloride. I think pH and other factors should be included before conclusions are draw. Also pH should be very easy to test for and included with the already collected data.
Interesting thought Daniel! To my knowledge, this study did not consider the ingestion of hard water. It seems to me that dermal exposure to hard water is what will lead to symptoms of AD as opposed to ingestion. After a quick search, there is evidence that having hard drinking water may affect the cardiovascular system.
DeleteIn terms of correlation and causation, the point you made is totally valid. The Huffington Post article included a quote from the author stating that they were unsure if pH could be responsible instead. The journal article also explores mechanisms of skin barrier breakdown, in terms of pH, in their discussion. That being said, it seems strange that they did not consider this avenue more.
I agree with you on the skimping of detail and results, Shannon. While I understand the need to appeal to the general public, the author did not even mention the fact that the authors looked at three configurations of water quality compared to a control group. This is highly misleading and undercuts the scientific rigor. The author of the Huff Post article states "The level of chlorine in the family's water supply was also taken into consideration...". Saying that chlorine was taken into consideration makes it sound like it was treated as a confounder, when it was a variable. In addition, one of the results of the study was that chlorine's effect was not clear. If the Huffington Post author introduced the fact that chlorine was "considered", it might have been helpful to the reader. Overall this is a very interesting topic, and I admit that the Huff Post article will probably be relatively successful because it is such an easy read.
ReplyDeleteThanks for the comment Aubrey! I definitely agree with you. It is too bad that Bell did not take the time to make her article as clear and accurate as possible. Yet, like you said, it's an easy read. Because of that and the fact that it was authored for a popular media outlet, it will reach a lot of people. It's unfortunate that these readers won't be receiving a more representative interpretation of the research.
DeleteGood job, Shannon! You chose an interesting topic and have illustrated the article quite clearly. I agree with your conclusion that while the author was not entirely factually inaccurate, she failed to provide an appropriate amount of detail. I am wondering two things. One is that why the researchers choose the group that encompassed households with low [CaCO3] & low total chlorine (CaL/ClL) as a baseline for comparison? The other is that how Bell made the statement that "hard water is linked to an 87 percent increased risk of eczema for babies of three months of age." Refreshing topic and well done!
ReplyDeleteThanks Cherry! I'm going to do my best to address your questions. Based on my interpretation of the journal, the researchers chose to combine their variables (CaCO3 concentration & chlorine level) into a hybrid variable so that they could investigate the associations between this hybrid variable and some confounding variables. Ideally, households in the CaL/ClL group should show little to no signs of AD which is why they assigned it as the baseline group (because there is no assumed relationship). When there are changes in the hybrid variable, such as CaH/ClH, one would assume that there are changes in the severity of AD symptoms as well. By comparing these other three groups to the baseline, you may be able to make some generalizations. For example, if the concentration of CaCO3 went up and so did signs of AD (compared to the baseline), you might be able to say that these are related. I hope that didn't make things even more confusing!
DeleteIn terms of why Bell made the statement that "hard water is linked to an 87 percent increased risk of eczema for babies of three months of age," this is related to the adjusted odds ratio that she chose to present. The baseline group, CaL/ClL, had an odds ratio of 1, meaning that the exposure to this kind of water doesn't affect outcomes related to AD. Any ratio higher than this would mean that the odds that exposure to hard water leads to AD symptoms are higher. So, after adjusting for confounding variables, the CaH/ClL group had an adjusted odds ratio of 1.87. This value is 87% higher than the baseline of 1 meaning that the odds of developing AD from water in this group is 87% higher than if one had been exposed to water from the baseline group. I know that was a lot, but I hope it makes sense and doesn't leave you with more questions!
I agree with your assessment of the author's coverage of the original research article. Reading both publications, it seems that the news article raises more questions than it answers due to the details it left out or misrepresented. Unfortunately, I am not sure that the average reader would come to this conclusion, which is why I think it is very important that more people approaches these news articles with a more critical eye. Good job, Shannon!
ReplyDeleteThanks Liz! I have to agree. It's rather unfortunate that more people will come across Bell's misrepresentation of the journal publication than the research article itself. But like you said, people should approach popular media sources with a more critical eye. If they did, it may lead to further investigation on their part where they could perhaps uncover some more meaningful information!
DeleteIt does seem like the article and Huff Post write-up raise even more questions than it does provide answers. I find it pretty disturbing that the Huff Post article is putting CaCO3 in such a negative light (like it is a terribly toxic substance). If you look up the MSDS for CaCO3 there are virtually no health risks with the compound. In fact, we all know that it is often used as a diet supplement for heartburn and indigestion. But I can certainly understand that infants who are predisposed to AD and other skin conditions how the level of CaCO3 may effect them...often times infants and babies are more susceptible to skin irritation. I do think it would be interesting to learn about the mechanism of action and the actual connection between AD and CaCO3 (and chlorine). I also wonder why the 3 month old age is the age group examined for this research. Shannon, I do think you may want to be careful with your definition of pH above in your post. I do think that by your definition any ion in solution will contribute to pH.
ReplyDeleteThanks for bringing that up Rory! I hadn't really thought about other potential health effects of CaCO3 while I wrote this. It seems to me that if there are virtually no health risks other than it's potential connection to AD, researchers should want to explore the true mechanism of action in terms of how AD symptoms are generated due to hard water exposure. As mentioned in the post, the researchers were unsure if the effects were a direct result of water hardness or if they were potentially due to pH.
DeleteI was curious as to why they specificially looked at 3 months old as well; I'm not quite sure what the significance of the that age is.
And thank you for calling me out on my definition of pH. I see now that my generalization is in fact inaccurate (how ironic!) As stated in the journal publication, "The higher domestic water CaCO3 concentration, the higher its alkalinity and the higher the pH." I suppose including that statement from the journal's discussion section might have been more representative of what I was meaning to get across.
Very interesting topic! I too only thought of the hardness of water was a concern in relation to drinking water. Overall, I think this study has a lot of conditional factors which could lead to larger errors. How some of these factors are taken into consideration are beyond me. On that note, I highly doubt that all the babies were bathed in the same water for 2 years straight. Some would move or travel with families and therefore change their water source. How would this be taken into account? I'm glad to see that the authors of the journal publication did not state any radical conclusions and used caution when doing so. Great blog post.
ReplyDeleteThat's a great question! I hadn't thought about that and I'd be interested to know if the researchers thought about considering travel as a confounder.
DeleteGreat analysis of the Huffington Post article. I agree that Bell inflated the results of the study by stating that any level of hardness in water can be linked to a high risk of infant ezcema. I also appreciated your background on water hardness; it provided for a good segway into the more technical aspects of the scientific article.
ReplyDeleteI'm interested to see what kind of results a similar study would generate in the United States. FLG mutations are more common in Europe (https://www.ncbi.nlm.nih.gov/pubmed/22960809), so it makes sense that the researchers emphasized that those with FLG mutations are more likely to develop AD due to water hardness. The confounding factors listed were home location, gender, race, etc. It'd be interesting to compare data from the US and UK.
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DeleteThanks for pointing that out Kesiree. I had no idea that FLG mutations are more common in Europe. It would definitely be interesting to see results for a US based study.
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