Tuesday, February 19, 2013

The weekly dose: are there measurable risks associated with Clorox bleach?

{Once a week we will examine the evidence pertaining to a health-related matter-- usually something that would be of interest to families with young children.  You should expect a thought out and concise summary of the issue along with several solid references-- there may or may not be a true conclusion.  Sometimes, “more research is needed”  really is the best answer that can be given.  Please leave me a comment if you have thoughts, questions, or another topic idea that you’d like addressed.}

After discovering the other week that it really is better to avoid food coloring, I’ve been curious about other “natural” claims that I often run into, but usually ignore.  As a former dental assistant, infection control is something that is close to my heart, so I thought I’d start thinking about cleaning products.

Clorox bleach happens to be my favorite home disinfectant for the bathroom and kitchen-- there’s just something about it that smells so clean, and it does such a good job making sinks look sparkling clean, and making mold and mildew disappear.  Not surprisingly though, the greener/more natural crowd does not look kindly upon Clorox bleach.  A quick google search about “household use of bleach as a disinfectant” brings up quite a range of hits, from an article from Reader’s Digest listing the amazing things you can do with bleach, to an article from National Geographic about natural alternatives to bleach.

With each question I try to formulate and research, I feel like I find a million more questions that need answering.  There are so many facets to the issue of household use of Clorox bleach, from the chemistry and toxicity of bleach, to the ideas/theories behind our standards of a cleanly home, to the efficacy of natural alternatives.  In short, I feel like I need a background in chemistry to fully understand, and then probably the length of a book to explain.

But, with no further excuse, the question I wish to address today is: are there measurable risks associated with household use of Clorox bleach?

Clorox bleach (from here on I’ll simply call it bleach) contains 5-10% sodium hypochlorite (NaClO) and is extremely basic with a pH value around 12(1)(the pH scale ranges from 0 to 14, with a pH of 7 being neutral).  According to the MSDS, bleach is corrosive, and may cause severe irritation or damage to skin and eyes.  It is also harmful if swallowed(1).  None of this sounds good, but MSDS’s never sound good since they give you a worse-case scenario and, I feel, do not really represent the potential risks from reasonable household use.  To understand what the more realistic risks are I spent time searching PubMed for an appropriate study to read and summarize.

In 2009, Zock, et al., published a study looking at the domestic use of bleach in 10 European countries and allergic sensitization and respiratory symptoms in adults (2).  The authors had a significant number of participants since their study was part of a larger study designed to identify risk factors for asthma and allergies which had 7,263 participants.  The participants were interviewed and asked a variety of questions regarding their household use of bleach.  Other lab tests, including spirometry (to measure lung function) and blood work (to measure certain antibodies to quantify allergies) were performed. The study also collected dust samples from some homes.  The authors then analyzed the collected data to see if there was any association between bleach use, allergies, and respiratory symptoms.

In short, the study concluded that the health effects of bleach are paradoxical.  It appears that bleach use in the home is associated with fewer allergies, but it is also associated with an increase in non-allergic lower respiratory symptoms. 

One observation that the study made was that their results are specific for the use of bleach, and not simply the overall cleanliness of a home.  The authors considered many possible confounders (a third factor which, in this case would independently effect both those who use bleach and those who don’t) and adjusted for a variety of characteristics without observing a difference in the observed associations.  If cleanliness was a confounder and they did not adequately adjust for it their results, any potential associations could be distorted, but this was not the case.

Although I found this to be an interesting study to analyze, after pulling out some notes form a class years ago, I confirmed that these observed associations, although statistically significant were weak to moderate at best.  Because of this, and a few other factors, I don’t feel like this study is strong enough to suggest that bleach actually causes either a decrease in allergies or an increase in respiratory symptoms.  But then again, I really was just looking for good associations.

To properly answer my question though, yes I believe this study showed that there are measurable risks associated with household use of bleach.  However, it gets trickier since this study also showed measurable benefits associated with the use of bleach-- the paradoxical nature of this study.

This study has given me much food for thought in my quest to understand bleach and the possible pros and cons in regularly using it in my home.  Perhaps some of the puzzle is starting to come together. 

But that said, as far as my recommendations go, and what I will be doing in my home, I’m afraid all I have to say is, “more research is needed.” 

(1)The Clorox Company. (2009). Material Safety Sheet: Clorox Regular Bleach.  Retrieved from www.thecloroxcompany.com/downloads/msds/bleach/cloroxregularbleach0809_.pdf.
(2) Zock JP, Plana E, Antó JM, Benke G, Blanc PD, Carosso A, Dahlman-Höglund A, Heinrich J, Jarvis D, Kromhout H, Lillienberg L, Mirabelli MC, Norbäck D, Olivieri M, Ponzio M, Radon K, Soon A, van Sprundel M, Sunyer J, Svanes C, Torén K, Verlato G, Villani S, Kogevinas M. (2009 Oct.). Domestic use of hypochlorite bleach, atopic sensitization,  and respiratory symptoms in adults. J Allergy Clin Immunol.,124(4):731-8.e1. doi: 10.1016/j.jaci.2009.06.007. Epub 2009 Aug 8. Retrieved from http://www.ncbi.nlm.nih.gov/pubmed/19665775

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