The Headlines:
Study: This common household chore is as damaging as smoking 20 cigarettes a day The Atlanta Journal-Constitution
Study: Lung Function Declines Faster in Women Who Use Cleaning Products - Sci News
Actual Study:
Cleaning at home and at work in relation to lung function decline and airway obstruction
The Gist:
- Over 6000 men and women completed questionnaires on how much they clean at home or work and what cleaning products they use.
- Lung function declined faster in women who cleaned at home or at work than in women who did not clean.
- The decline in lung function for female occupational cleaners was somewhat less but comparable to that of heavy smokers (>20 “pack-years”).
- There was no difference in lung function trends in men who cleaned compared to men who did not clean.
- Use of cleaning sprays and other cleaning agents were associated with accelerated decline in lung function.
Questions:
Did the headline accurately capture the gist of the study? Were the study's conclusions warranted?
My Take:
The headline "This common household chore is as damaging as smoking 20 cigarettes a day" overstates what the researchers found, which was that rate of lung function decline for women who cleaned for a living was somewhat less but comparable to that of heavy smokers. The headline, "Study: Lung Function Declines Faster in Women Who Use Cleaning Products" accurately captures the study's author's own conclusions. However, those conclusions are misleading, because the authors don't account for the dose effect.
Dose-effect: relationship between the dose of harm-producing substances or factors and the severity of their effect on exposed organisms or matter.
In other words, the authors don't distinguish whether a person cleaned or used a cleaning product once a week, twice a week, or 50 times a week. They simply collapsed any weekly cleaning or use of a cleaning products into single categories, as their 'Methods' section makes this clear:
Based on the entrance questions participants were categorised as “not cleaning”, “cleaning at home” and “occupational cleaning”. Participants responding “yes” to at least one module entrance question, answered a questionnaire concerning use of cleaning agents (sprays, other cleaning agents); defining the exposure categories “not cleaning”, “≥1 cleaning spray ≥1/week”, and “≥1 other cleaning product ≥1/week”.
Why did the study authors use such a crude measure for cleaning frequency for their paper? They actually had much more specific data not just on frequency but on types of cleaning products as well, per the questionnaire completed by participants:
Source: Selected Questions about Cleaning: http://www.ecrhs.org/Quests.htm
The researchers should also have asked questions about amount of exposure to cleaning products per week, e.g., "how many minutes or hours a week do you use the following products" (Possible responses: Never, less than 30 minutes/wk, 30-59 minutes/wk, 1-3 hours/wk, over 3 hours/wk). As it is, we have no idea what products might be dangerous at what level of exposure.
Why weren't the authors more specific? My guess is that their research is mission-driven and their mission is to stop people from using cleaning products. This agenda is clear from the authors' own statements in which they describe cleaning chemicals as "unnecessary" and propose that microfiber cloths and water are "enough for most purposes". The lead author, Oistein Svanes, summed up the take-home message of the study: "in the long run cleaning chemicals very likely cause rather substantial damage to your lungs".
Since many cleaning products irritate the mucous membranes of the airways and repetitive use of cleaning products may impair immunological function, reducing their use sounds like a worthy cause. But desired study outcomes shouldn't influence how research is carried out or the findings described. Science isn't about getting what we want - it's about getting closer to the truth of things.
While we get closer to the truth of cleaning products, I'll continue cleaning scuff marks with ammonia (maximum 5 minutes/week).
Reference:
Svanes, O at al Cleaning at home and at work in relation to lung function decline and airway obstruction. American Journal of Respiratory and Critical Care Medicine ISSN: 1073-449X Published Online: February 16, 2018. https://www.atsjournals.org/doi/abs/10.1164/rccm.201706-1311OC