The Sweet Smell of … Cardiovascular Hazards?

Kyle Ward is an intern in EDF's Health Program.  Jennifer McPartland, Ph.D., is a Health Scientist.

When you think of air fresheners what is the first thing that comes to mind?  Fresh spring flowers?  French vanilla?  Reduced Heart Rate Variability?  While that last one may not be on everyone’s mind, it certainly has been for one team of scientists.  They have recently conducted the first study ever to examine the potential for exposure to household cleaning sprays, air fresheners and scented products to adversely affect people’s cardiovascular systems.  Their findings, published in last month’s Environmental Health Perspectives, show a linkage between long-term use of household sprays and scented products and reduced heart rate variability (HRV).  Reduced HRV is associated with increased risk for a host of negative health effects ranging from heart attack to death.  

Heart rate variability is a measure of variation in time between heartbeats.  Like blood pressure or pulse, HRV is used to assess cardiovascular health.   Reduced HRV is associated with an increased risk of nonfatal cardiovascular events such as heart attacks and increased blood pressure, as well as increased risk of all-cause mortality in the general population (the annual number of deaths in a particular age group).  

The subjects of the new study are part of the ongoing Swiss Cohort Study on Air Pollution and Lung and Heart Diseases in Adults (SAPALDIA) established in 1991.  The researchers collected HRV data on 581 Swiss adults meeting the study criteria (see here) and looked to see whether HRV was correlated with each subject’s use of household cleaning sprays and scented products. 

Participants’ HRV was measured using 24-hour electrocardiogram (ECG) monitoring.  Specifically, data from ECG monitoring was used to calculate two different values that are expressions of heart rate variability—much the same way that beats per minute is an expression of pulse.

The results of the analysis are striking:  increased use of all studied household products (cleaning sprays, air freshening sprays, and scented products) was associated with reduced HRV.   The greatest reductions in HRV came from individuals who used air freshening sprays 4-7 days a week, representing the highest exposure category of participants in this study.  When compared to unexposed participants, these individuals averaged an 11% reduction in one of the two measures of HRV and a 29% reduction in the other.

Quite interestingly, the study also found that individuals already suffering from obstructive lung disease (OBS) appeared to be more susceptible to exposure-associated reductions in HRV than other participants.   OBS includes asthma, bronchitis, and chronic obstructive pulmonary disease (COPD), all of which obstruct air flow to and from the lungs.  In particular, individuals with symptoms or other evidence of COPD showed significantly greater reductions in HRV compared to individuals with similar exposure patterns to household sprays and scented products but without such indications. 

These findings reflect the need to consider different sub-populations when assessing a chemical’s risks, as certain groups—such as those with pre-existing conditions—may be more susceptible than others to the same exposures. 

The biological mechanisms linking reduced HRV to the use of household sprays and scented products are not fully understood, but the authors point to two publications from the American Heart Association (AHA) for insight. 

  • A 2004 AHA statement summarizes evidence suggesting that short-term inhalation of fine particulate matter (PM) in air pollution can irritate lung receptors or nerves, causing disturbance of the autonomic nervous system—the part of the nervous system that controls involuntary actions of certain muscles and organs, including the heart. 
  • AHA notes in its 2010 report that most epidemiological studies of exposure to fine PM have found an association between short-term exposure and an elevated risk of cardiovascular events such as stroke, arrhythmia, and heart attack in susceptible individuals; these include the elderly and those with unrecognized, existing coronary artery or structural heart disease.  The report also notes that the risk of long-term exposures to fine PM is greater than the risk from short-term exposures.  

While the 2004 and 2010 AHA reports refer to particulate matter in outdoor air pollution, the authors of this study hypothesize that the same irritation could occur from long-term indoor exposure to spray products.  They postulate that volatile organic compounds (VOCs) and other toxic contaminants found in the cleaning sprays may be to blame.

Given the very widespread extent of exposures to household cleaning sprays, air fresheners and scented products, it is surprising just how little research has been conducted on their potential health effects.  As the authors of the study state, “To our knowledge, this is the first study to evaluate the effect of long-term use of household sprays and scented products on cardiovascular health.”  

There are, of course, many other factors in addition to long-term use of household sprays and scented products that can generally influence cardiovascular health and can specifically affect HRV.  These factors, which also vary across a given population, include individuals’ smoking status, daily exposure to tobacco smoke, cardiovascular medication intake, daily physical activity, and alcohol consumption.  The authors adjusted the models used in this study to control for such variables so as to eliminate or minimize their influence on the results.

The authors note several limitations to their study that should be addressed in future work, including that:  they did not measure indoor particulate matter and gaseous pollutants; exposure may have been misclassified in some cases due to reliance on self-reporting by participants of their cleaning activities and use of scented products; and information was not collected on home characteristics such as ventilation and room size during use of the household cleaning sprays, air fresheners and scented products.  

This study is another example of how dangerously little we know about the effects of chemicals to which we are exposed every day.  The Toxic Substances Control Act (TSCA) is supposed to give EPA the authority necessary to protect our health and the environment from toxic chemicals.  It was enacted 36 years ago, during an era when it was still legal to smoke in planes and hospitals.  While much has changed since its enactment, TSCA remains in the veritable Stone Age.  It is the only major environmental statute that has not been updated since its passage.

There is hope, however!  The Safe Chemicals Act, recently voted out of the Senate Environment and Public Works committee, would make major strides toward fixing our broken chemicals policies.  This legislation would put the responsibility on chemical companies to ensure their chemicals are safe as a condition of entering or remaining on the market, in contrast to the status quo under TSCA currently, which puts the burden on EPA to prove a chemical poses an “unreasonable risk” before being able to act. 

This common-sense approach would go a long way toward addressing the concerns highlighted in the study we’ve reviewed in this post.

 

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