Recent research conducted as part of the Canadian Healthy Infant Longitudinal Development (CHILD) study has prompted a rebuke from the cleaning products industry. The American Cleaning Institute (ACI) suggests a paper examining the links between exposure to household disinfectants and childhood obesity, published in the peer-reviewed Canadian Medical Association Journal earlier this month, makes “sensational claims”.
Richard Sedlak, ACI’s executive vice president, technical and international affairs, chastises the slate of 15 authors affiliated with health sciences faculties of six Canadian universities — the Universities of Alberta, British Columbia, Manitoba and Toronto; and McMaster and Simon Fraser Universities — for overlooking the role disinfectants play in infection control and public health.
“These products are trusted by families to effectively clean, sanitize and disinfect areas of their homes, reducing opportunities for these young ages to suffer significant illnesses,” asserts Sedlak, who holds a Master of Science in Engineering degree. “Coming off a deadly flu season in 2017-18, it is a crucial reminder that proper use of EPA-registered disinfectants play an important role in helping prevent the spread of flu.”
However, CHILD study research is focused on the genetic and environmental determinants of hypersensitive allergic reactions that underlie diseases such as asthma, eczema and a range of allergies. It is following a cohort of approximately 3,500 children born in Vancouver, Edmonton, Winnipeg and Toronto between 2009 and 2012, capturing information as they grow. Researchers from more than 20 interrelated scientific disciplines are involved, building biological, psychological, genetic and environmental profiles of participating children and their parents.
“These profiles enable researchers to track the onset of asthma, allergies, obesity, diabetes and other chronic diseases across a large group of individuals,” an explanatory synopsis on the CHILD study website states. “CHILD is the largest multidisciplinary, longitudinal, population-based birth cohort study in Canada and is designed to be one of the most informative studies of its kind in the world.”
Exploring the hygiene hypothesis
The scrutiny of disinfectants’ impact on gut microbial ecosystems was meant to fill in one of the many pieces of that comprehensive picture. It is also in line with a range of accredited research underpinning what’s known as the hygiene hypothesis of allergic and autoimmune diseases. This has shown that exposure to environmental microbes contributes to resistance to allergic and metabolic disease.
In this case, the CHILD study researchers tracked the relationship between the balance of microbes in infants’ guts and propensity to obesity, and then made connections to the environmental influences on those microbes. They explored data from 757 children, and compared exposures to three product categories — disinfectants, detergents and eco-friendly formulations — to draw their conclusions.
“We found that infants living in households where disinfectants were used a least weekly were twice as likely to have higher levels of the bacteria called Lachnospiraceae at three to four months of age. At three years of age, those same children had a higher body mass index than children who were not exposed to frequent home use of disinfectants as infants,” reports Anita Kozyrskyj, the study’s principal investigator and a pediatrics professor at the University of Alberta.
In keeping with reputable scientific research, the authors were transparent about three limitations in their work: reliance on parental reporting which could be subject to “recall bias”; the generic division of products into the three categories of disinfectant, detergent and eco-friendly rather than a specific breakdown by brand name and ingredients; and reliance on infant gut microbiota profiled at a single time point.
While referring to these as “notable limitations”, Sedlak also critiques the study’s failure to look at “all interventions in the children’s lives between three months and three years of age” or the timing of when various foods were introduced into children’s diets.
“We are disappointed at the sensational claims made by the researchers in this study,” Sedlak reiterates, but does not comment on researchers’ findings related to eco-friendly formulations.
“We found Lachnospiraceae to be enriched in infant gut microbiota with frequent postnatal use of domestic disinfectants, but not eco-friendly products,” the study’s conclusion states. “Further study is required on the mechanisms through which household cleaning products alter gut microbial composition and the subsequent role this might have on metabolic disease.”
Barbara Carss is editor-in-chief of Canadian Property Management.