An assessment of long-term residential pollution exposures among Canadian children

Occupational And Environmental Health

The Canadian Healthy Infant Longitudinal Development (CHILD) Study

One in 3 preschoolers has difficulty breathing and 1 in 5 children will develop Asthma in the first few years of life. It is thought that the environment plays a role in the increased number of children suffering from Asthma today than in the past.  The PRIMARY OBJECTIVE of this national study is to understand how the environment interacts with a child’s genetics, immune system and other personal characteristics leading them to develop Asthma and allergies. The goal of the CHILD Study is to address the major concerns about rising prevalence of allergies and asthma in the population, especially in children. These conditions are disabling, costly to society in medical care, school absenteeism, loss of work capacity and even premature death. The outcomes from this study of 5000 pregnant women and their children across the country can provide tangible strategies to prevent asthma, improved construction practices to create safer homes and provide valuable knowledge that policy makers can use to develop guidelines and standards that improve the health of all Canadian children.  

The basic infrastructure of this important study is supported by grants from the Canadian Institutes for Health Research (CIHR) the Allergy, Genes and Environment Network of Centres of Excellence (AllerGen NCE), Health Canada, Environment Canada , the Canadian Mortgage and Housing Corporation, as well as industrial and charitable partners. The CHILD Study requires an additional $35M dollars over the next 5 years to conduct a full analysis of the data emerging from the 5000 children enrolled and to obtain the maximum value from this study.

Primary Benefits of the CHILD Study:  Reducing the impact and cost of Asthma and allergies on children, their families and the Healthcare System

The facts that 300 million people suffer from Asthma worldwide and that Canada has the 5^th highest asthma rate in the world, above US, Germany and France have made this disease a public health priority.  Over two million Canadians suffer from Asthma and each year this condition contributes to approximately 500 deaths. Asthma symptoms in children under 5 years of age have tripled in one generation and serious food allergy (i.e., peanut allergy) has doubled. Annual direct and indirect costs due to Asthma in Canada are estimated to be between $864M to $1B annually.

The development of allergies and Asthma is a result of interactions between personal predisposition (genetics) and environmental exposure.  This includes not only what we breathe (indoor and outdoor air with its pollutants), but also what we eat and drink, what stresses occur in families, vaccinations, use of antibiotics, even mode of birth and the possible effect of these exposures on expression of our genes (studied by the new science of Epigenetics). In contrast to other Canadian and international studies who focus on children who either already have Asthma or those who are at high risk for developing this life-long disease, the CHILD Study has the opportunity to establish the causes of Asthma in healthy children by following them and the types of environmental exposures that impact their genetics from before birth until they are school aged.  The CHILD Study has already established the necessary infrastructure and leadership to be able to address the involvement of these complex variables in the origins of Asthma. 

Asthma and allergy have been described as the “canaries in the mine” because these diseases predict the origins of not only chronic lung disease, but also cardiac and vascular diseases which are common causes of premature death in later life.  A comprehensive study focused on allergy and Asthma in childhood will act as a proxy for many other chronic diseases that present later in life.  In addition, differences in outcomes of allergy and Asthma exist according to socioeconomic status, not only in their initial development but also in illness severity in childhood and adulthood. The CHILD Study will identify the roots of these disparities and suggest methods for alleviating them.

Secondary benefits of the CHILD Study:  Knowledge translation to support the housing industry

In addition to collecting clinical and biological information from children and their parents over a period of 5 years, the CHILD Study will be conducting inspections of 5,000 homes. These inspections will profile the indoor built environment typical of many Canadian families and will give policy makers information to shape guidelines that impact the health of Canadian children.

· The Federal government legislates standards for housing construction, air ventilation, energy efficiency and safety standards for consumer products that are used in the home. The CHILD Study offers a significant opportunity to those with the responsibility to develop these standards.

· The Government works in collaboration with various industry representatives to develop guidelines that will yield significant health and economic value to Canadians. The government spends millions of dollars annually on agencies, departments and consultants to disburse information to many audiences. Consider, however, where these agencies and departments obtain their information and how accurately the information addresses the Canadian experience.

Therefore, the secondary benefit of the CHILD Study has far reaching implications for the building and home renovation industry. The insight gained through these visits will be strategic to policy makers in the short-term and at the five year mark.

Supporters of CHILD

The CHILD Study developed through multiple consultations with both academic and government partners.  The resultant proposal was submitted to CIHR in response to a request for applications for research in this area.  As such, it was independently reviewed by an international peer-review committee of experts in epidemiology, child health, allergy and asthma, and the environment who commended the study as “excellent science” and recommended full funding.   

Funding for this study will come from an alliance of government and business sponsors. To date, 5 institutes within the CIHR (Institute of Human Development, Child and Youth Health (IHDCYH), Institute of Circulatory and Respiratory Health (ICRH), Institute of Gender and Health (IGH), Institute of Genetics (IG), and Institute of Infection and Immunity (III)) have committed $6 million over 6 years.  This was matched by the AllerGen NCE, and strongly supported by in-kind contributions from the federal government agencies including the Canada Mortgage and Housing Corporation (providing training in home assessments), Health Canada and Environment Canada, providing environmental exposure data and facilitating sample analyses for a subset of samples noted in Dr. Takaro’s funding. In addition, considerable international interest has been evident, leading to interactions and in some instances partnerships (through AllerGen NCE) with birth-cohort teams in Australia, Europe, India and Asia. 

Progress to date

The CHILD Study team started the Phase 1(Vanguard) recruitment in 2008, recruiting 200 mothers during pregnancy from centres in Vancouver, Edmonton, Winnipeg and Toronto.  This phase carefully evaluated recruitment, applicability to the general population of Canada, ease and acceptability of the study to parents. Recruitment for the main study started after incorporating changes learned in the Vanguard cohort.  By the summer of 2009, recruitment recommenced in all 4 centres, and some 1300 families are participating to date.

Current CIHR/AllerGen funding has supported the development of a functional infrastructure. Staff teams have been developed at all sites (i.e., we currently employ 40 FTE) who recruit pregnant mothers to the study and perform the study questionnaires, home assessments, and clinical assessments. Data collection tools and standard operating procedures have been finalized for all clinical tests and data entry has been centralized at the National Coordinating Centre. Biologic sample collection (cord blood, parental blood, breast milk, baby nasal swabs, urine, meconium and stool), processing and storage pending future analyses have been finalized. In addition, these funds have supported the procurement and development of an online data management system.  

For more information see:

http://www.canadianchildstudy.ca/