Health disturbances stemming from overcrowding and inadequate housing among indigenous peoples within Canada

Introduction

Soon after colonization and continuing over many generations, Inuit and First Nations Peoples in Canada experienced multiple challenges that have undermined their psychological and physical health, including increased vulnerability to communicable and non-communicable diseases. Aside from the harms caused by numerous past government actions, ongoing inequalities related to colonial policies and institutional systems have created impoverished living conditions. These include issues related to the child and family welfare system, access to healthcare, substandard education, limited employment opportunities, persistent stigmatization, and systemic racism. Housing has also been insufficient, with just over one-third (35.7%) of First Nations people on-reserve and just over half (52.9%) of Inuit in Inuit Nunangat¹ living in crowded conditions, although this varied regionally and across communities (1).²

Beyond serving as a shelter that allows for comfort, privacy, safety, and security, individuals may form emotional and meaningful attachments with their homes (2, 3), which might foster social resilience (4). Indeed, housing can be a potent determinant of psychological and physical health (5, 6), affecting social interactions and the capacity to cope with stressors, which contribute to well-being, especially among marginalized communities (7).

Within Canada, the provision and management of housing in reserves is the responsibility of First Nations with the understanding that financial assistance is committed by the federal government and transferred through Indigenous Services Canada and the Canada Mortgage and Housing Corporation (CMHC). However, despite the inequities and continuing housing shortages and overcrowding, the 2024 Federal budget allocated only $4 billion over 7 years to deal with this, whereas the Assembly of First Nations estimated that $44 billion may be required to address the severe housing shortage and needed repairs (8).

Together with the distress promoted by overcrowding and exacerbated by food insecurity (9, 10), health risks are often elevated in homes within First Nations and Inuit communities owing to the presence of indoor toxicants. The problems of crowding are compounded as houses are frequently in need of repair, including extensive plumbing and electrical work (1, 11). Ventilation is frequently inadequate so that mold is prominent, and potable water may be unavailable. For example, a comprehensive analysis of housing conditions and indoor environmental quality in homes within four First Nations in Northwestern Ontario revealed the general inadequacy of the housing resulting from overcrowding, moisture damage, inadequate ventilation, and building- and system failures (12). Twelve of 100 homes tested had sufficient visible mold and moisture damage to lead to airborne spores and fragments known to harm human health. While most homes in the study did not show severe visible mold and dampness, minor failures that could progress to hazardous conditions were common. Levels of endotoxins in these homes were much higher than those found in homes in non-Indigenous communities in Canada. Consistent with high rates of overcrowding, just over one-quarter of homes had sustained CO₂ concentrations higher than what is considered healthy (12). For example, a study in Kanehsatake First Nation revealed that over one-quarter of houses were in need of major repairs, and multiple indicators of indoor air quality revealed harmful levels of air contaminants (13). In First Nations homes in North Central British Columbia, one-third exceeded thresholds for three or more indoor air pollutants (14).

Efforts to remedy the problems have been undertaken, but these attempts have most often been unsuccessful (15). A report issued by the Canadian Federal government and approved by Indigenous and Northern Affairs Canada (INAC) acknowledged that overcrowding, poor states of homes, and inadequate infrastructure, are widespread among First Nations Peoples living on reserves (16). The prevalence of dilapidated housing serves as a visible reminder of the continued influence of colonial policies, forced relocation, and settler exploitation of traditional lands and resources, and living under these conditions is not conducive to emotional healing (17, 18).

The consequences of substandard living conditions may be compounded by the uncertainties created by housing unavailability (19). This situation is aggravated by First Nations communities lacking autonomy concerning housing construction, along with siloed funding and housing development programs that are dictated by federal policies. Moreover, individuals are not entitled to own their own homes since reserve land belongs to the Crown or the First Nation, and thus cannot be used as collateral for housing loans. The instability and unpredictability concerning housing undermines “pride of ownership” [(11); see also Report of the Standing Committee on Indigenous and Northern Affairs (20)], so that upkeep and repairs, including safety precautions (e.g., smoke detectors, air ventilation) may be viewed by inhabitants as someone else's problem.

In this report we describe the psychological and physical health consequences of inadequate housing and overcrowding among Indigenous Peoples within Canada, as well as among Indigenous populations in other countries. In doing so, the many challenges are considered in the context of cumulative historical traumas that had been experienced, the presence of other environmental challenges, several social determinants, and biological processes that affect health.

Impact of overcrowding and poor quality housing

Housing inadequacies and overcrowding may contribute to the emergence and exacerbation of psychological and physical illnesses, including communicable and noncommicable diseases (21–23). The actions of inadequate housing among Indigenous People within Canada may interact with cultural, environmental, physical, and psychosocial elements, in affecting health outcomes, individual and social development, education, and economic development (16).

Owing to the shortage of housing, Chiefs and band councils necessarily consider community priorities in making decisions concerning the demand for on-reserve housing (and other community infrastructure that is located within the confines of the allocated reserve borders) (17, 19). Because of wait lists for on-reserve homes, community members might live with persistent uncertainty concerning housing assignments and whether and for how long they will be able to remain in their current home. Like First Nations living on-reserve, relatively few Inuit living in Nunavut and Nunavik own their own houses, with 80% of the population living in subsidized housing. In Nunavut and Nunavik, a rehousing intervention led to the reduction in the number of adults in Inuit households and an increase in their sense of home, which was, in turn, associated with a significant decline in psychological distress (24). Participants in Nunavut reported that their new housing helped to improve mental well-being by creating a safe space, feelings of self-determination and control, and improved family dynamics and identity repair (25).

Much like the effects of other stressful experiences that exacerbate individual and familial distress (26), housing inadequacy may promote the proliferation of stressors. Among other things, crowded housing conditions have been associated with poor parenting practices, and may perpetuate lateral violence (19, 27–30), as well as undermining social support that might act against distress related to poor housing conditions (31).

Making the situation worse and adding to the ongoing distress, the appearance of unsafe housing was accompanied by elevated risk of residents being investigated by child welfare services (27) and Indigenous children are more likely to be placed in care outside of their home relative to non-Indigenous children (32). The burden on Indigenous parents may be especially prominent since maintaining custody of their children requires that they meet specific housing requirements, such as having adequate bedroom space for children as defined by Western standards (33). Ironically, social assistance programs may contribute to precariousness of housing. Specifically when a child is placed into the child welfare system, a single parent may be evicted from their home owing to the limited housing available for single adults with no children (34). Ordinarily, a person's home is often considered to be a safe place and provides connections to family and community that are critical for resilience (34–36). Regretably, for Indigenous people who experience housing insecurity, the home functions as a point of convergence for the detrimental psychological, social, and environmental impacts of colonialism.

Health impact of housing inadequacy and crowding

It is broadly acknowledged that environmental pollutants are among the greatest risk factors for disease and premature death worldwide (37). Aside for accounting for one in six deaths, environmental factors contribute to congenital anomalies that occur in 3.2 million children, with about 300,000 infants dying within the first month of life (38). Likewise, unsafe indoor environments take a significant toll on health. Numerous illnesses may accompany overcrowded housing (39), including respiratory diseases, tuberculosis, gastroenteritis, and diarrhea, as well as typhoid fever, meningococcal disease, dengue fever, methicillin-resistant Staphylococcus aureus, and Toxoplasma gondii infection, rheumatic fever and heart disease. Furthermore, a review of 42 studies conducted in the US indicated that housing instability was associated with elevated prevalence of obesity, diabetes, hypertension, and cardiovascular diseases (40).

Indigenous people worldwide experience inordinate levels of chronic respiratory diseases accompanied by elevated risks of mortality owing to diverse risk factors present within these communities (41). Aside from poverty, poor nutrition, premature births and low birthweight, inadequate ventilation and high levels of humidity foster the development of mold, allergens in dust, dust mites, and cockroaches, which could promote biological changes that favor the development of illnesses (42). Epidemiological studies confirmed that dampness within homes was associated with respiratory illnesses (43, 44), particularly among individuals from low socio-economic communities (45). Viruses as well as bacterial and fungal toxins develop in humid environments that occur when too many people live in a home that is not well ventilated (46). Morevover, endotoxins (derived from the cell wall of certain bacteria) present on surfaces can increase the risk for pulmonary-related illnesses, more so if these appear as an aerosol (e.g., clustering within house dust), [e.g., (47, 48)]. In addition to physical harms, a scoping review indicated that dampness and the presence of mold was associated with increased frequency of varied psychological disturbances (5).

Pollutants can promote inflammation and oxidative stress, together with disturbed immune functioning, thereby contributing to health disturbances (49). Health problems related to poor air quality have been particularly pronounced in the homes of Indigenous people in Canada and elsewhere, with the greatest consequences occurring among those who spend the longest periods indoors, notably the very young, the elderly, and individuals with serious pre-existing medical conditions (50, 51). In general, children exposed to high levels of particulate matter are at elevated risk for the development of asthma, and hospitalization rates were similarly elevated (52–55).

Among children living in damp houses and thus exposed to mold, incidents of respiratory illnesses and symptoms of infection were particularly marked (56). The disproportionate occurrence of asthma and bronchitis among First Nations and Inuit children has been associated with overcrowding, housing in need of major repairs, poor ventilation, together with exposure to tobacco smoke (57–59). An analysis conducted among First Nations people on reserves in Saskatchewan confirmed that the high incidence of chronic bronchitis was associated with overcrowding (60). Indeed, overcrowding in Northern communities was associated with a marked elevation (250%) of hospital admission for lower respiratory tract infections, including respiratory syncytial virus (RSV) infection (61). Not unexpectedly, overcrowded housing was linked to increased occurrence of infectious diseases, such as tuberculosis (TB) and was associated with the occurrence of SARS-CoV-2 infections and increased risk of death (62). As well, in pregnant First Nations, Inuit, and Métis women, overcrowding and poor housing was associated with elevated occurrence of preterm births and infant mortality (63).

A comparison between communities provided telling results that were relevant to the ties between housing conditions and the occurrence of TB. Specifically, the incidence of TB was much higher in a northern Denè community at Lac Brochet relative to that of the southern Ojibway community at Valley River. Houses in both communities were generally small, but relative to the Valley River community, crowding was more pronounced in Lac Brochet where more than two-thirds of homes also lacked adequate heat recovery/ventilation systems. Predictably, mold accumulation was much higher in Lac Brochet houses compared to those in Valley River (44 vs. 19%), and the elevated incidence of self-reported latent or active TB was directly related to the number of permanent residents in the homes (64).

Despite considerable evidence showing the adverse consequences of insufficient and inadequate housing, limited progress has been made in diminishing the problems (65). The Canadian Government attempted to relocate communities as a possible solution, but this often had unintended negative consequences (66). Among other things, moving people to a new location disturbed social networks, disrupted childcare support and schooling, and earning opportunities were diminished [e.g., (67)]. These moves were accompanied by the loss of social, cultural, and spiritual connections rooted in the land, which undermines cultural, physical, and economic survival, thereby disturbing well-being. The effectiveness of moving residents was further subverted by the construction of housing and infrastructure that was often inappropriate for the existing climatic conditions [e.g., (68)].

Like the problems witnessed in Canada, overcrowding and inadequate housing conditions and the resulting health disturbances were reported elsewhere, including Latin America (69) and South Africa (70). The stress associated with housing instability (which comprised living in poor or overcrowded conditions, moving frequently, or spending the majority of household income on housing costs) was linked to physical and mental health challenges. In remote Australian Indigenous communities, overcrowding was common and house designs were inadequate for the tropical climate. The housing conditions were linked to downstream effects that manifested as chronic disease, depression, conflict, limited employment, and poor school attendance (71), and overcrowding itself was accompanied by a substantial increase (23%–46%) in the risk of child sexual abuse (72). Beyond the influence of housing conditions, the health inequities among Indigenous people in Australia were associated with cumulative (and historical) stressors, and more proximal challenges, such as discrimination, which mapped onto biological markers of stress (73). Given that inadequate and insufficient housing may vary with the social and cultural contexts in which specific measures are taken, it is important that policy makers and technical advisors consider them, as well as the costs to beneficiaries in introducing changes (39).

Viral and bacterial illnesses related to housing and crowding

An impressively extensive review indicated that infectious diseases are disproportionately elevated among Indigenous Peoples in Canada and the US (74). For instance, First Nations people in Canada were 4–5 times more likely to be hospitalised owing to influenza and pneumonia relative to that within the general Canadian population. Other respiratory illnesses (e.g., RSV and bronchiolitis) likewise occur more frequently among Inuit and First Nations people. SARS-CoV-2 infection was far greater among First Nations people, just as infection was more common during the 2009 H1N1 pandemic (75), which was linked to poor housing, overcrowding, and inadequate access to household water (76). It was similarly observed that various bacterial infections were more frequent among First Nations people (74). This included the occurrence of invasive pneumococcal disease, Methicillin-resistant Staphylococcus aureus (MRSA), and tuberculosis, as well as gastrointestinal and hepatic infections (e.g., Hepatitis A, B, and C). The occurrence of many of these diseases was related to household crowding, multifamily or multigenerational living quarters, indoor air pollution, limited access to running water, and the presence of underlying medical conditions. In this regard, tuberculosis in young people (less than 15 years of age but primarily in those younger than 5 years of age) within northern Saskatchewan First Nations was elevated, predominantly in those communities experiencing low income, low education, and inadequate housing (77).

Consistent with such findings, poor living conditions, such as the lack of complete indoor plumbing or access to potable water were related to early SARS-CoV-2 infection in American Indian and Alaskan Native populations (78, 79). A scoping review commissioned by the US Office of Health Policy indicated that numerous psychosocial factors influenced SARS-CoV-2 infection, but chief among these was substandard and inadequate housing (80). Paralleling these reports, chronic diseases among Indigenous people living in remote areas of Australia were especially high, which may have been related to the lack of health services, food insecurity, poor access to water, sanitation issues, and insufficient housing so that relatively large family groups lived within a single home. Predictably, the incidence of SARS-CoV-2 infection and related health problems were elevated among Indigenous Australian people relative to non-Indigenous groups (81).

In addition to bacterial and viral illnesses, parasitic infections can occur with substandard housing and crowding (82, 83). These conditions are relatively infrequent in Canada (1 in 100 are affected each year), but have been increasing in Northern regions, possibly owing to climate change together with the lack of potable water. Cryptosporidium and Giardia presence in fresh surface water may increase with rising temperatures, thereby potentially affecting Northern communities (84), and was already found in Iqaluit (85). As well, parasitic worms, notably Echinococcus multilocularis and E. canadensis, have been emerging in Northern regions. These parasites are common in wildlife, and may come to affect dogs who can pass it on to humans through feces around homes or direct contact with humans. As these parasites prefer cool moist environments they can pose a risk for human infection if homes are not adequately ventilated.

Microbiota

The many bacterial species present within the gut, mouth, and on the skin, live harmoniously with one another (i.e., commensal bacteria). However, altered abundance or imbalances between bacterial species (dysbiosis) or high amounts of certain bacteria, have been associated with numerous illnesses (86), likely owing to multiple hormonal and immune alterations (86–90). The health disturbances related to microbial alterations (including viruses, fungi, archaea, and protists) have included neurodevelopmental and psychological disorders (anxiety, depression, PTSD), and numerous non-communicable diseases that involve inflammatory processes, such as allergic disease, asthma, obesity, type 2 diabetes, heart disease, and some forms of cancer [e.g., (91–93)]. These effects have most often been related to lifestyles (poor diet and lack of exercise) and stressful experiences, and it appears that inadequate housing, poor air and water quality, and crowded living conditions may disturb microbial communities, thereby favoring disease occurrence [e.g., (94, 95)].

The influence of the microbiome on health begins during prenatal development, being affected by the diet consumed by a pregnant woman. As well, microbiota are acquired during birth through vaginal fluids, and subsequently from breastmilk (96). Gut microbiota and immune system functioning mature in tandem, and early life factors that favor microbiota disturbances may affect the development of immune-related health conditions (97). Moreover, these early microbial alterations may influence ageing processes and favor earlier death (98, 99), likely stemming from effects on immune and inflammatory factors together with altered hormonal functioning (e.g., cortisol, estrogen) [e.g., (87, 100, 101)].

Microbiota composition within industrialized societies differs appreciably from that of the pre-industrial ancestoral microbiota. These differences may have come about owing to environmental pressures that evolved as a result of lifestyle changes, shifts in diet, and the use of antibiotics (102, 103). Consistent with this view, studies of several Indigenous populations (e.g., Orang Asli of Malaysia, Hadza hunter-gatherers of Tanzania, and Yanomami Amerindian) suggested that their microbiota had at one time matched their environments, but changed markedly with the introduction of Western lifestyles (104–107). With these changes, inflammatory processes were elevated, leading to more frequent health disturbances (108, 109). An intriguing report that compared gut microbiota (based on fecal samples) in Hadza hunter-gatherers of Tanzania and those of individuals living in Nepal and California revealed that numerous microbial species had been vanishing in industrialized populations. People from industrialized regions exhibited gut microbes with enriched genes related to oxidative stress, perhaps reflecting a microbiome adaptation to inflammatory processes (104). Furthermore, individuals from a Yanomami Amerindian village whose members had never encountered members of outside societies exhibited the greatest gut (fecal) and skin microbiome diversity ever reported in humans (105).

Chronic stressful experiences can have marked effects on microbiota (110) and the actions of the microbiome on disease occurrence may be influenced by the individual's sex (111) and genetic factors (112). Certain foods, such as whole grains, legumes, vegetable, fruits, nuts and seeds, cause microbiota to produce short chain fatty acids (butyrate, acetate, and propionate) that act against harmful bacteria, thereby favoring good health. Other foods (e.g., emulsifiers used to stabilize processed foods) can alter the gut microbiota so that inflammation is encouraged, thereby promoting negative health outcomes (108, 109).

Due to a combination of cost and accessibility, unhealthy highly processed foods have become a common dietary staple among Inuit and First Nations people. Over the past century the Inuit diet has shifted from traditional diets to more Westernized foods, resulting in alterations of the microbiome, which favor ill health, particularly type 2 diabetes (113). In this respect, the Inuit microbiota was deficient of several microbes (e.g., Prevotella) that could provide health benefits.

Analyses of microbiota related to illness have most often centered on those present within the gut, but microbiota on the skin are critical to well being, acting as a barrier against a variety of health threats. Microbes on the skin are influenced by ambient temperature, ventilation, humidity, air quality, sunlight, and small particulate matter, and may have greater and faster actions than those present at other body sites (114). By affecting skin microbiota, toxicants encountered within the home can have considerable sway on the development of illnesses. As well, bacteria ordinarily produce spores that can survive in open air so that people living within the same home may share a similar microbiome (115, 116). Indeed, family members exhibit gut, oral, and skin microbiota that are more like one another than those observed among unrelated individuals (116). Of course, this does not imply that bacteria transmission does not occur within or between communities. For instance, while differences were found between Cheyenne and Arapaho tribes in Oklahoma relative to that of non-Native individuals (117), because of their social and familial connections, bacterial transmission occurred in neighboring communities (118).

In addition to gut and skin, disturbances of oral microbiota have been associated with numerous physical illnesses and have been implicated in poor emotional health (119). Within some countries, such as Australia, stark differences of oral microbiota composition and diversity exist between Indigenous and non-Indigenous individuals, raising the possibility that this might contribute to the health disparities that exist between groups (120, 121).

Summarizing briefly, Indigenous people living on or near their ancestral lands, and who maintain traditional diets may harbor microbial communities that provide health advantages. Factors that promote dysbioisis or alter the abundance of certain microbes may undermine well-being. Aside from the limited availability of healthy foods, both inadequate housing and overcrowding may profoundly influence microbiota and immune functioning, leading to health disturbances. There is a need to identify the “unseen factors” that influence well-being related to colonized places and people (122), and microbial disturbances may constitute one of the unseen influences that pose potent health threat among Indigenous people. However, as in other health-related domains, research linking microbiota and health in Indigenous communities is still lacking, although efforts have been made to bridge this knowledge gap while allowing Indigenous Peoples to determine and steward the research (123, 124).

Impact of environmental toxicants through the lens of stress and trauma

There is little debate regarding the impacts of stressful experiences on the development and exacerbation of diverse illnesses. The questions that have persisted concern the biological processes promoted by stressors that lead to these pathologies, and the factors that moderate these actions. We have extensively reviewed the links between stressors, biological changes, and the evolution of diseases (110, 125, 126), so we will only consider several key issues here that appear especially relevant to Indigenous people.

While stressors are typically considered in the form of psychological or physical challenges, they may also comprise biological perturbations within the body and brain (e.g., elevated levels of blood sugars, immune activation, and elevated presence of inflammatory factors). These “systemic stressors” produce many of the same biological effects as those elicited by psychogenic and neurogenic challenges, thereby favoring the occurrence of illnesses (110, 126). Thus, in addition to the distress created by overcrowding and poor living conditions, indoor pollutants can act as stressors that can impact well-being.

Stressful events give rise to multiple hormonal, brain neurochemical, growth factor (neurotrophin), and immune changes that may serve in an adaptive capacity to limit the adverse actions that would otherwise occur. Among other changes, stressors cause the release of hormones, such as cortisol, that facilitate energy regulation and permit other hormones to behave in a protective capacity. Likewise through endorphin release, pain regulatory processes may be activated, and peripheral norepinephrine release augments cardiovascular functioning, thereby promoting oxygenation of various organs, including the brain. Concurrently, increased synthesis and release of several neurotransmitters and altered neurotrophin levels within the brain favor cognitive and behavioral coping, and brain microglial changes in response to moderate acute stressors are viewed as operating in a protective capacity.

As much as these systems ordinarily operate well, there are limits in their protective capabilities. When challenges occur on a chronic basis, these biological processes may be overly taxed (allostatic overload) so that pathologies are more likely to arise (127, 128). For instance, excessive hippocampal glucocorticoid stimulation may result in neuronal cell loss and diminished levels of neurotrophins, thereby favoring the occurrence of psychological disturbances. As well, excessive activation of brain microglia favor inflammation, which can instigate neuronal damage (e.g., 108). Importantly, chronic stressors can disturb innate and adaptive immune functioning (129), as well as sterile immunity (130), thereby increasing vulnerability to communicable and noncommunicable diseases (110). As well, social challenges can instigate a form of allostatic overload that culminates in behavioral, cognitive, and physical disorders (131). This is especially pertinent to our present discussion since chronic stressor experiences beginning in early life, together with familial challenges related to poverty, and disturbances of social structures, may have profound negative consequences that may even appear over successive generations (132).

Chronic stressful events, irrespective of whether they comprise psychological, physical, or systemic challenges, affect virtually every cell within the body. In turn, these effects may influence the functioning of all physical organs and the brain, potentially leading to psychological illnesses (anxiety disorders, depression, posttraumatic stress disorder, autism spectrum disorder, schizophrenia, bipolar disorder, and substance use disorders), immune/inflammatory disorders (infectious illnesses, autoimmune disorders), neurodegenerative disorders (e.g., Parkinson's disease and Alzheimer's disease), metabolic disorders (metabolic syndrome, type 2 diabetes), cardiovascular diseases, and several types of cancer (110, 125). These actions are exponentially greater if individuals had previously encountered strong stressors, including systemic challenges (e.g., toxicants secondary to overcrowding), which could engender the sensitization of neurobiological and cognitive processes that favor the emergence of illnesses. Predictably, the characteristics and experiences of individuals or groups who had previously encountered intense adverse events affect the impacts of ongoing stressors (126).

Indigenous people in Canada, the US, and Australia (and several other countries) have experienced multiple historical traumas and continue to experience diverse stressful events. The health consequences of these experiences cannot readily be dissociated from one another, and it may not be productive (or feasible) to attempt to isolate the effects of any single stressor on health outcomes. It may be more appropriate to consider a specific challenge as part of a broader “condition” that can undermine health and well-being through multiple routes. This said, the imposition of chronic stressors on a background of historical stressors or those encountered during early life, can have particularly powerful adverse effects. In evaluating the impacts of challenges, it is not only essential to evaluate the conditions under which adverse outcomes are most apt to occur, but also to consider the cumulative biological and psychosocial challenges that lend themselves to health disturbances.

Studies that assessed the health impacts of stressors typically evaluated a limited number of biological factors that might contribute to the emergence of pathology. Since the consequences of stressors on health may involve the concurrent actions of many processes, it was proposed that a better predictor of health risk might be obtained by assessing multiple indices comprising neuroendocrine, immune, metabolic, and cardiovascular system functioning, that together form an “allostatic load index” (133, 134). This approach may also be useful in defining the conditions by which early life adversities affect later health risks. Moreover, it lends itself to a precision medicine approach in which specific components that reflect allostatic load might be most closely aligned with certain pathologies.

Numerous reports have revealed that allostatic load index was related to the occurrence of illnesses [e.g., (135)]. The components that were included in an allostatic load index differed from one another across studies, sometimes simply being based on the ease of obtaining measures. In other studies an extensive multisystem index of biological dysregulation was adopted that included several biomarkers to capture cardiometabolic and cardiopulmonary functioning, glucose metabolism, inflammation, and organ functioning. Measures that make up the allostatic load index have comprised several cardiovascular markers (blood pressure, cholesterol, triglyceride, homocysteine), metabolic functioning (BMI, A1C, albumin, estimated glomerular filtration rate), and the presence of inflammation (e.g., CRP, cytokines) (136, 137). Measures such as these were predictive of subclinical health disturbances and their progression over years.

It was reported that among Indigenous people within Australia, allostatic load related to stressors experienced throughout life may have contributed to metabolic, cardiovascular and psychological disorders (138). Specifically, physiological stress measures, including altered cortisol levels, urinary epinephrine, and heart rate variability, were frequent among Indigenous Australian people, which were linked to symptoms of psychiatric disorders (73). As expected, experiences of racial discrimination frequently contributed to physiological changes depending upon the social and economic contexts in which these were experienced (139).

Within Canada, allostatic load was linked to health disturbances, varying beween males and females, and were tied to socioeconomic factors (140). Among Inuit in Nunavik, household overcrowding and the resulting increase of toxicants, was associated with elevated allostatic load reflected by a several physiological measures, which were related to increased illness occurrence, especially among women (30), and similar relations were observed among Greenland Inuit (29, 141). As indicated earlier, the ways by which individuals cope with stressors is fundamental in determining whether pathologies will emerge. Thus, it is essential to underscore that overcrowding among Inuit in Nunavik was accompanied by diminished social support, which could have contributed to the health-related disparities (31). It is significant that in Nunavut and Nunavik, reductions of overcrowding by increasing newly constructed housing were accompanied by a decline in psychological distress (24).

Predictably, much like the findings among Indigenous people in Australia, racial discrimination during the preceding year experienced by Indigenous groups within Canada was associated with elevations of several physiological indices of allostatic load, which were diminished in the presence of cultural continuity (142). Likewise, among Indigenous university students, childhood racial discrimination was associated with an elevated allostatic load index, and these too were diminished among individuals who expressed relatively high levels of cultural continuity (143).

In considering the various factors that cumulatively contribute to allostatic overload, it is essential to include systemic challenges, such as presence of environmental toxicants that stem from overcrowding and features of the home (poor ventilation, dampness, and accumulation of mold). From this vantage, especially when combined with ongoing psychosocial stressors, poor housing within First Nations and Inuit communities can be potent forces that undermine psychological and physical health.

Sequential or concurrent influences on mental and physical illnesses

According to a “two-hit” or “multiple hit” view, illnesses may emerge from two or more factors that occur concurrently or sequentially. Genetic disposition or stressors that were encountered prenatally or during early life, may serve as a first hit that increases risk for illness. However, pathology might only emerge with a second hit. The second hit may comprise another genetic influence, stressor experiences, or certain environmental challenges. From this perspective health issues among Indigenous people may have their roots in negative experiences encountered during early life (144) or they may stem from historical trauma (i.e., those experienced by their forebears).

Inherited genes can influence both good health and susceptibility to illnesses, and varied adverse life experiences can influence the expression of certain genes (suppressed or enhanced), which can affect diverse phenotypes. For instance, these “epigenetic” changes can influence the expression of genes that code for hormonal or immune processes (145), thereby affecting the emergence of various illnesses (146–148). Following from the “Developmental Origins of Health and Disease” (DOHaD) hypothesis [e.g., (149)], in utero or early life exposures to chemical and biological products may promote epigenetic changes that favor the development of multiple diseases (150, 151), and may promote illnesses that emerge in adulthood (152, 153). Furthermore, as epigenetic changes occur with diverse experiences and accumulate over time, and may be a key driver of the ageing process, the constellation of epigenetic changes that are present has been used as index of ageing (epigenetic ageing; EpiAge) (154). The negative consequences related to epigenetic changes may include physical illnesses, and several psychological conditions, including depression, PTSD, and substance use disorders (155, 156). Aside from psychological stressors, epigenetic effects that influence health can be engendered by toxicants, such as fine particulate matter, herbicides, insecticides, fungicides, endocrine disrupting chemicals, such as the androgenic fungicide vivclozolin, the estrogenic peptide methoxychlor, as well as bacterial or viral agents (157).

Linking particular epigenetic changes to specific illnesses has been exceedingly difficult. Among other things, complex disorders typically involve the contribution of multiple genes, and the accumulation of epigenetic alterations over the lifetime might be fundamental in promoting illnesses [e.g., (158)]. Nonetheless, the identification of epigenetic markers that predict disease occurrence may inform treatment strategies to limit disease (159). For most stressors that have been examined (acute stress, chronic stress, early childhood stressors, and traumatic experiences), epigenetic changes occurred on core genes (Nr3c1, FKBP5, OXTR, SLC6A4, and BDNF) involved in neuronal development and hormonal regulation. These epigenetic changes have been tied to anxiety disorders, depression, and PTSD, and physical illnesses (e.g., heart disease, Type 2 diabetes, autoimmune disorders) (160, 161), which occur disproportionately among Indigenous people in Canada, the US and Australia [e.g., (162, 163)].

Global maps of regulatory elements and their presumed activators and repressors within diverse cell types were described by The National Institutes of Health Roadmap Epigenomics, which may facilitate the identification of discrete elements (and their interactions) relevant to disease conditions (164). This can be improved by identifying the factors that moderate the actions of these epigenetic changes, and how these can be preserved or erased (165). For instance, the occurrence of epigenetic changes can be moderated by the individual's ethnic and cultural background, their social and physical environment, as well as their stressor experiences, which may be especially relevant among Indigenous people (166).

Both outdoor and indoor pollutants were associated with epigenetic changes that could favor the development of lung-related disturbances (e.g., chronic obstructive pulmonary disease, asthma), as well as heart disease, type 2 diabetes, several forms of cancer, and neurological disorders [e.g., (54, 167–170)]. Moreover, poor housing conditions and exposure to pollution and environmental problems may influence epigenetic ageing (171). While few epigenetic studies have been conducted among Indigenous people in North America, an epigenome wide association study among minority groups, including American Indians, suggested that immune and hormonal processes could be influenced by early life adverse experiences, which could increase vulnerability to asthma and allergies (172). Moreover, housing instability and poor housing conditions were associated with depression among mothers and their children, and this relation was mediated by epigenetic processes (173). Likewise, housing insecurity that is notable in older adults, has been associated with epigenetioc changes that could impact health (174).

It has frequently been maintained that toxins produced by certain types of mold (mycotoxins) can have multiple adverse health effects (175, 176), although it was argued that the evidence supporting this has been meagre (177). Nonetheless, the presence of mold, along with other microbes, can promote epigenetic changes in the host (178), which can modulate immune functioning and vulnerability to inflammatory diseases (179), possibly operating through epigenetic alterations (180, 181). By affecting various aspects of immune functioning, including diminished levels of activated lymphocytes, impaired functioning of macrophages, and disturbed pathogen clearance, the development of pathology can be elevated (182, 183). In fact, the presence of mycotoxins may be a risk factor for the developement of asthma (184) and may contribute to the adverse effects of SARS-CoV-2 infection (185). Following from a two-hit hypothesis, it is conceivable that mold may selectively affect individuals who are elevated risk for particular health conditions related to environmental toxicants.

Epigenetically driven intergenerational and transgenerational effects of stressors

The marked cellular proliferation and differentiation that occurs during fetal development and early life, makes these periods especially sensitive to epigenetic changes produced by stressors or environmental toxicants (186). In rodents, challenges encountered during the first trimester of pregnancy increased the occurrence of epigenetic changes on genes that code for various hormones (187, 188). Moreover, maternal immune activation and infection can engender epigenetic changes that increase disease susceptibility (189).

Prenatal stressors in humans promoted epigenetic changes in the fetus (190), and adverse early life experiences, particularly childhood abuse, were likewise associated with numerous epigenetic changes (191). These included actions related to inflammatory processes that could influence the development of pathology that emerged in adulthood (192). Beyond epigenetic changes that are transmitted from the mother to the fetus, epigenetic changes that occur on germline cells (ova or sperm) can be transmitted across multiple generations (transgenerational effects) so that biological alterations and related pathologies can occur over several generations (147, 157, 193). While epigenetic links have, in the main, been examined among females, epigenetic changes in paternal sperm can also affect offspring (194).

Stressful events have been identified as being potent in eliciting epigenetic changes, as have environmental toxicants (195), and in rodents the epigenetic alterations elicited by toxicants can be transmitted across several generations (196). Given how difficult it is to follow humans across several generations, relatively few studies examined the intergenerational and transgenerational effects that might occur. Nonetheless, it was reported that the parental/ancestral environment may influence health and disease in the ensuing generations (197). Studies conducted in the children of Holocaust survivors revealed that the risk for psychiatric disorders, such as PTSD, were associated with epigenetic factors linked to cortisol receptors (198, 199), more so if both parents had experienced PTSD. To be sure, the intergenerational actions may be independent of epigenetic changes, possibly being linked to the influence of parental mental health, parenting style, and attachment quality (200).

In addition to the studies conducted in the children of Holocaust survivors, intergenerational consequences attributable to traumatic experiences were reported in the offspring of pregnant women who experienced sexual violence or torture during the war in Kosovo. These women frequently developed PTSD symptoms, and epigenetic changes in their subsequently born children were found in genes that code for several biological processes related to pathology (201). Consistent with these findings epigenetic changes on genes coding for cortisol receptors and immune functioning were present in the children of Tutsi mothers who had been pregnant during the Rwandan genocide (202, 203). Of particular significance, the war-related violence in Syria was found to promote epigenetic changes that appeared to be transmitted across three generations (204).

Intergenerational outcomes were similarly reported among survivors of the Dutch Hunger Winter and their children. Near the end of World War II, in retribution for the government in exile supporting the allies, the Nazi regime cut off food supplies to residents in the western parts of the Netherlands. Children born shortly afterward frequently displayed epigenetic changes within genes related to LDL cholesterol levels and genes that influence birth weight (205). In concert with these findings, among individuals who had been prenatally exposed to this condition, persistent epigenetic changes were found on genes related to insulin-like growth factor 2 (IGF2) (206), which have been associated with the development of type 2 diabetes. Aside from this, risk of psychological disturbances comprising elevated stressor reactivity, depression, schizophrenia, and accelerated ageing, were elevated in offspring who had been conceived during the Dutch Hunger Winter (207). Paralleling some of these findings, the adult offspring of mothers who were pregnant during the 1959–1961 famine in the Suihua area of China were at elevated risk of hyperglycemia and type 2 diabetes (208), which was attributed to epigenetic changes on the gene coding for IGF2 (209, 210). More recently it was reported that among women pregnant during the genocide against ethnic Tutsi in Rwanda was associated with epigenetic changes in offspring relative to that evident in unexposed mothers and children (202). Of particular significance, the war-related violence in Syria was found to promote epigenetic changes that appeared to be transmitted across three generations (204).

The negative effects associated with traumatic experiences associated with Indian Residential Schools in one generation were related to disturbed well-being in subsequent generations [e.g., (211–213)]. While not excluding a role for the transmission of poor parenting behaviors across generations, the possibility was raised that epigenetic changes might contribute to these outcomes. This supposition was largely based on studies mentioned earlier in which epigenetic changes were transmitted across generations in traumatized populations, as well as those that indicated that stressors experienced during pregnancy could affect the health of offspring [e.g., (214, 215)]. However, only a single study has been reported assessing this relationship. Specifically, among Alaskan Native individuals who experienced multiple collective, historical traumas, blood samples from two distinct communities revealed several epigenetic changes that were related to feelings of loss that individuals expressed. These genes comprised serum/glucocorticoid regulated kinase 1 (SGK1), mitogen-activated protein kinase 10 (MAPK10), CREB binding protein (CREBBP), and heat shock protein 90 alpha family class A member 1 (HSP90AA1), several of which have been implicated in stress responses (216). Once more, as observed in other contexts, aspects of cultural connectivity could buffer the impact of earlier trauma, thereby facilitating healing. In addition to the intergenerational actions of trauma on psychological well-being, epigenetic changes stemming from such experiences have been implicated in the development of obesity among Indigenous people (217). However, the specific genes involved remain to be identified.

Despite the limitations concerning the conclusions that can be drawn from these studies, the fact that intergenerational and transgenerational consequences can occur has important health and social implications. Although some of the transgenerational effects that have been identified may have their roots in epigenetic actions, it is just as likely that being born in traumatic times could have affected children for other reasons, notably poverty, food shortages, safety concerns, or the parental care children received (132). In this respect, prenatal or early life trauma could create a behavioral or emotional milieu (e.g., detachment, social rejection sensitivity, poor coping methods, or changes in family dynamics) that might favor the development of pathology (212). It was, indeed, suggested that negative early experiences among Indigenous people were accompanied by numerous toxic community stressors (poverty, abuse, and substance use), which might have fostered pathology. As such, rather than pointing to any single trauma, societal strife as a whole might create an environment in which epigenetic actions could influence cognitive, emotional, and physical health (218).

In assessing the immediate and intergenerational consequences of trauma it is important to consider that the negative consequences of trauma could be moderated by post-trauma experiences, particularly economic conditions and the availability of “safe spaces” that allow for healing. This is particularly germane to Inuit and First Nations people living on-reserve that continue to experience substandard living conditions, including poor housing, food insecurity, and numerous other negative experiences stemming from colonial policies and practices (219).

It is of practical and theoretical importance that epigenetic changes introduced by stressors or toxicants are reversible so that negative health consequences linked to epigenetic alterations could be precluded. In particular, treatment of rodents with compounds, such as methionine or trichostatin A, could reverse the epigenetic changes introduced by maternal stressors experienced during early life (220). Similarly, toxicant-provoked epigenetic changes could be altered by increasing folate (vitamin B-9) in the maternal diet (221) or by increasing the availability of methyl donors to limit epigenesis. It is especially significant that being raised in an enriched environment could prevent the adverse transgenerational actions of stressors (222, 223). Consistent with studies in rodents, in humans, lifestyles, including consumption of certain dietary components limit the health risks created by earlier epigenetic actions (224–226). Moreover, as already described, housing insecurity can engender epigenetic actions, and environmental toxicants, including mycotoxins, can promote epigenetic changes that can occur transgenerationally. In effect, the adverse experiences of stressors, which include inadequate and overcrowded housing (recall that virtually all stressors promote numerous common epigenetic changes), can be modified by postnatal environmental and social conditions.

Concluding comments

Based on a broad review of various relevant research literatures, it is apparent that the impact of inadequate housing on the physical and mental health of Indigenous people globally is a component of a broader set of conditions, including environmental and social determinants, as well as individual difference characteristics. A conceptual representation of these linkages is provided in Figure 1. While it would have been preferable to undertake a meta-analysis or systematic review to directly assess the impact of housing insufficiencies in undermining the health and well-being of Indigenous people, such an approach was precluded by the limited quantitative studies of the links between specific or general housing inadequacy and health among Indigenous groups. Instead, we have delineated the complex relations among the factors contributing to the physical and psychological health of Indigenous people by drawing on the findings from different research domains.

The dearth of research evaluating well being owing to improved housing is also true, and where studies exist, the findings are not necessarily consistent. For example, although it was demonstrated within an Inuit community that rehousing individuals can produce improvements in health and well-being among some individuals [e.g., (24, 25)], this effect was not evident among First Nations people. As indicated earlier, relocating individuals from their lands into regions that were viewed as “not their own” was fraught with problems, including disruption of social, cultural, and spiritual connections rooted in the land as well as disturbances related to cultural, physical, and economic survival [e.g., (67)].

It is unfortunate that research on this topic is so sparse. While marginalized groups are often absent in mainstream research, many Indigenous groups are reluctant to engage in research owing the history of harmful experiments conducted on Inuit and First Nations people. For instance, research conducted from 1942 to 1952 in Indigenous communities and Indian Residential Schools concerned the influence of supplements among children maintained on starvation diets, even depriving them of dental care allegedly to maintain the integrity of the research [see (227)]. In other studies undertaken with the backing of the National Research Council and Indian Affairs, Indigenous children and adults in Canada were coerced into participating in studies to assess the effectiveness of the bacille Calmette-Guerin (BCG) vaccine to treat tuberculosis. For decades, only ending in the late 1970's, Indigenous women were forced to undergo sterilization to preclude the birth of children with “mental deficiencies” (228). In the United States, studies conducted with blood samples for diabetes research were used in inappropriate and unauthorized analyses attempting to link genetic factors in inbreeding/population origins and migration to schizophrenia (229). All to often, researchers entered Indigenous communities, collected data for their own end, and left without providing any benefits to communities.

As a result of these practices, in recent years Indigenous Peoples in Canada have pushed back and have limited research with Indigenous populations so that they have a say in determining their destinies (“Nothing about us without us”). For example, the First Nations Information Governance Centre has established a set of principles that must be respected (OCAP – Ownership, Control, Access, and Possession of data). Similarly, research conducted with Inuit must acquire a license to do so from the Nunavut Research Institute. In both instances, the communities involved must be willing and active partners to the research. With the assertion of their rights to the determination and governance of research with Indigenous Peoples, collaborative research has increased, even including genomic analyses to identify potential epigenetic changes linked to genertions of trauma that may be responsible the development of pathological conditions [e.g., (230)].

Collective, historical assaults perpetuated against Indigenous Peoples within the US, Australia and Canada that were aimed at eliminating the group's identity have been described as creating a lasting, pervasive “soul wound” (231). These experiences contributed to the deterioration of psychological and physical health of individuals and disturbed social integration, which persisted for generations (211, 212). This said, there are instances in which collective trauma may actually strengthen the group's resilience. Finding meaning and posttraumatic growth may serve in this capacity, as can having a strong social identity and sense of self derived from group membership (232). For instance, immune disturbances were evident among individuals of the Blackfeet reserve (Browning, Montana) who had encountered adverse early life experiences. However, among individuals who had strong ties with their community, these negative immune outcomes were diminished (233).

Ample reason exists to suppose that the physical and psychological consequences of collective, historical trauma can be transmitted across generations through epigenetic mechanisms and through parental behaviors. At the same time, following collective trauma and ongoing systemic discrimination, poverty may be pervasive, and living conditions may be exceptionally disrupted, culminating in elevated risk of diverse pathologies independent of the contribution of epigenetic actions. Even if individuals who experienced collective, historical trauma might appear as if they were no longer affected by these events, physiological stress responses and emotional distress can be triggered by reminders of the indignities experienced by their group, thereby facilitating adverse health outcomes (219). In addition to their independent effects on health, inadequate living conditions (e.g., crowded and poor housing) may serve as reminders of trauma experiences, thereby increasing the risk of diverse pathologies.

Indigenous Peoples across nations have had strong connections with their natural environments, and they are often viewed as the guardians of the land, forests, and waters. These connections have been passed down across generations through cultural practices, narratives, and traditions, and it is believed that they may foster health and well-being. Thus, it is ironic that First Nations people have so often been victims of spoiled natural environments, (placing toxic sites adjacent to reserves, and land descration through through resource extraction) as well as overcrowding and substandard housing that may lead to toxic environments. Such problems on First Nations reserves have been prevalent for several decades, and progress in averting the negative consequences has been slow in materializing.

Despite having fought for a say in determining their destinies, stark housing inadequacies and overcrowding continue to exist in First Nations communities largely stemming from colonial policies that undermine socioeconomic status and contribute to the continuing disenfranchisement from Indigenous territories. Ultimately, like other G8 countries, Canada needs a national housing strategy for Indigenous and non-Indigenous people (234) and public policy to encourage the implementation of remedial actions to attenuate the hazards of poor housing and overcrowding and greater efforts need to be made to translate recommendations into actions. This perspective is hardly new [e.g., (235)], and as indicated at the outset of this report, international bodies have confirmed the need for active steps to be undertaken. Failing this, on-reserve housing issues are likely to worsen, and children and adults will continue to feel the health effects, which can potentially be passed on across generations.

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Footnotes

Edited by: Lutchmie Narine, Syracuse University, United States

Reviewed by: Ana Laura Cervantes-Nájera, National Polytechnic Institute (IPN), Mexico

Footnotes

Inuit Nunangat is the traditional homeland of Inuit, which includes Nunatsiavut (Labrador), Nunavik (Northern Quebec), Nunavut and the Inuvialuit region (Northwest Territories).

According to the World Health Organization (39), household crowding is defined as the number of occupants exceeding the capacity of the dwelling space available, although this varies with the age of individuals, their sex, and the relationship of individuals within the dwelling. In this context, overcrowding is usually considered to exist when extra bedrooms are required so that a cohabiting adult couple or persons over the age of 21 do not have their own bedroom or when same sex pairs of children aged 10–20 years lack a bedroom. As well, crowding is considered an issue when people need to crowd into a room because other parts of the home are uninhabitable (e.g., because of cold).