Objective: Traumatic brain injury (TBI) is increasingly recognized as a common and impactful health determinant in homeless and precariously housed populations. We sought to describe the history of TBI in a precariously housed sample and evaluate how TBI was associated with the initial loss and lifetime duration of homelessness and precarious housing. Method: We characterized the prevalence, mechanisms, and sex difference of lifetime TBI in a precariously housed sample. We also examined the impact of TBI severity and timing on becoming and staying homeless or precariously housed; 285 precariously housed participants completed the Brain Injury Screening Questionnaire in addition to other health assessments. Results: A history of TBI was reported in 82.1% of the sample, with 64.6% reporting > 1 TBI, and 21.4% reporting a moderate or severe TBI. Assault was the most common mechanism of injury overall, and females reported significantly more traumatic brain injuries due to physical abuse than males (adjusted OR = 1.26, 95% CI = 1.14 to 1.39, P < 0.0001). The first moderate or severe TBI was significantly closer to the first experience of homelessness ( b = 2.79, P = 0.003) and precarious housing ( b = 2.69, P < 0.0001) than was the first mild TBI. In participants who received their first TBI prior to becoming homeless or precariously housed, traumatic brain injuries more proximal to the initial loss of stable housing were associated with a longer lifetime duration of homelessness (RR = 1.04, 95% CI = 1.02 to 1.06, P < 0.0001) and precarious housing (RR = 1.03, 95% CI = 1.01 to 1.04, P < 0.0001). Conclusions: These findings demonstrate the high prevalence of TBI in this vulnerable population, and that aspects of TBI severity and timing are associated with the loss and lifetime duration of stable housing.

Background Homeless and precarious housed persons are particularly prone to traumatic brain injuries (TBIs), but existent incidence rates are hampered by poor case acquisition. We rigorously documented TBIs in precariously housed persons transitioning in and out of homelessness. MethodsBetween December 2016 and May 2018, 326 precariously housed participants enrolled in a longitudinal study in Vancouver, Canada were assessed monthly for TBI occurrences after education on sequelae. Over one participant-year, 2433 TBI screenings were acquired for 326 person-years and variables associated with odds of incident TBI were evaluated.Findings One hundred participants acquired 175 TBIs, yielding an observed incidence proportion of 30¢7% and event proportion of 53¢7%. Of the injured, 61% reported one TBI and 39% reported multiple injuries. Acute intoxication was present for more than half of the TBI events assessed. Additionally, 9¢7% of TBI events occurred in the context of a drug overdose. Common injury mechanisms were falls (45¢1%), assaults (25¢1%), and hitting one's head on an object (13¢1%). In this community-based but non-randomly recruited sample, exploratory analyses identified factors associated with odds of an incident TBI over one year of follow-up, including: schizophrenia disorders (odds ratio (OR) = 0¢43, 95% confidence interval (CI) 0¢19, 0¢94), role functioning (OR = 0¢69, 95% CI 0¢52, 0¢91), opioid dependence (OR = 2¢17, 95% CI 1¢27, 3¢72) and those reporting past TBIs (OR = 1¢99, 95% CI 1¢13, 3¢52).Interpretation Given the ubiquity of TBIs revealed in this precariously housed sample, we identify an underappreciated and urgent healthcare priority. Several factors modified the odds of incident TBI, which can facilitate investigations into targeted prevention efforts.

Salmon aquaculture is among the fastest growing food-producing industries worldwide, growing from 12,000 tonnes in 1980 to over 3.2 million tonnes by (Asche et al., 2013FAO, 2020). Canada is now the fourth largest producer of farmed salmon behind Norway, Scotland and Chile producing over 100,000 tonnes of farmed salmon in 2019 (DFO, 2018a). This industry relies on permeable open net pen structures placed directly into nearshore coastal waters to hold the salmon (Asche et al., 2013). These open net pens are efficient for rearing salmon as the open transfer of seawater provides exposure to natural fluctuations in water conditions such as salinity, temperature, nutrients and dissolved oxygen.Outbreaks of parasitic sea lice (Lepeophtheirus salmonis and Caligus spp.) are a major issue in open net pen salmon farming worldwide (Costello, 2006;Krkošek et al., 2005). These ectoparasites feed on the host's skin, mucus and underlying tissue, leaving the host fish susceptible to secondary infection and disease (Costello, 2006).Outbreaks of sea lice represent the greatest source of mortality and economic losses to fish farms, causing estimated global losses of $500 million annually, accounting for 6% of product value (Costello, 2009;Mustafa et al., 2001).

Early life stages of Pink salmon (Oncorhynchus gorbuscha) are at risk of exposure to the active ingredients of chemotherapeutant formulations (hydrogen peroxide [HP], azamethiphos [AZ], emamectin benzoate [EB], cypermethrin [CP] and deltamethrin [DM]) used to control sea lice in salmon aquaculture. LC50 values (95% con dence intervals) for acute 48-h water exposures in order of least to most toxic to seawater-adapted pink salmon fry were: mg/L), EB (1090EB ( [676-2006 µg/L), µg/L), ] µg/L), and DM (980 [640-1800] ng/L). In subchronic 10-d lethality sediment exposure tests, LC50 values (95% con dence intervals) in order of least to most toxic were: EB (2065 [1384-3720] µg/kg), µg/kg), and DM (1035DM ( [640-2000 ng/kg). Alterations in behaviour varied between chemicals; no chemical attracted pink salmon fry; sh avoided HP to a limited extent at 50 mg/L), as well as EB (300 µg/L), and AZ (50 µg/L). Signi cant concentration-dependent decreases in olfactory responsiveness to food extract were seen following AZ, CP and DM exposures that occurred at lower concentrations with longer exposure periods (10 µg/L, 0.5 µg/L and 100 ng/L thresholds at 168 h). Following 10-d sediment exposures, olfaction was only affected by CP exposure at 50 µg/kg. Signi cant decreases in swimming performance (Ucrit) occured for HP, AZ, CP and DM at concentrations as low as 100 mg/L, 10 µg/L, 2 µg/L and 200 ng/L, respectively. This study provides comprehensive data on the lethal and sublethal effects of aquaculture chemotherapeutant exposure in early life stage pink salmon.