Human behaviour directs household-level exposure to malaria vectors in Bandarban, Bangladesh.

BACKGROUND: Bangladesh has reduced malaria incidence and mortality by over 75% between 2010 and 2020. Widespread long-lasting insecticidal net (LLIN) distribution and use is one of the measures responsible for this success. Recalcitrant malaria hotspots within the Chittagong Hill Tracts districts suggest important drivers of malaria risk may remain uncharacterized. METHODS: Towards understanding how household-level human behaviour impacts exposure to mosquitoes, parallel human landing catches and human behavioural observations were conducted in four households for 6 months (May-October) over the rainy season in the Bandarban District. Analysis quantifies spatiotemporal human behaviour-adjusted exposure to Anopheles with and without LLINs. RESULTS: This small-scale operational study demonstrates that human spatial and temporal presence along with LLIN use drives exposure to Anopheles. Though the four households had both outdoor and indoor exposure, especially in the evening (1800-2000 h) and early morning (0400-0500 h), data points to household-based heterogeneity in malaria exposure even with similar LLIN access. CONCLUSION: Incorporating human behaviour into exposure estimates can be used to understand the efficacy and limitations of local vector control strategies and identify gaps in protection, as well as where present intervention strategies may be optimized.

Intrafamilial Exposure to SARS-CoV-2 Associated with Cellular Immune Response without Seroconversion, France.

We investigated severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2)-specific antibodies and T-cell responses against SARS-CoV-2 and human coronavirus (HCoV) 229E and OC43 in 11 SARS-CoV-2 serodiscordant couples in Strausbourg, France, in which 1 partner had evidence of mild coronavirus disease (COVID-19) and in 10 unexposed healthy controls. Patients with confirmed COVID-19 were considered index patients and their partners close contacts. All index patients displayed positive SARS-CoV-2-specific antibody and T-cell responses that lasted up to 102 days after symptom onset. All contacts remained seronegative for SARS-CoV-2; however, 6 reported COVID-19 symptoms within a median of 7 days after their partners, and 4 of those showed a positive SARS-CoV-2-specific T-cell response against 3 or 4 SARS-CoV-2 antigens that lasted up to 93 days after symptom onset. The 11 couples and controls displayed positive T-cell responses against HCoV-229E or HCoV-OC43. These data suggest that exposure to SARS-CoV-2 can induce virus-specific T-cell responses without seroconversion.

The epidemiological trends in the burden of lung cancer attributable to PM2.5 exposure in China.

OBJECTIVE: PM2.5, which is a major contributor to air pollution, has large effects on lung cancer mortality. We want to analyse the long-term trends in lung cancer burden attributable to PM2.5 exposure and provide evidence that can be used for preventive measures and health resource planning. METHODS: Mortality data related to lung cancer were obtained from the Global Burden of Disease (GBD) 2019 project. A joinpoint regression analysis was used to assess the magnitude and direction of the trends in mortality from 1990 to 2019, and the age-period-cohort method was used to analyse the temporal trends in the mortality rate of lung cancer attributable to PM2.5 exposure by age, period, and cohort. RESULTS: From 1990 to 2019, the age-standardized mortality rate (ASMR) attributable to PM2.5 exposure trended slowly upwards, and the ASMR due to ambient PM2.5 exposure (APE) increased significantly, that due to household PM2.5 exposure (HPE) decreased. The longitudinal age curves show that the mortality rates due to PM2.5 exposure among younger individuals were low, and they significantly increased from their levels among those in the 45-49 age group to their levels among those in the over-85 age group. From 1990 to 2019, the period RRs due to APE increased, but those due to HPE decreased. Similar trends were observed in the cohort RRs. The overall net drift per year attributable to PM2.5 exposure was below 0. The local drift values increased with age and were above 0 for the over-80 age groups. The overall net drifts per year were above zero for APE and below zero for HPE. The corresponding results among males were higher than those among females. CONCLUSIONS: In China, the type of air pollution responsible for lung cancer has changed from household air pollution to ambient air pollution. PM2.5 exposure is more harmful among males and older people. Ambient air pollution should be emphasized, and China should strengthen its implementation of effective public policies and other interventions.

Transmission of Bacterial Zoonotic Pathogens between Pets and Humans: The Role of Pet Food.

Recent Salmonella outbreaks associated with dry pet food and treats raised the level of concern for these products as vehicle of pathogen exposure for both pets and their owners. The need to characterize the microbiological and risk profiles of this class of products is currently not supported by sufficient specific data. This systematic review summarizes existing data on the main variables needed to support an ingredients-to-consumer quantitative risk model to (1) describe the microbial ecology of bacterial pathogens in the dry pet food production chain, (2) estimate pet exposure to pathogens through dry food consumption, and (3) assess human exposure and illness incidence due to contact with pet food and pets in the household. Risk models populated with the data here summarized will provide a tool to quantitatively address the emerging public health concerns associated with pet food and the effectiveness of mitigation measures. Results of such models can provide a basis for improvements in production processes, risk communication to consumers, and regulatory action.

Effect of large-scale land acquisition by domestic and international entities on farm investment in northern Ghana.

Rural households remained the access-marginalized demographic in Africa despite massive land rushes by both domestic and foreign enterprises. As a result, investment decisions made by agricultural households are affected. To resolve this issue, a study that examines how exposure to large-scale land acquisition (LSLA) impacts people's agricultural investment decisions is required. Using data from 664 households selected using a multistage sampling technique, we examined the nexus between LSLA under local and foreign organizations and short-term investment (STI) and long-term investments (LTI) in land-improving measures. The results revealed that although LSLA under domestic and foreign entities tends to have a negative and statistically significant impact on the probability of LTI, it has a positive and significant impact on the probability of doing so for STI. The results also showed a simultaneity between LSLA and farm investment. Thus, giving farmers legal ownership safeguards them as they undertake LTI. To encourage household investment and reduce further exposure to LSLA, improvements in legal land ownership can be made.

Spatiotemporal distribution and bionomics of Anopheles stephensi in different eco-epidemiological settings in Ethiopia.

BACKGROUND: Malaria is a major public health concern in Ethiopia, and its incidence could worsen with the spread of the invasive mosquito species Anopheles stephensi in the country. This study aimed to provide updates on the distribution of An. stephensi and likely household exposure in Ethiopia. METHODS: Entomological surveillance was performed in 26 urban settings in Ethiopia from 2021 to 2023. A kilometer-by-kilometer quadrant was established per town, and approximately 20 structures per quadrant were surveyed every 3 months. Additional extensive sampling was conducted in 50 randomly selected structures in four urban centers in 2022 and 2023 to assess households' exposure to An. stephensi. Prokopack aspirators and CDC light traps were used to collect adult mosquitoes, and standard dippers were used to collect immature stages. The collected mosquitoes were identified to species level by morphological keys and molecular methods. PCR assays were used to assess Plasmodium infection and mosquito blood meal source. RESULTS: Catches of adult An. stephensi were generally low (mean: 0.15 per trap), with eight positive sites among the 26 surveyed. This mosquito species was reported for the first time in Assosa, western Ethiopia. Anopheles stephensi was the predominant species in four of the eight positive sites, accounting for 75-100% relative abundance of the adult Anopheles catches. Household-level exposure, defined as the percentage of households with a peridomestic presence of An. stephensi, ranged from 18% in Metehara to 30% in Danan. Anopheles arabiensis was the predominant species in 20 of the 26 sites, accounting for 42.9-100% of the Anopheles catches. Bovine blood index, ovine blood index and human blood index values were 69.2%, 32.3% and 24.6%, respectively, for An. stephensi, and 65.4%, 46.7% and 35.8%, respectively, for An. arabiensis. None of the 197 An. stephensi mosquitoes assayed tested positive for Plasmodium sporozoite, while of the 1434 An. arabiensis mosquitoes assayed, 62 were positive for Plasmodium (10 for P. falciparum and 52 for P. vivax). CONCLUSIONS: This study shows that the geographical range of An. stephensi has expanded to western Ethiopia. Strongly zoophagic behavior coupled with low adult catches might explain the absence of Plasmodium infection. The level of household exposure to An. stephensi in this study varied across positive sites. Further research is needed to better understand the bionomics and contribution of An. stephensi to malaria transmission.

The mortality trends analysis of ischemic heart disease attributed to (PM) 2.5 exposure in China from 1990 to 2019 in APC model.

OBJECTIVE: To analyze the mortality trend of ischemic heart disease (IHD) attributed to particulate matter (PM) 2.5 exposure among Chinese populations from 1990 to 2019. To evaluate the influences of cohort, period, and age on long-term of IHD mortality trends. METHODS: Global burden of disease (GBD) data in 2019 regarding IHD death rate attributed to exposure to (PM) 2.5 in China from 1990 to 2019 were adopted. The age-period-cohort (APC) model based on the R language produced by the National Cancer Institute of the United States was used for statistical analysis to investigate the influences of different ages, periods, and cohorts on IHD death rate attributed to exposure to (PM) 2.5. RESULTS: The age-standardized death rate of IHD attributed to exposure to ambient (PM) 2.5 in China revealed an uptrend from 1990 to 2019. This increased from 8.63/100,000 in 1990 to 21.31/100,000 in 2019. This was an increase of 1.47%. The age-standardized IHD death rate attributed to exposure to household (PM) 2.5 showed a decreasing trend. This decreased from 19.61/100,000 in 1990 to 8.72/100,000 in 2019. This was a decrease of 0.74%. The results of the APC model indicated that the annual net drift of IHD mortality attributed to exposure to (PM) 2.5 was -0.10%. The annual net drifts of exposure to household and ambient (PM) 2.5 were -4.54% and 3.44%, respectively. The IHD death rate attributed to ambient and household (PM) 2.5 exposure in the same birth cohort enhanced with age. With time, the rate ration (RR) of period effects of IHD mortality attributed to ambient (PM) 2.5 exposure for both male and female showed an upward trend. The RR of period effects of IHD death rate attributed to household (PM) 2.5 exposure suggested a downtrend. In the consecutive birth cohorts, the population in China with a later birth cohort presented a higher risk of IHD death attributed to exposure to ambient (PM) 2.5 and a lower risk of IHD death attributed to household (PM) 2.5 exposure. CONCLUSIONS: In China for the burden of IHD attributed to exposure to (PM) 2.5, the primary environmental risk was ambient (PM) 2.5 exposure compared to exposure to household PM2.5. IHD exposure to environmental air pollution posed a greater risk to young people.

Indoor Household Exposures and Associated Morbidity and Mortality Outcomes in Children and Adults in South Africa.

Human exposure to indoor pollution is one of the most well-established ways that housing affects health. We conducted a review to document evidence on the morbidity and mortality outcomes associated with indoor household exposures in children and adults in South Africa. The authors conducted a scientific review of the publicly available literature up to April 2022 using different search engines (PubMed, ProQuest, Science Direct, Scopus and Google Scholar) to identify the literature that assessed the link between indoor household exposures and morbidity and mortality outcomes in children and adults. A total of 16 studies with 16,920 participants were included. Bioaerosols, allergens, dampness, tobacco smoking, household cooking and heating fuels, particulate matter, gaseous pollutants and indoor spray residue play a significant role in different morbidity outcomes. These health outcomes include dental caries, asthma, tuberculosis, severe airway inflammation, airway blockage, wheeze, rhinitis, bronchial hyperresponsiveness, phlegm on the chest, current rhinoconjunctivitis, hay fever, poor early life immune function, hypertensive disorders of pregnancy, gestational hypertension, and increased incidence of nasopharyngeal bacteria, which may predispose people to lower respiratory tract infections. The findings of this research highlight the need for more initiatives, programs, strategies, and policies to better reduce the negative consequences of indoor household exposures.

Association between household exposure and cycle threshold in COVID-19 infected health care workers.

OBJECTIVE: Household SARS-COV-2 contact constitutes a high-risk exposure for health care workers (HCWs). Cycle threshold (Ct) of reverse transcriptase-polymerase chain reaction testing provides an estimate of COVID-19 viral load, which can inform clinical and workplace management. We assessed whether Ct values differed between HCWs with COVID-19 with and without household exposure. METHODS: We analyzed HCW COVID-19 cases whose Ct data could be compared. We defined low Ct at a cut-point approximating a viral load of 4.6 × 106 copies per ml. Logistic regression tested the association of household exposure and symptoms at diagnosis with a low Ct value. RESULTS: Of 77 HCWs with COVID-19, 20 were household exposures cases and 34 were symptomatic at testing (7 were both household-exposed and symptomatic at testing). Among household exposures, 9 of 20 (45%) manifested lower Ct values compared to 14 of 57 (25%) for all others. In a bivariate model, household exposure was not statistically associated with lower Ct (Odds Ratio [OR] 1.20; 95% Confidence Interval [CI] 0.97-1.51). In multivariable modelling both household exposure (OR] 1.3; 95% CI 1.03-1.6) and symptoms at diagnosis (OR 1.4; 95% CI 1.15-1.7) were associated with a low Ct value. DISCUSSION: Household exposure in HCWs with newly diagnosed COVID-19 was associated with lower Ct values, consistent with a higher viral load, supporting the hypothesis that contracting COVID-19 in that manner leads to a greater viral inoculum.

Household Cleaning and Poor Asthma Control Among Elderly Women.

BACKGROUND: Asthma control is suboptimal in nearly half of adults with asthma. Household exposure to disinfectants and cleaning products (DCP) has been associated with adverse respiratory effects, but data on their association with asthma control are scant. OBJECTIVES: To investigate the association between household use of DCP and asthma control in a large cohort of French elderly women. METHODS: We used data from a case-control study on asthma (2011-2013) nested in the E3N cohort. Among 3023 women with current asthma, asthma control was defined by the Asthma Control Test (ACT). We used a standardized questionnaire to assess the frequency of cleaning tasks and DCP use. We also identified household cleaning patterns using a clustering approach. Associations between DCP and ACT were adjusted for age, smoking status, body mass index, and education. RESULTS: Data on ACT and DCP use were available for 2223 women (70 ± 6 years old). Asthma was controlled (ACT = 25), partly controlled (ACT = 20-24), and poorly controlled (ACT ≤ 19) in 29%, 46%, and 25% of the participants, respectively. Weekly use of sprays and chemicals was associated with poorly controlled asthma (odds ratio [95% confidence interval]: 1 spray: 1.31 [0.94-1.84], ≥2 sprays: 1.65 [1.07-2.53], P trend: .01; 1 chemical: 1.24 [0.94-1.64], ≥2 chemicals: 1.47 [1.03-2.09], P trend: .02). Risk for poor asthma control increased with the patterns "very frequent use of products" (1.74 [1.13-2.70]) and "infrequent cleaning tasks and intermediate use of products" (1.62 [1.05-2.51]). CONCLUSION: Regular use of DCP may contribute to poor asthma control in elderly women. Limiting their use may help improve asthma management.

Environmental chemical exposures in the urine of dogs and people sharing the same households.

INTRODUCTION: Urothelial carcinoma (UCC) develops in both humans and dogs and tracks to regions of high industrial activity. We hypothesize that dogs with UCC may act as sentinels for human urothelial carcinogen exposures. The aim of this pilot study was to determine whether healthy people and dogs in the same households share urinary exposures to potentially mutagenic chemical carcinogens. METHODS: We measured urinary concentrations of acrolein (as its metabolite 3-HPMA), arsenic species, 4-aminobiphenyl, and 4-chlorophenol (a metabolite of the phenoxyherbicide 2,4-D) in healthy dogs and their owners. We assessed possible chemical sources through questionnaires and screened for urothelial DNA damage using the micronucleus assay. RESULTS: Biomarkers of urinary exposure to acrolein, arsenic, and 4-chlorophenol were found in the urine of 42 pet dogs and 42 owners, with 4-aminobiphenyl detected sporadically. Creatinine-adjusted urinary chemical concentrations were significantly higher, by 2.8- to 6.2-fold, in dogs compared to humans. Correlations were found for 3-HPMA (r = 0.32, P = 0.04) and monomethylarsonic acid (r = 0.37, P = 0.02) between people and their dogs. Voided urothelial cell yields were inadequate to quantify DNA damage, and questionnaires did not reveal significant associations with urinary chemical concentrations. CONCLUSIONS: Healthy humans and pet dogs have shared urinary exposures to known mutagenic chemicals, with significantly higher levels in dogs. Higher urinary exposures to acrolein and arsenic in dogs correlate to higher exposures in their owners. Follow-up studies will assess the mutagenic potential of these levels in vitro and measure these biomarkers in owners of dogs with UCC.

Pattern of food, drug and chemical poisoning in Qassim region, Saudi Arabia from January 2017 to December 2017.

BACKGROUND: Poisoning has become a widespread and dangerous phenomenon worldwide. The purpose of our study was to determine and analyze the pattern of poisoning cases induced with food, drugs, and chemicals reported to the Department of Environmental and Occupational Health in Qassim province in the Kingdom of Saudi Arabia. The study also evaluated the correlation of demographic variables such as age, type of toxicity and geographical distribution associated with poisoning in Qassim province. METHODS: This retrospective cross-sectional study was performed on 381 cases of poisoning. The data was collected from Jan 2017 to Dec 2017 and revealed that out of 381 cases, 120 have food poisoning (65 % females and 35 % males), 180 have drug poisoning (55.56 % females and 44.44 % males), whereas 81 cases have chemical poisoning (41.98 % female and 58.02 % male). Data were statistically analyzed using SPSS/PC statistical package. The study revealed that the most common agents involved in acute poisoning were drugs (47.25 %), especially analgesics such as Paracetamol (Acetaminophen), followed by antipsychotic drugs. Food poisoning was the second acute poisoning with (31.40 %). Finally, chemical poisoning involved in acute poisoning with 21.20 % of cases reported household products accomplished strongest bleach (chlorines)(Clorox®) and insecticides were the secondary source for chemical poisoning.

Increased household exposure to respiratory pathogens in HIV exposed uninfected children due to maternal HIV.

Little is known about household exposures to respiratory pathogens in HIV-exposed uninfected children (HEU) in Indian families. This case series investigates the nasopharyngeal carriage of Streptococcus pneumoniae, Staphylococcus aureus, and respiratory viruses at multiple points in three mother child pairs: (1) an HIV-infected child and mother, (2) an HEU child and HIV-infected mother, and (3) an HIV-unexposed uninfected (HUU) child and mother. Nasopharyngeal carriage densities of Streptococcus pneumoniae and Staphylococcus aureus were higher in mothers and children living in HIV-affected households, regardless of the child's HIV status. Maternal HIV and ART status impact these household exposures.

Pleural mesothelioma in household members of asbestos-exposed workers in Friuli Venezia Giulia, Italy.

OBJECTIVES: Malignant mesothelioma is closely associated to asbestos exposure. One such exposure may occur through contact with occupationally exposed household members and their belongings. This study examines the features of pleural mesothelioma attributable only to asbestos brought home by another family member. MATERIAL AND METHODS: The data sources were 1063 mesothelioma cases diagnosed between 1995 and 2014, from the Friuli Venezia Giulia Mesothelioma Register. In all cases the diagnosis of mesothelioma was based on the pathology report. Exposure information and demographic data were acquired by an occupational medical standardized questionnaire/interview. RESULTS: Household-exposure mesothelioma cases included 33 women and 2 men. Relationships were: wives (N = 22), daughters (N = 9), sons (N = 2), and mothers (N = 2). Asbestos exposure in the workers predominantly occurred in shipyards. Out of the 35 pleural cases, 19 were epithelial, 9 biphasic, 3 sarcomatoid, and 4 not specified. The mean age at diagnosis was 77 years old. The mean latency was 59 years, with wives having a significant shorter latency than offspring. Latency was not significantly related to morphology and asbestosis. The overall mean survival was 16 months (median 11 months) but treatment was beneficial (mean 16 months vs. 7 months). Biphasic/sarcomatoid histology and presence of asbestosis were associated with a decreased survival, although not with statistical significance. CONCLUSIONS: Our data confirms that household exposure increases the risk for pleural mesothelioma amongst women with no history of occupational asbestos exposure. This is an ongoing problem in many countries, as well as in Italy, where the evaluation of a framework for the compensation of these cases is under debate. Int J Occup Med Environ Health 2017;30(3):419-431.

Impacto da exposição domiciliar ao tabaco e da composição familiar sobre a precocidade de uso de tabaco e álcool em adolescentes brasileiros / Impact of household exposure to tobacco and family composition on the early onset of alcohol use in Brazilian adolescents

O uso precoce de tabaco e álcool associa-se à maior morbimortalidade e manutenção desse consumo na vida adulta. Esta tese investiga o papel de fatores domiciliares e familiares sobre o início precoce do uso dessas substâncias entre adolescentes. Os dados analisados são do Estudo de Riscos Cardiovasculares em Adolescentes (ERICA), que investigou 74.589 adolescentes de escolas públicas e privadas, com idades entre 12 e 17 anos, residentes de 124 municípios com mais de 100 mil habitantes no país. O primeiro manuscrito teve como objetivo estimar o efeito da presença de fumantes no domicílio sobre o início mais precoce de tabagismo entre adolescentes. O segundo manuscrito teve como objetivo estimar o efeito da composição familiar sobre o início mais precoce de tabagismo e do uso de álcool entre adolescentes. Em ambas as análises foram usados Modelos de Regressão de Cox não ajustados e ajustados por um conjunto de variáveis com intuito de controlar vieses de confundimento. Os Hazard Ratios estimados no manuscrito 1 mostraram um aumento de 51% (IC95%: 31%-65%) na chance de um adolescente não fumante e exposto ao tabaco em casa começar a fumar mais precocemente do que aquele que não convivia com tabagistas no domicílio. Nos resultados do segundo manuscrito observou-se uma influência importante da composição familiar sobre a precocidade de início do uso de tabaco e álcool entre adolescentes. Segundo os Hazard Ratios estimados, houve um aumento de 68% (IC95%: 50%-89%) na chance de um adolescente não fumante que não residia com ambos os pais iniciar o uso de tabaco antes de um adolescente que residia com pai e mãe. Quanto àqueles que residiam apenas com a mãe ou apenas com o pai, esse aumento foi de 46% (IC95%: 32%-60%) e 54% (IC95%: 28%-84%), respectivamente. Em relação ao início do consumo de bebidas alcoólicas, observou-se um aumento de 35% (IC95%: 21%-52%) na chance de um adolescente que não bebe e não reside com pai e mãe de iniciar o uso de álcool mais precocemente do que aqueles que residiam com ambos os pais. Quanto aos adolescentes que residiam apenas com a mãe ou apenas com o pai, esse aumento foi de 22% (IC95%: 17%-28%) e 36% (IC95%: 24%-50%), respectivamente. O terceiro manuscrito teve como objetivo investigar o uso conjunto de tabaco e álcool através de análises de coocorrência e de agrupamento, assim como descrever a relação temporal do início do uso das duas substâncias entre adolescentes tabagistas e usuários de álcool. Para a análise de agrupamento foram obtidas razões entre os valores observados (O) e esperados (E) de uso de tabaco e álcool. Na amostra total a razão O/E foi 3,51 (IC95%: 3,39-3,65) indicando o agrupamento do uso dessas substâncias. Já a Razão de Chances de Prevalência foi de 14,7 (IC95%: 12,4-17,4). A maior parte dos usuários (45,2%) de ambas as substâncias iniciou pelo uso de álcool. Nossos resultados reforçam as propostas de que ações preventivas não devem estar focadas em cada droga isoladamente, e devem incluir não só o adolescente, mas também seu universo familiar.

Early use of tobacco and alcohol is associated with increased morbimortality and maintenance of their use during adulthood. This thesis investigates the role of household and family factors on adolescents' early onset of these substances. The data analyzed are from the Cardiovascular Risk Factors Study (ERICA), which investigated 74,589 adolescents from public and private schools, aged between 12 and 17 years old, living in 124 municipalities with more than 100 thousand inhabitants in the country. The first manuscript aimed to estimate the effect of the presence of smokers in the household on the earlier onset of smoking habit among adolescents. The objective of the second manuscript was to estimate the effect of family composition on the earlier onset of smoking and alcohol use among adolescents. In both analyses, unadjusted and adjusted Cox Regression Models were used to control for confounding variables. The Hazard Ratio estimated in manuscript 1 showed a 51% increase (95% CI: 31%-65%) in the chance that a nonsmoking adolescent exposed to tobacco at home would start smoking earlier than one who did not live with smokers. The results of the second manuscript depicted an important impact of family composition on the early onset of tobacco and alcohol use among adolescents. According to the estimated Hazard Ratios, there was a 68% increased chance (95% CI: 32%-60%) that a nonsmoking adolescent who did not live with both parents would initiate tobacco use earlier than an adolescent living with both parents. As for those who resided with only the mother or only the father, the increase was 46% (95% CI:32%-60%) and 54% (95%CI: 28%-84%), respectively. Regarding the onset of consumption of alcoholic beverages, there was a 35% increase (95% CI:21%-52%) in the chance of an adolescent who does not drink and does not reside with both parents to initiate alcohol use earlier than those living with the mother and the father. As for adolescents living only with the mother or only the father, this increase was 22% (95%CI: 17%-28%) and 36% (95%CI: 24%-50%), respectively. The third manuscript investigated the concurrent use of tobacco and alcohol through co-occurrence and clustering analyses. It also described the temporal relationship between the onset of tobacco and alcohol use among adolescents consuming both substances. For the clustering analysis, we calculated ratios between observed (O) and expected (E) values of tobacco and alcohol use. In the total sample, the O/E ratio was 3.51 (95% CI: 3.39-3.65), indicating the clustering of the use of these substances. The prevalence odds ratio was 14.7 (95% CI: 12.4- 17.4). Most of the users (45.2%) of both substances started with the use of alcohol. Our results reinforce the proposal that preventive actions should not be focused on each drug separately and should include the adolescents and their families.