Revisión rápida: monitoreo de la presencia e infectividad del virus SARS-CoV-2 y otros coronavirus en aguas residuales / Quick review: monitoring the presence and infectivity of SARS-CoV-2 and other coronaviruses in wastewater

Resumen: Objetivo: Describir la evidencia sobre la presencia e infectividad de SARS-CoV-2 y otros coronavirus en aguas residuales y su potencial uso como herramienta de vigilancia epidemiológica. Material y métodos: Búsqueda de publicaciones en PubMed y medRxiv desde enero 2003 hasta el 8 de junio de 2020 de acuerdo con la guía de revisiones rápidas de Cochrane. Resultados: Se incluyeron 29 publicaciones. El ARN de SARS-CoV-2 no infectivo se encontró en agua residual hospitalaria, agua residual cruda, tratada y lodos de plantas de tratamiento. Los niveles cuantitativos de ARN viral en agua residual presentan relación con el número de casos de Covid-19. SARS-CoV-1 y otros coronavirus permanecieron infectivos en agua residual cruda hasta por dos días. Conclusiones: Hasta esta revisión no existe evidencia sobre la presencia de virus infectivos de SARS-CoV-2 en agua residual cruda o tratada. La cuantificación de ARN de SARS-CoV-2 en agua residual es útil para la vigilancia epidemiológica.

Abstract: Objective: To describe the current evidence on the presence and infectivity of SARS-CoV-2 and other coronaviruses in wastewater; and its potential use as an epidemiological surveillance tool. Materials and methods: A search was performed in PubMed and medRxiv databases from January 2003 to June 8, 2020 according to the Cochrane Rapid Review Guide. Results: Twenty-nine publications were included. Non-infective RNA of SARS-CoV-2 has been detected in hospital sewage; raw and treated wastewater, and primary sludges from sewage treatment plants. Quantitative levels of viral RNA in wastewater are related with the number of Covid-19 cases. SARS-CoV-1 and other coronaviruses remained infective in wastewater up to two days. Conclusions: Currently, there is no evidence of the presence of infective SARS-CoV-2 in wastewater and its inactivation through treatment/disinfection has been proven. Quantification of SARS-CoV-2 RNA in wastewater can be a useful epidemiological surveillance tool.

Household water quality in areas irrigated with wastewater in the Mezquital Valley, Mexico.

Wastewater for irrigation in low- and middle-income countries can recharge aquifers and potentially contaminate supply sources. The infiltration rate has increased 13-fold in Mexico's Mezquital Valley, the largest agricultural area wastewater-irrigated worldwide, thus we assume that wastewater had contaminated supply sources. Fecal indicator bacteria (FIB) counts were enumerated in household water of two wastewater-irrigated areas, Tula and Tlahuelilpan, and a groundwater irrigated area, Tecozautla. During 2016-2017, household water, wastewater, and groundwater were sampled, analyzing fecal coliforms, fecal enterococci, and Escherichia coli, following membrane filtration procedures, and confirming the presence of E. coli by polymerase chain reaction. Nearly 50% of household water contained fecal contamination of up to 4.62 × 104 CFU/100 mL. Significant differences between FIB counts in household water from Tula and Tecozautla were observed by Kruskal-Wallis and Dunnett tests. Household water samples from Tula contained highest FIB counts. Wastewater from Tula and Tlahuelilpan contained counts of six orders-of-magnitude of FIB. Counts were high when residual chlorine was <0.2 mg L-1 and underwater storage. This research serves as a baseline to observe improvement with a newly installed wastewater treatment plant. Safe irrigation wastewater reuse should be performed under strict surveillance, considering human safety a priority.

Modeling Spatial Risk of Diarrheal Disease Associated with Household Proximity to Untreated Wastewater Used for Irrigation in the Mezquital Valley, Mexico.

BACKGROUND: Reusing wastewater for irrigation is a longstanding practice that enhances crop yields and improves climate resilience. Without treatment, however, wastewater contains harmful pathogens and chemicals. Reuse of untreated wastewater has been shown to be harmful to the health of nearby communities, but the routes of exposure are unknown and do not appear to be occupational. Some routes occur throughout entire communities, such as food contamination. Other routes may be spatially dependent, such as spread by domestic animals or through aerosolization. OBJECTIVES: To examine whether those wastewater exposure routes with a spatial dependency affect health, we estimated the risks of diarrheal disease in children under age 5 associated with living near wastewater canals, while adjusting for potential individual- and household-level confounders. METHODS: We conducted three surveys over 1 y in the Mezquital Valley, Mexico, to measure diarrhea in children. The distance between each participating household and a wastewater canal was measured using GPS coordinates. The association between proximity and diarrhea was estimated with a multilevel logistic regression model accounting for spatial autocorrelation. RESULTS: A total of 564 households completed one to three surveys, resulting in 1,856 survey observations of 646 children. Children living 100m from a canal had 45% lower odds of diarrhea than those living within 10m of a canal, and children living 1000m away had 70% lower odds of diarrhea [100m vs. 10m adjusted odds ratio (OR)=0.55, 95% credible interval (CI): 0.33, 0.91; 1000m vs. 10m adjusted OR=0.30, 95% CI: 0.11, 0.82]. DISCUSSION: The estimated decline in diarrheal prevalence with household distance from a canal persisted after controlling for occupational exposure. Identifying the specific routes of exposure that drive this relationship will help identify which interventions, such as upstream treatment, can reduce health risks for entire communities where wastewater exposure occurs. https://doi.org/10.1289/EHP6443.

Revisión rápida: monitoreo de la presencia e infectividad del virus SARS-CoV-2 y otros coronavirus en aguas residuales.

Objetivo. Describir la evidencia sobre la presencia e infectividad de SARS-CoV-2 y otros coronavirus en aguas residuales y su potencial uso como herramienta de vigilancia epidemiológica. Material y métodos. Búsqueda de publicaciones en PubMed y medRxiv desde enero 2003 hasta el 8 de junio de 2020 de acuerdo con la guía de revisiones rápidas de Cochrane. Resultados. Se incluyeron 29 publicaciones. El ARN de SARS-CoV-2 no infectivo se encontró en agua residual hospitalaria, agua residual cruda, tratada y lodos de plantas de tratamiento. Los niveles cuantitativos de ARN viral en agua residual presentan relación con el número de casos de Covid-19. SARS-CoV-1 y otros coronavirus permanecieron infectivos en agua residual cruda hasta por dos días. Conclusiones. Hasta esta revisión no existe evidencia sobre la presencia de virus infectivos de SARS-CoV-2 en agua residual cruda o tratada. La cuantificación de ARN de SARS-CoV-2 en agua residual es útil para la vigilancia epidemiológica.

A follow-up study after an improved cookstove intervention in rural Mexico: Estimation of household energy use and chronic PM2.5 exposure.

The benefits of improved biomass cookstoves (ICS) depends on their adoption and sustained use. Few studies have documented if and how they are used more than five years after being introduced. We conducted a 9-year prospective cohort study among young rural women in the highlands of Michoacan, Mexico. Participants had received a Patsari ICS during a community trial either in 2005 or 2006. With retrospective information collected in 2012-13, we studied the households' energy use, ICS survival, and cooking practices during the follow-up period. Using an exposure model constructed with personal PM2.5 measurements in a subsample of homes at the time of the initial trial in 2005, we estimated the exposure associated with different energy use patterns during the follow-up period. The ICS had a mean lifespan of 4 years, after which more than half of the stoves were not in use; therefore, the use of open fire increased, particularly among the indigenous communities. ICS use peak was achieved two years after the initial trial, either exclusively or combined with open fire. Yearly household energy use and other variables were used to estimate chronic air pollution exposure. Mean PM2.5 exposure during the follow-up period ranged from 51 to 319 µg/m3; the median was 102 and 146 µg/m3 for mainly ICS and mainly open fire use, respectively. The ICS has a useful period after which it needs maintenance, repair, or replacement. Unfortunately, many programs have not afforded a follow-up component. Exposure to biomass smoke air pollutants can be reduced by using an ICS instead of the traditional open fire. Household energy strategies should ensure equitable access to clean energy options adapted to local needs and preferences with culturally appropriate technology implemented on a sustainable perspective.

Environmental Health Promotion of a Contaminated Site in Mexico.

Entangled in complex ecological, sociocultural, and economic systems, current environmental health problems require integrated participatory approaches. Alpuyeca, a semi-urban, highly marginalized community in South-Central Mexico burdened by lead and polychlorinated biphenyl (PCB) contamination, dengue fever, and intestinal diseases, illustrates this. Its residents are distinctive, however, for their concerted actions in the face of environmental problems and the presence of defenders of a prehispanic worldview based on the protection of nature. This article addresses the health impacts of an integrated environmental health promotion strategy implemented through a participatory action research intervention based on qualitative and quantitative methods. Different actors, sectors, dimensions, and knowledge types were harmonized in a collaborative space created specifically for our interdisciplinary research team, community residents and local authorities. Reflections, plans and actions were developed collectively in this space with the view of finding solutions anchored in the local culture. Results included sharp reductions in blood-lead concentrations among children, in entomological indices, and in PCB contamination, as well as capacity strengthening. Medium-level community participation was achieved. This work contributes evidence that participatory environmental health research can be effective in analyzing and reducing problems in communities with multiple environmental health concerns. It complements ecohealth and environmental health literacy approaches.

Evaluation of the effect of an environmental management program on exposure to manganese in a mining zone in Mexico.

BACKGROUND: In the state of Hidalgo, Mexico, is found the largest second deposit of Manganese (Mn) in Latin America. Various studies on the sources of emission, exposure, and the effects on the health of children and adults have been conducted utilizing an ecosystem approach. Given the findings of Mn levels in air and the neurocognitive effects, an Environmental Management Program (EMP) was designed and implemented with the purpose of reducing exposure to Mn of the population, including various actions for reducing Mn emissions into the atmosphere. OBJECTIVE: To evaluate the impact of the EMP on the concentrations of Mn in air, as well as the modification of exposure to Mn in the blood and hair of adult residents of the communities intervened. METHODS: A quasi-experimental study was conducted in five rural communities, in which Mn concentrations were evaluated in air and in blood in the years 2002 and 2007, pre-intervention, and in 2013, postintervention. In 2003, the concentration of hair Mn among the communities was evaluated. Measurements were carried out of Particulate Matter (PM) of >10 and 2.5µm (PM10 and PM2.5), and Mn in PM10 and PM2.5 were measured using proton-induced X-ray emissions (PIXE). The method of Difference in Differences (DID) was applied to estimate the impact of EMP on Mn concentrations in particulate matter via linear regression through multilevel models. To evaluate the effect of Mn concentrations in air over Mn concentrations in blood in both study periods in the mining communities per year (2002 and 2013), a linear regression model for each year was employed. RESULTS: We estimated that the EMP contributed to reducing the average daily concentrations of Mn in PM10 and PM2.5 by 92 and 85%, respectively. The adjusted model did not show an effect of Mn concentrations in air over Mn concentrations in blood in both study periods. CONCLUSIONS: The results suggest that the measures implemented to reduce Mn emissions in air exerted a significant impact on the reduction of inhaled exposure in adult population.

Health risks from exposure to untreated wastewater used for irrigation in the Mezquital Valley, Mexico: A 25-year update.

Wastewater reuse for agriculture is common worldwide; wastewater treatment, however, is rare in many countries, leading to high potential for exposure to harmful pathogens. Mexico City, one of the largest producers of untreated wastewater for agricultural use worldwide, was the site of key epidemiologic studies conducted in the 1990s. We both reviewed the literature on and conducted a cross-sectional study of diarrheal risk and wastewater contamination to provide an updated assessment of health risks and to inform an upcoming update of the 2006 WHO guidelines on wastewater reuse. We surveyed communities in the Mezquital Valley that use wastewater for irrigation and communities that use well water to compare the prevalence of self-reported diarrheal disease in children under five years old. Wastewater, well water, household environmental samples, and stool samples were collected and analyzed. Communities exposed to wastewater had a higher one-week prevalence of diarrhea (10%) compared to unexposed communities (5%). This association remained in an adjusted modified Poisson regression model (PR = 2.31, 95% CI 1.00, 5.31), but not when limited to households engaged in agriculture. Water quality indicators document differences between irrigation water from the two community groups. These results are in agreement with 25 population studies identified by our review that were conducted since or not included in the 2006 WHO guidelines and show consistent negative impacts of wastewater exposure on health. While overall diarrheal prevalence has declined when compared to studies conducted over 25 years ago in the same region, the association of diarrheal disease and wastewater exposure has remained and possibly increased. With rising urbanization worldwide, attention to these risks and wastewater treatment is becoming increasingly important.

Modeling and estimating manganese concentrations in rural households in the mining district of Molango, Mexico.

Airborne manganese (Mn) is considered the most hazardous route of exposure since Mn particles can enter into the body through the lung and may access the brain directly through olfactory uptake, thereby bypassing homeostatic excretory mechanisms. Environmental indoor and outdoor manganese concentrations in PM2.5 were monitored in ten rural households from two communities of Hidalgo, Mexico, from 2006 to 2007. Indoor and outdoor air samples of PM2.5 were collected using MiniVol samplers, and Mn concentrations in the filters were measured using proton-induced X-ray emission (PIXE). An adjusted generalized linear mixed model was applied and then used for estimating indoor concentrations in non-monitored households. Our monitoring results showed a higher daily average concentration of indoor PM2.5 vs. outdoor PM2.5 (46.4 vs. 36.2 µg/m(3), respectively); however, manganese concentration in PM2.5 indoor and outdoor was 0.09 µg/m(3) in both sceneries. Predictor variables of indoor Mn concentration were outdoor Mn concentration (64.5% increase per 0.1 µg/m(3) change in Mn) and keeping the windows open (4.2% increase). Using these predictors, the average estimated indoor Mn concentration in PM2.5 was 0.07 µg/m(3) (SD = 0.05). Our results confirm the direct effect of outdoor Mn levels, opening house windows, and the distance to the mining chimney in indoor Mn levels in houses.

Persistent organic pollutants (POPs) and metals in primiparous women: a comparison from Canada and Mexico.

Under the North American Commission for Environmental Cooperation (CEC) and its Sound Management of Chemicals (SMOC) program, a tri-national human contaminant monitoring initiative was completed to provide baseline exposure information for several environmental contaminants in Canada, Mexico and the United States (U.S). Blood samples were collected from primiparous women in Canada and Mexico, and were analysed for a suite of environmental contaminants including polychlorinated biphenyls (PCBs), dichlorodiphenyldichloroethylene(p,p'-DDE),beta-hexachlorocyclohexane (ß-HCH), mercury and lead. A multiple stepwise linear regression analysis was conducted using data from Canadian and Mexican primiparous mothers, adjusting for ethnicity group, age, pre-pregnancy BMI, years at current city and ever-smoking status. Concentrations of p,p'-DDE, ß-HCH, and lead were found to be higher among Mexican participants; however, concentrations of most PCBs among Mexican participants were similar to Canadian primiparous women after adjusting for covariates. Concentrations of total mercury were generally higher among Mexican primiparous women although this difference was smaller as age increased. This initial dataset can be used to determine priorities for future activities and to track progress in the management of the selected chemicals, both domestically and on a broader cooperative basis within North America.

Persistent organic pollutant concentrations in first birth mothers across Mexico.

This project was initiated by the North America Commission for Environmental Cooperation (CEC). Its main purpose was to obtain an initial profile on pregnant woman's exposure to persistent organic pollutants (POPs) in North America (Canada, the United States and Mexico). Persistent organic pollutants are transferred to the fetus via the placenta during the pregnancy or to the infant via maternal milk; therefore, the pregnant woman's body burden is important because of the higher exposures and potential health effects in the fetus and infant. This paper presents the results from 240 pregnant women in 10 Mexican cities, and includes the concentrations of various POPs such as polychlorinated biphenyls (PCBs), organochlorine pesticides and polychlorinated dibenzo dioxins and furans (PCDDs and PCDFs) in maternal plasma. We found concentrations of p,p'-DDE in maternal samples from Coatzacoalcos to be ∼60% higher than those found in Ciudad Obregon, which had the second highest concentration. Pregnant women from Merida had higher mean concentrations of PCBs than all women in other regions. Results for PCDDs and PCDFs plus dioxin-like PCBs data were only available on the basis of composite samples, and their concentrations are similar in most cities except for Coatzacoalcos, which had more than double the concentration found in other cities. Although this study provides useful information on the variability of POPs in specific populations and possible regional/local differences, these results cannot be generalized to the entire Mexican population because of differences in age, gender, sources of exposure and nonrandom nature of the sample.