Environmental impact of wastewater irrigation in central Mexico: An overview

The current knowledge on the environmental impact and public health risks associated with wastewater irrigation in central Mexico is summarized and discussed. Wastewater reuse in that semiarid region represents a valuable resource in agricultural production, due to the irrigation supply and considerable nutrients input to the farming soil. Nevertheless, there is evidence of increased prevalence of parasitic infections among agricultural workers and their families exposed to raw wastewater irrigation. Negative environmental effects may result from long‐term wastewater application, due to heavy metal accumulation in soils, increasing amounts of immediately mobile and easily mobilizable metal fractions, as well as crops uptake. First investigations carried out on soil fertility suggest the occurrence of important nitrogen losses, which could represent potential risks to public health induced by elevated nitrate concentrations in groundwater. Emphasis is given on future research priorities and measures that have to be taken for minimizing public health risks and environmental pollution.     

Effects of wastewater irrigation of pastures on the health of farm animals and humans.

Wastewater recycling and reuse through agricultural irrigation can provide an economical means of preventing pollution of surface water sources, while conserving water resources and valuable nutrients for increased crop production and grazing pastures. With proper methods of wastewater treatment, health risks to farmers and farm animals as well as to the public who consume agricultural produce can be prevented. The possibility of transmission of the beef tapeworm Taenia saginata, Salmonella sp. and Mycobacteria sp. to farm animals grazing on wastewater-irrigated pasture is evaluated. While such transmission is possible when raw, untreated wastewater is used for irrigation, the risk is greatly reduced and essentially eliminated with effluent treated to meet the new World Health Organisation (WHO) recommended microbial guidelines for effluent. These guidelines call for one or less helminth eggs per litre and a mean of 1,000 faecal coliform bacteria per 100 ml. In warm climates and where land is available, one of the most economical methods of achieving this standard is the use of multi-cell stabilisation ponds designed for a 25-day detention period. In colder climates and where land is a limiting factor of wastewater treatment, conventional secondary biological treatment followed by disinfection can also be applied to meet this standard.     

A Review of Health Risks and Pathways for Exposure to Wastewater Use in Agriculture

Background:

Wastewater is increasingly being used in the agricultural sector to cope with the depletion of freshwater resources as well as water stress linked to changing climate conditions. As wastewater irrigation expands, research focusing on the human health risks is critical because exposure to a range of contaminants must be weighed with the benefits to food security, nutrition and livelihoods.

Objectives:

The goal of this paper was to review research examining health risks and exposure pathways associated with wastewater irrigation to identify research trends and gaps.

Methods:

We conducted a review of the literature and identified a total of 126 studies published from 1995 to 2013. Findings were summarized based on several themes including types of exposure pathways, wastewater contaminants, methodological approaches and the geographical distribution of research.

Results:

Only 23 studies used epidemiological methods, while most research applied alternative methods to estimate risk, such as quantitative risk assessment models or comparisons of crop contamination to established guidelines for wastewater reuse. A geographic breakdown demonstrated a focus on microbiological contaminants in specific regions such as sub-Saharan Africa and Southeast Asia, despite growing chemical risks associated with rapid urbanization and industrialization that may change the types and distribution of wastewater contaminants.

Conclusions:

To provide a more comprehensive understanding of the health risks of wastewater use in agriculture, future research should consider multiple exposure routes, long-term health implications, and increase the range of contaminants studied, particularly in regions heavily dependent on wastewater irrigation.

Citation:

Dickin SK, Schuster-Wallace CJ, Qadir M, Pizzacalla K. 2016. A review of health risks and pathways for exposure to wastewater use in agriculture. Environ Health Perspect 124:900–909; http://dx.doi.org/10.1289/ehp.1509995     

Challenges and Opportunities for Urban Environmental Health and Sustainability: the HEALTHY-POLIS initiative

Cities around the world face many environmental health challenges including contamination of air, water and soil, traffic congestion and noise, and poor housing conditions exacerbated by unsustainable urban development and climate change. Integrated assessment of these risks offers opportunities for holistic, low carbon solutions in the urban environment that can bring multiple benefits for public health. The Healthy-Polis consortium aims to protect and promote urban health through multi-disciplinary, policy-relevant research on urban environmental health and sustainability. We are doing this by promoting improved methods of health risk assessment, facilitating international collaboration, contributing to the training of research scientists and students, and engaging with key stakeholders in government, local authorities, international organisations, industry and academia. A major focus of the consortium is to promote and support international research projects coordinated between two or more countries. The disciplinary areas represented in the consortium are many and varied, including environmental epidemiology, modelling and exposure assessment, system dynamics, health impact assessment, multi-criteria decision analysis, and other quantitative and qualitative approaches. This Healthy-Polis special issue presents a range of case studies and reviews that illustrate the need for a systems-based understanding of the urban environment.     

Assessment of Trace Metal and Metalloid Accumulation and Human Health Risk from Vegetables Consumption through Spinach and Coriander Specimens Irrigated with Wastewater

This study focused on evaluating the metal and metalloid contamination and associated risks in the two vegetables crops, coriander (Coriandrum sativum) and spinach (Spinacia oleracea) treated with three water regimes, canal water, groundwater and municipal wastewater. These vegetables are widely consumed by people and are also used in traditional medicine for treating various disorders. Metal and metalloid accumulation (Zn, Pb, Se, Cu, As, Mo, Fe, Ni) was found higher in vegetables treated with wastewater. Wastewater treated soil had high pollution load index. Fe, Zn, As and Pb had higher values in water, soil and vegetables as compared to other studied metals. Overall, metal correlation for soil and vegetables was significant and positive except for Fe and Cu in spinach. The highest value for daily metal intake was estimated for Fe while Se had the lowest value for the same index. It was thus concluded that trace metal and metalloid accumulation was a major health concern for the public consuming these vegetables.     

The health implications of wastewater reuse in vegetable irrigation: a case study from Malamulele,South Africa

Malamulele is located in an arid region where small-scale irrigation with wastewater is rife. A study was conducted to investigate the health implications of wastewater reuse in vegetable irrigation. Results showed that there are potential health hazards associated with this practice. The wastewater contained 103 helminth eggs/100 ml and zero helminth eggs for control group; vegetable wash water had 3 helminth eggs/100 ml for the exposed group and zero for control. The wastewater results exceeded the WHO guidelines whereas the vegetable wash water counts were within the guideline. Stool samples of farmers and their children indicated common infections with hookworm and Giardia lamblia. Hookworm infections were high (42%) among exposed group in comparison to the control group (27.5%). The farmers were able derive their livelihood from the sale of vegetables. The findings suggest that the health risks of using wastewater are real but can be managed by using the incomes that the farmers earn.     

Evaluation of the updated Onawi regulations for wastewater re-use and discharge

Guidelines for wastewater re-use quality are based on scientific and epidemiological findings. As such, it provides guidance towards making risk management decisions that are related to the protection of public health and environmental preservation (Hespanol, 1992). Over the last thirty years, or so, considerable work has been done to assess risks emerging from wastewater re-use and develop methods that would aid removal or minimization of the risks. For example reports by WHO, 1973 and 1989) have contributed greatly in reviewing and summarizing research and experience all over the world with the purpose of establishing sensible guidelines for wastewater re-use. Wastewater regulations are established by countries while adopting their national priorities and strategies. Attention is usually paid to technical, economical, social, cultural, hygienic practices, and political characteristics and constraints. The regulations for wastewater re-use and discharge in the Sultanate of Oman were first introduced in 1986. This paper gives a critical review of the updated regulations and makes procedural recommendations.     

Implementation of the WHO guidelines for the safe use of wastewater in Pakistan: balancing risks and benefits

The use of wastewater in agriculture is receiving renewed attention as a result of increasing global water scarcity. Wastewater use potentially poses a risk to public health if not properly managed. In Pakistan the use of wastewater in agriculture is already common, though in most cases its use is unregulated and wastewater untreated. In a four year study in Faisalabad, Pakistan, the risks and benefits of the use of untreated wastewater in agriculture were assessed. The study found an increased risk of intestinal disease in wastewater farmers but also found major financial and nutritional benefits for farmers and consumers in the city of Faisalabad. This paper presents a policy approach for the implementation of the WHO guidelines for the safe use of wastewater in agriculture in Pakistan.     

Application of toxicity identification evaluation procedures on wastewaters and sludge from a municipal sewage treatment works with industrial inputs

A comparison of influent and effluent wastewater toxicities to Daphnia magna was undertaken to determine the most representative aqueous fraction for future toxicity identification evaluation (TIE) studies. Wastewater samples originated from a wastewater treatment plant which receives mainly domestic wastewater and industrial effluents. The TIE results reveal that the key toxicant contained in the influent was 2-propylbezaldehyde oxime. Results suggest that greater attention needs to be given to the receiving influent containing 2-propylbezaldehyde oxime to avoid damaging the bacterial populations in the primary activated sludge process. In addition, in order to evaluate the applicability of the reuse of activated sludge as a fertilizer in agriculture, TIE studies were also performed on water extracts from surplus sludge.     

Assessment of wastewater effluent quality in Thessaly region, Greece, for determining its irrigation reuse potential

The objective of the present study is to assess wastewater effluent quality in Thessaly region, Greece, in relation to its physicochemical and microbiological burden as well as its toxic potential on a number of organisms. Wastewater may be used for agricultural as well as for landscape irrigation purposes; therefore, its toxicity potential is quite important. Thessaly region has been chosen since this region suffers from a distinct water shortage in summer period necessitating alternative water resources. During our research, treated effluents from four wastewater treatment plants operating in the region (Larissa, Volos, Karditsa, and Tirnavos) were tested for specific physicochemical and microbiological parameters [biochemical oxygen demand (BOD₅), chemical oxygen demand (COD), total suspended solids (TSS), pH, electrical conductivity, selected metals presence (Cd, Co, Cr, Cu, Fe, Mn, Ni, Pb, Zn, As), and fecal coliforms’ (FC) number]. The effluents were also tested for their toxicity using two different bioassays (Daphnia magna immobilization test and Phytotoxkit microbiotest). The findings were compared to relative regulations and guidelines regarding wastewater reuse for irrigation. The results overall show that secondary effluents in Thessaly region are generally acceptable for reuse for irrigation purposes according to limits set by legislation, if effective advanced treatment methods are applied prior to reuse. However, their potential toxicity should be closely monitored, since it was found that it may vary significantly in relation to season and location, when indicator plant and zooplankton organisms are used.     

A proposed core model of the new public health for a healthier collectivity: how to sustain transdisciplinary and intersectoral partnerships

At present, there is no conceptual model by which public health could be represented as intersectoral governance collaborating with society and the state, and acting as a collective on the determinants of health. In this article, our interdisciplinary group, representing core competencies in public health, suggest two complementary conceptual models as frameworks for a diverse public concerned with public health and its core functions. The first conceptual ‘core model’ roots from the Ottawa Charter for Health Promotion. It represents the interrelationships of the three main poles united at the biopower level: the collectivity (entire population), the contemporary state and public health. In the second conceptual model, we present the various components in the meta-network of public health governance. We also present the roles of heterogeneous actors and how they can collaborate within a prominent process of capacity building and development of practice in public health. Thus, we emphasize the importance of intersectoral partnerships the contemporary state can make with public health without inducing any rupture with the social fabric. Our two complementary models can help actors from all sectors better understand the most frequent questions in public health governance (functions, roles, ingredients) and the challenges that intersectoral actors may very likely encounter in the implementation of these frameworks. The sustainability of well-balanced transdisciplinary and intersectoral partnerships contribute to a successful implementation of public health governance, and most importantly to a good health status for the collectivity.     

Mathematical modeling to assess the effects of organic waste dumping on sanitary conditions of environmental waters

This article provides an overview of emerging trends in environmental approaches to wastewater management in the developing world. Organic matter present in wastewater is one of the main sources of water pollution. In large amounts it can increase the number of microorganisms and thus the excessive consumption of dissolved oxygen in the metabolic processes of its utilization and stabilization, leading to the disappearance and extinction of aerobic organisms, favoring the appearance of other life forms in anaerobic conditions, often producing toxic residues. The main focus of this article is to analyze the presence of organic matter in urban sewage using a water quality model whose main parameters are dissolved oxygen and biochemical oxygen demand. Wastewater management methodologies can contribute to public health, sanitation, and improved conservation of water resources.     

Knowledge, attitudes and behaviours related to climate change in Alberta, Canada: implications for public health policy and practice

Climate change has received recent extensive media attention (e.g., Kyoto Protocol) and is currently on the international public health agenda. The purpose of this study was to survey knowledge, attitudes and behaviours related to climate change in the province of Alberta, Canada. A random sample of 600 Alberta households, using proportional quotas based on the Canada Census of the Alberta population, was surveyed on knowledge, attitudes and behaviours related to climate change using a computer-assisted telephone interviewing protocol. Albertans are highly concerned, particularly about health problems related to the environment and air pollution; yet are only moderately informed about a variety of environmental issues. While the great majority of Albertans appear to be engaged in environmental behaviours at home, fewer consider energy efficiency when purchasing consumer goods. An even smaller percentage makes environmentally conscious transportation decisions. To encourage the population to make recommended environmental behaviours, mass media approaches may do well to target the specific beliefs that were deemed salient (e.g., promote the association between environment issues and health). The public health sector has a major role in working with inter-sectoral groups to address this significant public health issue.     

Recent epidemiological studies to test microbiological quality guidelines for wastewater use in agriculture and aquaculture.

BACKGROUND: New guidelines for wastewater reuse (WHO 1989) are controversial. Epidemiological studies are needed to test their validity. Cross-sectional studies of the impact of excreta use in aquaculture in Indonesia, and of wastewater use in irrigation in Mexico have been carried out. METHODS: Each study involved an exposed group using wastewater/excreta with no treatment, a control group with no wastes use, and an intermediate group, where wastewater/excreta was used but some health protection measure existed. In Mexico, the intermediate group used wastewater from a storage reservoir which met the new WHO guideline for restricted irrigation. In Indonesia, the intermediate group did not have domestic exposure to pondwater, whose quality was around forty times higher than the tentative WHO bacterial guideline for fishpond water. RESULTS: In Indonesia, the prevalence of diarrhoeal disease was low in adults, and unrelated to exposure, but high in children under 5 years. Multiple logistic regression analysis gave odds ratios of 1.4 (p = .06) for consumer exposure, 1.9 (p = .01) for recreational or occupational exposure and 1.6 (p = .01) for domestic exposure, when allowance was made for all other exposures and several confounding factors. In Mexico, preliminary analysis of the wet season data suggests that the increased risks of Ascaris infection and diarrhoeal disease from the use of raw wastewater are removed when water of WHO guideline quality from storage reservoirs is used. CONCLUSION: WHO (1989) guidelines can be tested using cross-sectional epidemiological studies which indicate that guidelines for restricted irrigation and for aquaculture may be around the right level.     

“双碳”背景下的空气污染和气候变化流行病学研究进展与展望

气候变化是21世纪人类面临的重大健康挑战, 空气污染也是全球重要的公共卫生问题。我国提出2030年前实现碳达峰、2060年前实现碳中和的"双碳"目标, 不仅会对我国空气污染和气候状况产生深远影响, 也会全面影响人群健康。空气污染和气候变化流行病学是环境流行病学的重要分支, 本文将围绕"双碳"目标背景下的空气污染和气候变化流行病学研究现状和未来趋势展开论述, 以期为后续更好地开展环境与健康研究提供思路和建议。     

High volume hydraulic fracturing operations: potential impacts on surface water and human health

High volume, hydraulic fracturing (HVHF) processes, used to extract natural gas and oil from underground shale deposits, pose many potential hazards to the environment and human health. HVHF can negatively affect the environment by contaminating soil, water, and air matrices with potential pollutants. Due to the relatively novel nature of the process, hazards to surface waters and human health are not well known. The purpose of this article is to link the impacts of HVHF operations on surface water integrity, with human health consequences. Surface water contamination risks include: increased structural failure rates of unconventional wells, issues with wastewater treatment, and accidental discharge of contaminated fluids. Human health risks associated with exposure to surface water contaminated with HVHF chemicals include increased cancer risk and turbidity of water, leading to increased pathogen survival time. Future research should focus on modeling contamination spread throughout the environment, and minimizing occupational exposure to harmful chemicals.     

An Assessment of Heavy Metal Contamination in Vegetables Grown in Wastewater-Irrigated Areas of Titagarh,West Bengal,India

The effects of municipal wastewater irrigation on the accumulation of heavy metals (Pb, Zn, Cd, Cr, Cu and Ni) in soil and vegetables were investigated by monitoring wastewater-irrigated agricultural field of Titagarh, 24-Parganas (North), West Bengal, India. The mean concentrations of Pb, Ni, Cu in the irrigation water and the mean Cd content in soil were much above the recommended level. The concentrations of Pb, Zn, Cd, Cr and Ni in all the examined vegetables were beyond the safe limits. The study reveals that heavy metal-contaminated vegetables grown in wastewater-irrigated areas may pose public health hazards.     

Health risks in wastewater irrigation: comparing estimates from quantitative microbial risk analyses and epidemiological studies

The combination of standard quantitative microbial risk analysis (QMRA) techniques and 10,000-trial Monte Carlo risk simulations was used to estimate the human health risks associated with the use of wastewater for unrestricted and restricted crop irrigation. A risk of rotavirus infection of 10(-2) per person per year (pppy) was used as the reference level of acceptable risk. Using the model scenario of involuntary soil ingestion for restricted irrigation, the risk of rotavirus infection is approximately 10(-2) pppy when the wastewater contains < or =10(6) Escherichia coli per 100ml and when local agricultural practices are highly mechanised. For labour-intensive agriculture the risk of rotavirus infection is approximately 10(-2) pppy when the wastewater contains < or = 10(5) E. coli per 100ml; however, the wastewater quality should be < or = 10(4) E. coli per 100ml when children under 15 are exposed. With the model scenario of lettuce consumption for unrestricted irrigation, the use of wastewaters containing < or =10(4) E. coli per 100ml results in a rotavirus infection risk of approximately 10(-2) pppy; however, again based on epidemiological evidence from Mexico, the current WHO guideline level of < or =1,000 E. coli per 100ml should be retained for root crops eaten raw.     

Relationship between water supply,sanitation, public health,and environment: elements for the formulation of a sanitary infrastructure planning model

The understanding of sanitation infrastructure, public health, and environmental relations is a fundamental assumption for planning sanitation infrastructure in urban areas. This article thus suggests elements for developing a planning model for sanitation infrastructure. The authors performed a historical survey of environmental and public health issues related to the sector, an analysis of the conceptual frameworks involving public health and sanitation systems, and a systematization of the various effects that water supply and sanitation have on public health and the environment. Evaluation of these effects should guarantee the correct analysis of possible alternatives, deal with environmental and public health objectives (the main purpose of sanitation infrastructure), and provide the most reasonable indication of actions. The suggested systematization of the sanitation systems effects in each step of their implementation is an advance considering the association between the fundamental elements for formulating a planning model for sanitation infrastructure.     

全球环境与卫生的关联性:政策响应与制度构建

本文依据全球治理的理论从政策和制度层面系统地考察了全球环境与卫生的关联性,并对全球环境与卫生治理的结构特征及未来挑战进行了分析。从制度层面看,全球环境与卫生的关联性主要体现在议题关联、法律关联、规范关联、治理模式关联、行为体关联以及机构关联六个方面。当前全球环境与卫生治理的结构呈现三大特点:全球环境与卫生治理正在迅速形成之中;全球环境与卫生治理依然松散和脆弱,未来有很大的发展空间;科学研究、工程技术、资金和外交技巧等方面的优势使发达国家掌握着全球环境与卫生治理的主导权。环境与卫生之间也存在着潜在的冲突。这种冲突既可能来自价值观的不同,也可能来自对环境、卫生与发展之间的关系理解不同。未来全球环境与卫生治理面临环境与卫生问题的政治化与国家安全考量等诸多挑战。