Monitoring and surveillance represent essential environmental public health services (NCEH 2014). Unfortunately, potable water quality remains under examined, particularly in rural areas and private wells where exposures to contaminants of emerging concern (e.g., PFAS, endocrine disruptors, antibiotics), and even historically recognized threats, are unknown. Some efforts, including the Unregulated Contaminant Monitoring Rule (UCMR), which was developed in the United States to examine suspected contaminants in drinking water that lack health-based standards, focus on rural drinking water (EPA 2018a). However, these activities are inherently limited in spatial scope and for which contaminants are evaluated (Oxenford and Barrett 2016). For example, cyanotoxins represent an increasingly important public health threat (Brooks et al. 2016), but only a few were recently included in UCMR activities, and they are commonly not evaluated in source waters. Similarly, diverse PFAS compounds exist with limited toxicology information (Patlewicz et al. 2019), yet these emerging threats are not routinely monitored in drinking water supplies. Drinking water quality from private wells across the United States remains largely unknown.

As highlighted by recent lead contamination (Pieper et al. 2018) and Legionnaires’ disease (Schwake et al. 2016) events in Flint, Michigan, differential management effectiveness and aging drinking water infrastructure continue to present risks to public health. Population growth, urbanization, and climate change are further stressing existing systems. However, addressing such infrastructure deficiencies while advancing innovation in urban water systems promises to increase urban water security and resiliency (Zodrow et al. 2017). Although drinking water infrastructure in urban areas has received increased attention, private water supplies (e.g., wells) and small and rural systems have received less study than larger municipal utilities (Allaire et al. 2018). The extent of public health risks from compromised drinking water infrastructure in these smaller systems and in rural areas requires future assessment.

Drinking water quality of private wells and small and rural systems can be impaired by diverse biological and chemical agents (Allaire et al. 2018). Herein, impoverished and minority communities are often affected, which highlights diverse environmental justice challenges for addressing rural health disparities (Balazs et al. 2011; Stillo and MacDonald Gibson 2017). Our analysis indicates that private water supplies (e.g., wells) and points of personal uses (e.g., inside personal residences) remain difficult to sample due to jurisdictional barriers, and when drinking water quality is examined in these settings, EH professionals routinely inform community members of findings but often cannot enforce and implement corrective measures or drinking water standards compliance. Further, if drinking water exceedances are observed in private wells, which are not regulated by the U.S. Environmental Protection Agency (EPA), then we identify that EH professionals cannot retest water quality unless asked by the property owner. These collective challenges may result in decreased public trust in health departments, which further challenges effective delivery of EH services. Systems research is needed to improve delivery of essential services and address this issue.

Drought and mismanagement of source waters directly threaten drinking water quantity and then intersect with potable water quality concerns. In some drought-prone regions, excessive aquifer withdrawals, which are not consistently governed across the United States, are resulting in brackish conditions that impair drinking water quality and compromise conventional treatment technologies (Konikow 2013), but these brackish groundwaters can augment drinking water resources if desalination occurs (Ahdab et al. 2018). When groundwater is excessively contaminated with arsenic from natural or anthropogenic sources, diverse chronic health risks, including cancers, emerge from inorganic arsenic, particularly in drought-susceptible rural areas (Gong et al. 2011, 2015). Innovative approaches, such as the National Aeronautics and Space Administration (NASA)'s Gravity Recovery and Climate Experiment (GRACE) mission, are providing novel technologies to assess groundwater deficits and derive groundwater drought indices that can support monitoring, surveillance, and forecasting efforts (Thomas et al. 2017). Clearly, leveraging such technologies to identify regions where stressed source water quality elevates public health risks, particularly in small and rural systems and private wells, represents a pressing EH research opportunity.

In the United States, at least 20% of the population is served by decentralized (or onsite) wastewater treatment technologies (e.g., septic and advanced aerobic) (EPA 2002, 2005). These decentralized systems are not directly regulated by the EPA, which focuses on centralized municipal and industrial wastewater treatment plants and thus transfers responsibilities for onsite sewage management to tribes and states (EPA 2018b). Regulatory responsibility is then routinely passed on to the local level of government, which performs site assessments and permits construction of decentralized systems (EPA 2018b). Onsite wastewater management activities, training, and workforce capacity differ among and within states. Although such differences in local policies and practices exist, the extent to which this fractured management system presents risks to public health and the environment is often not directly studied until surface water quality impairments are observed and regulatory actions proceed (e.g., through development of total maximum daily loads).

New decentralized technologies are routinely evaluated to meet several general water quality parameters. For example, these technologies are tested independently and certified for conformance to standards prior to installation [e.g., standard 40 from the National Sanitation Foundation International/American National Standards Institute (NSFI 2018)]. However, when onsite systems are improperly installed or not functioning, use impairments for drinking water, fisheries, and recreation result (Bremer and Harter 2012; Withers et al. 2014; Scott et al. 2016, 2019). Such degradation of surface water and groundwater quality directly occurs from bacteria, anthropogenic chemicals, and nutrients (Schaider et al. 2017), which can stimulate development of harmful algal blooms (Brooks et al. 2016). Delivery of implementation, assessment, and enforcement activities for onsite systems varies among and within states, resulting in diverse risks to public health and the environment. Spatial magnitude, frequency, and duration of these public health risks remain poorly understood.

Installation of new onsite wastewater treatment systems includes site assessments using a prescriptive approach, in which locations with characteristics (e.g., soil types and location to wells) suitable for a given technology (e.g., septic) and use scenario (e.g., sewage volume per day) are determined (NOWRA 2006). Watershed heterogeneity inherently challenges consistent implementation of this paradigm. Performance-based standards are ideally risk based and include specific measures of parameters that, if not exceeded, are expected to protect public health and the environment (NOWRA 2006). Such performance-based codes for decentralized systems promise to more closely resemble compliance to water quality goals of centralized systems. For example, a model code framework has been developed to advance performance-based practice (NOWRA 2006), particularly as onsite technologies continue to advance to address diverse and emerging water quality challenges (Garcia et al. 2013; Du et al. 2014). However, strategic EH research is needed to provide appropriate data to support identification and implementation of robust performance-based efforts across the United States.

It has been estimated that over $1 trillion is needed over the next two decades to address aging water and wastewater infrastructure in the United States (Selvakumar et al. 2015). Degradation of centralized sewage treatment is now recognized as a major need; however, infrastructure challenges for decentralized systems has received limited attention, similar to the rural and small drinking water systems described above. Revitalizing improperly functioning decentralized infrastructure appears critically important because diverse adverse health outcomes and surface water quality impairments (e.g., recreational use due to enteric bacterial contamination) are associated with failing septic tanks when these systems are decades old or were not installed properly (Borchardt et al. 2003; Tollestrup et al. 2014). For example, hookworm is reemerging in socioeconomically challenged rural areas of the southeastern United States due to exposure from onsite wastewater (McKenna et al. 2017). Although these decentralized systems are often considered a rural issue, periurban and urban water quality issues have been reported, particularly when higher-density housing with onsite systems is developed in vulnerable watersheds of urbanizing unincorporated areas (Forbis-Stokes et al. 2016; Scott et al. 2016, 2019). Research is needed to identify high-risk regions across the rural–periurban–urban gradient. This information will support prioritization of areas requiring public health interventions.

Onsite technologies continue to advance to address nutrient pollution and other stresses to water quality. Although these systems must undergo standard testing as described above, empirical performance data in response to extreme weather events are lacking in the refereed literature. This information is necessary because the global magnitude, frequency, and duration of environmental disasters are increasing (IPCC 2012; Field et al. 2012). As evidenced during the 2017 hurricane season, some regions, such as the Houston–Galveston region with over 300,000 onsite systems (www.h-gac.com), are particularly vulnerable. For example, based on sampling after Hurricane Harvey, widespread presence of antibiotic resistance bacteria were reported in surface waters of the Houston area (Yu et al. 2018). Such observations require further attention because over 80% of surface waters in this region were previously identified as impaired, including 47% of waterways exceeding water quality standards for indicator bacteria (E. coli) (Clean Rivers Program 2015). Here again, research is needed to identify watersheds for interventions, develop more robust treatment systems, and ensure new onsite technologies are resilient when disasters occur.

Healthy housing programs include diverse topics that are routinely engaged by EH professionals in the United States (CDC and HUD 2006). For example, a number of drinking water, wastewater, and vectors problem statements are associated with common healthy homes topics and are discussed elsewhere in this paper. Similarly, recreational pools and spas represent an important healthy housing program commonly delivered by EH professionals. Evaluation of spas and swimming pools routinely focus on bacterial exposures, although recent studies identified exposure to carcinogens (i.e., disinfection byproducts) in spas, which requires additional attention (Daiber et al. 2016). Similar to challenges associated with private wells and point-of-use drinking water surveillance identified above, EH programs for healthy homes efforts routinely are challenged by restricted access to private property. Although lead exposure from drinking water in Flint, Michigan has rightly received attention, identifying the extent of degraded potable water and wastewater infrastructure is inherently challenged by limited access to perform point-of-use sampling. However, instead of retrospective action following identification of problems, inspector-generated housing inspections present opportunities to prioritize locations for interventions (Korfmacher and Holt 2018).

Another problem statement was directly related to the necessity of more prospective interventions in healthy housing: Officials are only reacting to hoarding and filthy housing situations once they have become a public health and safety problem. Here again, EH professionals are often responsible for engaging domestic health and safety issues associated with unsanitary conditions after exposures occur. It thus appears clear that, in the absence of national scale changes in consistent regulatory responsibilities to protect public health from such threats in residences, additional research is needed to develop and implement technologies (e.g., sensors) and communication channels (e.g., through smartphone apps) that could be voluntarily adopted by the public. These advances could provide near-real-time information on conditions of individual residences or those approaching unsanitary conditions in their community to EH professionals.

Asthma, particularly in children, is directly triggered by diverse environmental factors (e.g., mold, dust mites, particulates) and can be exacerbated by poor indoor air quality (Ege et al. 2011), including exposures to diverse organic chemicals (Bornehag et al. 2005; Salthammer et al. 2018). Unfortunately, such observations can be pronounced in some regions (Lowe 2018), particularly when outdoor air quality is degraded. It appears that public awareness of the diverse factors influencing asthma is limited, which presents translational research opportunities for collaboration with and among EH professionals and community health education specialists.

Despite an understanding of linkages between lead exposure and impacts on children for centuries (Needleman 2009), some children continue to experience blood lead levels that exceed CDC guidelines in communities across the United States (Benson et al. 2017). Recently, a high-profile example of lead exposure was observed in Flint, Michigan (Ruckart et al. 2019). However, despite this important event, lead from contaminated drinking water may represent a relatively lower age-dependent point of exposure for children, especially in infants possibly consuming formula prepared with tap water, compared with lead from paint and dust in many areas of the United States (Dixon et al. 2009; Zartarian et al. 2017). Elevated blood lead levels observations in children are routinely associated with pre-1978 housing, which may have used lead-based paint prior to the ban in residential use, and industrial sources, especially when local interventions are ineffective (Dixon et al. 2009). Further, elevated blood lead levels are often associated with socioeconomically depressed areas in which higher proportions of minority populations reside (Schultz et al. 2017). Blood lead testing results provide an important safety net for children who have been exposed to lead. However, primary prevention of lead exposure, before children are poisoned, should be advanced to prevent effects on childhood development in the United States.

Health equity intersections with challenges delivering environmental public health services remain palpable in some regions of the United States (Morello-Frosch and Shenassa 2006). Such social determinants of health are often highlighted by housing conditions and corresponding health inequities experienced by underserved populations (Jacobs et al. 2009), including immigrant populations. If rental property owners abdicate their responsibilities to ensure healthy housing for tenants, then adverse health outcomes can result. Unfortunately, much like the EH delivery system, consistent implementation of building codes and health homes goals for rental housing appears fractured within and among states. Research is needed to define the extent to which unacceptable conditions are being experienced by tenants and which interventions are necessary in local communities.

Ensuring food safety through regulation and inspection is a primary service of most local and state health departments (NACCHO 2016; ASTHO 2016). Reductions in local health department capacity and budgets have resulted in negative impacts to EH services, including food safety programs (Li and Elligers 2014). The food safety landscape continually evolves with the introduction of new food types and alternative food service settings (e.g., food trucks and home kitchens). The observation of critical food safety risk factors among food trucks is not uncommon; however, difficulties in locating trucks can create regulatory challenges (Faw and Tuttle 2014). These conditions are also applicable in the case of home kitchens. Identification and effective regulation of these food service anomalies, which are becoming more and more common, requires increased EH program capacity.

Cottage foods are those prepared in a home kitchen and sold to the public at a variety of venues such as farmers’ markets. Acknowledging the challenges associated with regulating cottage foods, the Association of Food and Drug Officials published a guidance document on best practices for regulating cottage foods (AFDO 2012). Jurisdictional laws on cottage food regulation vary across the United States, creating challenges for regulating these facility types. Conducting inspections is a necessary regulatory function, yet home kitchens are not easily identified, especially in the absence of permitting requirements (AFDO 2012). The Food and Drug Administration (FDA) approves the use of certain food additives and offers a decision tree for determining the regulatory status of additives (FDA 2018). While certain food additives may be assigned a regulatory classification, challenges remain in determining whether unsafe, unregulated additives are added to foods.

Food safety training is recognized as a primary intervention for ensuring food service workers follow safe food handling practices. Certification, commonly preceded by training, has shown to result in increased food service worker knowledge (Brown et al. 2014). Additionally, research shows that training may improve knowledge and influence behaviors associated with proper hand hygiene (Soon et al. 2012). While training occurs and benefits to being trained are noted, food service workers may not consistently apply their food safety knowledge in the kitchen or operational settings.

The FDA Food Code requires that workers exhibiting certain symptoms of illness (e.g., diarrhea) be excluded from work (FDA 2017). However, high percentages of food service employees work while sick. This may be associated with factors such as restaurant policies not addressing sick workers, concerns about leaving the restaurant short-staffed, and the threat of job loss for not coming to work (Carpenter et al. 2013; Norton et al. 2015). Charles and Radke (2017) explained that federal laws like the Health Insurance Portability and Accountability Act and Americans with Disabilities Act do not prevent managers from speaking with employees about illness. Managers may consider promoting a culture of open communication, encouraging staff to discuss illness-related symptoms with management. Policies encouraging staff to talk with managers when ill may also lead to fewer workers working while ill (Sumner et al. 2011).

Rapid changes and developments in the food safety arena require increased programmatic capacity and a robust workforce. This, in turn, necessitates governing body support for enhancing food safety programs. Government decision-makers and leaders face challenges when determining priority programs or areas to receive, in most cases, already limited available resources. Communicating the value of related interventions, such as training for food service workers and performing regulatory services, is important for ensuring awareness of the value of food safety interventions and increasing support and resources for strengthening food safety programs.

Emerging vector-borne diseases and the spread of vectors to new geographic areas (e.g., Zika virus and Aedes aegypti and Aedes albopictus mosquitoes), particularly with changing climate, reinforces the need for increased resources and enhancement of surveillance, educational, and policy-related interventions (Imperato 2016). While mosquito vectors are spreading to new areas, local and state health department arboviral surveillance capacity has decreased (Hadler et al. 2015). In general, the emergence of vector-borne pathogens and disease, along with significant increases in tick-borne disease rates, require strengthened vector and vector-borne disease surveillance (Rosenberg et al. 2018) and research to identify and manage such threats as climatic and habitat changes occur.

Limitations in existing pest management policies may restrict jurisdictional use of new approaches and strategies for controlling vectors and public health pests. Factors such as pesticide resistance require new vector control methods. The methods include, for example, biocontrol strategies such as use of biological organisms or releasing sterile mosquitoes to impact vector populations and control vectors (Benelli et al. 2016). Technological advances and development of alternative control methods may require evaluation of existing pest management policies and ensuring the ability to employ new vector control strategies.

Bed bugs, which are not known to transmit disease but are recognized as pests of public health significance, can be a source of public concern (Goddard and deShazo 2009; Kaylor et al. 2015). Addressing bed bug infestations, especially in multifamily housing units, is challenging and requires an integrated pest management approach consisting of a range of strategies (Bennett et al. 2016). Bed bugs present significant public health challenges and concerns (Lai et al. 2016), yet agency policies are not consistent among and within states and do not always clearly specify the authority to respond or enforce requirements to address bed bugs infestations.

The Interim CDC Recommendations for Zika Vector Control in the Continental United States highlighted communication and educating the public about controlling A. aegypti and A. albopictus mosquitoes as an essential element for preparing to control Zika virus vectors and the potential for disease transmission (CDC 2019). Additionally, educating the community about EH issues is one of the 10 essential environmental public health services (CDC 2016). However, much like indoor air and allergen challenges discussed above, there remain limitations in the public’s awareness of vector prevention and control strategies. Here again, this area presents an opportunity for collaboration with community health educators.

Anthropogenic changes or alterations to the environment, specifically landscapes, can create conditions (i.e., safe harborage spaces) conducive to vector presence and potential vector-borne disease transmission (Reisen 2010). Establishing relationships between governmental partners, planners, contractors, and others involved in community design or construction is essential for addressing environmental factors in the community that may create vector habitats or be conducive to the presence of vectors and pests. Efforts to encourage increased coordination among stakeholders could prevent the creation of vector habitats as they may result from community design and construction projects.

The expansion of EH regulatory responsibilities in nontraditional areas and facility types (e.g., body art, cannabis-infused products, or large-scale community events of varying themes and attractions) requires the incorporation of science and best practices into regulatory functions. However, delegation and requirements to fulfill such responsibilities are commonly accompanied with an urgent need to respond. This urgency limits opportunities to establish regulatory approaches based on current knowledge and science. Research is needed to advance proactive, rather than reactive, response systems to ensure the timely development of best practice–based guidelines.

The availability of up-to-date standards for EH professionals is crucial for effectively regulating traditional and new facility types. Responses to the need for such standards include the CDC’s release of the Model Aquatic Health Code (2018) and NEHA’s release of a Body Art Model Code and subsequent updates (Hlavsa et al. 2015; Armstrong and Fell 2000; NEHA 2018). While current standards may exist, jurisdictions sometimes face legislative challenges with adopting new standards and regulatory guidelines. Research is needed to examine best practices, modify existing standards where necessary, and develop new standards to address outdated practices.

Recognizing the emergence of public health threats and the need for rapid response to and recovery from emergencies and disasters, there has been a call to action for ensuring an equipped and ready EH workforce (National Environmental Health Partnership Council 2017). EH professionals fulfill a critical role in emergency response and recovery; however, they are commonly left out of community emergency response preparedness (e.g., planning, exercises, and training) efforts in the United States. Collaboration among EH, emergency responders, and other community stakeholders can establish a high level of community-based emergency preparedness (Eldridge and Tenkate 2006; Gamboa-Maldonado et al. 2012), particularly given increased recognition of noncommunicable diseases following disasters (Ryan et al. 2018). Future research is needed to comparatively examine the structure of emergency response systems to optimize preparedness and disaster risk reduction efforts.

Public health departments are engaging in population health and health equity initiatives to address health disparities in communities without EH involvement. However, involvement from multiple public health disciplines is essential to addressing community health disparities (Richardson 2016). Health departments are seeking accreditation through the Public Health Accreditation Board, which exemplifies engagement in an initiative leading to improved population health and addressing health equity (Yeager et al. 2016; Wooten et al. 2018). EH plays an important role in the accreditation process (Gerding et al. 2013), which likely extends to other initiatives aimed at improving population health and addressing health equity. Future research efforts are clearly needed in this space.

Sustainability and community planning are topics receiving much attention from local and state governments, and EH has an undefined role to play. In terms of community planning, the built environment and community design are areas that can benefit from EH expertise. For example, EH professionals may be able to contribute to transportation planning efforts to address related community health impacts or inform a parks and recreation program’s approach to protecting sensitive environments and increasing green space to promote physical activity (Whitfield and Wendel 2015; Merriam 2016). Urban sprawl is another phenomenon with sustainability and environmental implications for air pollution, land use, and water quality and quantity (Frumkin 2002). EH professionals have a vested interest in and can make substantial contributions to sustainability and community planning, yet a defined role is lacking in most jurisdictions.