Analysis of building plumbing system flushing practices and communications.

Drinking water distribution system contamination incidents can prompt public agencies and drinking water utilities to issue do-not-drink and do-not-use advisories. After the contaminant is cleared from distribution mains, consumers are often directed to flush their plumbing. However, little validated guidance and few evaluated communications strategies are available on using flushing to decontaminate building water systems. Additionally, limited data support the effectiveness of current practices and recommendations. In this study, expert elicitation was used to assess existing flushing guidance and develop validated flushing guidance and communications for single-family residences. The resulting guidance recommends progressively opening all cold-water taps from the closest to point of entry to the furthest and allowing the water to run for at least 20 minutes. Hot-water taps should be opened progressively and run for at least 75 minutes. The guidance language and format conformed to grade-level and readability scores within recommended health communication ranges. The readability of eight other flushing guidance documents was also evaluated for contamination incidents from 2008-2015. Seven were written at a 10th-12th grade level, above the 6th-7th grade level recommended for health communications.

Communicating with healthcare providers.

Studies of risk communication have identified healthcare providers, especially physicians, as the source of information most trusted by the public on issues of environmental health. Nothing in medical, nursing or most healthcare provider training actually prepares practitioners to play this role and healthcare providers are generally more oriented toward treatment and medical care than prevention and public health. Healthcare providers require education in order to play this role but rarely seek it. Gaps in the knowledge of professional on the issue of Cryptosporidium illustrate the problem. For members of the professional water community, communicating with healthcare providers is best done when messages are delivered in familiar settings, such as hospital Grand Rounds (a universal format for teaching conferences) and provided in a narrative (case-based) form but gaining access is difficult if the topic is not obviously clinical in nature. In addition to being a critically important target group itself, public health professionals are easier to reach and may mediate good working relationships with medical practitioners. We suggest a strategy for water utilities based on partnerships with academic public health and providing education through well-recognized formats in continuing medical and nursing education.

DC Water and Sewer Authority and lead in drinking water: a case study in environmental health risk management.

In 2001, following a change in disinfection agent in anticipation of the Environment Protection Agency Disinfection Byproduct Rule, lead levels began rising in drinking water in Washington, District of Columbia, and in 2002, the DC Water and Sewer Authority was found to have exceeded the Environment Protection Agency lead action level, requiring compliance with a series of measures under the Lead and Copper Rule. In 2004, the issue became a public concern, drawing considerable media attention. The problem was eventually resolved through the application of orthophosphate but while it played out, the utility was forced to respond to a novel public health issue with few risk management options. This case study examines the lessons learned.

Elevated lead in drinking water in Washington, DC, 2003-2004: the public health response.

BACKGROUND: In 2003, residents of the District of Columbia (DC) experienced an abrupt rise in lead levels in drinking water, which followed a change in water-disinfection treatment in 2001 and which was attributed to consequent changes in water chemistry and corrosivity. OBJECTIVES: To evaluate the public health implications of the exceedance, the DC Department of Health expanded the scope of its monitoring programs for blood lead levels in children. METHODS: From 3 February 2004 to 31 July 2004, 6,834 DC residents were screened to determine their blood lead levels. RESULTS: Children from 6 months to 6 years of age constituted 2,342 of those tested; 65 had blood lead levels > 10 microg/dL (the "level of concern" defined by the Centers for Disease Control and Prevention), the highest with a level of 68 microg/dL. Investigation of their homes identified environmental sources of lead exposure other than tap water as the source, when the source was identified. Most of the children with elevated blood lead levels (n = 46; 70.8%) lived in homes without lead drinking-water service lines, which is the principal source of lead in drinking water in older cities. Although residents of houses with lead service lines had higher blood lead levels on average than those in houses that did not, this relationship is confounded. Older houses that retain lead service lines usually have not been rehabilitated and are more likely to be associated with other sources of exposure, particularly lead paint. None of 96 pregnant women tested showed blood lead levels > 10 microg/dL, but two nursing mothers had blood lead levels > 10 microg/dL. Among two data sets of 107 and 71 children for whom paired blood and water lead levels could be obtained, there was no correlation (r(2) = -0.03142 for the 107). CONCLUSIONS: The expanded screening program developed in response to increased lead levels in water uncovered the true dimensions of a continuing problem with sources of lead in homes, specifically lead paint. This study cannot be used to correlate lead in drinking water with blood lead levels directly because it is based on an ecologic rather than individualized exposure assessment; the protocol for measuring lead was based on regulatory requirements rather than estimating individual intake; numerous interventions were introduced to mitigate the effect; exposure from drinking water is confounded with other sources of lead in older houses; and the period of potential exposure was limited and variable.

Protecting children from toxic exposure: three strategies.

To a toxicologist, "poisonings" are cases in which the child has a defined pattern of symptoms, corresponding to toxic effects at a mid to high level of exposure. "Toxicity" refers to a broader spectrum of effects. At lower levels of toxicity a child may have no specific, individual symptoms but may be affected subclinically. There are three basic strategies to protect children: individual intervention, the preventive medicine strategy, and the public health strategy. This article uses lead exposure as a model for discussing these differences in terminology and the three different protective strategies.

Defining susceptibility for microbial risk assessment: results of a workshop.

An interdisciplinary workshop was convened by the George Washington University in June 2001 to discuss how to incorporate new knowledge about susceptibility to microbial pathogens into risk assessment and management strategies. Experts from government, academic, and private sector organizations discussed definitions, methods, data needs, and issues related to susceptibility in microbial risk assessment. The participants agreed that modeling approaches need to account for the highly specific nature of host-pathogen relationships, and the wide variability of infectivity, immunity, disease transmission, and outcome rates within microbial species and strains. Concerns were raised about distinguishing between exposure and dose more clearly, interpreting experimental and outbreak data correctly, and using thresholds and possibly linearity at low doses. Recommendations were made to advance microbial risk assessment by defining specific terms and concepts more precisely, designing explicit conceptual frameworks to guide development of more complex models and data collection, addressing susceptibility in all steps of the model, measuring components of immunity to characterize susceptibility, reexamining underlying assumptions, applying default methods appropriately, obtaining more mechanistic data to improve default methods, and developing more biologically relevant and continuous risk estimators. The interrelated impacts of selecting specific subpopulations and health outcomes, and of increasing model complexity and data demands, were considered in the contexts of public policy goals and resources required. The participants stated that zero risk is unattainable, so targeted and effective risk reduction and communication strategies are essential not only to raise pubic awareness about water quality but also to protect the most susceptible members of the population.