Water-Related Research Activities
Occupational Exposure to Aerosolized Brevetoxins during Florida Red Tide Events: Effects on a Healthy Worker Population
Objective: To examine the effects on self-reported symptoms and pulmonary function from inhaling aerosolized brevetoxins during red tide events.
Background: Karenia brevis (formerly Gymnodinium breve) is a marine dinoflagellate responsible for red tides that form in the Gulf of Mexico. K. brevis produces brevetoxins, the potent toxins that cause neurotoxic shellfish poisoning. There is also limited information describing human health effects from environmental exposures to brevetoxins, including anecdotal information from lifeguards, who are exposed to marine aerosols during their job-related activities.
Methods: HSB recruited 28 healthy lifeguards who are occupationally exposed to red tide toxins during their daily work-related activities. Lifeguards performed spirometry tests and reported symptoms before and after their 8-hour shifts during a time when there was no red tide (unexposed period) and again when there was a red tide (exposed period). HSB also examined how mild exercise (riding a stationary bicycle) affected the reported symptoms and spirometry tests during unexposed and exposed periods with a subgroup of the same lifeguards. Environmental sampling (K. brevis cell concentrations in seawater and brevetoxin (concentrations in seawater and air) was used to confirm unexposed/exposed status.
Results: Compared with unexposed periods, the group of lifeguards reported more upper respiratory symptoms during the exposed periods. HSB did not observe any effects of exposure to aerosolized brevetoxins, with or without mild exercise, on pulmonary function.
Recreational Exposure to Microsystins during Algal Blooms in two California Lakes
Objectives: To: 1. Determine whether microcystins (MYC) could be detected in blood samples of people engaged in recreational activities on fresh water lakes during a microcystin-producing algal bloom, 2. Assess toxin concentrations from nasal swabs as an improved measure of individual exposure, 3. Verify previous findings of MYC aerosolization due to recreational activities such as water skiing, boating, and wakeboarding, and 4. Collect health-symptom data to generate hypotheses regarding relationships between environmental (MYC) exposures and adverse health effects for future studies.
Background: Although outbreaks of human illness associated with CyanoHABs have been sporadically recorded for decades, information about clinical signs and symptoms from cyanobacterial toxin poisonings is primarily from animal poisonings and laboratory studies. A significant source of cyanobacterial toxin exposure is recreational use of contaminated fresh water bodies because large populations are likely to be exposed and toxins may occur in high concentrations. Evidence of adverse health effects from epidemiologic exposures has been inconsistent, but a recent study by Stewart et al. (2006) found that persons who used personal watercraft on lakes with high cyanobacteria concentrations (cell surface area> 12.0 mm2/mL) were 2.1 (CI, 1.1–4.0) times more likely to report symptoms, particularly respiratory symptoms, than were persons who used their personal watercraft on lakes with low cyanobacteria concentrations (cell surface area < 2.4 mm2/mL).
Methods: HSB recruited 81 children and adults planning recreational activities on either of three California reservoirs, two with significant, ongoing blooms of toxin-producing cyanobacteria, including Microcystis aeruginosa (Bloom Lakes), and one without a toxin-producing algal bloom (Control Lake). HSB analyzed water samples for algal taxonomy, microcystin concentrations, and potential respiratory viruses (adenoviruses and enteroviruses). HSB measured microcystins in personal air samples, nasal swabs, and blood samples. HSB interviewed study participants for demographic and health symptoms information.
Results: HSB found highly variable microcystin concentrations in Bloom Lakes (<10 mg/L to >500 mg/L); microcystinwas not detected in the Control Lake.HSB did not detect adenoviruses or enteroviruses in any of the lakes. Low microcystin concentrations were found in personal air samples (<0.1 ng/m3 [limit of detection]–2.89 ng/m3) and nasal swabs (<0.1 ng [limit of detection]–5 ng). Microcystin concentrations in the water-soluble fraction of all plasma samples were below the limit of detection (1.0 mg/L).
Investigation to Assess Risk Factors for Well Water Contamination after Flooding
Objective: To assess risk factors for well water contamination after flooding.
Background: About 15% of the US population, or nearly 50 million people, obtains their drinking water from sources not protected by the Safe Drinking Water Act, such as private wells. CDC recently reported that the percentage of waterborne disease outbreaks associated with these unregulated sources of drinking water is increasing. Even when well-constructed and maintained, wells are at risk for contamination from flooding. Wells can become contaminated by human pathogens such as Escherichia coli O157:H7, Giardia, Cryptosporidium, and enteric viruses, nitrates from fertilizer, and pesticides applied on nearby lands. There is minimal information about which characteristics of flooding events are the most important risk factors for well contamination. This project looks at contaminants in flood water to assess their potential public health significance.
Methods: In May 2010, Nashville, TN experienced significant flooding following heavy rainfall. HSB staff traveled to Nashville in May to collect 10 floodwater samples, and subsequently in June and August, 2010 to collect well water samples from flooded and non-flooded wells. In April 2011, Kentucky experienced significant flooding. From May 1–4, at team worked with the Kentucky Department of Public Health (KDPH) to collect flood water samples from 4 different affected regions of Kentucky. From July 25–26, a team collected follow-up surface water samples from these same locations.
Comparing Contaminant Exposures in Local Dolphin Populations to those in People Eating the Same Local Seafood
Exposure to contaminants in fish, dolphins, and humans
Objective: We are conducting three pilot studies to see whether dolphins can be sentinels for exposure to and accumulation of environmental contaminants in human populations that share the same coastal resources.
Background: Small fish eat smaller marine animals. Bigger fish eat smaller fish. Dolphins eat bigger fish. Sharing the top of this marine food chain with dolphins are people who also eat fish. Environmental contaminants that accumulate in the marine food chain put human populations at risk for exposure. Common environmental contaminants found in the marine environment include chemicals such as polychlorinated biphenyls (PCBs), dioxins, and chlorinated pesticides. These compounds linger in the environment long after production or use has ended and they accumulate in the fat of marine life and people.
Methods: We conducted pilot studies in three locations – northern Biscayne Bay, FL; Charleston Harbor, SC; and Sapelo Island, GA to see if people who eat locally caught fish have similar exposures to dolphins that eat the same fish. In each location, we asked questions, collected seafood meal samples, and took blood samples of nine people who ate seafood caught in local waters at least twice a week. We plan to compare the levels of chemicals measured in these 27 individuals with levels found in their seafood meals and with levels found in dolphins that live nearby.
Results: Data analysis is planned to be completed and published during 2015. For more information see our Sapelo Fact Sheet [PDF - 255 KB]
4 Villages: Investigation of Unregulated Water Use and a Household Survey in 4 Rural Alaskan Villages
Objective: 1. To characterize water quality in various surface drinking water sources and other unregulated water sources in four rural Alaska villages; 2. To characterize drinking water quality in homes; 3. To evaluate household water source, use, storage and handling practices to assess public health risks and develop appropriate public health education messages; and 4. To determine if water hauling behaviors or water contamination risks vary between summer and winter seasons.
Background: The use of unregulated drinking water sources represents a potential public health risk for communities with these water sources not routinely treated or tested for biological or chemical contaminants. Though some rural Alaskan villages are being connected to regulated community water, many villages still rely on water hauling from unregulated water sources for their drinking water. This study will take a comprehensive look at water quality and contamination drinking water sources used by four select Alaskan villages which will include rivers, wells, tundra ponds, and other surface water sources.
Methods: We worked with the Alaskan Native populations, CDC Arctic Investigations Program, Alaska Native Tribal Health Consortium (ANTHC), and the local communities during a two-week field study in both March and August, 2010. Both of these data collection periods were preceded by a training we developed to prepare the 14 individuals participating in our field teams with the understanding and technical expertise to conduct work in the villages.
This study investigated unregulated drinking water sources used for drinking water sources near the four selected villages. These water sources were sampled and tested for a panel of inorganic chemicals, concentrations of persistant organic chemicals (e.g., PCBs, dioxins, chlorinated pesticides), and microbial contaminants (e.g. total coliforms, E. coli, Cryptosporidum, Giardia, norovirus, enterovirus, and Salmonella). The regulated water treatment facility in each village was also tested for all of the above contaminants for comparison. A household survey was also conducted to include all 300 households within the four villages. At each household a sample of water from each drinking water source used by the household was collected. These water samples will be analyzed for inorganic chemicals and bacterial contamination (total coliform and E. coli). In addition, one adult in each household was interviewed regarding drinking water source, use, and handling practices, knowledge and beliefs regarding water safety, and self-reported health effects. The household surveys were conducted in close collaboration with ANTHC and the local community supervisor for each village. This study was repeated in 5 villages in both the summer and winter seasons using the same population for comparison.
Evaluation of Water Cistern Contamination and Health Risks in the Navajo Nation
Objective: To determine whether cisterns on the Navajo Nation contain biological or chemical contamination at levels that can cause human health effects.
Background: Approximately 14,347 households (30%) on the Navajo Nation are not connected to a public water system. Providing access to a public water system is particularly problematic due to limited available water sources and the widely distributed housing. As a result, some households haul water from unregulated, untreated water sources. Households with an individual chronically ill or medically impaired are often provided cisterns (underground storage tanks) from the Indian Health Service (IHS) as a "medical referral".
The Indian Health Service installs these water cisterns as a service for members of the Navajo Nation that have significant health issues. The homeowners are given a 30-minute briefing on how to care for and clean their water cistern. After that point, IHS takes no responsibility for the maintenance or repair of the cisterns so they often fall into disrepair. Currently there are thousands of cisterns located throughout the Navajo Nation. Due to observations from the Navajo Nation Environmental Protection Agency (NNEPA) such as the growth of algae inside of cisterns, there is great concern that these cisterns may actually become a health hazard due to biological and chemical water contaminants. Compounding this issue is the fact that these contaminants would be impacting a population already suffering from other illnesses.
Methods: Two hundred households with water cisterns were randomly selected for participation in the study. Collaborating with the NNEPA, observational data was collected on the cistern structure and water quality. Water samples were collected and analyzed for biological contaminants such as total coliform, E. coli, Cryptosporidium, Giardia, norovirus, enterovirus, legionella, and Salmonella. Water samples were analyzed for chemical contaminants such as arsenic, uranium, cadmium, and lead, as well as nitrates and atrazine.
Household Survey of Drinking Water Sources and Contaminant Exposures at the Navajo Nation, 2006-2007
Background: Approximately 30% of households on Navajo Nation are currently not connected to a public water system. Many haul water from unregulated, untreated sources that are not approved for human consumption and may contain natural chemicals, bacteria and other contaminants. In order to determine the quality of water used by Navajo households that haul water, we tested unregulated water sources (e.g., livestock wells, springs) used for hauling drinking water on Navajo Nation.
Methods: A total of 229 unregulated water sources, such as wells that pump water for livestock and natural springs, were identified; 199 water samples were collected for analysis. Data was collected about the condition of wells from which a sample was collected. Water samples were analyzed for inorganic contaminants (e.g., metals, nitrates), coliform, and basic water composition.
Results: Of 199 water samples collected from unregulated sources, 12% (24/199) exceeded primary drinking water standards (DWS) for one or more contaminants. Twenty-four wells exceeded the maximum contaminant level (MCL) for arsenic, nine exceeded the MCL for uranium, one well exceeded the MCL for barium, one well for beryllium, and one well for lead. Five wells exceeded the MCL for nitrates. Iron and manganese were the most frequent secondary drinking water contaminants detected above their secondary DWS. E. coli contaminated 21% of the wells; 76% were contaminated with total coliforms. No association could be made between the observed recorded condition of the well and the presence/ absence of bacterial contamination.
Conclusion: There are opportunities to improve the quality of water available to households in Navajo Nation that are not currently connected to public water. Mechanisms to improve the quality of water at existing sources can be explored, public health interventions to reduce exposure to contaminants in unregulated sources can be identified, and barriers that may impede implementation can be identified and addressed. Some households may never have direct access to a public water system, and safe alternatives should be identified.
Investigation of Drinking Water exposures in Unregulated Water Sources at the Navajo Nation, 2008-2009
Background: Approximately 30% of households on Navajo Nation are currently not connected to a public water system. These households must transport or “haul” drinking water from outside water sources that are often unregulated and may contain dangerous chemical or bacterial contaminants. The objectives of this study were to identify whether Navajo households haul drinking water from contaminated water sources, examine contaminant levels in humans, and define community health risks.
Methods: We conducted a cross-sectional survey of 296 households (with and without access to community water) that were randomly selected from 5 Navajo Nation communities in the state of New Mexico. Questionnaire data were collected regarding water use and hauling practices from selected participants. Water and urine samples were collected from households and participants, and analyzed for concentrations of uranium, arsenic, and cadmium (drinking water and urine) and bacterial contaminants (drinking water).
Results: Of 296 water samples collected, 33 (11%) samples exceeded safe drinking water standards for arsenic and 6 (2%) samples exceeded safe water standards for uranium. Ninety-four (33%) of the drinking water samples tested positive for total coliform bacteria and 23 (8%) tested positive for E. coli. Of the 244 urine samples collected, 93 (39%) had elevated uranium levels (>95% of levels seen in the US population as defined by National Health and Nutrition Examination Survey).
Conclusion: The study population had unusually high urine uranium levels, though only a few water samples exceeded the EPA standard for uranium. Uranium contamination of drinking water sources does not appear to be the primary cause of increased uranium levels found in urine. Bacterial contamination levels were significantly higher in hauled water samples indicating a public health risk.
- Page last reviewed: January 13, 2012
- Page last updated: October 7, 2015
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