Last data update: Apr 22, 2024. (Total: 46599 publications since 2009)
Records 1-29 (of 29 Records) |
Query Trace: Backer LC [original query] |
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Harmful algal bloom exposures self-reported to poison centers in the United States, May-October 2019
Lavery AM , Kieszak SM , Law R , Bronstein AC , Funk AR , Banerji S , Brown K , Backer LC . Public Health Rep 2023 138 (6) 333549221146654 The National Poison Data System (NPDS) comprises self-reported information from people who call US poison center hotlines. NPDS data have proven to be important in identifying emerging public health threats. We used NPDS to examine records of people who had self-reported exposure to harmful algal blooms (HABs). Participating poison centers then contacted people who had called their centers from May through October 2019 about their HAB exposure to ask about exposure route, symptoms, health care follow-up, and awareness of possible risks of exposure. Of 55 callers who agreed to participate, 47 (85%) reported exposure to HABs while swimming or bathing in HAB-contaminated water. Nine callers reported health symptoms from being near waters contaminated with HABs, suggesting potential exposure via aerosolized toxins. Symptoms varied by the reported routes of exposure; the most commonly reported symptoms were gastrointestinal and respiratory. More public and health care provider education and outreach are needed to improve the understanding of HAB-related risks, to address ways to prevent HAB-related illnesses, and to describe appropriate support when exposures occur. |
Arsenic in private well water and birth outcomes in the United States.
Bulka CM , ScannellBryan M , Lombard MA , Bartell SM , Jones DK , Bradley PM , Vieira VM , Silverman DT , Focazio M , Toccalino PL , Daniel J , Backer LC , Ayotte JD , Gribble MO , Argos M . Environ Int 2022 163 107176 BACKGROUND: Prenatal exposure to drinking water with arsenic concentrations >50g/L is associated with adverse birth outcomes, with inconclusive evidence for concentrations 50g/L. In a collaborative effort by public health experts, hydrologists, and geologists, we used published machine learning model estimates to characterize arsenic concentrations in private wells-federally unregulated for drinking water contaminants-and evaluated associations with birth outcomes throughout the conterminous U.S. METHODS: Using several machine learning models, including boosted regression trees (BRT) and random forest classification (RFC), developed from measured groundwater arsenic concentrations of 20,000 private wells, we characterized the probability that arsenic concentrations occurred within specific ranges in groundwater. Probabilistic model estimates and private well usage data were linked by county to all live birth certificates from 2016 (n=3.6 million). We evaluated associations with gestational age and term birth weight using mixed-effects models, adjusted for potential confounders and incorporated random intercepts for spatial clustering. RESULTS: We generally observed inverse associations with term birth weight. For instance, when using BRT estimates, a 10-percentage point increase in the probability that private well arsenic concentrations exceeded 5g/L was associated with a -1.83g (95% CI: -3.30, -0.38) lower term birth weight after adjusting for covariates. Similarly, a 10-percentage point increase in the probability that private well arsenic concentrations exceeded 10g/L was associated with a -2.79g (95% CI: -4.99, -0.58) lower term birth weight. Associations with gestational age were null. CONCLUSION: In this largest epidemiologic study of arsenic and birth outcomes to date, we did not observe associations of modeled arsenic estimates in private wells with gestational age and found modest inverse associations with term birth weight. Study limitations may have obscured true associations, including measurement error stemming from a lack of individual-level information on primary water sources, water arsenic concentrations, and water consumption patterns. |
Evaluation of syndromic surveillance data for studying harmful algal bloom-associated illnesses - United States, 2017-2019
Lavery AM , Backer LC , Roberts VA , DeVies J , Daniel J . MMWR Morb Mortal Wkly Rep 2021 70 (35) 1191-1194 Harmful algal and cyanobacterial blooms (harmful algal blooms) are large colonies of algae or cyanobacteria that can harm humans, animals, and the environment (1-3). The number of algal blooms has been increasing in the United States, augmented by increasing water temperatures and nutrients in water from industry and agricultural run-off (4,5). The extent to which harmful algal bloom exposures cause human illness or long-term health effects is unknown. As the number of blooms increases annually, the likelihood of negative health outcomes (e.g., respiratory or gastrointestinal illness) from exposure also increases (4,5). To explore the utility of syndromic surveillance data for studying health effects from harmful algal bloom exposures, CDC queried emergency department (ED) visit data from the National Syndromic Surveillance Program (NSSP) for harmful algal bloom exposure-associated administrative discharge diagnosis codes and chief complaint text terms related to harmful algal bloom exposure (6). A total of 321 harmful algal bloom-associated ED visits were identified during January 1, 2017-December 31, 2019. An increase in harmful algal bloom-associated ED visits occurred during warmer months (June-October), consistent with seasonal fluctuations of blooms and recent publications (6,7). Although syndromic surveillance data are helpful for understanding harmful algal bloom-associated ED visits in the United States, exposures were documented infrequently with discharge diagnosis codes; 67% of harmful algal bloom-associated ED visits were identified through querying chief complaint text. Improving the documentation of harmful algal bloom exposures in medical records would further benefit future health studies. |
Machine Learning Models of Arsenic in Private Wells Throughout the Conterminous United States As a Tool for Exposure Assessment in Human Health Studies
Lombard MA , Bryan MS , Jones DK , Bulka C , Bradley PM , Backer LC , Focazio MJ , Silverman DT , Toccalino P , Argos M , Gribble MO , Ayotte JD . Environ Sci Technol 2021 55 (8) 5012-5023 Arsenic from geologic sources is widespread in groundwater within the United States (U.S.). In several areas, groundwater arsenic concentrations exceed the U.S. Environmental Protection Agency maximum contaminant level of 10 μg per liter (μg/L). However, this standard applies only to public-supply drinking water and not to private-supply, which is not federally regulated and is rarely monitored. As a result, arsenic exposure from private wells is a potentially substantial, but largely hidden, public health concern. Machine learning models using boosted regression trees (BRT) and random forest classification (RFC) techniques were developed to estimate probabilities and concentration ranges of arsenic in private wells throughout the conterminous U.S. Three BRT models were fit separately to estimate the probability of private well arsenic concentrations exceeding 1, 5, or 10 μg/L whereas the RFC model estimates the most probable category (≤5, >5 to ≤10, or >10 μg/L). Overall, the models perform best at identifying areas with low concentrations of arsenic in private wells. The BRT 10 μg/L model estimates for testing data have an overall accuracy of 91.2%, sensitivity of 33.9%, and specificity of 98.2%. Influential variables identified across all models included average annual precipitation and soil geochemistry. Models were developed in collaboration with public health experts to support U.S.-based studies focused on health effects from arsenic exposure. |
Human health and ocean pollution
Landrigan PJ , Stegeman JJ , Fleming LE , Allemand D , Anderson DM , Backer LC , Brucker-Davis F , Chevalier N , Corra L , Czerucka D , Bottein MD , Demeneix B , Depledge M , Deheyn DD , Dorman CJ , Fénichel P , Fisher S , Gaill F , Galgani F , Gaze WH , Giuliano L , Grandjean P , Hahn ME , Hamdoun A , Hess P , Judson B , Laborde A , McGlade J , Mu J , Mustapha A , Neira M , Noble RT , Pedrotti ML , Reddy C , Rocklöv J , Scharler UM , Shanmugam H , Taghian G , van de Water Jajm , Vezzulli L , Weihe P , Zeka A , Raps H , Rampal P . Ann Glob Health 2020 86 (1) 151 BACKGROUND: Pollution - unwanted waste released to air, water, and land by human activity - is the largest environmental cause of disease in the world today. It is responsible for an estimated nine million premature deaths per year, enormous economic losses, erosion of human capital, and degradation of ecosystems. Ocean pollution is an important, but insufficiently recognized and inadequately controlled component of global pollution. It poses serious threats to human health and well-being. The nature and magnitude of these impacts are only beginning to be understood. GOALS: (1) Broadly examine the known and potential impacts of ocean pollution on human health. (2) Inform policy makers, government leaders, international organizations, civil society, and the global public of these threats. (3) Propose priorities for interventions to control and prevent pollution of the seas and safeguard human health. METHODS: Topic-focused reviews that examine the effects of ocean pollution on human health, identify gaps in knowledge, project future trends, and offer evidence-based guidance for effective intervention. ENVIRONMENTAL FINDINGS: Pollution of the oceans is widespread, worsening, and in most countries poorly controlled. It is a complex mixture of toxic metals, plastics, manufactured chemicals, petroleum, urban and industrial wastes, pesticides, fertilizers, pharmaceutical chemicals, agricultural runoff, and sewage. More than 80% arises from land-based sources. It reaches the oceans through rivers, runoff, atmospheric deposition and direct discharges. It is often heaviest near the coasts and most highly concentrated along the coasts of low- and middle-income countries. Plastic is a rapidly increasing and highly visible component of ocean pollution, and an estimated 10 million metric tons of plastic waste enter the seas each year. Mercury is the metal pollutant of greatest concern in the oceans; it is released from two main sources - coal combustion and small-scale gold mining. Global spread of industrialized agriculture with increasing use of chemical fertilizer leads to extension of Harmful Algal Blooms (HABs) to previously unaffected regions. Chemical pollutants are ubiquitous and contaminate seas and marine organisms from the high Arctic to the abyssal depths. ECOSYSTEM FINDINGS: Ocean pollution has multiple negative impacts on marine ecosystems, and these impacts are exacerbated by global climate change. Petroleum-based pollutants reduce photosynthesis in marine microorganisms that generate oxygen. Increasing absorption of carbon dioxide into the seas causes ocean acidification, which destroys coral reefs, impairs shellfish development, dissolves calcium-containing microorganisms at the base of the marine food web, and increases the toxicity of some pollutants. Plastic pollution threatens marine mammals, fish, and seabirds and accumulates in large mid-ocean gyres. It breaks down into microplastic and nanoplastic particles containing multiple manufactured chemicals that can enter the tissues of marine organisms, including species consumed by humans. Industrial releases, runoff, and sewage increase frequency and severity of HABs, bacterial pollution, and anti-microbial resistance. Pollution and sea surface warming are triggering poleward migration of dangerous pathogens such as the Vibrio species. Industrial discharges, pharmaceutical wastes, pesticides, and sewage contribute to global declines in fish stocks. HUMAN HEALTH FINDINGS: Methylmercury and PCBs are the ocean pollutants whose human health effects are best understood. Exposures of infants in utero to these pollutants through maternal consumption of contaminated seafood can damage developing brains, reduce IQ and increase children's risks for autism, ADHD and learning disorders. Adult exposures to methylmercury increase risks for cardiovascular disease and dementia. Manufactured chemicals - phthalates, bisphenol A, flame retardants, and perfluorinated chemicals, many of them released into the seas from plastic waste - can disrupt endocrine signaling, reduce male fertility, damage the nervous system, and increase risk of cancer. HABs produce potent toxins that accumulate in fish and shellfish. When ingested, these toxins can cause severe neurological impairment and rapid death. HAB toxins can also become airborne and cause respiratory disease. Pathogenic marine bacteria cause gastrointestinal diseases and deep wound infections. With climate change and increasing pollution, risk is high that Vibrio infections, including cholera, will increase in frequency and extend to new areas. All of the health impacts of ocean pollution fall disproportionately on vulnerable populations in the Global South - environmental injustice on a planetary scale. CONCLUSIONS: Ocean pollution is a global problem. It arises from multiple sources and crosses national boundaries. It is the consequence of reckless, shortsighted, and unsustainable exploitation of the earth's resources. It endangers marine ecosystems. It impedes the production of atmospheric oxygen. Its threats to human health are great and growing, but still incompletely understood. Its economic costs are only beginning to be counted.Ocean pollution can be prevented. Like all forms of pollution, ocean pollution can be controlled by deploying data-driven strategies based on law, policy, technology, and enforcement that target priority pollution sources. Many countries have used these tools to control air and water pollution and are now applying them to ocean pollution. Successes achieved to date demonstrate that broader control is feasible. Heavily polluted harbors have been cleaned, estuaries rejuvenated, and coral reefs restored.Prevention of ocean pollution creates many benefits. It boosts economies, increases tourism, helps restore fisheries, and improves human health and well-being. It advances the Sustainable Development Goals (SDG). These benefits will last for centuries. RECOMMENDATIONS: World leaders who recognize the gravity of ocean pollution, acknowledge its growing dangers, engage civil society and the global public, and take bold, evidence-based action to stop pollution at source will be critical to preventing ocean pollution and safeguarding human health.Prevention of pollution from land-based sources is key. Eliminating coal combustion and banning all uses of mercury will reduce mercury pollution. Bans on single-use plastic and better management of plastic waste reduce plastic pollution. Bans on persistent organic pollutants (POPs) have reduced pollution by PCBs and DDT. Control of industrial discharges, treatment of sewage, and reduced applications of fertilizers have mitigated coastal pollution and are reducing frequency of HABs. National, regional and international marine pollution control programs that are adequately funded and backed by strong enforcement have been shown to be effective. Robust monitoring is essential to track progress.Further interventions that hold great promise include wide-scale transition to renewable fuels; transition to a circular economy that creates little waste and focuses on equity rather than on endless growth; embracing the principles of green chemistry; and building scientific capacity in all countries.Designation of Marine Protected Areas (MPAs) will safeguard critical ecosystems, protect vulnerable fish stocks, and enhance human health and well-being. Creation of MPAs is an important manifestation of national and international commitment to protecting the health of the seas. |
Environmental contaminants in coastal populations: Comparisons with the National Health and Nutrition Examination Survey (NHANES) and resident dolphins
Backer LC , Bolton B , Litz JA , Trevillian J , Kieszak S , Kucklick J . Sci Total Environ 2019 696 Background: People living in coastal communities are at risk for exposure to environmental hazards, including legacy chemicals. We can use databases such as NHANES to assess whether contaminants in coastal communities are present in higher levels than in the United States overall. We can use information from studies of local animal populations to assess which of these contaminants could have been transferred to people from their shared environment. Objective(s): Our objectives were to examine the POP profiles in human populations in areas where there are published POP profiles in resident dolphins and to compare our results with data from NHANES and the dolphin studies. Method(s): We identified three areas where POPs have been analyzed in local resident dolphin populations (total N = 73). We identified human communities in the same areas, and asked 27 eligible adults to read and sign a consent form, complete a questionnaire about demographics and seafood consumption, provide nine 10-mL blood samples, and provide one sample of seafood (N = 33). Blood and seafood were analyzed for a suite of POPs similar to those analyzed in published dolphin population studies. We compared the results from human blood analyses with NHANES and with data from the published reports of dolphin studies. Result(s): Levels and proportions of specific POPs found in people and animals reflect POPs found in the local environment. Compared with the nationally representative data reported in NHANES, the levels of many POPs found in high levels in dolphins were also higher in the corresponding human communities. Conclusion(s): Contaminants measured in marine animals, such as dolphins, can be used to identify the types and relative levels of environmental contaminants expected to occur in people sharing the same environment. Likewise, contaminants measured in coastal human populations can provide insight into which contaminants may be found in nearby animal populations. |
Outbreaks associated with untreated recreational water - United States, 2000-2014
Graciaa DS , Cope JR , Roberts VA , Cikesh BL , Kahler AM , Vigar M , Hilborn ED , Wade TJ , Backer LC , Montgomery SP , Secor WE , Hill VR , Beach MJ , Fullerton KE , Yoder JS , Hlavsa MC . MMWR Morb Mortal Wkly Rep 2018 67 (25) 701-706 Outbreaks associated with untreated recreational water can be caused by pathogens, toxins, or chemicals in fresh water (e.g., lakes, rivers) or marine water (e.g., ocean). During 2000-2014, public health officials from 35 states and Guam voluntarily reported 140 untreated recreational water-associated outbreaks to CDC. These outbreaks resulted in at least 4,958 cases of disease and two deaths. Among the 95 outbreaks with a confirmed infectious etiology, enteric pathogens caused 80 (84%); 21 (22%) were caused by norovirus, 19 (20%) by Escherichia coli, 14 (15%) by Shigella, and 12 (13%) by Cryptosporidium. Investigations of these 95 outbreaks identified 3,125 cases; 2,704 (87%) were caused by enteric pathogens, including 1,459 (47%) by norovirus, 362 (12%) by Shigella, 314 (10%) by Cryptosporidium, and 155 (5%) by E. coli. Avian schistosomes were identified as the cause in 345 (11%) of the 3,125 cases. The two deaths were in persons affected by a single outbreak (two cases) caused by Naegleria fowleri. Public parks (50 [36%]) and beaches (45 [32%]) were the leading settings associated with the 140 outbreaks. Overall, the majority of outbreaks started during June-August (113 [81%]); 65 (58%) started in July. Swimmers and parents of young swimmers can take steps to minimize the risk for exposure to pathogens, toxins, and chemicals in untreated recreational water by heeding posted advisories closing the beach to swimming; not swimming in discolored, smelly, foamy, or scummy water; not swimming while sick with diarrhea; and limiting water entering the nose when swimming in warm freshwater. |
Estimating the high-arsenic domestic-well population in the conterminous United States
Ayotte JD , Medalie L , Qi SL , Backer LC , Nolan BT . Environ Sci Technol 2017 51 (21) 12443-12454 Arsenic concentrations from 20450 domestic wells in the U.S. were used to develop a logistic regression model of the probability of having arsenic >10 mug/L ("high arsenic"), which is presented at the county, state, and national scales. Variables representing geologic sources, geochemical, hydrologic, and physical features were among the significant predictors of high arsenic. For U.S. Census blocks, the mean probability of arsenic >10 mug/L was multiplied by the population using domestic wells to estimate the potential high-arsenic domestic-well population. Approximately 44.1 M people in the U.S. use water from domestic wells. The population in the conterminous U.S. using water from domestic wells with predicted arsenic concentration >10 mug/L is 2.1 M people (95% CI is 1.5 to 2.9 M). Although areas of the U.S. were underrepresented with arsenic data, predictive variables available in national data sets were used to estimate high arsenic in unsampled areas. Additionally, by predicting to all of the conterminous U.S., we identify areas of high and low potential exposure in areas of limited arsenic data. These areas may be viewed as potential areas to investigate further or to compare to more detailed local information. Linking predictive modeling to private well use information nationally, despite the uncertainty, is beneficial for broad screening of the population at risk from elevated arsenic in drinking water from private wells. |
An updated review of ciguatera fish poisoning: Clinical, epidemiological, environmental, and public health management
Friedman MA , Fernandez M , Backer LC , Dickey RW , Bernstein J , Schrank K , Kibler S , Stephan W , Gribble MO , Bienfang P , Bowen RE , Degrasse S , Flores Quintana HA , Loeffler CR , Weisman R , Blythe D , Berdalet E , Ayyar R , Clarkson-Townsend D , Swajian K , Benner R , Brewer T , Fleming LE . Mar Drugs 2017 15 (3) Ciguatera Fish Poisoning (CFP) is the most frequently reported seafood-toxin illness in the world. It causes substantial human health, social, and economic impacts. The illness produces a complex array of gastrointestinal, neurological and neuropsychological, and cardiovascular symptoms, which may last days, weeks, or months. This paper is a general review of CFP including the human health effects of exposure to ciguatoxins (CTXs), diagnosis, human pathophysiology of CFP, treatment, detection of CTXs in fish, epidemiology of the illness, global dimensions, prevention, future directions, and recommendations for clinicians and patients. It updates and expands upon the previous review of CFP published by Friedman et al. (2008) and addresses new insights and relevant emerging global themes such as climate and environmental change, international market issues, and socioeconomic impacts of CFP. It also provides a proposed universal case definition for CFP designed to account for the variability in symptom presentation across different geographic regions. Information that is important but unchanged since the previous review has been reiterated. This article is intended for a broad audience, including resource and fishery managers, commercial and recreational fishers, public health officials, medical professionals, and other interested parties. |
Sentinel animals in a one health approach to harmful cyanobacterial and algal blooms
Backer LC , Miller M . Vet Sci 2016 3 (2) 8 People, domestic animals, and wildlife are all exposed to numerous environmental threats, including harmful algal blooms (HABs). However, because animals exhibit wide variations in diet, land use and biology, they are often more frequently or heavily exposed to HAB toxins than are people occupying the same habitat, making them sentinels for human exposures. Historically, we have taken advantage of unique physiological characteristics of animals, such as the sensitivity of canaries to carbon monoxide, to more quickly recognize threats and help protect human health. As HAB events become more severe and widespread worldwide, exposure and health outcome data for animals can be extremely helpful to predict, prevent, and evaluate human exposures and health outcomes. Applying a One Health approach to investigation of HABs means that lessons learned from animal sentinels can be applied to protect people, animals and our shared environment. |
Assessing arsenic exposure in households using bottled water or point-of-use treatment systems to mitigate well water contamination
Smith AE , Lincoln RA , Paulu C , Simones TL , Caldwell KL , Jones RL , Backer LC . Sci Total Environ 2015 544 701-710 There is little published literature on the efficacy of strategies to reduce exposure to residential well water arsenic. The objectives of our study were to: 1) determine if water arsenic remained a significant exposure source in households using bottled water or point-of-use treatment systems; and 2) evaluate the major sources and routes of any remaining arsenic exposure. We conducted a cross-sectional study of 167 households in Maine using one of these two strategies to prevent exposure to arsenic. Most households included one adult and at least one child. Untreated well water arsenic concentrations ranged from <10mug/L to 640mug/L. Urine samples, water samples, daily diet and bathing diaries, and household dietary and water use habit surveys were collected. Generalized estimating equations were used to model the relationship between urinary arsenic and untreated well water arsenic concentration, while accounting for documented consumption of untreated water and dietary sources. If mitigation strategies were fully effective, there should be no relationship between urinary arsenic and well water arsenic. To the contrary, we found that untreated arsenic water concentration remained a significant (p≤0.001) predictor of urinary arsenic levels. When untreated water arsenic concentrations were <40mug/L, untreated water arsenic was no longer a significant predictor of urinary arsenic. Time spent bathing (alone or in combination with water arsenic concentration) was not associated with urinary arsenic. A predictive analysis of the average study participant suggested that when untreated water arsenic ranged from 100 to 500mug/L, elimination of any untreated water use would result in an 8%-32% reduction in urinary arsenic for young children, and a 14%-59% reduction for adults. These results demonstrate the importance of complying with a point-of-use or bottled water exposure reduction strategy. However, there remained unexplained, water-related routes of exposure. |
Marine harmful algal blooms, human health and wellbeing: challenges and opportunities in the 21st century
Berdalet E , Fleming LE , Gowen R , Davidson K , Hess P , Backer LC , Moore SK , Hoagland P , Enevoldsen H . J Mar Biol Assoc U K 2015 2015 Microalgal blooms are a natural part of the seasonal cycle of photosynthetic organisms in marine ecosystems. They are key components of the structure and dynamics of the oceans and thus sustain the benefits that humans obtain from these aquatic environments. However, some microalgal blooms can cause harm to humans and other organisms. These harmful algal blooms (HABs) have direct impacts on human health and negative influences on human wellbeing, mainly through their consequences to coastal ecosystem services (fisheries, tourism and recreation) and other marine organisms and environments. HABs are natural phenomena, but these events can be favoured by anthropogenic pressures in coastal areas. Global warming and associated changes in the oceans could affect HAB occurrences and toxicity as well, although forecasting the possible trends is still speculative and requires intensive multidisciplinary research. At the beginning of the 21st century, with expanding human populations, particularly in coastal and developing countries, mitigating HABs impacts on human health and wellbeing is becoming a more pressing public health need. The available tools to address this global challenge include maintaining intensive, multidisciplinary and collaborative scientific research, and strengthening the coordination with stakeholders, policymakers and the general public. Here we provide an overview of different aspects of the HABs phenomena, an important element of the intrinsic links between oceans and human health and wellbeing. |
Current approaches to cyanotoxin risk assessment and risk management around the globe
Ibelings BW , Backer LC , Kardinaal WE , Chorus I . Harmful Algae 2015 49 63-74 Toxic cyanobacteria became more widely recognized as a potential health hazard in the 1990s, and in 1998 the World Health Organization (WHO) first published a provisional Guideline Value of 1 μg L(-1) for microcystin-LR in drinking-water. In this publication we compare risk assessment and risk management of toxic cyanobacteria in 17 countries across all five continents. We focus on the three main (oral) exposure vehicles to cyanotoxins: drinking-water, water related recreational and freshwater seafood. Most countries have implemented the provisional WHO Guideline Value, some as legally binding standard, to ensure the distribution of safe drinking-water with respect to microcystins. Regulation, however, also needs to address the possible presence of a wide range of other cyanotoxins and bioactive compounds, for which no guideline values can be derived due to insufficient toxicological data. The presence of microcystins (commonly expressed as microcystin-LR equivalents) may be used as proxy for overall guidance on risk management, but this simplification may miss certain risks, for instance from dissolved fractions of cylindrospermopsin and cyanobacterial neurotoxins. An alternative approach, often taken for risk assessment and management in recreational waters, is to regulate cyanobacterial presence - as cell numbers or biomass - rather than individual toxins. Here, many countries have implemented a two or three tier alert level system with incremental severity. These systems define the levels where responses are switched from Surveillance to Alert and finally to Action Mode and they specify the short-term actions that follow. Surface bloom formation is commonly judged to be a significant risk because of the elevated concentration of microcystins in a scum. Countries have based their derivations of legally binding standards, guideline values, maximally allowed concentrations (or limits named otherwise) on very similar scientific methodology, but underlying assumptions such as bloom duration, average body size and the amount of water consumed while swimming vary according to local circumstances. Furthermore, for toxins with incomplete toxicological data elements of expert judgment become more relevant and this also leads to a larger degree of variation between countries' thresholds triggering certain actions. Cyanobacterial blooms and their cyanotoxin content are a highly variable phenomenon, largely depending on local conditions, and likely concentrations can be assessed and managed best if the specific conditions of the locality are known and their impact on bloom occurrence are understood. Risk Management Frameworks, such as for example the Water Safety Plan concept of the WHO and the 'bathing water profile' of the European Union are suggested to be effective approaches for preventing human exposure by managing toxic cyanobacteria from catchment to consumer for drinking water and at recreational sites. |
Evaluating evidence for association of human bladder cancer with drinking-water chlorination disinfection by-products
Hrudey SE , Backer LC , Humpage AR , Krasner SW , Michaud DS , Moore LE , Singer PC , Stanford BD . J Toxicol Environ Health B Crit Rev 2015 18 (5) 1-29 Exposure to chlorination disinfection by-products (CxDBPs) is prevalent in populations using chlorination-based methods to disinfect public water supplies. Multifaceted research has been directed for decades to identify, characterize, and understand the toxicology of these compounds, control and minimize their formation, and conduct epidemiologic studies related to exposure. Urinary bladder cancer has been the health risk most consistently associated with CxDBPs in epidemiologic studies. An international workshop was held to (1) discuss the qualitative strengths and limitations that inform the association between bladder cancer and CxDBPs in the context of possible causation, (2) identify knowledge gaps for this topic in relation to chlorine/chloramine-based disinfection practice(s) in the United States, and (3) assess the evidence for informing risk management. Epidemiological evidence linking exposures to CxDBPs in drinking water to human bladder cancer risk provides insight into causality. However, because of imprecise, inaccurate, or incomplete estimation of CxDBPs levels in epidemiologic studies, translation from hazard identification directly to risk management and regulatory policy for CxDBPs can be challenging. Quantitative risk estimates derived from toxicological risk assessment for CxDBPs currently cannot be reconciled with those from epidemiologic studies, notwithstanding the complexities involved, making regulatory interpretation difficult. Evidence presented here has both strengths and limitations that require additional studies to resolve and improve the understanding of exposure response relationships. Replication of epidemiologic findings in independent populations with further elaboration of exposure assessment is needed to strengthen the knowledge base needed to better inform effective regulatory approaches. |
Paralytic shellfish poisonings resulting from an algal bloom in Nicaragua
Callejas L , Darce AC , Amador JJ , Conklin L , Gaffga N , Schurz Rogers H , DeGrasse S , Hall S , Earley M , Mei J , Rubin C , Aldighieri S , Backer LC , Azziz-Baumgartner E . BMC Res Notes 2015 8 74 BACKGROUND: During an October 2005 algal bloom (i.e., a rapid increase or accumulation in the population of algae) off the coast of Nicaragua, 45 people developed symptoms of paralytic shellfish poisoning (PSP) and one person died. PSP in humans is caused by ingestion of saxitoxin, which is a neurotoxin often associated with shellfish contaminated by algal blooms. To explore the relationship between the algal bloom and human illnesses, we performed a case-control study of residents living in a coastal island. We administered a standardized clinical questionnaire, sampled locally harvested seafood and algae, and obtained urine samples for saxitoxin testing from symptomatic and asymptomatic persons. PSP case-patients were defined as island residents who developed at least one neurological symptom during the November 4-16 intoxication period. Seafood and algal samples were analyzed for saxitoxins using the receptor-binding assay and high-performance liquid chromatography. Two urine samples were analyzed for saxitoxins using a newly developed immunoassay. FINDINGS: Three shellfish and two algal samples tested positive for saxitoxins. Ten (9%) of 107 participants developed neurological symptoms during the specified time period and five required hospitalization. While 6 (67%) of 9 possible case-patients and 21 (21%) of 98 controls had eaten fish (p=0.008), all case-patients and 17 (17%) of controls had eaten clams (P<0.0001). The saxitoxin concentration in the urine of a hospitalized case-patient was 21 ng saxitoxin/g creatinine compared to 0.16 ng saxitoxin/g creatinine in the single control patient's urine. CONCLUSIONS: These findings suggest that a bloom of saxitoxin-producing algae resulted in saxitoxin accumulation in local clams and was responsible for the PSP intoxication. |
Cyanobacteria and algae blooms: review of health and environmental data from the Harmful Algal Bloom-Related Illness Surveillance System (HABISS) 2007-2011
Backer LC , Manassaram-Baptiste D , LePrell R , Bolton B . Toxins (Basel) 2015 7 (4) 1048-64 Algae and cyanobacteria are present in all aquatic environments. We do not have a good sense of the extent of human and animal exposures to cyanobacteria or their toxins, nor do we understand the public health impacts from acute exposures associated with recreational activities or chronic exposures associated with drinking water. We describe the Harmful Algal Bloom-related Illness Surveillance System (HABISS) and summarize the collected reports describing bloom events and associated adverse human and animal health events. For the period of 2007-2011, Departments of Health and/or Environment from 11 states funded by the National Center for Environmental Health (NCEH), Centers for Disease Control and Prevention contributed reports for 4534 events. For 2007, states contributed 173 reports from historical data. The states participating in the HABISS program built response capacity through targeted public outreach and prevention activities, including supporting routine cyanobacteria monitoring for public recreation waters. During 2007-2010, states used monitoring data to support 196 public health advisories or beach closures. The information recorded in HABISS and the application of these data to develop a wide range of public health prevention and response activities indicate that cyanobacteria and algae blooms are an environmental public health issue that needs continuing attention. |
Recreational water-associated disease outbreaks - United States, 2009-2010
Hlavsa MC , Roberts VA , Kahler AM , Hilborn ED , Wade TJ , Backer LC , Yoder JS . MMWR Morb Mortal Wkly Rep 2014 63 (1) 6-10 Recreational water-associated disease outbreaks result from exposure to infectious pathogens or chemical agents in treated recreational water venues (e.g., pools and hot tubs or spas) or untreated recreational water venues (e.g., lakes and oceans). For 2009-2010, the most recent years for which finalized data are available, public health officials from 28 states and Puerto Rico electronically reported 81 recreational water-associated disease outbreaks to CDC's Waterborne Disease and Outbreak Surveillance System (WBDOSS) via the National Outbreak Reporting System (NORS). This report summarizes the characteristics of those outbreaks. Among the 57 outbreaks associated with treated recreational water, 24 (42%) were caused by Cryptosporidium. Among the 24 outbreaks associated with untreated recreational water, 11 (46%) were confirmed or suspected to have been caused by cyanobacterial toxins. In total, the 81 outbreaks resulted in at least 1,326 cases of illness and 62 hospitalizations; no deaths were reported. Laboratory and environmental data, in addition to epidemiologic data, can be used to direct and optimize the prevention and control of recreational water-associated disease outbreaks. |
Canine cyanotoxin poisonings in the United States (1920s-2012): review of suspected and confirmed cases from three data sources
Backer LC , Landsberg JH , Miller M , Keel K , Taylor TK . Toxins (Basel) 2013 5 (9) 1597-628 Cyanobacteria (also called blue-green algae) are ubiquitous in aquatic environments. Some species produce potent toxins that can sicken or kill people, domestic animals, and wildlife. Dogs are particularly vulnerable to cyanotoxin poisoning because of their tendency to swim in and drink contaminated water during algal blooms or to ingestalgal mats.. Here, we summarize reports of suspected or confirmed canine cyanotoxin poisonings in the U.S. from three sources: (1) The Harmful Algal Bloom-related Illness Surveillance System (HABISS) of the National Center for Environmental Health (NCEH), Centers for Disease Control and Prevention (CDC); (2) Retrospective case files from a large, regional veterinary hospital in California; and (3) Publicly available scientific and medical manuscripts; written media; and web-based reports from pet owners, veterinarians, and other individuals. We identified 231 discreet cyanobacteria harmful algal bloom (cyanoHAB) events and 368 cases of cyanotoxin poisoning associated with dogs throughout the U.S. between the late 1920s and 2012. The canine cyanotoxin poisoning events reviewed here likely represent a small fraction of cases that occur throughout the U.S. each year. |
The influence of physicochemical properties on the internal dose of trihalomethanes in humans following a controlled showering exposure
Silva LK , Backer LC , Ashley DL , Gordon SM , Brinkman MC , Nuckols JR , Wilkes CR , Blount BC . J Expo Sci Environ Epidemiol 2012 23 (1) 39-45 Although disinfection of domestic water supply is crucial for protecting public health from waterborne diseases, this process forms potentially harmful by-products, such as trihalomethanes (THMs). We evaluated the influence of physicochemical properties of four THMs (chloroform, bromodichloromethane, dibromochloromethane, and bromoform) on the internal dose after showering. One hundred volunteers showered for 10 min in a controlled setting with fixed water flow, air flow, and temperature. We measured THMs in shower water, shower air, bathroom air, and blood samples collected at various time intervals. The geometric mean (GM) for total THM concentration in shower water was 96.2 mcg/l. The GM of total THM in air increased from 5.8 mcg/m(3) pre shower to 351 mcg/m(3) during showering. Similarly, the GM of total-blood THM concentration increased from 16.5 ng/l pre shower to 299 ng/l at 10 min post shower. THM levels were significantly correlated between different matrices (e.g. dibromochloromethane levels) in water and air (r=0.941); blood and water (r=0.845); and blood and air (r=0.831). The slopes of best-fit lines for THM levels in water vs air and blood vs air increased with increasing partition coefficient of water/air and blood/air. The slope of the correlation plot of THM levels in water vs air decreased in a linear (r=0.995) fashion with increasing Henry's law constant. The physicochemical properties (volatility, partition coefficients, and Henry's law constant) are useful parameters for predicting THM movement between matrices and understanding THM exposure during showering. (Journal of Exposure Science and Environmental Epidemiology advance online publication, 25 July 2012; doi:10.1038/jes.2012.80.) |
Assessing the incidence of ciguatera fish poisoning with two surveys conducted in Culebra, Puerto Rico, during 2005 and 2006
Azziz-Baumgartner E , Luber G , Conklin L , Tosteson TR , Granade HR , Dickey RW , Backer LC . Environ Health Perspect 2012 120 (4) 526-9 BACKGROUND: Although ciguatera fish poisoning (CFP) is the most common seafood intoxication worldwide, its burden has been difficult to establish because there are no biomarkers to diagnose human exposure. OBJECTIVE: We explored the incidence CFP, proportion of CFP case-patients with laboratory confirmed ciguatoxic meal remnants, cost of CFP illness, and potential risk factors for CFP. METHODS: During 2005 and again during 2006, we conducted a census of all occupied households in the island of Culebra, Puerto Rico, where locally caught fish are a staple food. We defined CFP case-patients as persons with gastrointestinal symptoms (i.e., abdominal pain, vomiting, diarrhea, or nausea) and neurological symptoms (i.e., extremity paresthesia, arthralgia, myalgia, malaise, pruritus, headache, dizziness, metallic taste, visual disturbance, circumoral paresthesia, or temperature reversal, or toothache) or systemic symptoms (e.g., bradycardia) within 72 hours of eating a fish during the previous year. Participants were asked to save fish remnants eaten by cases for ciguatoxins analysis at the Food and Drug Administration laboratory in Dauphin Island. RESULTS: We surveyed 340 households during 2005 and 335 households during 2006. The estimated annual incidence of possible CFP was 4.0/1000 person-years and probable CFP was 7.5/1000 person-years. One of three fish samples submitted by probable case-patients was positive for ciguatoxins. None of the case-patients required respiratory support. Households that typically consumed barracuda were more likely to report CFP (p = 0.02). CONCLUSIONS: Our estimates, which are consistent with previous studies using similar case-finding, contribute to the overall information available to support public health decision-making about CFP prevention. |
Unregulated drinking water initiative for environmental surveillance and public health
Backer LC , Tosta N . J Environ Health 2011 73 (7) 31-2 The critical public health need to assess and protect the drinking water used by 37 million Americans requires attention and resources. NCEH, in partnership with states, has begun the process to identify information available on unregulated drinking water sources to improve the availability of data to support decisive public health actions and resource allocation. Far more attention and resources are needed to complete this process. |
Nitrates in drinking water and methemoglobin levels in pregnancy: a longitudinal study
Manassaram DM , Backer LC , Messing R , Fleming LE , Luke B , Monteilh CP . Environ Health 2010 9 60 BACKGROUND: Private water systems are more likely to have nitrate levels above the maximum contaminant level (MCL). Pregnant women are considered vulnerable to the effects of exposure to high levels of nitrates in drinking water due to their altered physiological states. The level of methemoglobin in the blood is the biomarker often used in research for assessing exposure to nitrates. The objective of this study was to assess methemoglobin levels and examine how various factors affected methemoglobin levels during pregnancy. We also examined whether differences in water use practices existed among pregnant women based on household drinking water source of private vs. public supply. METHODS: A longitudinal study of 357 pregnant women was conducted. Longitudinal regression models were used to examine changes and predictors of the change in methemoglobin levels over the period of gestation. RESULTS: Pregnant women showed a decrease in methemoglobin levels with increasing gestation although <1% had levels above the physiologic normal of 2% methemoglobin, regardless of the source of their drinking water. The multivariable analyses did not show a statistically significant association between methemoglobin levels and the estimated nitrate intake from tap water among pregnant women around 36 weeks gestation (beta = 0.046, p = 0.986). Four women had tap water nitrate levels above the MCL of 10 mg/L. At enrollment, a greater proportion of women who reported using water treatment devices were private wells users (66%) compared to public system users (46%) (p < 0.0001). Also, a greater proportion of private well users (27%) compared to public system users (13%) were using devices capable of removing nitrate from water (p < 0.0001). CONCLUSION: Pregnant women potentially exposed to nitrate levels primarily below the MCL for drinking water were unlikely to show methemoglobin levels above the physiologic normal. Water use practices such as the use of treatment devices to remove nitrates varied according to water source and should be considered in the assessment of exposure to nitrates in future studies. |
Evaluation of conventional and alternative monitoring methods for a recreational marine beach with nonpoint source of fecal contamination
Shibata T , Solo-Gabriele HM , Sinigalliano CD , Gidley ML , Plano LR , Fleisher JM , Wang JD , Elmir SM , He G , Wright ME , Abdelzaher AM , Ortega C , Wanless D , Garza AC , Kish J , Scott T , Hollenbeck J , Backer LC , Fleming LE . Environ Sci Technol 2010 44 (21) 8175-81 The objectives of this work were to compare enterococci (ENT) measurements based on the membrane filter, ENT(MF) with alternatives that can provide faster results including alternative enterococci methods (e.g., chromogenic substrate (CS), and quantitative polymerase chain reaction (qPCR)), and results from regression models based upon environmental parameters that can be measured in real-time. ENT(MF) were also compared to source tracking markers (Staphylococcus aureus, Bacteroidales human and dog markers, and Catellicoccus gull marker) in an effort to interpret the variability of the signal. Results showed that concentrations of enterococci based upon MF (<2 to 3320 CFU/100 mL) were significantly different from the CS and qPCR methods (p < 0.01). The correlations between MF and CS (r = 0.58, p < 0.01) were stronger than between MF and qPCR (r ≤ 0.36, p < 0.01). Enterococci levels by MF, CS, and qPCR methods were positively correlated with turbidity and tidal height. Enterococci by MF and CS were also inversely correlated with solar radiation but enterococci by qPCR was not. The regression model based on environmental variables provided fair qualitative predictions of enterococci by MF in real-time, for daily geometric mean levels, but not for individual samples. Overall, ENT(MF) was not significantly correlated with source tracking markers with the exception of samples collected during one storm event. The inability of the regression model to predict ENT(MF) levels for individual samples is likely due to the different sources of ENT impacting the beach at any given time, making it particularly difficult to to predict short-term variability of ENT(MF) for environmental parameters. |
Personal exposure to aerosolized red tide toxins (brevetoxins)
Cheng YS , Zhou Y , Naar J , Irvin CM , Su WC , Fleming LE , Kirkpatrick B , Pierce RH , Backer LC , Baden DG . J Occup Environ Hyg 2010 7 (6) 326-31 Florida red tides occur annually in the Gulf of Mexico from blooms of the marine dinoflagellate, Karenia brevis, which produces highly potent natural polyether toxins, brevetoxins. Several epidemiologic studies have demonstrated that human exposure to red tide aerosol could result in increased respiratory symptoms. Environmental monitoring of aerosolized brevetoxins was performed using a high-volume sampler taken hourly at fixed locations on Siesta Beach, Florida. Personal exposure was monitored using personal air samplers and taking nasal swab samples from the subjects who were instructed to spend 1 hr on Sarasota Beach during two sampling periods of an active Florida red tide event in March 2005, and in May 2008 when there was no red tide. Results showed that the aerosolized brevetoxins from the personal sampler were in modest agreement with the environmental concentration taken from a high-volume sampler. Analysis of nasal swab samples for brevetoxins demonstrated 68% positive samples in the March 2005 sampling period when air concentrations of brevetoxins were between 50 to 120 ng/m(3) measured with the high-volume sampler. No swab samples showed detectable levels of brevetoxins in the May 2008 study, when all personal samples were below the limit of detection. However, there were no statistical correlations between the amounts of brevetoxins detected in the swab samples with either the environmental or personal concentration. Results showed that the personal sample might provide an estimate of individual exposure level. Nasal swab samples showed that brevetoxins indeed were inhaled and deposited in the nasal passage during the March 2005 red tide event. |
Traditional and molecular analyses for fecal indicator bacteria in non-point source subtropical recreational marine waters
Sinigalliano CD , Fleisher JM , Gidley ML , Solo-Gabriele HM , Shibata T , Plano LR , Elmir SM , Wanless D , Bartkowiak J , Boiteau R , Withum K , Abdelzaher AM , He G , Ortega C , Zhu X , Wright ME , Kish J , Hollenbeck J , Scott T , Backer LC , Fleming LE . Water Res 2010 44 (13) 3763-72 The use of enterococci as the primary fecal indicator bacteria (FIB) for the determination of recreational water safety has been questioned, particularly in sub/tropical marine waters without known point sources of sewage. Alternative FIB (such as the Bacteroidales group) and alternative measurement methods (such as rapid molecular testing) have been proposed to supplement or replace current marine water quality testing methods which require culturing enterococci. Moreover, environmental parameters have also been proposed to supplement current monitoring programs. The objective of this study was to evaluate the health risks to humans from exposure to subtropical recreational marine waters with no known point source. The study reported symptoms between one set of human subjects randomly assigned to marine water exposure with intensive environmental monitoring compared with other subjects who did not have exposure. In addition, illness outcomes among the exposed bathers were compared to levels of traditional and alternative FIB (as measured by culture-based and molecular-based methods), and compared to easily measured environmental parameters. Results demonstrated an increase in self-reported gastrointestinal, respiratory and skin illnesses among bathers vs. non-bathers. Among the bathers, a dose-response relationship by logistic regression modeling was observed for skin illness, where illness was positively related to enterococci enumeration by membrane filtration (odds ratio = 1.46 [95% confidence interval = 0.97-2.21] per increasing log10 unit of enterococci exposure) and positively related to 24 h antecedent rain fall (1.04 [1.01-1.07] per increasing millimeters of rain). Acute febrile respiratory illness was inversely related to water temperature (0.74 [0.56-0.98] per increasing degree of water temperature). There were no significant dose-response relationships between report of human illness and any of the other FIB or environmental measures. Therefore, for non-point source subtropical recreational marine waters, this study suggests that humans may be at increased risk of reported illness, and that the currently recommended and investigational FIB may not track gastrointestinal illness under these conditions; the relationship between other human illness and environmental measures is less clear. |
The BEACHES Study: health effects and exposures from non-point source microbial contaminants in subtropical recreational marine waters
Fleisher JM , Fleming LE , Solo-Gabriele HM , Kish JK , Sinigalliano CD , Plano L , Elmir SM , Wang JD , Withum K , Shibata T , Gidley ML , Abdelzaher A , He G , Ortega C , Zhu X , Wright M , Hollenbeck J , Backer LC . Int J Epidemiol 2010 39 (5) 1291-8 BACKGROUND: Microbial water-quality indicators, in high concentrations in sewage, are used to determine whether water is safe for recreational purposes. Recently, the use of these indicators to regulate recreational water bodies, particularly in sub/tropical recreational marine waters without known sources of sewage, has been questioned. The objectives of this study were to evaluate the risk to humans from exposure to subtropical recreational marine waters with no known point source, and the possible relationship between microbe densities and reported symptoms in human subjects with random-exposure assignment and intensive individual microbial monitoring in this environment. METHODS: A total of 1303 adult regular bathers were randomly assigned to bather and non-bather groups, with subsequent follow-up for reported illness, in conjunction with extensive environmental sampling of indicator organisms (enterococci). RESULTS: Bathers were 1.76 times more likely to report gastrointestinal illness [95% confidence interval (CI) 0.94-3.30; P = 0.07]; 4.46 times more likely to report acute febrile respiratory illness (95% CI 0.99-20.90; P = 0.051) and 5.91 times more likely to report a skin illness (95% CI 2.76-12.63; P < 0.0001) relative to non-bathers. Evidence of a dose-response relationship was found between skin illnesses and increasing enterococci exposure among bathers [1.46 times (95% CI 0.97-2.21; P = 0.07) per increasing log(10) unit of enterococci exposure], but not for gastrointestinal or respiratory illnesses. CONCLUSIONS: This study indicated that bathers may be at increased risk of several illnesses relative to non-bathers, even in the absence of any known source of domestic sewage impacting the recreational marine waters. There was no dose-response relationship between gastroenteritis and increasing exposure to enterococci, even though many current water-monitoring standards use gastroenteritis as the major outcome illness. |
Recreational exposure to microcystins during algal blooms in two California lakes
Backer LC , McNeel SV , Barber T , Kirkpatrick B , Williams C , Irvin M , Zhou Y , Johnson TB , Nierenberg K , Aubel M , LePrell R , Chapman A , Foss A , Corum S , Hill VR , Kieszak SM , Cheng YS . Toxicon 2010 55 (5) 909-21 We conducted a study of recreational exposure to microcystins among 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). We analyzed water samples for algal taxonomy, microcystin concentrations, and potential respiratory viruses (adenoviruses and enteroviruses). We measured microcystins in personal air samples, nasal swabs, and blood samples. We interviewed study participants for demographic and health symptoms information. We found highly variable microcystin concentrations in Bloom Lakes (<10 microg/L to >500 microg/L); microcystin was not detected in the Control Lake. We did not detect adenoviruses or enteroviruses in any of the lakes. Low microcystin concentrations were found in personal air samples (<0.1 ng/m(3) [limit of detection]-2.89 ng/m(3)) 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 microg/L). Our findings indicate that recreational activities in water bodies that experience toxin-producing cyanobacterial blooms can generate aerosolized cyanotoxins, making inhalation a potential route of exposure. Future studies should include collecting nasal swabs to assess upper respiratory tract deposition of toxin-containing aerosols droplets. |
The costs of respiratory illnesses arising from Florida gulf coast Karenia brevis blooms
Hoagland P , Jin D , Polansky LY , Kirkpatrick B , Kirkpatrick G , Fleming LE , Reich A , Watkins SM , Ullmann SG , Backer LC . Environ Health Perspect 2009 117 (8) 1239-43 BACKGROUND: Algal blooms of Karenia brevis, a harmful marine algae, occur almost annually off the west coast of Florida. At high concentrations, K. brevis blooms can cause harm through the release of potent toxins, known as brevetoxins, to the atmosphere. Epidemiologic studies suggest that aerosolized brevetoxins are linked to respiratory illnesses in humans. OBJECTIVES: We hypothesized a relationship between K. brevis blooms and respiratory illness visits to hospital emergency departments (EDs) while controlling for environmental factors, disease, and tourism. We sought to use this relationship to estimate the costs of illness associated with aerosolized brevetoxins. METHODS: We developed a statistical exposure-response model to express hypotheses about the relationship between respiratory illnesses and bloom events. We estimated the model with data on ED visits, K. brevis cell densities, and measures of pollen, pollutants, respiratory disease, and intra-annual population changes. RESULTS: We found that lagged K. brevis cell counts, low air temperatures, influenza outbreaks, high pollen counts, and tourist visits helped explain the number of respiratory-specific ED diagnoses. The capitalized estimated marginal costs of illness for ED respiratory illnesses associated with K. brevis blooms in Sarasota County, Florida, alone ranged from $0.5 to $4 million, depending on bloom severity. CONCLUSIONS: Blooms of K. brevis lead to significant economic impacts. The costs of illness of ED visits are a conservative estimate of the total economic impacts. It will become increasingly necessary to understand the scale of the economic losses associated with K. brevis blooms to make rational choices about appropriate mitigation. |
Exposure and effect assessment of aerosolized red tide toxins (brevetoxins) and asthma
Fleming LE , Bean JA , Kirkpatrick B , Cheng YS , Pierce R , Naar J , Nierenberg K , Backer LC , Wanner A , Reich A , Zhou Y , Watkins S , Henry M , Zaias J , Abraham WM , Benson J , Cassedy A , Hollenbeck J , Kirkpatrick G , Clarke T , Baden DG . Environ Health Perspect 2009 117 (7) 1095-100 BACKGROUND: In previous studies we demonstrated statistically significant changes in reported symptoms for lifeguards, general beach goers, and persons with asthma, as well as statistically significant changes in pulmonary function tests (PFTs) in asthmatics, after exposure to brevetoxins in Florida red tide (Karenia brevis bloom) aerosols. OBJECTIVES: In this study we explored the use of different methods of intensive ambient and personal air monitoring to characterize these exposures to predict self-reported health effects in our asthmatic study population. METHODS: We evaluated health effects in 87 subjects with asthma before and after 1 hr of exposure to Florida red tide aerosols and assessed for aerosolized brevetoxin exposure using personal and ambient samplers. RESULTS: After only 1 hr of exposure to Florida red tide aerosols containing brevetoxin concentrations > 57 ng/m(3), asthmatics had statistically significant increases in self-reported respiratory symptoms and total symptom scores. However, we did not see the expected corresponding changes in PFT results. Significant increases in self-reported symptoms were also observed for those not using asthma medication and those living ≥ 1 mile from the coast. CONCLUSIONS: These results provide additional evidence of health effects in asthmatics from ambient exposure to aerosols containing very low concentrations of brevetoxins, possibly at the lower threshold for inducing a biologic response (i.e., toxicity). Consistent with the literature describing self-reported symptoms as an accurate measure of asthmatic distress, our results suggest that self-reported symptoms are a valuable measure of the extent of health effects from exposure to aerosolized brevetoxins in asthmatic populations. |
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