Lora E. Fleming

Impacts of climate variability and future climate change on harmful algal blooms and human health.

Anthropogenically-derived increases in atmospheric greenhouse gas concentrations have been implicated in recent climate change, and are projected to substantially impact the climate on a global scale in the future. For marine and freshwater systems, increasing concentrations of greenhouse gases are expected to increase surface temperatures, lower pH, and cause changes to vertical mixing, upwelling, precipitation, and evaporation patterns. The potential consequences of these changes for harmful algal blooms (HABs) have received relatively little attention and are not well understood. Given the apparent increase in HABs around the world and the potential for greater problems as a result of climate change and ocean acidification, substantial research is needed to evaluate the direct and indirect associations between HABs, climate change, ocean acidification, and human health. This research will require a multidisciplinary approach utilizing expertise in climatology, oceanography, biology, epidemiology, and other disciplines. We review the interactions between selected patterns of large-scale climate variability and climate change, oceanic conditions, and harmful algae.

Neurotoxic Shellfish Poisoning

Neurotoxic shellfish poisoning (NSP) is caused by consumption of molluscan shellfish contaminated with brevetoxins primarily produced by the dinoflagellate, Karenia brevis. Blooms of K. brevis, called Florida red tide, occur frequently along the Gulf of Mexico. Many shellfish beds in the US (and other nations) are routinely monitored for presence of K. brevis and other brevetoxin-producing organisms. As a result, few NSP cases are reported annually from the US. However, infrequent larger outbreaks do occur. Cases are usually associated with recreationally-harvested shellfish collected during or post red tide blooms. Brevetoxins are neurotoxins which activate voltage-sensitive sodium channels causing sodium influx and nerve membrane depolarization. No fatalities have been reported, but hospitalizations occur. NSP involves a cluster of gastrointestinal and neurological symptoms: nausea and vomiting, paresthesias of the mouth, lips and tongue as well as distal paresthesias, ataxia, slurred speech and dizziness. Neurological symptoms can progress to partial paralysis; respiratory distress has been recorded. Recent research has implicated new species of harmful algal bloom organisms which produce brevetoxins, identified additional marine species which accumulate brevetoxins, and has provided additional information on the toxicity and analysis of brevetoxins. A review of the known epidemiology and recommendations for improved NSP prevention are presented.

Ciguatera Fish Poisoning: Treatment, Prevention and Management

Ciguatera Fish Poisoning (CFP) is the most frequently reported seafood-toxin illness in the world, and it causes substantial physical and functional impact. It produces a myriad of gastrointestinal, neurologic and/or cardiovascular symptoms which last days to weeks, or even months. Although there are reports of symptom amelioration with some interventions (e.g. IV mannitol), the appropriate treatment for CFP remains unclear to many physicians. We review the literature on the treatments for CFP, including randomized controlled studies and anecdotal reports. The article is intended to clarify treatment options, and provide information about management and prevention of CFP, for emergency room physicians, poison control information providers, other health care providers, and patients.

A sea change ahead for recreational water quality criteria

The United States Environmental Protection Agency is committed to developing new recreational water quality criteria for coastal waters by 2012 to provide increased protection to swimmers. We review the uncertainties and shortcomings of the current recreational water quality criteria, describe critical research needs for the development of new criteria, as well as recommend a path forward for new criteria development. We believe that among the most needed research needs are the completion of epidemiology studies in tropical waters and in waters adversely impacted by urban runoff and animal feces, as well as studies aimed to validate the use of models for indicator and pathogen concentration and health risk predictions.

Obesity in US Workers: The National Health Interview Survey, 1986 to 2002

OBJECTIVES Obesity has emerged as one of the most important public health issues in the United States. We assessed obesity prevalence rates and their trends among major US occupational groups. METHODS Self-reported weight and height were collected annually on US workers, aged 18 years or older, from the 1986 to 1995 and the 1997 to 2002 National Health Interview Surveys. Overall, occupation-, race-, and gender-specific rates of obesity (defined as a body mass index>30.0 kg/m2) were calculated with data pooled from both study periods (n>600,000). Annual occupation-specific prevalence rates were also calculated, and their time trends were assessed. RESULTS Obesity rates increased significantly over time among employed workers, irrespective of race and gender. The average yearly change increased from 0.61% (+/-.04) during the period from 1986 to 1995 to 0.95% (+/-.11) during the period from 1997 to 2002. Average obesity prevalence rates and corresponding trends varied considerably across occupational groups; pooled obesity prevalence rates were highest in motor vehicle operators (31.7% in men; 31.0% in women). CONCLUSIONS Weight loss intervention programs targeting workers employed in occupational groups with high or increasing rates of obesity are urgently needed.

Presence of Pathogens and Indicator Microbes at a Non-Point Source Subtropical Recreational Marine Beach

ABSTRACT Swimming in ocean water, including ocean water at beaches not impacted by known point sources of pollution, is an increasing health concern. This study was an initial evaluation of the presence of indicator microbes and pathogens and the association among the indicator microbes, pathogens, and environmental conditions at a subtropical, recreational marine beach in south Florida impacted by non-point sources of pollution. Twelve water and eight sand samples were collected during four sampling events at high or low tide under elevated or reduced solar insolation conditions. The analyses performed included analyses of fecal indicator bacteria (FIB) (fecal coliforms, Escherichia coli, enterococci, and Clostridium perfringens), human-associated microbial source tracking (MST) markers (human polyomaviruses [HPyVs] and Enterococcus faecium esp gene), and pathogens (Vibrio vulnificus, Staphylococcus aureus, enterovirus, norovirus, hepatitis A virus, Cryptosporidium spp., and Giardia spp.). The enterococcus concentrations in water and sand determined by quantitative PCR were greater than the concentrations determined by membrane filtration measurement. The FIB concentrations in water were below the recreational water quality standards for three of the four sampling events, when pathogens and MST markers were also generally undetectable. The FIB levels exceeded regulatory guidelines during one event, and this was accompanied by detection of HPyVs and pathogens, including detection of the autochthonous bacterium V. vulnificus in sand and water, detection of the allochthonous protozoans Giardia spp. in water, and detection of Cryptosporidium spp. in sand samples. The elevated microbial levels were detected at high tide and under low-solar-insolation conditions. Additional sampling should be conducted to further explore the relationships between tidal and solar insolation conditions and between indicator microbes and pathogens in subtropical recreational marine waters impacted by non-point source pollution.

Cancer incidence in a cohort of licensed pesticide applicators in Florida.

This study is a standardized incidence ratio (SIR) analysis of cancer incidence of licensed pesticide applicators in Florida, compared with that of Floridas general population. Through extensive data linkages, 33,658 applicators were assembled who had 1266 incident cancers and 279,397 person-years from January 1, 1975, to December 31, 1993. Disease risk from ethanol and tobacco use were significantly decreased. Among males, prostate cancer (SIR = 1.91; 95% confidence interval [CI], 1.72-2.13) and testicular cancer (SIR = 2.48; 95% CI, 1.57-3.72) were significantly elevated. No confirmed cases of soft tissue sarcoma (STS) were found, and the incidence of non-Hodgkins lymphoma was not increased. There were few female applicators; nevertheless, cervical cancer incidence (SIR = 3.69; 95% CI, 1.84-6.61) was significantly increased, while the incidence of breast cancer was significantly decreased. Cancers that have been associated with estrogen disrupters were found in male, but not female, pesticide applicators. The lack of soft tissue sarcoma is at odds with prior literature associated with the use of phenoxy herbicides.

Recreational exposure to aerosolized brevetoxins during Florida red tide events

Abstract During two separate Karenia brevis red tide events, we measured the levels of brevetoxins in air and water samples, conducted personal interviews, and performed pulmonary function tests on people before and after they visited one of two Florida beaches. One hundred and twenty-nine people participated in the study, which we conducted during red tide events in Sarasota and Jacksonville, FL, USA. Exposure was categorized into three levels: low/no exposure, moderate exposure, and high exposure. Lower respiratory symptoms (e.g. wheezing) were reported by 8% of unexposed people, 11% of the moderately exposed people, and 28% of the highly exposed people. We performed nasal–pharyngeal swabs on people who experienced moderate or high exposure, and we found an inflammatory response in over 33% of these participants. We did not find any clinically significant changes in pulmonary function test results; however, the study population was small. In future epidemiologic studies, we plan to further investigate the human health impact of inhaled brevetoxins.

Blue green algal (cyanobacterial) toxins, surface drinking water, and liver cancer in Florida

Abstract The blue green algae or cyanobacteria represent a diverse group of organisms that produce potent natural toxins. There have been case reports of severe morbidity and mortality in domestic animals through drinking water contaminated by these toxins. Microcystins, in particular, have been associated with acute liver damage and possibly liver cancer in laboratory animals. Although, there has been little epidemiologic research on toxin effects in humans, a study by Yu (1995) found an association between primary liver cancer and surface water. Surface water drinking supplies are particularly vulnerable to the growth of these organisms; current US drinking water treatment practices do not monitor or actively treat for blue green algal toxins including the microcystins. After a monitoring survey in Florida found organisms and microcystins (among other cyanobacterial toxins) in surface water drinking sources, a pilot ecological study was performed using a Geographic Information System (GIS) to evaluate the risk of primary hepatocellular carcinoma (HCC) and proximity to a surface water treatment plant at cancer diagnosis. The study linked all HCC cancers diagnosed in Florida from 1981 to 1998 with environmental databases. A significantly increased risk for HCC with residence within the service area of a surface water treatment plant was found compared to persons living in areas contiguous to the surface water treatment plants. However, this increased risk was not seen in comparison to persons living in randomly selected ground water treatment service areas or compared to the Florida cumulative incidence rate for the study period, using various comparison and GIS methodologies. Furthermore, these findings must be interpreted in light of significant issues of latency, high population mobility, and the lack of individual exposure information. Nevertheless, the issue of acute and chronic human health effects associated with the consumption of surface waters possibly contaminated by blue green algal toxins merits further investigation.

Trends in U.S. smoking rates in occupational groups: The National Health Interview Survey 1987-1994

Learning ObjectivesIdentify current rates of cigarette smoking in 209 occupations, and ways in which occupation and gender interact to determine smoking rates.Describe trends in smoking rates over the years 1987–1994, and characterize those occupational groups in which rates increased or declined in this period.Describe possible job-related measures for lowering prevalence rates of cigarette smoking. Abstract It is unknown if reductions in U.S. adult smoking rates are uniform across occupational groups. The National Health Interview Survey (NHIS) is a multistage area probability cross-sectional survey of the U.S. civilian population. Data on occupational and smoking status were collected on 141,122 adult participants from the 1987, 1988, and 1990 –1994 NHIS annual surveys. Overall smoking rates ranged from 58% in roofers to 4% in physicians, with higher rates found among blue collar professions. There were reductions in smoking from 1987–1994 within 72% of occupational groups; 19 of these downward trends were significant and occurred exclusively within white collar professions. Blue collar workers continue to smoke in large numbers, whereas white collar workers report lower rates along with corresponding significant downward trends in rates among selected occupational groups. The development of effective smoking prevention strategies targeting blue collar groups is needed.