Most previous studies of medical conditions associated with driver safety have focused on specific diseases. This analysis is based on a linkage of police report and hospital discharge data, and correlates various medical diagnostic categories and specific conditions with police determinations of driver culpability for all drivers admitted to Maryland hospitals during a 3-year period. Using odds ratios, various conditions have been identified which are associated with an increased risk of crash culpability. Further research is needed to confirm these findings, and to determine the role of the conditions vs. the possible influence of medications prescribed to treat these conditions. (+info)
Assessing the impact of Cry1Ab-expressing corn pollen on monarch butterfly larvae in field studies.
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Survival and growth of monarch larvae, Danaus plexippus (L.), after exposure to either Cry1Ab-expressing pollen from three Bacillus thuringiensis (Bt) corn (Zea mays L.) events differing in toxin expression or to the insecticide, lambda-cyhalothrin, were examined in field studies. First instars exposed to low doses ( approximately 22 grains per cm(2)) of event-176 pollen gained 18% less weight than those exposed to Bt11 or Mon810 pollen after a 5-day exposure period. Larvae exposed to 67 pollen grains per cm(2) on milkweed leaves from within an event-176 field exhibited 60% lower survivorship and 42% less weight gain compared with those exposed to leaves from outside the field. In contrast, Bt11 pollen had no effect on growth to adulthood or survival of first or third instars exposed for 5 days to approximately 55 and 97 pollen grains per cm(2), respectively. Similarly, no differences in larval survivorship were observed after a 4-day exposure period to leaves with 504-586 (within fields) or 18-22 (outside the field) pollen grains per cm(2) collected from Bt11 and non-Bt sweet-corn fields. However, survivorship and weight gain were drastically reduced in non-Bt fields treated with lambda-cyhalothrin. The effects of Bt11 and Mon810 pollen on the survivorship of larvae feeding 14 to 22 days on milkweeds in fields were negligible. Further studies should examine the lifetime and reproductive impact of Bt11 and Mon810 pollen on monarchs after long-term exposure to naturally deposited pollen. (+info)
Land use and transportation issues in environmental control.
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Analyses have been made of the effects of environmental controls and planning at regional, subarea, and project levels. The results obtained at the regional level are reviewed for a proposed highway development around Baltimore, Md. The findings for both short-term and long-term effects of alternative transport policies are summarized in respect of population and employment, economic indicators, traffic and travel, air quality, water and solid waste, noise, and environmentally sensitive areas. Problems at subarea and project levels are briefly considered. (+info)
Incidence of Vibrio parahaemolyticus in Chesapeake Bay.
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A Bay-wide survey of the distribution of Vibrio parahaemolyticus was carried out in Chesapeake Bay during May 1972, to determine whether the annual cycle of V. parahaemolyticus which was observed to occur in the Rhode River subestuary of Chesapeake Bay took place in other parts of Chesapeake Bay. In an earlier study, April to early June, when the water temperature rises from 14 to 19 C, was found to be a critical period in the annual cycle of the organism in the Rhode River, since this is the time period when the annual cycle is initiated. Results of this study, however, revealed that V. parahaemolyticus could not be found in the water column during May 1972. Nevertheless, several samples of sediment and plankton yielded V. parahaemolyticus isolates. Comparison of data with those for the Rhode River area examined in the earlier studies of the annual cycle of V. parahaemolyticus suggests that the time of initiation of the annual cycle of V. parahaemolyticus in the open Bay proper may be influenced by various factors such as temperature and salinity, i.e., deeper water locations may show initiation of the V. parahaemolyticus annual cycle later than shallow areas. Confirmation of the presence of the organisms in the samples studied was accomplished using numerical taxonomy with 19 reference strains also included in the analyses. (+info)
State monitoring activities related to Pfiesteria-like organisms.
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In response to potential threats to human health and fish populations, six states along the east coast of the United States initiated monitoring programs related to Pfiesteria-like organisms in 1998. These actions were taken in the wake of toxic outbreaks of Pfiesteria piscicida Steidinger & Burkholder in Maryland during 1997 and previous outbreaks in North Carolina. The monitoring programs have two major purposes. The first, rapid response, is to ensure public safety by responding immediately to conditions that may indicate the presence of Pfiesteria or related organisms in a toxic state. The second, comprehensive assessment, is to provide a more complete understanding of where Pfiesteria-like organisms may become a threat, to understand what factors may stimulate their growth and toxicity, and to evaluate the impacts of these organisms upon fish and other aquatic life. In states where human health studies are being conducted, the data from both types of monitoring are used to provide information on environmental exposure. The three elements included in each monitoring program are identification of Pfiesteria-like organisms, water quality measurements, and assessments of fish health. Identification of Pfiesteria-like organisms is a particularly difficult element of the monitoring programs, as these small species cannot be definitively identified using light microscopy; newly applied molecular techniques, however, are starting to provide alternatives to traditional methods. State monitoring programs also offer many opportunities for collaborations with research initiatives targeting both environmental and human health issues related to Pfiesteria-like organisms. (+info)
Field ecology of toxic Pfiesteria complex species and a conservative analysis of their role in estuarine fish kills.
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Within the past decade, toxic Pfiesteria outbreaks have been documented in poorly flushed, eutrophic areas of the largest and second largest estuaries on the U.S. mainland. Here we summarize a decadal field effort in fish kill assessment, encompassing kills related to Pfiesteria (49 major kills in North Carolina estuaries since 1991 and 4 in Maryland estuaries in 1997) and to other factors such as low oxygen stress (79 major fish kills in North Carolina estuaries). The laboratory and field data considered in developing our protocols are described, including toxic Pfiesteria behavior, environmental conditions conducive to toxic Pfiesteria activity, and impacts of toxic clonal Pfiesteria on fish health. We outline the steps of the standardized fish bioassay procedure that has been used since 1991 to diagnose whether actively toxic Pfiesteria was present during estuarine fish kills. Detailed data are given for a 1998 toxic Pfiesteria outbreak in the Neuse Estuary in North Carolina to illustrate of the full suite of diagnostic steps completed. We demonstrate that our conservative approach in implicating toxic Pfiesteria involvement in fish kills has biased in favor of causes other than Pfiesteria. Data are summarized from experiments that have shown stimulation of toxic Pfiesteria strains by nutrient (N, P) enrichment, supporting field observations of highest abundance of toxic strains in eutrophic estuaries. On the basis of a decade of research on toxic Pfiesteria, we present a conceptual model of the seasonal dynamics of toxic strains as affected by changing food resources and weather patterns. We also recommend protocols and research approaches that will strengthen the science of fish kill assessment related to Pfiesteria and/or other causative factors. (+info)
Cohort studies of health effects among people exposed to estuarine waters: North Carolina, Virginia, and Maryland.
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A variety of human symptoms have been associated with exposure to the dinoflagellate Pfiesteria and have been grouped together into a syndrome termed "possible estuary-associated syndrome." Prospective cohort studies of health effects associated with exposure to estuarine waters that may contain Pfiesteria spp. and related organisms are in progress in North Carolina, Virginia, and Maryland. The three studies recruited cohorts of 118-238 subjects who work or engaged in recreation in estuary waters. Baseline health and neuropsychological evaluations are conducted, and study subjects are followed prospectively for 2-5 years with periodic assessments of health and performance on a battery of neuropsychological tests. Health symptoms and estuary water exposure are recorded by telephone interviews or diaries every 1-2 weeks. Water quality information, including measurements of Pfiesteria spp., is collected in the areas where the subjects are working. Because it is not possible to measure individual exposure to Pfiesteria or a toxin produced by this organism, these studies examine surrogate exposure measures (e.g., time spent in estuary waters, in a fish kill area, or in waters where Pfiesteria DNA was detected by molecular amplification). Preliminary analyses of the first 2 years (1998-2000) of data indicate that none of the three ongoing cohorts have detected adverse health effects. However, there have not been any reported fish kills associated with Pfiesteria since the studies began, so it is possible that none of the study subjects have been exposed to toxin-producing Pfiesteria spp. (+info)
Human health effects and Pfiesteria exposure: a synthesis of available clinical data.
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An association between human illness and exposure to Pfiesteria was first observed among laboratory personnel working with the microorganism. In 1997, in the setting of Pfiesteria activity on the Pocomoke River in Maryland, difficulties with learning and memory were epidemiologically associated with high-level exposure to waterways in which the organism was known to be present. In the Maryland studies, neurocognitive function of affected persons returned to within normal ranges within a period of 3-6 months. Persons with the most severe neurocognitive deficits were significantly more likely to have skin lesions characterized on biopsy by evidence of a toxic/allergic inflammatory reaction. Acute high-level exposures to waterways where Pfiesteria has been identified have been linked with eye and respiratory irritation, headache, and gastrointestinal complaints. Recent data, collected using molecular techniques, suggest that the organism is present in multiple locations in the Chesapeake Bay environment; available data are insufficient to comment on the possible cumulative health impact of chronic low-level environmental exposure to Pfiesteria. (+info)