Variation In Human Exposure Research Articles

Behaviour and distribution of Aedes aegypti mosquitoes and their relation to dengue incidence in two transmission hotspots in coastal Ecuador.

Dengue (DENV) transmission is endemic throughout coastal Ecuador, showing heterogeneous incidence patterns in association with fine-scale variation in Aedes aegypti vector populations and other factors. Here, we investigated the impact of micro-climate and neighbourhood-level variation in urbanization on Aedes abundance, resting behaviour and associations with dengue incidence in two endemic areas. Aedes aegypti were collected in Quinindé and Portoviejo, two urban cantons with hyperendemic dengue transmission in coastal Ecuador. Aedes vectors were sampled in and around houses within urban and peri-urban neighbourhoods at four time periods. We tested for variation in vector abundance and resting behaviour in relation to neighbourhood urbanization level and microclimatic factors. Aedes abundance increased towards the end of the rainy season, was significantly higher in Portoviejo than in Quinindé, and in urban than in peri-urban neighbourhoods. Aedes vectors were more likely to rest inside houses in Portoviejo but had similar abundance in indoor and outdoor resting collections in Quinindé. Over the study period, DENV incidence was lower in Quinindé than in Portoviejo. Relationships between weekly Ae. aegypti abundance and DENV incidence were highly variable between trapping methods; with positive associations being detected only between BG-sentinel and outdoor Prokopack collections. Aedes aegypti abundance was significantly higher in urban than peri-urban neighbourhoods, and their resting behaviour varied between study sites. This fine-scale spatial heterogeneity in Ae. aegypti abundance and behaviour could generate site-specific variation in human exposure and the effectiveness of indoor-based interventions. The trap-dependent nature of associations between Aedes abundance and local DENV incidence indicates further work is needed to identify robust entomological indicators of infection risk.

Diel activity patterns of two distinct populations of Aedes aegypti in Miami, FL and Brownsville, TX

The diel biting activity of Aedes (Stegomyia) aegypti (L) populations was extensively investigated in the early 1900s to gain more information on the biology of Ae. aegypti, and this information was used to devise effective approaches to controlling populations of this species and protect the human population from widespread arbovirus outbreaks. However, few contemporary studies are available regarding the diel activity patterns of Ae. aegypti. To assess the diel activity patterns of Ae. aegypti in southern Florida and Texas, we conducted 96-h uninterrupted mosquito collections once each month from May through November 2019 in Miami, Florida, and Brownsville, Texas, using BG-Sentinel 2 Traps. The overall diel activity pattern in both cities was bimodal with morning and evening peak activity between 7:00 and 8:00 and between 19:00 and 20:00. There were significant daily, monthly, seasonal, and site-specific differences in activity patterns, but these differences did not affect the overall peak activity times. These differences suggest daily, monthly, seasonal, and site-specific variations in human exposure to Ae. aegypti. Our observations can be used in planning and executing Ae. aegypti vector control activities in southern Florida and southern Texas, specifically those targeting the adult mosquito populations.

The changing face of lower tropospheric sulfur oxides in the United States

Abstract Sulfur oxides, sulfur dioxide and airborne sulfate, SOx, are short-lived species in the troposphere whose concentrations in air and precipitation have changed dramatically in association with fossil fuel combustion. The historic rise in concentration is coincident with the era of the so-called “Anthropocene.” Unlike concentrations of long-lived species such as carbon dioxide, atmospheric SOx in the United States (US) peaked between 1970 and 2005 then declined. The rise and fall of SOx is traced by comparing national data on emission changes, ambient concentrations, and precipitation sulfate from prior to World War II to the present. Surface SOx concentrations and precipitation sulfate have decreased with emissions in most parts of the US after the late 1970s. Continued reduction toward a natural “background” condition has depended on aggressive management of anthropogenic emission sources. Annual average ambient concentrations of SO2 and SO4 have become more uniform across the US at levels of 1–3 ppbv and 0.3–3 µg/m3, respectively. Precipitation SO4 has a nominal concentration generally less than 0.5 mg/L. The effective lifetime of SOx in the troposphere is a few days. This duration limits the spatial extent of emission source influence of SOx to regional scales, wherein spatial gradients in species concentrations lead to variations in human exposure and impacts on vulnerable terrestrial and aquatic ecosystems. The effects of domestic emission reductions on SOx levels are moderated by intra- and intercontinental transport of SOx from Canada, Mexico, Asia and elsewhere. The trends in tropospheric SOx concentrations illustrate the results of more than a century of rising public awareness and action to progressively reduce a US environmental risk, accomplished with advances in energy production technology that have maintained economic well-being.

Trends in indoor–outdoor PM2.5 research: A systematic review of studies conducted during the last decade (2003–2013)

There has been growing concern about potential health risks from exposure to PM2.5 (fine particulate matter). The importance of conducting simultaneous indoor and outdoor measurements emerged because people, especially in developed countries, spend more than 90% of their time indoors. Great spatial and temporal variations in human exposure to PM2.5 have recently been reported. This review aims to identify the main research areas that have attracted recent attention, any possible gaps in the measurements of PM2.5 in various microenvironments, and the relationships between indoor and outdoor concentrations. This study also provides recommendations for further studies on PM2.5 measurement methods and exposure levels. To achieve these goals, this review included articles published online from 2003 to 2013 in the Science Direct and Web of Science databases. In the initial screening stage, 113 abstracts selected while 61 articles were remained for full review. The reviewed studies consistently showed positive correlations between indoor and outdoor PM2.5. Sulfate/sulfur concentrations were used intensively for calculating the infiltration factor (FINF). The higher FINF indicated high infiltration of outdoor PM2.5 into indoor areas. Great percentage (42%) of the reviewed filter–based studies was conducted in Europe, followed by a similar amount (38%) in the USA, and 20% in Asia, indicating a lack in PM2.5 research in other parts of the world. It was difficult to conclude that ambient fixed–site monitoring provided accurate estimations of actual exposure to PM2.5– Studies shown trends of higher personal concentrations compared to indoor and outdoor ones. Higher indoor levels of OC (organic carbon), compared to outdoor levels, were consistently reported. The opposite trend was true for EC (elemental carbon), and there were higher indoor OC/EC ratios than outdoor OC/EC ratios. There was a consistent general trend of a high (r>0.70) correlation between indoor and outdoor EC, while the correlation between indoor and outdoor OC was much weaker (r=022–0.75). The higher indoor OC/EC ratios, compared to the outdoor OC/EC ratios, reflects multiple sources of indoor OC. Sulfate (SO42–), nitrate (NO3–), and ammonium (NH4+) were primary contributors to PM2.5 mass.

Regional Variation in Human Exposure to Persistent Organic Pollutants in the United States, NHANES.

We examined serum levels of persistent organic pollutants (POPs) among geographical regions of the United States as defined by the US Census Bureau. National Health and Nutrition Examination Survey (NHANES) data for adults aged 20 years and older are presented for selected survey periods between 1999 and 2010. From NHANES 1999 through 2004, dichlorodiphenyldichloroethylene (DDE) concentration levels were consistently higher among people living in the West than in the Midwest, Northeast, or South. In 2003–2010, perfluorinated compound concentrations tended to be highest in the South. The sum of 35 polychlorinated biphenyls (PCBs) congeners was significantly higher in the Northeast [GM: 189; 95% CI: 173–204 ng/g lipid] than the remaining regions. The regional differences in higher body burdens of exposure to particular POPs could be attributed to a variety of activities, including region-specific patterns of land use and industrial and agricultural chemical applications, as well as different levels of regulatory activity.

Abstract SY04-03: Gut microbiome-driven exposure to anti-inflammatory dietary bioactives in humans

Abstract Chronic, low-grade systemic inflammation is hypothesized to be a risk factor for carcinogenesis. In humans, dietary patterns, foods, and dietary constituents are associated with concentrations of circulating inflammation biomarkers (e.g., CRP, IL-6, IL-18, and TNF-α); meat-based or “Western” diet patterns have been positively associated with inflammation markers, whereas vegetable- and fruit-based or “healthy” diet patterns have been inversely associated. The gut microbiome may contribute to chronic inflammation in part through its interaction with host diet. Diet influences amounts and types of gut microbes, and gut microbial metabolism of dietary constituents produces compounds that can be protective or harmful to the host. We have shown that differences in gut microbial metabolism and diversity of the microbial community among individuals accounts for some of the variation in human exposure to phytochemicals. Components of diet also serve as substrates for certain groups of bacteria, such that changes in diet can result in a gut microbial community with greater or lesser inflammatory potential. Our findings suggest that a greater understanding of diet-gut microbiome interactions may inform future cancer-prevention strategies. Citation Format: Johanna Wyss Lampe. Gut microbiome-driven exposure to anti-inflammatory dietary bioactives in humans. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr SY04-03. doi:10.1158/1538-7445.AM2014-SY04-03

A coupled sensor-spectrophotometric device for continuous measurement of formaldehyde in indoor environments

Despite long-standing awareness of adverse health effects associated with chronic human exposure to formaldehyde, this hazardous air pollutant remains a challenge to measure in indoor environments. Traditional analytical techniques evaluate formaldehyde concentrations over several hours to several days in a single location in a residence, making it difficult to characterize daily temporal and spatial variation in human exposure to formaldehyde. There is a need for portable, easy-to-use devices that are specific and sensitive to gas-phase formaldehyde over short sampling periods so that dynamic processes governing formaldehyde fate, transport, and potential remediation in indoor environments may be studied more effectively. A recently developed device couples a chemical sensor element with spectrophotometric analysis for detection and quantification of part per billion (ppbv) gas-phase formaldehyde concentrations. This study established the ability of the coupled sensor-spectrophotometric device (CSSD) to report formaldehyde concentrations accurately and continuously on a 30-min sampling cycle at low ppbv concentrations previously untested for this device in a laboratory setting. Determination of the method detection limit (MDL), based on 40 samples each at test concentrations of 5 and 10 ppbv, was found to be 1.9 and 2.0 ppbv, respectively. Performance of the CSSD was compared with the dinitrophenylhydrazine (DNPH) derivatization method for formaldehyde concentrations ranging from 5-50 ppbv, and a linear relationship with a coefficient of determination of 0.983 was found between these two analytical techniques. The CSSD was also used to monitor indoor formaldehyde concentrations in two manufactured homes. During this time, formaldehyde concentrations varied from below detection limit to 65 ppbv and were above the US National Institute for Occupational Safety and Health (NIOSH) recommended exposure limit (REL) of 16 ppbv, which is also the exposure limit value now adopted by the US Federal Emergency Management Agency (FEMA) to procure manufactured housing, 80% and 100% of the time, respectively.

First Attempt To Validate Human IgG Antibody Response to Nterm-34kDa Salivary Peptide as Biomarker for Evaluating Exposure to Aedes aegypti Bites

BackgroundMuch effort is being devoted for developing new indicators to evaluate the human exposure to Aedes mosquito bites and the risk of arbovirus transmission. Human antibody (Ab) responses to mosquito salivary components could represent a promising tool for evaluating the human-vector contact.Methodology/Principal findingsTo develop a specific biomarker of human exposure to Aedes aegypti bites, we measured IgG Ab response to Ae. aegypti Nterm-34 kDa salivary peptide in exposed children in 7 villages of Southern Benin (West Africa). Results showed that specific IgG response presented high inter-individual heterogeneity between villages. IgG response was associated with rainfall and IgG level increased from dry (low exposure) to rainy (high exposure) seasons. These findings indicate that IgG Ab to Nterm-34 kDa salivary peptide may represent a reliable biomarker to detect variation in human exposure to Ae. aegypti bites.Conclusion/SignificanceThis preliminary study highlights the potential use of Ab response to this salivary peptide for evaluating human exposure to Ae. aegypti. This biomarker could represent a new promising tool for assessing the risk of arbovirus transmission and for evaluating the efficacy of vector control interventions.

Age and gender related dietary dose from90Sr in fallout from nuclear tests and the Chernobyl accident in Finland

Annual intake of 90 Sr trough foodstuffs and drinking water was assessed for eleven age categories of Finnish females and males in 1955–2010. Maximum intakes were received by young men in 1963–64. Cereals and milk contributed more than 80% to the dietary dose then. Per capita dose from ingestion of 90 Sr corresponded to the dose for a boy 13 years of age and a man older than 65 years. Lifetime committed effective dose from ingestion of 90 Sr for a newborn male was 0.49 mSv and for a 20 years old male 0.32 mSv, when the exposure of 70 and 50 years started in the beginning of 1955. For females the doses were 0.39 and 0.25 mSv, respectively. The activity concentrations of 90 Sr in milk varied in the whole country by a factor of two in the years of maximum fallout and decreased towards the 1980s. Also other than soil related factors have contributed to the variation in human exposure to dietary 90 Sr.

Assessing Human Exposure to Animal Neurocarcinogens: A Pilot Study

MAB4-O-04 Introduction: The assessment of multimedia and multipathway exposures to known and suspected animal neurocarcinogens (ANCs) in an epidemiologic investigation of brain cancer has not been attempted previously. We hypothesize that the poor associations or absence of causal links between exposure to a chemical agent and brain tumors may be due to inadequate exposure data underlying the analysis and/or exposure data nonspecific to chemicals, which have been demonstrated to cause neurocarcinogenicity in animal models. Methods: We present new human exposure assessment tools and methods used in support of a case-control study of brain tumors, with a focus on known and/or suspected animal neurocarcinogens. We initially reviewed the toxicity literature and compiled a list of 27 known ANCs and 15 suspected ANCs. Subsequently, we performed a comprehensive review of the physical, chemical, toxicological, environmental fate, and transport information for each compound to determine exposure media and pathway(s) of concern for each chemical of interest. Results: A neurocarcinogen-specific questionnaire was developed using occupational, environmental, and dietary exposure questions pertaining to specific exposure scenarios to assess overall human ANC exposure with consideration for the expected environmental media (air, water, and soil) and expected pathways of exposure (ingestion, inhalation, dermal). Data were obtained on approximately 200 cases from brain tumor clinics 180 friend and 180 sibling controls. Exposure specific indices created from these responses provide variation in human exposure for epidemiologic analysis. Preliminary results suggest exposures to selected ANCs in the breathing zone may increase the risk of brain tumors. Discussion and Conclusions: A neurocarcinogen questionnaire and detailed exposure matrix are essential for estimation of cumulative exposure index across pathway(s), across media, and across multiple chemicals. This exposure matrix links each compound to relevant questions in the questionnaire and allows calculation of an exposure score as a relative indicator of pathway-specific or cumulative exposure of an individual within the study population. These data, combined with biomarkers of exposure, will eventually provide a comprehensive assessment of ANCs and brain cancer.

Phytotoxicology. I. Major problems associated with poisonous plants.

Phytotoxicology (the study of poisoning of man and animals by plants) is an area of medical neglect in both clinical and experimental aspects. Poisonings, for the most part, are poorly investigated, poorly reported, and rarely attract appropriate experimentation. Vernacular or common names for plants are tenuous at best, and their use has led to serious errors in treatment and in medical literature. Frequently the origin of information available to the medical profession in current authoritative publications is of a prior century, or earlier, and derived from experience elsewhere than in North America. These facts often are not obvious. Figures for level of toxicity and statements of symptoms and lesions of such origin often reflect experimental conditions which should invalidate the results, as far as basing responsible present‐day treatments on them. General information from such unspecified sources ignores factors of botanical and human variability with time and place, including ecological, genetic, and nomenclatural variation, variation in human exposure, and variation with horticultural manipulation. Fact and myth are intermingled freely in what the American population believes about poisonous plants. Therefore, what colors any medical history is apt to be vastly different from reality. Induced emesis, catharsis, or gastric lavage are frequently performed when ingested plant material is entirely innocuous and none of these procedures indicated. A plant experimentally established as nontoxic, for example, is among the 10 plants most frequently reported as ingested and believed poisonous by poison control centers. Not all poisonous plants have yet been recognized as such. To establish a list of any set number of “important” poisonous plants is irresponsible on the basis of present knowledge if it results in others being overlooked when poisonings or ingestions are diagnosed.

Measurement of background radiation for epidemiologic studies.

Methods being used in a survey of cancer incidence and its relation to background radiation in New England communities are outlined. The measurement of background radiation for epidemiologic purposes is discussed in terms of the application of technics capable of detecting geographic variation in human exposure to both external and internal natural sources of radioactivity at very low levels. The equivalent uranium content was calculated for 58 geological formations in New Hampshire, 5 in Maine, and 24 in Vermont. From this an average equivalent uranium value for the minor civil division, weighted by the proportion overlying each geological formation, was obtained. Illustrations are provided showing the distribution of geological formations and their respective equivalent uranium concentrations in minor civil divisions of New Hampshire. The findings suggest that even within small civil divisions there may be marked differences in terrestrial radiation. Radiometric analysis of small amounts of hiological material, such as individual teeth, are being used to estimate the body burden of radium and other emitters in largescale population studies. A method is described for assaying Ra/sup 226/, Ra/sup 224/, Ra/sup 223/, and Po/sup 210/ in a single tooth. (T CO)