Interlaboratory evaluation of endotoxin analyses in agricultural dusts--comparison of LAL assay and mass spectrometry

Endotoxin exposure is associated with wheeze and asthma morbidity, while early life exposure may reduce risk of allergy and asthma. Unfortunately, it is difficult to compare endotoxin results from different laboratories and environments. We undertook this study to determine if lipopolysaccharide (LPS) extraction efficiency could account for differences among laboratories. We generated and collected aerosols from chicken and swine barns, and corn processing. We randomly allocated side-by-side filter samples to five laboratories for Limulus assay of endotoxin. Lyophilized aliquots of filter extracts were analyzed for 3-hydroxy fatty acids (3-OHFAs) as a marker of LPS using gas chromatography-mass spectrometry. There were significant differences in endotoxin assay and GC-MS (LPS) results between laboratories for all dust types (p < 0.01). Patterns of differences between labs varied by dust type. Relationships between assay and GC/MS results also depended on dust type. The percentages of individual 3-OHFA chain lengths varied across labs (p < 0.0001) suggesting that each lab recovered a different fraction of the LPS available. The presence of large amounts of particle associated LPS and absence of a freezing thawing cycle were associated with lower correlations between LPS and bioactivity, consistent with an absence of Limulus response to cell-bound endotoxin. These data suggest that extraction methods affect endotoxin measurements. The LAL methods may be most suitable when comparing exposures within similar environments; GC-MS offers additional information helpful in optimizing sample treatment and extraction. GC-MS may be of use when comparing across heterogeneous environments and should be considered for inclusion in future studies of human health outcomes.     

S-100 protein and neuron-specific enolase in amniotic fluid as markers of abdominal wall and neural tube defects in the fetus

The aim of this study was to determine whether there is increased leakage of neuron-specific enolase (NSE) and S-100 protein into amniotic fluid in pregnancies with neural tube defects, since both these proteins are produced by neural tissue, and to compare the value of these substances for detecting such defects with that of the more conventional techniques of alpha-fetoprotein (AFP) and acetylcholinesterase (AChE) gel electrophoresis. Amniotic samples from 25 mid-pregnancies (15–17 weeks' gestation) with neural tube defects (14 with open spina bifida and 11 with anencephaly) and from seven mid-pregnancies with abdominal wall defects were compared with a control material consisting of 80 amniotic fluid samples from 80 consecutive mid-pregnancy amniocenteses, with normal karyotypes and AFP concentrations. All of the above cases of abnormalities were primarily detected through increased AFP levels in the amniotic fluid. Amniotic fluid samples from 13 pregnancies with fetuses with autosomal chromosomal abnormalities and seven amniotic fluid samples contaminated with blood were also included in the investigation. It is concluded from the results that the conventional AFP assay combined with AChE gel electrophoresis is the best method for screening amniotic fluid for neural tube defects and defects of the abdominal wall. Neither NSE nor S-100 assay alone proved to be superior for the detection of these cases in mid-trimester amniotic fluid. The S-100 assay, however, could give additional information in cases where AChE gel electrophoresis is not decisive; for example, in samples contaminated with blood.     

Elevated concentrations of endotoxin in indoor air due to cigarette smoking

Exposure to environmental tobacco smoke (ETS) is an important worldwide public health issue. The present study demonstrates that cigarette smoke can be a major source of endotoxin (lipopolysaccharide, LPS) in indoor environments. Gas-chromatography/mass-spectrometry was used to determine 3-hydroxy fatty acids as markers of endotoxin in air-borne house dust in homes of smokers and non-smokers. Air concentrations of endotoxin were 4-63 times higher in rooms of smoking students than in identical rooms of non-smoking students. The fact that cigarette smoke contains large amounts of endotoxin may partly explain the high prevalence of respiratory disorders among smokers and may also draw attention to a hitherto neglected risk factor of ETS.     

Communicative Aspects of Environmental Management by Objectives: Examples from the Swedish Context

Management by objectives (MBO) is a technique for integrating ecological concerns into national political and administrative structures. Politicians determine environmental objectives and interim targets to be implemented and assessed by civil servants in national, regional, and local contexts. Well-developed organizational communication is a prerequisite for MBO. However, communication-related obstacles can arise when using MBO in public environmental management. We examine communicative aspects of environmental MBO, looking specifically at the implementation, administration, and assessment of Swedish environmental quality objectives. Our argument is illustrated by quotations from individual and focus group interviews. We conclude that communicative problems may arise, because different actors interpret messages from different perspectives, depending on their agendas, prior knowledge and experience, and positions in the administrative system. It is crucial to recognize the dialogical aspects of communication, by involving the receiver of a message in a process of response. In addition, the different timeframes underlying different arguments could contribute to misunderstandings between actors involved in handling environmental issues. In assessing the achievement of environmental objectives, indicators are used as communicative tools. It is important to investigate whether and how these indicators contribute to the de- and recontextualization of environmental objectives.     

Fixed wavelength fluorescence to detect PAH metabolites in fish bile: Increased statistical power with an alternative dilution method

Polyaromatic hydrocarbons (PAHs) are a group of environmental toxicants mainly emitted from diffuse sources. Fixed wavelength fluorescence of fish bile is a simple screening method that allows environmental monitoring of PAH exposure to fish. One drawback with this method is that the results can be biased by the presence of a so-called inner filter effect. This effect can be reduced by dilution of the bile samples. However, bile samples differ in density and extensive dilution may cause increased measurement error. An alternative method is to adjust the dilution rate to the density of each bile sample. Here, both methods have been applied to bile samples collected from caged rainbow trout. The bile density was estimated using biliverdin. The results show that the variance within experimental groups is reduced when the dilution rate is adjusted to the bile density, resulting in increased statistical power to detect differences when applied for environmental monitoring.     

Use of mass spectrometry for determining microbial toxins in indoor environments

We know little about the health consequences of human exposure to microorganisms in the environment. This may largely be due to the lack of universally accepted, sensitive, reproducible, non-discriminatory, and health relevant methods for characterizing the exposure. In this review, some of the different mass spectrometry methods that have been developed for measuring endotoxin and peptidoglycan from bacteria and mycotoxins from moulds in samples from-mainly damp-indoor environments are discussed.     

Recent advances in mercury speciation analysis with focus on spectrometric methods and enriched stable isotope applications

This paper discusses some recent advances in spectrometric methods and approaches for mercury speciation analysis of environmental samples with focus on isotope dilution techniques for determination of mercury species' concentrations in gaseous samples and reaction rates in soils and sediments. Such analytical data is important inter alia in fundamental research on mercury biogeochemistry and for risk assessments of mercury-contaminated soils and sediments and for designing effective remedial actions. The paper describes how the use of enriched stable isotope tracers in mercury speciation analysis can improve the traceability and accuracy of results, facilitate rational method developments, and be useful for studying biogeochemical processes, i.e. rate of reactions and fluxes, of mercury species. In particular the possibilities to study and correct for unwanted species transformation reactions during sample treatment and to study "natural" transformations of species in environmental samples, or micro- and mesocosm ecosystems, during incubations are highlighted. Important considerations to generate relevant data in isotope tracer experiments as well as reliability and quality assurance of mercury speciation analysis in general are also discussed.     

Nitrogen fixation by cyanobacteria stimulates production in Baltic food webs

Filamentous, nitrogen-fixing cyanobacteria form extensive summer blooms in the Baltic Sea. Their ability to fix dissolved N₂ allows cyanobacteria to circumvent the general summer nitrogen limitation, while also generating a supply of novel bioavailable nitrogen for the food web. However, the fate of the nitrogen fixed by cyanobacteria remains unresolved, as does its importance for secondary production in the Baltic Sea. Here, we synthesize recent experimental and field studies providing strong empirical evidence that cyanobacterial nitrogen is efficiently assimilated and transferred in Baltic food webs via two major pathways: directly by grazing on fresh or decaying cyanobacteria and indirectly through the uptake by other phytoplankton and microbes of bioavailable nitrogen exuded from cyanobacterial cells. This information is an essential step toward guiding nutrient management to minimize noxious blooms without overly reducing secondary production, and ultimately most probably fish production in the Baltic Sea.     

Baltic Sea ecosystem-based management under climate change: Synthesis and future challenges

Ecosystem-based management (EBM) has emerged as the generally agreed strategy for managing ecosystems, with humans as integral parts of the managed system. Human activities have substantial effects on marine ecosystems, through overfishing, eutrophication, toxic pollution, habitat destruction, and climate change. It is important to advance the scientific knowledge of the cumulative, integrative, and interacting effects of these diverse activities, to support effective implementation of EBM. Based on contributions to this special issue of AMBIO, we synthesize the scientific findings into four components: pollution and legal frameworks, ecosystem processes, scale-dependent effects, and innovative tools and methods. We conclude with challenges for the future, and identify the next steps needed for successful implementation of EBM in general and specifically for the Baltic Sea.