Levels of oxylipins, endocannabinoids and related lipids in plasma before and after low-level exposure to acrolein in healthy individuals and individuals with chemical intolerance

Laboratory Test Results in Patients with Workplace Moisture Damage Associated Symptoms—The SAMDAW Study

The mechanisms of health effects of moisture damage (MD) are unclear, but inflammatory responses have been suspected. The usefulness of laboratory and allergy tests among patients in secondary healthcare with symptoms associated with workplace MD were examined. Full blood count, erythrocyte sedimentation rate (ESR), C-reactive protein (CRP), total serum immunoglobulin E (IgE), fractional exhaled nitric oxide (FeNO), and skin prick testing were assessed and analyzed in relation to multiple chemical sensitivity (MCS) and perceived stress in 99 patients and 48 controls. In analysis, t-tests, Mann-Whitney tests, and chi-squared tests were used. Minor clinically insignificant differences in blood counts were seen in patients and controls, but among patients with asthma an elevated neutrophil count was found in 19% with and only in 2% of patients without asthma (p = 0.003). CRP levels and ESR were low, and the study patients’ FeNO, total IgE, or allergic sensitization were not increased compared to controls. The level of stress was high among 26% of patients and 6% of controls (p = 0.005), and MCS was more common among patients (39% vs. 10%, p < 0.001). Stress or MCS were not significantly associated with laboratory test results. In conclusion, no basic laboratory or allergy test results were characteristic of this patient group, and neither inflammatory processes nor allergic sensitization were found to explain the symptoms among these patients. While the value of basic laboratory tests should not be ignored, the use of allergy tests does not seem necessary when symptoms are indicated to be workplace-related.

Symptoms and oxylipins in plasma before and after exposure to rooms in which individuals have both experienced and not experienced building-related symptoms - an exploratory study

The aim of this study was to investigate if there are differences in symptom ratings and plasma concentrations of oxylipins as a measure of acute inflammation between individuals with building-related symptoms (BRS) and referents during exposure to rooms where people experienced BRS and rooms where they did not experience BRS. Medically examined individuals with BRS and healthy, age and sex matched referents working in the same building were exposed for 60 min. Ratings of symptoms and collection of blood to measure oxylipins in plasma were performed before and after each exposure. Individuals with BRS reported more symptoms (mostly mucosal) than the referents in the problem rooms and there was a tendency towards a difference between the groups in concentration of metabolites from the cyclooxygenase pathway (COX). The mean reported intensity of symptoms among all participants was also found to be positively correlated with both COX and lipoxygenase (LOX-15) oxylipins in problem rooms.

'Omics in environmental epidemiological studies of chemical exposures: A systematic evidence map

BACKGROUND

Systematic evidence maps are increasingly used to develop chemical risk assessments. These maps can provide an overview of available studies and relevant study information to be used for various research objectives and applications. Environmental epidemiological studies that examine the impact of chemical exposures on various 'omic profiles in human populations provide relevant mechanistic information and can be used for benchmark dose modeling to derive potential human health reference values.

OBJECTIVES

To create a systematic evidence map of environmental epidemiological studies examining environmental contaminant exposures with 'omics in order to characterize the extent of available studies for future research needs.

METHODS

Systematic review methods were used to search and screen the literature and included the use of machine learning methods to facilitate screening studies. The Populations, Exposures, Comparators and Outcomes (PECO) criteria were developed to identify and screen relevant studies. Studies that met the PECO criteria after full-text review were summarized with information such as study population, study design, sample size, exposure measurement, and 'omics analysis.

RESULTS

Over 10,000 studies were identified from scientific databases. Screening processes were used to identify 84 studies considered PECO-relevant after full-text review. Various contaminants (e.g. phthalate, benzene, arsenic, etc.) were investigated in epidemiological studies that used one or more of the four 'omics of interest: epigenomics, transcriptomics, proteomics, and metabolomics . The epidemiological study designs that were used to explore single or integrated 'omic research questions with contaminant exposures were cohort studies, controlled trials, cross-sectional, and case-control studies. An interactive web-based systematic evidence map was created to display more study-related information.

CONCLUSIONS

This systematic evidence map is a novel tool to visually characterize the available environmental epidemiological studies investigating contaminants and biological effects using 'omics technology and serves as a resource for investigators and allows for a range of applications in chemical research and risk assessment needs.

Odor perception and symptoms during acrolein exposure in individuals with and without building-related symptoms

Building-related symptoms (BRS) is a significant work-related and public health problem, characterized by non-specific symptoms occurring in a particular building. The cause of BRS is unknown, but certain reactive compounds are suggested risk factors. The aim of this controlled exposure study was to investigate whether BRS cases report more odor annoyance and symptoms and show altered autonomous nervous system (ANS) response during exposure to the reactive aldehyde, acrolein in comparison with referents. Individuals with BRS (n = 18) and referents (n = 14) took part in two exposure sessions (80 min). One session contained heptane alone, and the other heptane and acrolein. Perceived odor annoyance; eye, nose, and throat symptoms; and ANS response were measured continuously. BRS cases did not experience more odor annoyance; eye, nose, and throat symptoms; or altered ANS response in comparison with referents during the exposures. Supplementary analyses revealed that BRS cases that also reported chemical intolerance perceived more symptoms than referents during acrolein exposure. Acrolein exposure at a concentration below previously reported sensory irritation detection thresholds is perceived as more irritating by a subgroup of BRS individuals compared with referents. The results of this study indicate that a subset of individuals with building related symptoms (BRS) has a lowered sensory irritation threshold towards acrolein exposure. Future guidelines on chemical exposures to acrolein should take time and individual sensitivity into account.

Multiple Chemical Sensitivity in Patients Exposed to Moisture Damage at Work and in General Working-Age Population-The SAMDAW Study

A considerable proportion of patients having respiratory tract or voice symptoms associated with workplace moisture damage (MD) could have multiple chemical sensitivity (MCS). MCS is characterized by symptoms of different organ systems in association with low-level chemical exposure. The objective of this study was to assess the prevalence of MCS among patients referred to secondary health care because of respiratory or voice symptoms associated with workplace MD compared to the general working-age population. Using three subscales of the QEESI© questionnaire, we assessed MCS in the study patients and 1500 controls in the same district randomly selected from the Finnish Population Information System. Study patients had significantly more often high scores in chemical intolerance (39% vs. 23%, p = 0.001), symptom severity (60% vs. 27%, p < 0.001), and life impact subscales (53% vs. 20%, p < 0.001). Asthma, chronic rhinosinusitis, laryngeal problems, and atopy were not associated with the presence of MCS. MCS is common among patients referred to secondary health care with respiratory tract and/or voice symptoms associated with workplace MD, and it considerably affects their everyday life. MCS should be considered as a possible explanatory factor for MD-associated symptoms.

The role of sensory and olfactory pathways in multiple chemical sensitivity

Multiple chemical sensitivity (MCS) is characterised by non-specific and recurring symptoms affecting multiple organs and associated with exposure to chemicals, even at low concentrations, which are, under normal circumstances, harmless to the general population. Symptoms include general discomfort, cardiovascular instability, irritation of the sensory organs, breath disorders, hypersensitivity affecting the skin and epithelial lining of the gut, throat and lungs, anxiety, and learning and memory loss. Chemical intolerance is a key distinguishing feature of MCS, limiting considerably patients' lifestyle with serious social, occupational and economic implications. Since no specific diagnostic markers are currently available for chemical intolerance, the diagnosis relies on clinical symptoms. Despite the formulation of several hypotheses regarding the pathophysiology of MCS, its mechanisms remain undefined. A person-centred care approach, based on multidisciplinary and individualised medical plans, has shown promising results. However, more definite treatment strategies are required. We have reviewed the main experimental studies on MCS pathophysiology, focusing on the brain networks involved, the impact of environmental pollution on the olfactory system and the correlation with other pathologies such as neurodegenerative diseases. Finally, we discuss treatment strategies targeting the olfactory system.

A micro salting-out assisted liquid-liquid extraction combined with ultra-high performance liquid chromatography tandem mass spectrometry to determine anandamide and 2-arachidonoylglycerol in rat brain samples

A simple and reliable method was developed and validated to determine the endocannabinoids anandamide (AEA) and 2-arachidonoylglycerol (2-AG) in rat brain samples by micro salting-out assisted liquid-liquid extraction combined with ultra-high performance liquid chromatography tandem mass spectrometry (SALLLE/UHPLC-MS/MS). The SALLE parameters (brain homogenate volume, salting-out agent, salt concentration, salt solution volume, organic solvent, organic solvent volume, and centrifugation temperature) were optimized to improve sensitivity and selectivity of the method. The SALLE/UHPLC-MS/MS method presented linear ranges from 2.00 to 20.00 ng mL^-1 for AEA and from 0.300 to 10.00 μg mL^-1 for 2-AG, no significant matrix effect, and inter- and intra-assay precision and accuracy with CV and RSE values lower than 15%, respectively. This innovative method was successfully applied to determine AEA and 2-AG in brain hemispheres from a 6-OHDA animal model of Parkinson's disease (PD).

Application of systematic evidence mapping to assess the impact of new research when updating health reference values: A case example using acrolein

BACKGROUND

The environmental health community needs transparent, methodologically rigorous, and rapid approaches for updating human health risk assessments. These assessments often contain reference values for cancer and/or noncancer effects. Increasingly, the use of systematic review methods are preferred when developing these assessments. Systematic evidence maps are a type of analysis that has the potential to be very helpful in the update process, especially when combined with machine-learning software advances designed to expedite the process of conducting a review.

OBJECTIVES

To evaluate the applicability of evidence mapping to determine whether new evidence is likely to result in a change to an existing health reference value, using inhalation exposure to the air pollutant acrolein as a case example.

METHODS

New literature published since the 2008 California Environmental Protection Agency's Office of Environmental Health Hazard Assessment (OEHHA) Reference Exposure Level (REL) for acrolein was assessed. Systematic review methods were used to search the literature and screening included the use of machine-learning software. The Populations, Exposures, Comparators and Outcomes (PECO) criteria were kept broad to identify studies that characterized acute and chronic exposure and could be informative for hazard characterization. Studies that met the PECO criteria after full-text review were briefly summarized before their suitability for chronic point of departure (POD) derivation and calculation of a reference value was considered. Studies considered potentially suitable underwent a targeted evaluation to determine their suitability for use in dose-response analysis.

RESULTS

Over 15,000 studies were identified from scientific databases. Both machine-learning and manual screening processes were used to identify 60 studies considered PECO-relevant after full-text review. Most of these PECO-relevant studies were short-term exposure animal studies (acute or less than 1 month of exposure) and considered less suitable for deriving a chronic reference value when compared to the subchronic study in rats used in the 2008 OEHHA assessment. Thirteen epidemiological studies were identified but had limitations in the exposure assessment that made them less suitable for dose-response compared to the subchronic rat study. Among the 13 studies, there were four controlled trial studies that have the potential to be informative for future acute reference value derivation. Thus, the 2008 subchronic rat study used by OEHHA appears to still be the most appropriate study for chronic reference value derivation. In addition, advances in dosimetric modeling for gases, including new evidence pertinent to acrolein, could be considered when updating existing acrolein toxicity values.

CONCLUSIONS

Evidence mapping is a very useful tool to assess the need for updating an assessment based on understanding the potential impact of new studies on revising an existing health reference value. In this case example, the focus was to identify studies suitable for chronic exposure dose-response analysis, while also identifying studies that may be important to consider for acute exposure scenarios, hazard identification, or for future research. This allows the evidence map to be a useful resource for a range of decision-making contexts. Specialized systematic review software increased the efficiency of the process in terms of human resources and time to conduct the analysis.

Determination of anandamide in cerebrospinal fluid samples by disposable pipette extraction and ultra-high performance liquid chromatography tandem mass spectrometry

This work describes the development and validation of an ultra-high performance liquid chromatography tandem mass spectrometry method that uses disposable pipette extraction (DPX-UHPLC-MS/MS) to determine the endocannabinoid anandamide (AEA) in cerebrospinal fluid samples (CSF). The DPX parameters sorption equilibrium time, sample volume, number of draw-eject cycles, washing solvent volume, and elution solvent volume were optimized by design of experiments (DOE) techniques. The simple DPX protocol proposed herein required a reduced amount of CSF sample and organic solvent. The DPX-UHPLC-MS/MS method presented linear range from 0.10 ng mL^-1 (LLOQ) to 3.0 ng mL^-1, inter- and intra-assay accuracy with EPR values varying from -8.2% to 9.6%, inter- and intra-assay precision with CV values ranging from 1.3% to 14.8% (except for the LLOQ), and no significant matrix effect. The innovative DPX-UHPLC-MS/MS method was successfully applied to determine AEA in CSF samples from Parkinson's disease (PD) patients and should therefore be used in clinical studies.

Chemical intolerance: involvement of brain function and networks after exposure to extrinsic stimuli perceived as hazardous

Background

Chemical intolerance (CI) is a chronic condition characterized by recurring and severe symptoms triggered by exposure to low levels of odorous or pungent substances. The etiology of CI has been a controversial subject for a long time. The aim of this review is to summarize findings on the neurological processing of sensory information during and after exposure to low levels of odorous or pungent substances in individuals with CI, focusing on the brain function and networks.

Methods

Scientific studies on CI published between 2000 and 2019 in academic peer-reviewed journals were systematically searched using medical and scientific literature databases. Only peer-reviewed articles reporting original research from experimental human studies directly associated with CI, and involving related neurological responses or brain imaging after exposure to odorous or pungent substances (i.e., in chemical provocation tests), were considered.

Results

Forty-seven studies were found to be eligible for a full-text review. Twenty-three studies met the selection criteria and were included in this review. Evidence indicated that differences between subjects with CI and healthy controls were observed by brain imaging during and after exposure to odorous or pungent substances. Differences in brain imaging were also observed between initial exposure and after exposure to these substances. Neurological processing of sensory information after exposure to extrinsic stimuli in the limbic system and related cortices were altered in subjects with CI. A previous documentable exposure event was likely to be involved in this alteration.

Conclusions

This review documents consistent evidence for the altered neurological processing of sensory information in individuals with CI. Further neurophysiological research exploring the processing of extrinsic stimuli and cognition of sensation through the limbic system and related cortices in CI, and the appearance of symptoms in individuals with CI, are required.

Mass spectrometry profiling reveals altered plasma levels of monohydroxy fatty acids and related lipids in healthy humans after controlled exposure to biodiesel exhaust

Experimental human exposure studies are an effective tool to study adverse health effects from acute inhalation of particulate matter and other constituents of air pollution. In this randomized and double-blinded crossover study, we investigated the systemic effect on bioactive lipid metabolite levels after controlled biodiesel exhaust exposure of healthy humans and compared it to filtered air at a separate exposure occasion. Eicosanoids and other oxylipins, as well as endocannabinoids and related lipids, were quantified in plasma from 14 healthy volunteers at baseline and at three subsequent time points (2, 6, and 24 h) after 1 h exposure sessions. Protocols based on liquid chromatography (LC) coupled to tandem mass spectrometry (MS/MS) methods were developed to detect temporal changes in circulating levels after biodiesel exhaust exposure. The exhaust was generated by a diesel engine fed with an undiluted rapeseed methyl ester fuel. Among the 51 analyzed lipid metabolites, PGF_2α, 9,10-DiHOME, 9-HODE, 5-HETE, 11-HETE, 12-HETE, and DEA displayed significant responsiveness to the biodiesel exhaust exposure as opposed to filtered air. Of these, 9-HODE and 5-HETE at 24 h survived the 10% false discovery rate cutoff (p < 0.003). Hence, the majority of the responsive lipid metabolites were monohydroxy fatty acids. We conclude that it is possible to detect alterations in circulating bioactive lipid metabolites in response to biodiesel exhaust exposure using LC-MS/MS, with emphasis on metabolites with inflammation related properties and implications on cardiovascular health and disease. These observations aid future investigations on air pollution effects, especially with regard to cardiovascular outcomes.