Systemic inflammatory effects of zinc oxide particles: is a re-evaluation of exposure limits needed?

Exposure to airborne substances such as gases, vapours, and particles remains a relevant health risk in many workplaces. A current topic and cause for discussion is the investigation of the health effects of particles containing zinc oxide (ZnO). Among other data, those collected from our study on human exposure data of ZnO in 2018 prompted the National Research Centre for the Working Environment 2021 to formulate a new, sharply lowered proposed occupational exposure limit (OEL) for zinc in workplaces.

Indoor air quality - An overview of methods for measuring odor detection thresholds of single substances.

Odor evaluation is an important topic in the field of indoor air quality. Odor detection threshold (ODT) values are used to derive limit values like odor guide values or odor activity value. However, ODT values for the same substance available in compilations or published before 2003 rarely have an accuracy of less than three orders of magnitude.

Construction of an In Vitro Air-Liquid Interface Exposure System to Assess the Toxicological Impact of Gas and Particle Phase of Semi-Volatile Organic Compounds.

Anthropogenic activities and industrialization render continuous human exposure to semi-volatile organic compounds (SVOCs) inevitable. Occupational monitoring and safety implementations consider the inhalation exposure of SVOCs as critically relevant. Due to the inherent properties of SVOCs as gas/particle mixtures, risk assessment strategies should consider particle size-segregated SVOC association and the relevance of released gas phase fractions.

No inflammatory effects after acute inhalation of barium sulfate particles in human volunteers.

Background: Most threshold limit values are based on animal experiments. Often, the question remains whether these data reflect the situation in humans. As part of a series of investigations in our exposure lab, this study investigates whether the results on the inflammatory effects of particles that have been demonstrated in animal models can be confirmed in acute inhalation studies in humans.

In vitro genotoxicity of dibutyl phthalate on A549 lung cells at air-liquid interface in exposure concentrations relevant at workplaces.

The ubiquitous use of phthalates in various materials and the knowledge about their potential adverse effects is of great concern for human health. Several studies have uncovered their role in carcinogenic events and suggest various phthalate-associated adverse health effects that include pulmonary diseases. However, only limited information on pulmonary toxicity is available considering inhalation of phthalates as the route of exposure.

Health effects after inhalation of micro- and nano-sized zinc oxide particles in human volunteers.

Inhalation of ZnO particles can cause inflammation of the airways and metal fume fever. It is unclear if different sizes of the particles alter these effects. However, various studies report higher biological activity of other nano-sized particles compared to microparticles.

Discrimination Between Atopic, Allergic, and Asthmatic Volunteers for Human Exposure Studies on Sensory Irritation.

Atopic, allergic, and especially asthmatic subjects might be particularly susceptible to sensory irritation induced by airborne chemicals compared to healthy individuals. Therefore, a good characterization of subjects is essential in inhalation exposure studies on sensory irritants. A total of 105 volunteers, 87% of whom reported to be non-allergic, participated in a medical examination that included skin prick test (SPT), measurements of total IgE, specific IgE (sIgE) to an ubiquitous allergen mix (sx1), and fractionated exhaled nitric oxide (FeNO), as well as pulmonary function and methacholine test.

Heart rate variability and cardiac repolarization after exposure to zinc oxide nanoparticles in healthy adults.

Background: Exposure to airborne zinc oxide (ZnO) particles occurs in many industrial processes, especially in galvanizing and welding. Systemic inflammation after experimental inhalation of ZnO particles has been demonstrated previously, but little is known about the impact on the cardiovascular system, particularly on the autonomic cardiac system and the risk of arrhythmias. In this study we investigated the short-term effects of ZnO nanoparticles on heart rate variability (HRV) and repolarization in healthy adults in a concentration-dependent manner at rest and during exercise in a controlled experimental set-up.

How Healthy Is Healthy? Comparison Between Self-Reported Symptoms and Clinical Outcomes in Connection with the Enrollment of Volunteers for Human Exposure Studies on Sensory Irritation Effects.

Controlled human exposure studies on sensory irritation effects are usually performed with healthy volunteers. Therefore, in most studies pre-screening by a health questionnaire and a detailed medical examination are combined. The aim of this report is to investigate whether self-reported information about smoking and health status is sufficient or whether additional clinical tests are necessary for a successful and safe enrollment of healthy volunteers.

Airway inflammation after inhalation of nano-sized zinc oxide particles in human volunteers.

Background: Workers in the zinc production and processing of galvanized sheet steel are exposed to a complex mixture of particles and gases, including zinc oxide (ZnO) that can affect human health. We aimed to study the effects of short-term controlled exposure to nano-sized ZnO on airway inflammatory markers in healthy volunteers.

Methods: Sixteen subjects (8 females, 8 men; age 19-42, non-smokers) were exposed to filtered air and ZnO nanoparticles (0.

Ethyl acrylate: influence of sex or atopy on perceptual ratings and eye blink frequency.

Occupational exposure limits (OELs) are derived for protection from health hazards, assuming that exposed subjects are healthy adult workers. Whether differences in susceptibility to sensory irritation effects from airborne chemicals have to be taken into account is currently under discussion. Thus, we chose atopics as a healthy but possibly susceptible subpopulation that can be identified with a clinical test.

Multi-walled carbon nanotubes induce stronger migration of inflammatory cells in vitro than asbestos or granular particles but a similar pattern of inflammatory mediators.

Biopersistent pro-inflammatory fibers are suspected human carcinogens. Cytotoxicity and transcription of pro- and anti-inflammatory mediators of different fibers were investigated in functional relationship to chemotaxis in vitro as a model for fiber-induced inflammation of the lung. We challenged NR8383 rat macrophages with multi-walled carbon nanotubes (MWCNT) and various asbestos fibers.

Effects of Exposure to Carbon Dioxide in Potash Miners.

Potash miners can become exposed to carbon dioxide (CO) during the blasting of basalt intrusions or loading and transporting the blasted salt. In a cross-shift study, we compared physiological effects of acute exposure to elevated CO concentrations in miners after long-term exposure to evaluate the possible health risks. A group of 119 miners was assessed by clinical examination, lung function tests, and blood gas content directly before and after the shift.

Methodological Implications and Repeatability of Nasal Nitric Oxide: Relevance for Challenge Studies.

There is an interest in assessing changes in nasal NO (nNO) levels as an effect marker of upper airways. In this study, we examined methodologic influences on short and long term repeatability of nNO levels assessed by a portable electrochemical analyzer. Nine atopic and eighteen healthy subjects were exposed for 4 h to ethyl acrylate concentration of 0.

Impact of Internal and External Factors on EBC-pH and FeNO Changes in Humans Following Challenge with Ethyl Acrylate.

Acute effects of ethyl acrylate exposure at 5 ppm for 4 h include changes of pH in exhaled breath condensate (EBC-pH) and exhaled nitric oxide (FeNO). So far, few data have been reported for atopic persons or the impact of the exposure conditions on biomarkers, e.g.

The Influence of Humidity on Assessing Irritation Threshold of Ammonia.

A large number of occupational exposure limit values (OELs) are based on avoiding of sensory irritation of the eyes and the upper respiratory tract. In order to investigate the chemosensory effect range of a chemical, odor and sensory irritation thresholds (lateralization thresholds, LTs) can be assessed. Humidity affects olfactory function and thus influences odor thresholds; however, a similar effect has not been shown for sensory irritation thresholds.

Clinical Effects, Exhaled Breath Condensate pH and Exhaled Nitric Oxide in Humans After Ethyl Acrylate Exposure.

Ethyl acrylate is an irritant known to affect the upper airways and eyes. An increase of the eye blink frequency in humans was observed during exposure to 5 ppm. Studies on the lower airways are scant and our study objective was the evaluation of pH in exhaled breath condensate (EBC-pH) and nitric oxide in exhaled breath (FeNO) as markers of inflammation.

Different Patterns in Changes of Exhaled Breath Condensate pH and Exhaled Nitric Oxide After Ozone Exposure.

Study objective was the evaluation of pH in exhaled breath condensate (EBC-pH) and nitric oxide in exhaled breath (FeNO) as biomarkers of ozone induced inflammation. We recently demonstrated that an ozone exposure of 240 ppb is sufficient to reduce lung function indices. We enrolled ten healthy subjects exposed in an intermittent exercise protocol to ozone concentrations of 240 ppb and 40 ppb (sham exposure).