Biomedical subjects

P Wolkoff

Publications and source records attributed to P Wolkoff.

18 recordsLinked to original sources

PubMed2006

Organic compounds in office environments - sensory irritation, odor, measurements and the role of reactive chemistry.

Abstract Sensory irritation and odor effects of organic compounds in indoor environments are reviewed. It is proposed to subdivide volatile organic compounds (VOCs) into four categories: (i) chemically non-reactive, (ii) chemically 'reactive', (iii) biologically reactive (i.e. form chemical bonds to receptor sites in mucous membranes) and (iv) toxic compounds. Chemically non-reactive VOCs are considered non-irritants at typical indoor air levels. However, compounds with low odor thresholds contribute to the overall perception of the indoor air quality. Reported sensory irritation may be the result of odor annoyance. It appears that odor thresholds for many VOCs probably are considerably lower than previously reported. This explains why many building materials persistently are perceived as odorous, although the concentrations of the detected organic compounds are close to or below their reported odor thresholds. Ozone reacts with certain alkenes to form a gas and aerosol phase of oxidation products, some of which are sensory irritants. However, all of the sensory irritating species have not yet been identified and whether the secondary aerosols (ultrafine and fine particles) contribute to sensory irritation requires investigation. Low relative humidity may exacerbate the sensory irritation impact. Practical Implications Certain odors, in addition to odor annoyance, may result in psychological effects and distraction from work. Some building materials continually cause perceivable odors, because the odor thresholds of the emitted compounds are low. Some oxidation products of alkenes (e.g. terpenes) may contribute to eye and airway symptoms under certain conditions and low relative humidity.

Air Pollutants↗

PubMed2006

Guest editorial.

Explore the source record for details and available documents.

Air Pollutants↗

PubMed2006

The modern office environment desiccates the eyes?

Eye irritation is a common complaint in the office environment. The purpose of this overview is to merge knowledge within indoor air science, ophthalmology, and occupational health to promote understanding eye irritation symptomatology, the cause of which is still partly unknown. High periocular relative humidity appears to protect the pre-corneal tear film against desiccation and sensory irritating pollutants and reduces the development of eye irritation symptoms. This is particularly relevant for intensive computer work, where the pre-corneal tear film is altered resulting in dry spot formation and eye dryness, in addition to enhanced susceptibility towards sensory irritating pollutants. The workplace, thermal conditions, and work schedule (including breaks) should be planned in such a way to help maintain a normal eye blink frequency to minimize alterations of the pre-corneal tear film. The role of relative humidity on eye irritation symptoms should not be underestimated. Multiple short breaks are justified by the beneficial effect on the pre-corneal tear film. In addition, longer breaks in tasks, which require demanding visual work, should be considered. In addition, air temperature as well as certain alkene oxidation products by ozone may worsen eye irritation symptoms, but the latter factor may be smaller at higher relative humidity.

Air Pollutants, Occupational↗

PubMed2005

Eye complaints in the office environment: precorneal tear film integrity influenced by eye blinking efficiency.

To achieve a common base for understanding work related eye complaints in the office environment, it is necessary to merge approaches from indoor air science, occupational health, and ophthalmology. Based on database searches, it is concluded that precorneal tear film (PTF) alteration leads to eye complaints that may be caused by: (1) thermal factors (low relative humidity; high room temperature); (2) demanding task content (attention decreases blinking and widens the exposed ocular surface area); and (3) individual characteristics (for example, tear film alterations, blinking anomalies, gland dysfunctions, and use of contact lenses). These factors and conditions are able to progressively increase water evaporation and faster thinning of the PTF, which causes dryness and dry spot formation on the cornea, possibly followed by corneal and conjunctiva epithelial alterations and eye complaints. Another possible cause of eye complaints is certain irritating chemical compounds, in addition to oxidation mixtures that are formed in reactions between ozone and unsaturated organic compounds (alkenes). The effect may be exacerbated by low relative humidity.

Air Pollutants, Occupational↗

PubMed2003

Trends in Europe to reduce the indoor air pollution of VOCs.

A strong research tradition in the European countries about volatile organic compounds (VOCs) and indoor air quality has led to several consensus reports about stategies for VOC measurements including the development of methods to measure VOC emissions from building products. European and Nordic standards have been developed for emission testing including several national and international labeling schemes. Proposals for guidelines for a number of different VOCs have been developed either nationally or by consensus. A compound-by-compound approach for health evaluation of VOCs has become more common and there appears to be a growing recognition to focus on the biologic relevance of organic compounds in indoor air (OCIAs).

Air Pollution, Indoor↗

PubMed2003

Sensory evaluation of emissions from selected building products exposed to ozone.

The interaction of ozone with eight different building products was studied in test chambers. The products were plasterboard, two types of paints on plasterboard, two types of carpet, linoleum, pinewood, and melamine-covered particleboard. Four months of conditioning prior to the experiment had left the products with a low emission. The products' ability to remove ozone from the air covered a wide range. For three of the products (plasterboard with paint, carpet, and pinewood), it was shown that the removal was primarily due to interactions in the products' surfaces and only to a minor extent due to gas-phase reactions. Sensory evaluations were carried out for five of the products, with different ozone-removal potentials. A sensory panel assessed the emissions from sets of two specimens of each product; one specimen was exposed to a high, but realistic, ozone concentration (10 or 80 ppb) and one specimen was exposed to no ozone (background level < 3 ppb). The panel assessed odor intensity and was asked to choose which odor of the two specimens they preferred. The perceivable changes in emissions due to exposure of the products to ozone depended on the type of product. The greatest effect was seen for carpet. Carpet was the only product that showed significantly higher odor intensity when exposed to ozone. Besides, the effect of ozone on preference was strongest for carpet and resulted in a clear negative sensory evaluation. A similar but less pronounced effect was seen for pinewood and plasterboard with paint. No clear preference was seen for melamine and linoleum.

Construction Materials↗

PubMed2001

Determination of ozone removal rates by selected building products using the FLEC emission cell.

Ozone removal by 16 aged (older than 1-120 months) but unused building products or materials was studied in a test system that included the field and laboratory emission cell (FLEC). The ozone removal was studied at 50 +/- 1 ppb ozone, a relative humidity of 50 +/- 5%, a temperature of 21 +/- 2 degrees C, and an air flow rate of 900 +/- 10 mL min(-1) through the FLEC (air velocity ca. 3 cm s(-1)). The ozone removal increased rapidly during the first 1-2 min and either remained at a constant level or decreased asymptotically to reach a steady state-like value. The ozone removal profiles for a given material showed good repeatability during replicate experiments. Ozone deposition velocities for the building products were calculated to be between 0.0007 cm s(-1) (lacquered ash) and 0.8 cm s(-1) (unpainted gypsum board).

Air Movements↗

PubMed2001

Chemical and biological evaluation of a reaction mixture of R-(+)-limonene/ozone: formation of strong airway irritants.

The airway irritation of a reaction mixture of R-(+)-limonene and ozone was evaluated by a mouse bioassay in which sensory irritation, bronchoconstriction and pulmonary irritation were measured. Significant sensory irritation (33% reduction of mean respiratory rate) was observed by dynamic exposure of the mice, during 30 min, to a ca. 16 s old reaction mixture of ozone and limonene. The initial concentrations were nominally 4 ppm O3 and 48 ppm limonene. After reaction, the residual O3 was <0.03 ppm. Conventional analytical chemical methods were used to measure the formation of readily identified and stable products. Besides the expected products, 1-methyl-4-acetylcyclohexene (AMCH), 3-isopropenyl-6-oxoheptanal (IPOH), formaldehyde and formic acid, autooxidation products of limonene and a series of compounds including acetone, acrolein and acetic acid, which may or may not be artefacts, were identified. Addition of the sensory irritation effects of the residual reactants and all the identified compounds could not explain the observed sensory irritation effect. This suggests that one or more strong airway irritants were formed. Since limonene is common in the indoor air, and ozone is infiltrated from outdoors and/or produced indoors (e.g., by photocopiers), such oxidation reactions may be relevant for indoor air quality.

Air Pollution, Indoor↗

PubMed2001

Effect of renovating an office building on occupants' comfort and health.

An intervention study was performed in a mechanically ventilated office building in which there were severe indoor climate complaints among the occupants. In one part of the building a new heating and ventilation strategy was implemented by renovating the HVAC system, and a carpet was replaced with a low-emitting vinyl floor material; the other part of the building was kept unchanged, serving as a control. A comprehensive indoor climate investigation was performed before and after the intervention. Over a 2-week period, the occupants completed a daily questionnaire regarding their comfort and health. Physiological examinations of eyes, nose and lungs were performed on each occupant. Physical, chemical and sensory measurements were performed before and after the intervention. The renewal of the flooring material was performed after a sensory test of alternative solutions in the laboratory. Before the floor material was installed in the office building, a full-scale exposure experiment was performed in the laboratory. The new ventilation strategy and renovation of the HVAC system were selected on the basis of laboratory experiments on a full-scale mock-up of a cellular office. The severity of occupants' environmental perceptions and symptoms was significantly reduced by the intervention.

Air Pollution, Indoor↗

PubMed2001

Formation of strong airway irritants in mixtures of isoprene/ozone and isoprene/ozone/nitrogen dioxide.

We evaluated the airway irritation of isoprene, isoprene/ozone, and isoprene/ozone/nitrogen dioxide mixtures using a mouse bioassay, from which we calculated sensory irritation, bronchial constriction, and pulmonary irritation. We observed significant sensory irritation (approximately 50% reduction of mean respiratory rate) by dynamically exposing the mice, over 30 min, to mixtures of isoprene and O3 or isoprene, O3, and NO2. The starting concentrations were approximately 4 ppm O3 and 500 ppm isoprene (+ approximately 4 ppm NO2. The reaction mixtures after approximately 30 sec contained < 0.2 ppm O3. Addition of the effects of the residual reactants and the identified stable irritant products (formaldehyde, formic acid, acetic acid, methacrolein, and methylvinyl ketone) could explain only partially the observed sensory irritation. This suggests that one or more strong airway irritants were formed. It is thus possible that oxidation reactions of common unsaturated compounds may be relevant for indoor air quality.

Air Pollution, Indoor↗

PubMed2000

Formation of strong airway irritants in terpene/ozone mixtures.

The American Society for Testing and Materials (ASTM) mouse bioassay, which quantifies airway irritation from reduction in the respiratory rate, was used to find evidence for the formation of highly irritating substances in reactions of ozone with terpenes (common indoor volatile organic compounds (VOCs)). No-observed-effect-levels (NOELs) and concentration-effect relationships were established for ozone, (+)-alpha-pinene and R-(+)-limonene, isoprene, and some of their major reaction products. Reaction mixtures of excess terpene and ozone considerably below their NOEL concentrations resulted in significant upper airway irritation. The reduction of the respiratory rate was from 30% to about 50%, lowest for the alpha-pinene and highest for the isoprene mixture. Chemical analysis of reaction mixtures by conventional methods showed that readily identified stable products and residual reactants at the concentrations found could not account for the observed reductions of the respiratory rate, assuming additivity of the reaction products. The results suggest that, in addition to known irritants (formaldehyde, acrolein, methacrolein, methyl vinylketone), one or more strong airway irritant(s) of unknown structure(s) were formed. Future indoor air quality (IAQ) guidelines for unsaturated VOCs (e.g., terpenes) and their emission from building products may require the consideration of reactions with oxidants, like ozone. Similarly, effects of ozone-emitting equipment should be re-evaluated.

Animals↗

PubMed2000

Effects of R-(+)- and S-(-)-limonene on the respiratory tract in mice.

The effects of airborne R-(+)- and S-(-)- limonene were studied in conscious BALB/c mice by continuous monitoring respiratory rate (f), tidal volume (VT) and mid-expiratory flow rate (VD) during an exposure period of 30 min. Both enantiomers decreasedf from a trigeminal reflex, i.e., due to sensory irritation. The exposure concentration decreasing f by 50% (RD50) in the first 10 min of the exposure period was estimated to be 1,076 ppm for R-(+)-limonene and 1,467 ppm for S-(-)-limonene. Results for sensory irritation of R-(+)-limonene in BALB/c mice and humans are in close agreement. The reported sensory irritation threshold is above 80 ppm in humans while the no-observed-effect level was estimated to be 100 ppm in mice. The enantiomers were devoid of pulmonary irritation or general anesthetic effects with R-(+)-limonene < or =1,599 ppm and S-(-)-limonene < or =2,421 ppm. R-(+)-limonene did not influence VT below 629 ppm. S-(-)-limonene increased VT above 1,900 ppm. Both enantiomers induced a mild bronchoconstrictive effect above 1,000 ppm.

Administration, Inhalation↗

PubMed1999

How to measure and evaluate volatile organic compound emissions from building products. A perspective.

The primary emissions of VOCs (e.g. solvents) from building products influence the perceived indoor air quality during the initial decay period. However, secondary emissions will continue thereafter (chemical or physical degradation, e.g. oxidation, hydrolysis, mechanical wear, maintenance), in addition to sorption processes. Emission testing for primary VOC emissions is necessary, but insufficient to characterise the impact of building products in their entire life span on the perceived air quality. Methods to distinguish between the two types of emissions are required. Also, the influence of climate parameters on the emission rates is necessary to know for proper testing. Future product development and selection strategies of new building products should consider the secondary emissions, in addition to the contribution from the use of auxiliary agents for cleaning, maintenance, and other potential impacts either physical or chemical in nature. Some of the requirements for emission testing are discussed in terms of secondary vs. primary emissions in order to develop 'healthier/better' building products for the indoor environment. In addition, some of the assumptions about the possible impact of VOCs on health and comfort in the indoor environment are presented. Odour thresholds for VOCs are one or more orders of magnitude lower than the corresponding airway irritation estimates, and it also appears that chemically non-reactive VOCs are not sufficiently strong irritants to cause airway irritation at concentrations normally encountered indoors. Finally, future requirements for analytical laboratory performances is proposed to accommodate the increasing need to establish which VOCs may be responsible for the perception of odour intensity from building products.

Air Pollution, Indoor↗

PubMed1999

Acute airway effects of formaldehyde and ozone in BALB/c mice.

1. Concentration and time-effect relationships of formaldehyde and ozone on the airways were investigated in BALB/c mice. The effects were obtained by continuous monitoring of the respiratory rate, tidal volume, expiratory flow rate, time of inspiration, time of expiration, and respiratory patterns. 2. With concentrations up to 4 p.p.m., formaldehyde showed mainly sensory irritation effects of the upper airways that decrease the respiratory rate from a trigeminal reflex. The no-effect level (NOEL) was about 0.3 p.p.m. This value is close to the human NOEL, which is about 0.08 p.p.m. 3. Ozone caused rapid, shallow breathing in BALB/c mice. Later on, the respiratory rate decreased due to another vagal response that indicated an incipient lung oedema. The NOEL in mice was about 1 p.p.m. during 30 min of ozone exposure. No major effect occurs in resting humans at about 0.4 p.p.m. 4. Thus, the upper airway irritant, formaldehyde, and the deep lung irritant, ozone, showed the same types of respiratory effects in humans and in BALB/c mice. Also, the sensitivity was nearly identical. Continuous monitoring of respiratory effects in BALB/c mice, therefore, may be a valuable method for the study of effects of other environmental pollutants, which, however, should be confirmed in further studies.

Animals↗

PubMed1998

Risk in cleaning: chemical and physical exposure.

Cleaning is a large enterprise involving a large fraction of the workforce worldwide. A broad spectrum of cleaning agents has been developed to facilitate dust and dirt removal, for disinfection and surface maintenance. The cleaning agents are used in large quantities throughout the world. Although a complex pattern of exposure to cleaning agents and resulting health problems, such as allergies and asthma, are reported among cleaners, only a few surveys of this type of product have been performed. This paper gives a broad introduction to cleaning agents and the impact of cleaning on cleaners, occupants of indoor environments, and the quality of cleaning. Cleaning agents are usually grouped into different product categories according to their technical functions and the purpose of their use (e.g. disinfectants and surface care products). The paper also indicates the adverse health and comfort effects associated with the use of these agents in connection with the cleaning process. The paper identifies disinfectants as the most hazardous group of cleaning agents. Cleaning agents contain evaporative and non-evaporative substances. The major toxicologically significant constituents of the former are volatile organic compounds (VOCs), defined as substances with boiling points in the range of 0 degree C to about 400 degrees C. Although laboratory emission testing has shown many VOCs with quite different time-concentration profiles, few field studies have been carried out measuring the exposure of cleaners. However, both field studies and emission testing indicate that the use of cleaning agents results in a temporal increase in the overall VOC level. This increase may occur during the cleaning process and thus it can enhance the probability of increased short-term exposure of the cleaners. However, the increased levels can also be present after the cleaning and result in an overall increased VOC level that can possibly affect the indoor air quality (IAQ) perceived by occupants. The variety and duration of the emissions depend inter alia on the use of fragrances and high boiling VOCs. Some building materials appear to increase their VOC emission through wet cleaning and thus may affect the IAQ. Particles and dirt contain a great variety of both volatile and non-volatile substances, including allergens. While the volatile fraction can consist of more than 200 different VOCs including formaldehyde, the non-volatile fraction can contain considerable amounts (> 0.5%) of fatty acid salts and tensides (e.g. linear alkyl benzene sulphonates). The level of these substances can be high immediately after the cleaning process, but few studies have been conducted concerning this problem. The substances partly originate from the use of cleaning agents. Both types are suspected to be airway irritants. Cleaning activities generate dust, mostly by resuspension, but other occupant activities may also resuspend dust over longer periods of time. Personal sampling of VOCs and airborne dust gives higher results than stationary sampling. International bodies have proposed air sampling strategies. A variety of field sampling techniques for VOC and surface particle sampling is listed.

Air Pollution, Indoor↗

PubMed1998

Respiratory effects in mice exposed to airborne emissions from Stachybotrys chartarum and implications for risk assessment.

Stachybotrys chartarum, a mycotoxin producing mould found in some damp buildings, was grown in aluminum dishes in closed exposure chambers. The loading factor, 5.12 m2/m3, corresponded to 2.8 times the loading in a normal room with all surfaces covered by mould. Sensory irritation, bronchoconstriction and pulmonary irritation effects were investigated using a sensitive mouse bioassay in which the airway reactions were measured plethysmographically. Little effect was seen from the vapours in agreement with the predicted effects of the low concentrations of volatile organic compounds measured. Even under the influence of an airflow about four times that measured in normal buildings, the concentration of liberated spores and other particles was very low, corresponding to the biological effects observed, and probably reflecting the high water content of the substrate. These results demonstrate that many factors are important for the transport of biologically active mould metabolites from building material to occupants and that no direct relationship may exist between immediate biological effects and surface area covered with mould. Therefore, risk assessments should be based on estimated effects of emitted vapours, effects of liberated particles, e.g. sensitization potentials of the mould spores and effects of the generated metabolites (mycotoxins).

Air Microbiology↗

PubMed1994

Volatile organic compounds and indoor air.

Volatile organic compounds represent one of the two major pollutant categories implicated in the sick-building syndrome. This article reviews measurement and analytic methods, presents a summary of the etiologic considerations, and presents newer, nonregulatory intervention strategies that can be used to prevent complaints resulting from this pollutant category.

Aerosols↗

PubMed1993

Ventilation, CO2 production, and CO2 exposure effects in conscious, restrained CF-1 mice.

Respiratory rate (f), tidal volume (VT) and carbon dioxide production (VECO2) were measured in restrained, conscious CF-1 mice. Mean f +/- S.D. and mean VT +/- S.D. were 270 +/- 8 breaths/min. and 0.123 +/- 0.024 ml (STPD) for male, and 274 +/- 15 breaths/min. and 0.115 +/- 0.023 ml (STPD) for female mice, respectively. VECO2 was obtained from a rebreathing (closed loop) system. The maximum VECO2 (STPD) amounted to 95.5 +/- 15.4 ml/(kg min.) in males and to 72.7 +/- 4.2 ml/(kg min.) in females. The CO2 concentration in the closed loop system increased slowly during a 30 min. rebreathing period and reached a concentration of about 2.7%. No effect was seen on f and on VT. Dynamic (abrupt) exposure up to 10.3% CO2 had no effect on f in male mice, whereas VT increased from 112% (2.3% CO2) to 181% (10.3% CO2). The estimated O2 concentrations decreased from 20.5% to 18.7% with increasing CO2 exposure. The equivalent CO2 experiments with O2 kept at 16% by N2 administration showed that the lower O2 concentration added an additional drive on the respiratory centre.

Animals↗