Airborne Chemicals Research Articles

Sensory irritation structure-activity study of inhaled aldehydes in B6C3F1 and Swiss-Webster mice

The sensory irritation potential of a series of saturated and unsaturated aliphatic and cyclic aldehydes was investigated in B6C3F1 and Swiss-Webster mice. With the reflex decrease in respiratory rate as the endpoint response, α,β-unsaturated aliphatic aldehydes yielded RD50 values (concentration which elicits a 50% decrease in respiratory rate) ranging from 1 to 5 ppm while saturated aliphatic aldehydes with two or more carbons produced RD50 values from 750 to 4200 ppm. Cyclic aldehydes produced intermediate RD50 values which ranged from 60 to 400 ppm. No statistically significant differences were found between concentration-response curves of B6C3F1 and Swiss-Webster mice. Saturated aliphatic aldehydes with two or more carbons were nearly 1000 times less potent than formaldehyde. Although the mechanisms responsible for stimulation of trigeminal nerve endings by airborne chemicals are poorly understood, several hypotheses may help to explain the differences seen in this study. For example, the sensory irritation potency of the saturated aliphatic aldehydes diminished with their reported dehydration constants which may determine the degree to which these aldehydes crosslink with receptor proteins. The sensory irritation potency of acrolein and crotonaldehyde was probably due to 1,2 or 1,4 addition reactions. Additionally, molecular conformation and a recently published physical mechanism may contribute to sensory irritation responses, particularly for the less reactive aldehydes. Tentative threshold limit values (TLVs), based upon prevention of sensory irritation, were extrapolated from the RD50 values of Swiss-Webster mice. With the exception of crotonaldehyde, good agreement was found with currently published TLVs.

Exposure of Embalmers to Formaldehyde and Other Chemicals

Seven funeral homes were surveyed in 1980 to determine the magnitude of embalmers' exposure to formaldehyde, other chemical vapors, and total and respirable particulates. Air was monitored for formaldehyde by personal and area samples, and assayed using the chromotropic acid method. Personal sampling revealed time-weighted average formaldehyde concentrations which ranged from 0.1 to 0.4 ppm (mean 0.3 ppm) and 0.5 to 1.2 ppm (mean 0.9 ppm) during the embalming of intact and autopsied bodies, respectively. Concentrations of other airborne chemicals and of particulates were negligible. In preparing autopsied bodies, embalming technique and condition of the body itself appeared to be major determinants of formaldehyde exposure.

Sensory irritation tolerance development to chlorine in F-344 rats following repeated inhalation

Upper respiratory tract irritation (sensory irritation) by airborne chemicals in animals causes a decrease in respiratory rate with no compensatory increase in tidal volume. This condition is an important respiratory tract defense mechanism. The purpose of this investigation was to determine whether sensory irritation tolerance would develop in F-344 rats following repeated Cl 2 inhalation. Male, F-344 rats were divided into four groups (40 to 50 animals/group) and exposed to 0, 1, 5, or 10 ppm Cl 2, 6 hr/day, 5 days/week for 2 weeks. Sensory irritation was quantified 16 to 24 hr following the last day of Cl 2 pretreatment by measuring respiratory rate depression during exposure of groups of three to four animals for 10 min to various Cl 2 concentrations (1 to 760 ppm). Concentration-response curves were compared to the curve obtained from rats receiving no pretreatment (naive group). Tolerance was seen after all Cl 2 pretreatments and was greatest in the 10-ppm group. When compared to the non-pretreated group, all Cl 2-pretreated rats had concentration-response curves with decreased slopes demonstrating increasing tolerance with increasing Cl 2 challenge concentration. The concentration of Cl 2 needed to elicit a reflex decrease in respiratory rate of 50% (RD 50) was 25 ppm in non-pretreated rats whereas Cl 2 pretreatments of 1, 5, or 10 ppm increased the RD 50 values to 90, 71, and 454 ppm, respectively. Tolerance development to sensory irritation is important because an organism's ability to perceive the presence or lung damaging concentrations of irritants may be compromised. Since the current threshold limit value for Cl 2 is 1 ppm, indications of tolerance development of rats exposed to Cl 2 at 1 ppm may be relevant to humans exposed repeatedly to this concentration.

Dose-response analysis in animal studies: prediction of human responses.

An animal bioassay has been used to evaluate a series of airborne chemicals for their sensory irritating properties to the upper respiratory tract. Teh results obtained can be used to rank their potency. An attempt has been made to predict "safe" levels of exposure for humans on the basis of this short-term assay. A good correlation was obtained between the predicted "safe" levels of exposure and current Threshold Limit Values established for industrial exposures.

Sensory irritation caused by various industrial airborne chemicals

A short inhalation experiment was performed on mice using 22 industrial airborne irritants. The parameter chosen as an index of sensory irritation was the reflex decrease in respiratory rate. For each compound, systematic determination of the concentration associated with a 50% decrease in the respiratory rate (RD5o) permitted, on the basis of the same end point, a comparison of their relative potencies. The possibility of using the obtained data as initial guidelines to establish acceptable Threshold Limit Values (TLVs) in the workplace was examined.

Effects of gaster extract trail concentration on the trail following behaviour of the Argentine ant, Iridomyrmex humilis (Mayr)

In the Argentine ant, optimum trail following to gaster extracts was displayed to 0.1 and 1.0 equivalents/50 cm of circular trail. Trail following to airborne components was demonstrated when ants exhibited normal trail following behaviour while walking 3 or 6 mm below a 0.1 ant equivalent trail. However, at 8 or 12 mm separation, following ceased, indicating that the height of the active space was ca. 6–8 mm. The average horizontal distance from the centre of the trail at which ants exhibited following behaviour increased with concentration to 3–4 mm beyond the applied trail boundaries, indicating both an ability to follow airborne chemicals, and possibly a non-tolerance of excessively high concentration. Activity of 0.1 ant equivalent trails on filter paper declined to about half the original level by four hours; after eight hours, responses were significantly different from, but almost as low as, solvent controls.

Chemical modulation of alveolar epithelial permeability.

The volume and composition of fluid on the surface of the alveoli can affect alveolar ventilation, gas diffusion, and macrophage function. The passive permeability and active processes of the alveolar epithelial lining play a role in regulating surface fluid and are a potential site of damage by airborne chemicals. Like other epithelial barriers, the alveolar lining is permeable to lipophilic substances but restricts the transmural flow of small ions and hydrophilic nonelectrolytes (equivalent pore radius ca. 0.5-1.5 nm). The mammalian fetal lung and alveolar sacs of the adult bullfrog secrete Cl- and K+ into the airspace. Secretion by the fetal lung ceases at birth. Many environmental agents increase the permeability of the capillary endothelium and/or respiratory epithelium and induce pulmonary edema. Studies with bullfrog alveolar sacs have demonstrated that selective effects may or may not be followed by general derangement of the epithelial barrier. Exposure of the luminal surface to HgCl2 (10(-6) to 10(-4) M) induces a selective increase in Cl- secretion that is followed by a fall in transport and a general increase in ion permeation. CdCl2 (10(-5) to 10(-3) M) depresses ciliomotion on cells on the trabecula of the alveolus but does not affect Cl- secretion or transepithelial conductance. HNO3, like other mineral acids, increases conductance and the radii or pores in the barrier, whereas NaNO3 selectively inhibits Cl- secretion. Amphotericin B(10(7) to 10(-5) MJ) induces K+ secretion into the lumen of both bullfrog and rat lung. We conclude that environmental agents induce changes in epithelial function that may compromise the lung's ability to regulate respiratory fluid without destroying the characteristic permeability of the epithelial lining.

Chemical Modulation of Alveolar Epithelial Permeability

The volume and composition of fluid on the surface of the alveoli can affect alveolar ventilation, gas diffusion, and macrophage function. The passive permeability and active processes of the alveolar epithelial lining play a role in regulating surface fluid and are a potential site of damage by airborne chemicals. Like other epithelial barriers, the alveolar lining is permeable to lipophilic substances but restricts the transmural flow of small ions and hydrophilic nonelectrolytes (equivalent pore radius ca. 0.5-1.5 nm). The mammalian fetal lung and alveolar sacs of the adult bullfrog secrete Cl- and K+ into the airspace. Secretion by the fetal lung ceases at birth. Many environmental agents increase the permeability of the capillary endothelium and/or respiratory epithelium and induce pulmonary edema. Studies with bullfrog alveolar sacs have demonstrated that selective effects may or may not be followed by general derangement of the epithelial barrier. Exposure of the luminal surface to HgCl2 (10(-6) to 10(-4) M) induces a selective increase in Cl- secretion that is followed by a fall in transport and a general increase in ion permeation. CdCl2 (10(-5) to 10(-3) M) depresses ciliomotion on cells on the trabecula of the alveolus but does not affect Cl- secretion or transepithelial conductance. HNO3, like other mineral acids, increases conductance and the radii or pores in the barrier, whereas NaNO3 selectively inhibits Cl- secretion. Amphotericin B(10(7) to 10(-5) MJ) induces K+ secretion into the lumen of both bullfrog and rat lung. We conclude that environmental agents induce changes in epithelial function that may compromise the lung's ability to regulate respiratory fluid without destroying the characteristic permeability of the epithelial lining.

NH 3 concentrations in the expired air of the rat: Importance to inhalation toxicology

Endogenously produced ammonia (NH 3) has been quantitated in the expired air of dogs and humans but data for rodents are not available. NH 3 in expired air may have importance in toxicology studies with inhaled gases, vapors, or aerosols because of its ability to form secondary reaction products. Depending upon the reaction product(s) formed, the toxicity of an airborne agent may be increased or decreased. The objective of this study was to quantitate NH 3 in the expired air of unanesthetized Fischer-344 rats, a species commonly used in inhalation toxicity studies. Whole body plethysmography and an indophenol, colorimetric assay were used to quantitate breath NH 3. Concentrations of NH 3 ranged from 10 to 353 ppb ( x = 78 ppb ) in nose-breathing animals and 34 to 744 ppb ( x = 286 ppb ) in tracheal cannulated animals. These differences were attributed to the absorptive effect of the moist, upper respiratory tract in nose-breathers which was absent in animals with tracheal cannulas. These results compared favorably with published reports using larger species. The presence of NH 3 in the expired air of the rat suggests that reaction products may be formed with a variety of airborne chemicals. This may be particularly significant in low-level, chronic inhalation studies.

Effects of Early Feeding Experience on Chemical Preference of the Northern Water Snake, Natrix s. sipedon (Reptilia, Serpentes, Colubridae)

Motion picture analyses of tongue flicking behavior by 15 neonate northern watersnakes (Natrix s. sipedon) to chemical extracts were used to investigate possible evidence for: (1) increased tongue flicking to air-borne chemicals; (2) modificaton of chemical preference by early feeding experience; (3) a relationship between the number of tongue flicks per extract and the mean flick duration. A novel technique for presenting only air-borne chemical extracts without any visual cue indicated more tongue flicking by s. sipedon to air-borne odors of frog extract than to a distilled water control. Early feeding experience had no effect on subsequent chemical preference. Natrix s. sipedon demonstrated a preference for extracts from a sympatric species of frog (Rana sylvatica) but not for extracts from a nonsympatric species of fish (Gambusia affinis), regardless of being fed exclusively on either this species of frog or fish or on earthworm (Lumbricus terrestris). This finding supports the hypothesis that newborn snakes show innate preference for sympatric species of normally eaten prey, and further suggests that this preference predominates over the effect of early feeding. A significant correlation between increasing number of tongue flicks and increasing mean flick duration was found only for presentations of distilled water. A relationship between increased number of tongue flicks and longer flick duration for preferred odors may be masked, since these

Sensory Irritation and Incapacitation Evoked by Thermal Decomposition Products of Polymers and Comparisons with Known Sensory Irritants

A decrease in respiratory rate in mice during exposure to irritating airborne chemicals has been utilized as a response parameter to characterize the degree of upper respiratory tract irritation (sensory irritation) to the thermal decomposition products of various polymers. These included polystyrene, polyvinyl chloride, flexible polyurethane foam, polytetrafluorethylene, a fiber glass reinforced polyester resin, and Douglas Fir. Each of the materials was thermally decomposed in a low-mass vertical furnace in an air atmosphere at a programmed heating rate of 20 degrees C/min. Mice, in groups of four, were exposed to graded concentrations of the thermal decomposition products of each of the above materials. Dose-response curves were obtained by utilizing the maximum percent decrease in respiratory rate as the response parameter during each exposure. Comparison of these dose-response curves with other sensory irritants such as chlorine, ammonia, hydrogen chloride, sulfur dioxide, and toluene diisocyanate gave an indication of the sensory irrtation potential of the thermal decomposition products of these various polymers versus that of well-known single airborne chemical irritants. Total stress and incapacitation of the organism during exposure to sensory irritants such as from the thermal decomposition products of synthetic polymers is discussed.

Sensory irritation evoked by the thermal decomposition products of plasticized poly(vinyl chloride)

AbstractA decrease in respiratory rate in mice during exposure to irritating airborne chemicals has been utilized as a response parameter to characterize the degree of upper respiratory tract irritation (sensory irritation) to the thermal decomposition products of plasticized poly(vinyl chloride). The plasticized poly(vinyl chloride) was placed in a low mass vertical furnace and thermally decomposed in an air atmosphere at a programmed heating rate of 20°C min−1. The thermogravimetric study of the plasticized poly(vinyl chloride) demonstrated that two distinct weight loss fractions occurred during the decomposition process. Groups of four male swiss‐webster mice were exposed to the thermal decomposition products of the first weight loss fraction in the range 0.03–0.77 mg l−1 and to the second weight loss fraction in the range 0.03–0.38 mg l−1. Dose‐response curves were plotted by utilizing the maximum percent decrease in respiratory rate during each exposure as the response parameter. Comparison of these curves to a dose‐response curve for hydrogen chloride showed that both the first and second weight loss fraction of plasticized poly(vinyl chloride) were more potent than hydrogen chloride in terms of sensory irritation. From these dose‐response relationships qualitative and quantitative predictions of human responses to the thermal decomposition products of plasticized.

Tobacco Budworm:1 Male Pheromone Suppressed Emission of Sex Pheromone by the Female2

Bioassays in 12×17×3-m field cages showed an airborne chemical was released from the hairpencils of the male Heliothis virescens (F.) before mating. When receptors on the female antennae detected the pheromone during courtship, release of female sex pheromone ceased. Emission of the female sex pheromone was effectively terminated if the females were exposed to 50 male equivalents of hairpencil extract or to untreated 2-day-old (virgin) male tobacco budworms. Extracts of hairpencils made with ethyl ether were almost as effective as live males, but extracts made with carbon disulfide did not successfully suppress the production of the sex pheromone.

Evidence for downwind flights by host-seeking mosquitoes

THE behaviour of flying insects which make use of airborne chemicals in their search for food, oviposition sites or sexual partners can be separated into two phases, the search flight bringing them into contact with the attractant plume and the approach flight leading them to its source1,2. The second phase is characterised by upwind orientation in response to the appropriate chemical stimuli3–6. Mosquitoes are known to fly upwind as they approach a warm-blooded host7–9. For most insects relatively little is known of the pattern of the preceding search flight which Haskell2 described as ‘wandering’, but where the wind is light it may be upwind1. Experiments in West Africa have shown that the majority of mosquitoes entered flight traps from the downwind side, that is they appeared to have been flying upwind, regardless of the presence or absence of a host (ref. 10 and W. F. Snow, unpublished). Here we report experiments that unexpectedly provide evidence for the opposite type of behaviour.

The State-of-the-Art of Measuring and Predicting Cooling Tower Drift and Its Deposition

One of the key elements in estimating the environmental effects associated with the deposition of airborne chemicals and, in particular, salt particles from cooling towers is the drift rate. Eight different experimental methods are currently employed to determine the drift rate from cooling towers. The difficulties associated with the various techniques vary from case to case, but they are mainly associated with collecting a representative sample, maintaining undisturbed air flow, determining the collection efficiency of the various sampling techniques and analyzing the samples for particle size. Several approaches have been taken to predict the deposition of salt water drift droplets on ground surfaces. Some use a simple analogy with the deposition of industrial dust, others use a combination of plume rise theories in conjunction with the Gaussian diffusion model to predict the air concentration of water droplets from which the ground deposition is then calculated. Other methods calculate the trajectorie...

Sensory irritation of the upper airways by airborne chemicals

Twenty-seven chemicals all containing the >CC< group have been tested for their potential sensory irritation properties to the upper respiratory tract when administered in an aerosol form to mice. An analytical model for the data is suggested for comparison of the activity of these compounds, and the essential molecular features for sensory irritant activity in these compounds are delineated. Correlation between the biological and chemical reactivity data suggests that these compounds initiate the sensory irritation reaction by associating with SH groups of a receptor molecule on the free nerve endings of the afferent trigeminal which are located at the surface of the nasal mucosa.

Sensory irritation by airborne chemicals.

(1973). Sensory Irritation by Airborne Chemicals. CRC Critical Reviews in Toxicology: Vol. 2, No. 3, pp. 299-363.

Toxicity of airborne chemicals: air quality standards--a national and international view.

Past reviews in this annual appearing under the broad title Toxicology have dealt respectively with selected organic and organometallic substances (1) l selected inorganic substances of both industrial and environmental concern (2), and Soviet toxicology, induding their general principles for establishing tolerance limits for environmental chemicals and their toxico­ logic methods of handling complex environmental problems (3). The pres­ ent review will provide (a) a critical comparison of the philosophic bases of the American and Soviet air quality standards accounting for the intercoun­ try differences in the limits of certain substances, (b) a critical discussion of the scientific background (criteria) of the air quality standards of a half-dozen of those airborne substances of greatest present-day concern for human exposures in both in-plant and urban communities in the USA, and ( c ) a presentation of the reasons for differences in the limits of the air qual­ ity standards for the two .

Those Airborne Chemicals

Those Airborne Chemicals

Cheilitis glandularis apostematosa

1. 1. Cases of three patients suffering from cheilitis glandularis apostematosa are presented. 2. 2. This chronic condition consists of a syndrome of (a) a disfiguring enlargement and ectropion of the lower lip, with certain changes in both the epithelium and the lamina propria of the mucosa of the vermilion zone; (b) a hyperplasia of the labial mucous glands; and (c) an enlargement and inflammation of the excretory ducts of these glands. 3. 3. Case histories and clinical and histologic examinations seem to indicate that this anomaly is due primarily to chronic chapping, scarring, and subsequent eversion of the lower lip. The ectropion, in turn, is followed by irritation of the exposed vestibular lip mucosa from the drying effect of the air, from actinic rays, air-borne chemicals, and, probably, the repeated contact of this tissue with saliva saturated with tobacco juice. 4. 4. Roentgen therapy and excision of the lesion have been advocated in the treatment of this condition, 8 but no consistently successful therapy is known. 13 In view of the absence of any complaint on the part of our patients, we recommended to them the use of a good lip pomade and asked them to stop using tobacco.