Sensory Irritation Research Articles

Exposure study to examine chemosensory effects of formaldehyde on hyposensitive and hypersensitive males

Main objective of this study was to examine the chemosensory effects of formaldehyde on hyposensitive and hypersensitive males at concentrations relevant to the workplace. Attention focused on objective effects on and subjective symptoms of the mucous membranes of the eyes, the nose, the upper respiratory tract and olfactory function. Forty-one male volunteers were exposed for 5 days (4 h per day) in a randomised schedule to the control condition (0 ppm) and to formaldehyde concentrations of 0.5 and 0.7 ppm and to 0.3 ppm with peak exposures of 0.6 ppm, and to 0.4 ppm with peak exposures of 0.8 ppm, respectively. Peak exposures were carried out four times a day over a 15-min period of time. Subjective pain perception induced by nasal application of carbon dioxide served as indicator for sensitivity to sensory nasal irritation. The following parameters were examined before and after exposure: subjective rating of symptoms and complaints (Swedish Performance Evaluation System), conjunctival redness, eye-blinking frequency, self-reported tear film break-up time and nasal flow rates. In addition, the influence of personality factors on the volunteer's subjective scoring was examined (Positive And Negative Affect Schedule). Formaldehyde exposures to 0.7 ppm for 4 h and to 0.4 ppm for 4 h with peaks of 0.8 ppm for 15 min caused no significant sensory irritation of the measured conjunctival and nasal parameters. No differences between hypo- and hypersensitive subjects were seen. Nevertheless, statistically significant differences were noted for olfactory symptoms, especially for the 'perception of impure air'. These subjective complaints were more pronounced in hypersensitive subjects. Formaldehyde concentrations of 0.7 ppm for 4 h and of 0.4 ppm for 4 h with peaks of 0.8 ppm for 15 min did not cause adverse effects related to irritation, and no differences between hypo- and hypersensitive subjects were observed.

Determination of descriptors for fragrance compounds by gas chromatography and liquid–liquid partition

Retention factors on a minimum of eight stationary phases at various temperatures by gas–liquid chromatography and liquid–liquid partition coefficients for five totally organic biphasic systems were combined to estimate descriptors for 28 fragrance compounds with an emphasis on compounds that are known or potential allergens. The descriptors facilitated the estimation of several properties of biological and environmental interest (sensory irritation threshold, odor detection threshold, nasal pungency threshold, skin permeability from water, skin–water partition coefficients, octanol–water partition coefficients, absorption by air particles, adsorption by diesel soot particles, air–water partition coefficients, and adsorption by film water). The descriptors are suitable for use in the solvation parameter model and facilitate the estimation of a wide range of physicochemical, chromatographic, biological, and environmental properties using existing models.

Investigation of the urge‐to‐cough sensation in healthy volunteers

Recently, there has been interest in the sensation of irritation that precedes the motor act of coughing, which has been termed the urge-to-cough (UTC). The aim of this study was to perform the largest evaluation to date of the UTC threshold (C(u)) in a healthy population. The specific aims were to investigate the relationship between C(u) and cough reflex sensitivity, to evaluate gender differences in the UTC and to assess the reproducibility of measurements of C(u). Standard capsaicin cough challenge methodology was employed to measure cough reflex sensitivity in 100 healthy adult non-smokers (50 females) with the additional measurement of C(u). A subgroup of 40 subjects (20 males) underwent repeat cough challenges after 1 week to examine the reproducibility of the measurements. All 100 subjects demonstrated motor cough in response to capsaicin. Twenty-one subjects (10 females) did not show a discernible C(u), as the motor cough event preceded a UTC sensation unaccompanied by cough. Although cough reflex sensitivity, as measured by the concentration of capsaicin inducing five or more coughs (C(5)), was enhanced in women, there was no gender difference in C(u). Similar to standard cough reflex sensitivity measurements, the measurement of C(u) was highly reproducible. These results demonstrate that the UTC threshold can be effectively and reproducibly measured using a modification of standard cough challenge methodology. Given its clinical significance as a prevalent symptom, UTC, as measured by C(u), represents an additional relevant end point for studies investigating the effects of pharmacological and other interventions in cough and cough reflex sensitivity.

1,8-Cineole, a TRPM8 Agonist, is a Novel Natural Antagonist of Human TRPA1

BackgroundEssential oils are often used in alternative medicine as analgesic and anti-inflammatory remedies. However, the specific compounds that confer the effects of essential oils and the molecular mechanisms are largely unknown. TRPM8 is a thermosensitive receptor that detects cool temperatures and menthol whereas TRPA1 is a sensor of noxious cold. Ideally, an effective analgesic compound would activate TRPM8 and inhibit TRPA1.ResultsWe screened essential oils and fragrance chemicals showing a high ratio of human TRPM8-activating ability versus human TRPA1-activating ability using a Ca2+-imaging method, and identified 1,8-cineole in eucalyptus oil as particularly effective. Patch-clamp experiments confirmed that 1,8-cineole evoked inward currents in HEK293T cells expressing human TRPM8, but not human TRPA1. In addition, 1,8-cineole inhibited human TRPA1 currents activated by allyl isothiocyanate, menthol, fulfenamic acid or octanol in a dose-dependent manner. Furthermore, in vivo sensory irritation tests showed that 1,8-cineole conferred an analgesic effect on sensory irritation produced by TRPA1 agonists octanol and menthol. Surprisingly, 1,4-cineole, which is structurally similar and also present in eucalyptus oil, activated both human TRPM8 and human TRPA1.Conclusions1,8-cineole is a rare natural antagonist of human TRPA1 that has analgesic and anti-inflammatory effects possibly due to its inhibition of TRPA1.

Smoking in Andrology: State of Art

Andrology (from Greek andros, man; and -λογία, -logia) is a medical specialty that deals with male health, particularly related to the problems of the male reproductive system and urological problems that are unique to men. However, the scope and mission of Andrology is expanded from being traditionally concerned with issues related to male infertility, erectile dysfunction and prostate diseases in the past to broader interests in wide aspects related to male reproductive health and male health in general. A matter of concern in science as well as experience is smoking as an andrologically related issue. Actually, despite worldwide anti- smoking campaigns, cigarette smoking is rather common with strong evidences that smoking behavior is related to social factors, particularly the influence of parents and peer groups. Taste and smell also influence the inclination to smoke where exciting sensory organs in the lips, mouth and throat provide sensations of touch, taste and irritation. Also, it has been suggested that high negative mood variability is a risk factor for future smoking escalation and that its mood-stabilizing effects may reinforce and maintain daily cigarette use among youths. Strong body of evidence has indicated the negative effect of cigarette smoking on male fertility affecting every system involved in the reproductive process. Different articles have demonstrated a negative impact of smoking on human semen parameters, correlated with cigarettes intensity and duration. Most articles argued that smokers demonstrate lower semen volume, sperm count, sperm motility, sperm viability and normal sperm morphology compared with non-smokers. In addition, they experience increased seminal leukocytes, oval sperm percentage, spermatozoa with cytoplasmic droplets, apoptotic markers, seminal lead and seminal cadmium. In addition, passive exposure to environmental tobacco smoke has been shown to result in measurable seminal nicotine and cotinine levels correlated with the degree of the reported exposure. Meanwhile, the combination of smoking and varicocele has been shown to be strongly related to the incidence of oligozoospermia having an incidence 10 times greater than non- smokers with varicocele and 5 times greater than smokers devoid of varicocele (1-3). On the other hand, many opinions were raised to deny that affection on male infertility where millions of smokers are fathers. However, although smokers as a group may not experience reduced fertility, males with marginal semen quality may benefit from quitting smoking. Also, smokers should quit smoking for the sense of responsibility for their future generation as tobacco smoke contains numerous mutagenic substances. Nevertheless, while it is clear that Erectile Dysfunction (ED) is multi-factorial, the direct and negative effects of smoking on erectile function are well documented where several epidemiological studies demonstrated that smoking or even chronic passive smoking not only increases the risk of ED, but also amplifies its risk associated with other risk factors as hypertension, diabetes, dyslipidaemia or aging. Cigarette smoking-induced ED in human or animal models has been associated with impaired arterial flow to the penis, acute vasospasm of penile arteries, decreased synthesis/availability of nitric oxide leading to endothelial damage with architectural and functional changes, oxidative damage to endothelial cells, increased production of cyclooxygenase dependent and independent vasoconstrictor eicosanoids, activated Rho-associated kinase activity and vascular stiffness. Another interesting aspect that should be considered is the association between smoking and decreased testosterone that plays a major role in men's sexual function, libido and cGMP formation, through nitric oxide synthase stimulation/catabolism through phosphodiesterase-5 activity. Although cessation of cigarette smoking can improve ED in a considerable proportion of smokers, age and severity of ED before cessation are inversely related to the chance of improvement. Prevention of smoking represents a very important approach for reducing the risk of ED.

Airway effects of repeated exposures to ozone-initiated limonene oxidation products as model of indoor air mixtures

Repeated low-level indoor air exposure to volatile organic compounds (VOCs) may influence the reporting of sensory irritation in the eyes and airways. The ozone-initiated reaction products of limonene, an abundant VOC, were used as a model of indoor air mixtures to study upper airway (sensory) irritation, bronchoconstrictive and alveolar level effects after repeated exposures. Mice were exposed 1h/day for 10 consecutive days to: air, limonene (52ppm/289mg/m3); ozone (0.1ppm/0.2mg/m3); a reaction mixture of limonene (52±8ppm) and ozone (0.5, 2.5 and 3.9ppm) resulting in ∼0.05ppm residual ozone. Neither the limonene nor the ozone exposures alone showed consistent effects on the respiratory parameters. In the limonene/ozone groups, the respiratory rate decreased concentration-dependently with an extrapolated no-effect-level of ∼0.3ppm admixed ozone. Both sensory irritation and airflow limitation were conspicuous effects of the mixtures; sensory irritation appeared rapidly and airflow limitation developed slowly during each exposure. The effects of these parameters did not change with increasing number of exposures. No firm conclusion could be drawn about alveolar level effects. Cells in bronchoalveolar lavage were unchanged irrespective of exposure to air, ozone, and limonene with and without ozone. In conclusion, the study indicated that repeated exposures to ozone-initiated limonene mixtures did not cause sensitization of sensory irritation and airflow limitation. Bronchoalveolar lavage after exposures to ozone, and limonene with and without ozone, respectively, did not show airway inflammation.

A Bisensory Method for Odor and Irritation Detection of Formaldehyde and Pyridine

A bisensory method was developed for determining the psychometric functions and absolute thresholds for odor and sensory irritation of two odorous irritants. Individual and group thresholds for formaldehyde or pyridine were measured for 31 age-matched subjects (18–35 years old). P 50 absolute thresholds were for formaldehyde odor 110 ppb (range 23–505), for pyridine odor 77 ppb (range 20–613), and for pyridine irritation 620 ppb (range 90–3,656); too few subjects’ formaldehyde irritation thresholds were possible to determine (human exposures limited to 1 ppm). In spite of large interindividual differences, all thresholds for irritation were higher than for odor. The average slopes of the 62 psychometric functions for odor and the 32 possible for sensory irritation were highest for formaldehyde odor (83% per log ppb) and equal for pyridine odor and irritation (68% per log ppb). The bisensory method for measuring odor and sensory irritation jointly produced detection functions and absolute thresholds compatible with those earlier published; however, a steeper slope for sensory irritation than odor was expected for pyridine. The bisensory method is intended for measuring odor and sensory irritation to broadband mixtures and dynamic exposures, like indoor air.

Dryer Vents: An Overlooked Source of Pollution?

Dryer Vents: An Overlooked Source of Pollution?

Acute airway irritation of methyl formate in mice

Methyl formate (MF) is a volatile solvent with several industrial applications. The acute airway effects of MF were evaluated in a mouse bioassay, allowing the assessment of sensory irritation of the upper airways, airflow limitation of the conducting airways and deep lung (pulmonary) irritation. MF was studied at vapour concentrations of 202–1,168 ppm. Sensory irritation was the only effect observed, which developed slowly over the 30-min exposure period. The potency at steady state was at least 10-fold higher than expected from a hypothetically similar, but non-reactive compound. Methyl formate may be hydrolysed in vivo to formic acid, a potent sensory irritant, and methanol, a low-potent sensory irritant. Hydrolysis may be catalysed by carboxyesterases, and therefore, the role of the esterases was studied using the esterase inhibitor tri-ortho-cresyl phosphate (TOCP). TOCP pre-treatment reduced the irritation response of MF, suggesting that carboxyesterase-mediated hydrolysis plays a role in the irritative effect. However, even after administration of TOCP, MF was considerably more irritating than expected from a quantitative structure–activity relationship (QSAR) model. The slope of the concentration–effect relationship for formic acid was lower than that for the MF in the low-dose range, suggesting that different receptor activation mechanisms may occur, which may include an effect of MF itself, in addition to an effect of formic acid and potentially an effect from formaldehyde.

Sensory irritations and pulmonary effects in human volunteers following short-term exposure to pinewood emissions

Pinewood (Pinus ssp.) is widely used for furniture and building purposes. However, despite its widespread use, information on possible human sensory irritations and pulmonary effects caused by exposure to volatile organic compounds (VOC) emitted from pinewood is sparse. For this purpose, (1) sensory irritation of eyes, nose and throat, (2) lung function parameters (FVC, FEV1), (3) exhaled nitrogen oxide (NO) concentration, (4) eye blink frequency, and (5) sensory evaluation (using the SD method) were investigated before, after, and partly during exposure of human volunteers to emissions from pinewood panels. Fifteen healthy nonsmokers were exposed for 2 h under controlled conditions to VOCs emitted from pinewood panels in a 48 m3 test chamber. VOC concentrations were about 5 mg/ m3 (loading rate, 1 m2/m3), 8 mg/m3 (loading rate, 2 m2/m3), and 13 mg/m3 (loading rate, 3 m2/m3), respectively. Terpene and aldehyde exposure concentrations ranged from about 3.50 ± 0.51 mg/m3 and 0.07 ± 0.008 mg/m3, 5.00 ± 0.95 mg/ m3, and 0.20 ± 0.02 mg/m3 or 9.51 ± 1.10 mg/m3 and 0.21 ± 0.04 mg/m3 for loading rates of 1, 2, and 3 m2/m3, respectively. The emissions consisted predominantly of α-pinene and δ3-carene. No concentration-dependent effects before or after exposure to the emissions were measured with respect to sensory irritation, pulmonary function, exhaled NO, and eye blink frequency. Only the odor of the emissions was perceived by the study subjects, rated as being closer to “pleasant” than to “unpleasant.” In conclusion, the results of our study suggest that short-term exposure to high VOC concentrations, even up to 13 mg/m3, released from pinewood does not elicit sensory irritation or pulmonary effects in healthy humans under controlled conditions.

Menthol attenuates respiratory irritation responses to multiple cigarette smoke irritants

Menthol, the cooling agent in peppermint, is added to almost all commercially available cigarettes. Menthol stimulates olfactory sensations, and interacts with transient receptor potential melastatin 8 (TRPM8) ion channels in cold-sensitive sensory neurons, and transient receptor potential ankyrin 1 (TRPA1), an irritant-sensing channel. It is highly controversial whether menthol in cigarette smoke exerts pharmacological actions affecting smoking behavior. Using plethysmography, we investigated the effects of menthol on the respiratory sensory irritation response in mice elicited by smoke irritants (acrolein, acetic acid, and cyclohexanone). Menthol, at a concentration (16 ppm) lower than in smoke of mentholated cigarettes, immediately abolished the irritation response to acrolein, an agonist of TRPA1, as did eucalyptol (460 ppm), another TRPM8 agonist. Menthol's effects were reversed by a TRPM8 antagonist, AMTB. Menthol's effects were not specific to acrolein, as menthol also attenuated irritation responses to acetic acid, and cyclohexanone, an agonist of the capsaicin receptor, TRPV1. Menthol was efficiently absorbed in the respiratory tract, reaching local concentrations sufficient for activation of sensory TRP channels. These experiments demonstrate that menthol and eucalyptol, through activation of TRPM8, act as potent counterirritants against a broad spectrum of smoke constituents. Through suppression of respiratory irritation, menthol may facilitate smoke inhalation and promote nicotine addiction and smoking-related morbidities.

Combination effects of cosmetic moisturisers in the topical treatment of acne vulgaris

Cosmetic moisturisers were applied to one side of the face of 18 male Japanese patients with acne vulgaris who were treated with a topical administration of adapalene and clindamycin phosphate gels. We assessed the alleviating effect of the moisturisers on the side effects of the treatment. The severity of acne and the number of inflammatory and non-inflammatory lesions were measured at 0, 2, and 4 weeks. The water content in the stratum corneum and transepidermal water loss were measured by comparing the moisturiser-treated and untreated sides of the face. The sensation of skin dryness and irritation on both sides of the face were assessed by the subjects. We observed that the use of moisturisers did not impact the efficacy of the standard topical treatment and they significantly improved the water content in the stratum corneum and the sensation of dryness. These results suggested that the use of moisturisers in combination with the standard topical treatment may improve adherence to therapy by alleviating the sensation of dryness.

Sensory irritation caused by two organic solvents-short-time single application and repeated occlusive test in stingers and non-stingers

Neurosensory irritation is a subjective phenomenon induced by a number of chemicals. Objectives. To investigate the sensory irritation induced by two organic solvents - n-octane and cumene - between two groups of volunteers, stingers and non-stingers, identified as such according to the results of a lactic acid stinging test (LAST). The immediate effects of the solvents were directly compared in a single simultaneous application test. The reaction intensities over time were studied in a repetitive irritation test over 4 days. The volunteers graded the reaction intensities by the use of a labelled magnitude scale. Cumene induced significantly stronger sensory irritation than octane in both the single and the repeated applications. Both substances induced less subjective irritation the more times the volunteers were exposed. The decline with time for cumene was statistically significant for the non-stingers but not for the stingers. However, no significant differences regarding the reaction intensities were detected in the direct comparisons of stingers and non-stingers. CONCLUSIONS. Further studies with larger sample sizes are needed to investigate a potential connection between the responsiveness to the sensory irritation caused by lipophilic irritants and lactic acid.

PELARGONIC ACID VANILYLLAMIDE (PAVA): RIOT CONTROL AGENT

Summary Riot control agents are highly potent sensory irritants of relatively low toxicity that produce dose and time-dependent acute site-specific toxicity. These compounds have been referred to as transient incapacitating agents or as lacrimators, and in common parlance they are known as tear gases. These compounds interact pharmacologically with sensory nerve receptors associated with mucosal surfaces and the skin at the site of contamination, resulting in localized discomfort or pain with associated reflexes. This biological response, e.g. ocular irritation, results in pain in the eye and excess reflex lacrimation and blepharospasm. Riot control agents have both civil and military applications and have been classified as either military chemicals or chemical warfare agents. Non-lethal or less lethal weapons have become increasingly popular for law enforcement use when confronting dangerous, combative individuals in the field, include riot control agents. Many incapacitating agents were developed during the Cold War. Oleoresin capsicum (OC) spray, an extracted resin from Capsicum pepper plants, was first developed in the 1970s as an alternative to CS (2-chlorobenzylidene malononitrile) and CN (chloroacetophenone) agents. Most recently, a synthetic form of capsaicin, PAVA (pelargonic acid vanillylamide), gained popularity as a defensive aerosol in the early 1990s. Chemical, pharmacological, and toxicological properties of PAVA are discussed in this paper.

The influence of alkane chain length on the skin irritation potential of 1,2-alkanediols

Several studies have reported that 1,2-alkanediols show increasing anti-microbial activity as their alkane chain length increases. However, there are no reports on the influence of alkane chain length on the skin irritation potential of 1,2-alkanediols. To investigate the influence of alkane chain length on the skin irritation potential of 1,2-alkanediols. The objective and subjective (sensory) skin irritation potentials of five 1,2-alkanediols - 1,2-butanediol, 1,2-pentanediol, 1,2-hexanediol, 1,2-octanediol and 1,2-decanediol - were evaluated. We also estimated percutaneous absorption by measuring in vitro skin penetration using a Franz diffusion cell system. Like anti-microbial activity, sensory irritation potential increased as alkane chain length increased, most likely due to increasing membrane interference and/or intrinsic toxicity of 1,2-alkanediols. 1,2-Hexanediol showed the lowest objective skin irritation potential, which increased when the alkane chain length decreased or increased. Furthermore, percutaneous absorption negatively correlated with the alkane chain length of 1,2-alkanediols. These results show that a lower skin absorption potential is not indicative of a low skin irritation potential. Our results suggest that the factors and processes involved in skin irritation potential are complex and that skin irritation potential is influenced by intrinsic toxicity and the potential for penetration or integration in the lipid bilayer.

Allergen and BDNF‐induced TRP Channel Expression in Nodose Cough‐fiber Neurons

We evaluated the effect of allergic inflammation on TRPV1 and TRPA1 expression in vagal nodose afferent Aδ “cough fibers” innervating the guinea pig trachea. Actively sensitized guinea pigs were exposed to ovalbumin, (OVA) via aerosol for three days. The nodose neurons innervating the trachea were identified via a standard retrograde trace dye injected into the tracheal wall 3 weeks earlier. Gene expression in indentified neurons was evaluated using single cell RT‐PCR methods. Relatively few trachea Aδ cough receptor neurons express TRPV1 mRNA (5–20% in a given ganglion). One day following the last OVA exposure, greater than 65% of the neurons expressed TRPV1 (P<0.01, χ2). Likewise, allergen exposure nearly doubled the % of cough receptor neurons expressing TRPA1 mRNA (P<0.01). We next characterized the neurotrophin receptor expression in these nodose “cough receptor” neurons. Over 80% of them expressed TRKB, but few expressed either TRKA or TRKC. We therefore went on to test whether BDNF (an agonist for TRKB) could mimic the neuroplasticity noted with allergen challenge. Local application of BDNF (200ng/ml) mimicked the effect of allergen challenge, in that over 65% of the nodose tracheal neurons were induced to express TRPV1 (P<0.01). BDNF did not increase the % of neurons expressing TRPA1. Allergen‐induced TRPA1 and TRPV1 in vagal A‐fiber neurons may contribute to the heightened sensory sensitivity of individuals to various sensory irritants. Supported by NIH HL062296 & HL07534, Bethesda, MD

Micronuclei, hemoglobin adducts and respiratory tract irritation in mice after inhalation of toluene diisocyanate (TDI) and 4,4′-methylenediphenyl diisocyanate (MDI)

Toluene diisocyanate (TDI) and 4,4′-methylenediphenyl diisocyanate (MDI), used in the production of polyurethane foam, are well known for their irritating and sensitizing properties. Contradictory results have been obtained on their genotoxicity. We investigated the genotoxicity and protein binding of inhaled TDI and MDI in mice by examining micronucleated polychromatic erythrocytes (PCEs) in bone marrow and peripheral blood and TDI- and MDI-derived adducts in hemoglobin. Male C57Bl/6J mice (8 per group) were exposed head-only to TDI vapour (mean concentrations 1.1, 1.5, and 2.4 mg/m 3; the mixture of isomers contained, on the average, 63% 2,4-TDI and 37% 2,6-TDI) or MDI aerosol (mean concentrations 10.7, 20.9 and 23.3 mg/m 3), during 1 h/day for 5 consecutive days. Bone marrow and peripheral blood were collected 24 h after the last exposure. Inhalation of TDI caused sensory irritation (SI) in the upper respiratory tract, and cumulative effects were observed at the highest exposure level. Inhalation of MDI produced SI and airflow limitation, and influx of inflammatory cells into the lungs. Hemoglobin adducts detected in the exposed mice resulted from direct binding to globin of 2,4- and 2,6-TDI and MDI, and dose-dependent increases were observed especially for 2,4-TDI-derived adducts. Adducts originating from the diamines of TDI (toluene diamine) or MDI (methylene dianiline) were not observed. No significant increase in the frequency of micronucleated PCEs was detected in the bone marrow or peripheral blood of the mice exposed to TDI or MDI. The ratio of PCEs and normochromatic erythrocytes (NCEs) was reduced at the highest concentration of MDI, and a slight reduction of the PCE/NCE ratio, dependent on cumulative inhaled dose, was also seen with TDI. Our results indicate that inhalation of TDI or MDI (1 h/day for 5 days), at levels that induce toxic effects and formation of TDI- or MDI-specific adducts in hemoglobin, does not have detectable genotoxic effects in mice, as studied with the micronucleus assay.

Gender Differences in Nasal Chemesthesis: A Study of Detection and Perceived Intensity

Women are generally more intolerant than men to ambient substances, for which sensory irritation plays an important role. The aim of the present study was to compare women and men with respect to response bias and sensitivity in irritation detection and to irritation intensity. Twelve women and 12 men were exposed to six concentrations of amyl acetate generated by a dynamic olfactometer. Each concentration was presented eight times in randomized order. Clean-air presentations were interrandomized among the series of amyl acetate stimuli to assess and control for response bias. Ratings of irritation intensity were performed with a Borg CR-100 scale. No gender difference in overall irritation detection sensitivity was found, but a significantly steeper psychometric detection function for women implies keener detectability at relatively high concentrations and poorer detectability at low concentrations. A higher false-alarm rate and higher intensity ratings for blank stimuli for women compared to men did almost reach statistical significance. The data showed no overall gender difference in irritation intensity, but a less steep power function for irritation intensity for women, with relatively weak concentrations being perceived as stronger by women than by men. The results suggest no overall gender difference in irritation detectability, but a larger increase in detectability among women across the stimulus span. The tendency of gender differences in response bias implies differences in strategies when detecting possible health hazards. These strategies together with weak concentrations being perceived as stronger may contribute to women being more intolerant than men to ambient substances.

Past, present and emerging toxicity issues for jet fuel

The US Air Force wrote the specification for the first official hydrocarbon-based jet fuel, JP-4, in 1951. This paper will briefly review the toxicity of the current fuel, JP-8, as compared to JP-4. JP-8 has been found to have low acute toxicity with the adverse effects being slight dermal irritation and weak dermal sensitization in animals. JP-4 also has low acute toxicity with slight dermal irritation as the adverse effect. Respiratory tract sensory irritation was greater in JP-8 than in JP-4. Recent data suggest exposure to jet fuel may contribute to hearing loss. Subchronic studies for 90 days with JP-8 and JP-4 showed little toxicity with the primary effect being male rat specific hydrocarbon nephropathy. A 1-year study was conducted for JP-4. The only tumors seen were associated with the male rat specific hydrocarbon nephropathy. A number of immunosuppressive effects have been seen after exposure to JP-8. Limited neurobehavioral effects have been associated with JP-8. JP-8 is not a developmental toxicant and has little reproductive toxicity. JP-4 has not been tested for immune, neurobehavioral or reproductive endpoints. JP-8 and JP-4 were negative in mutagenicity tests but JP-4 showed an increase in unscheduled DNA synthesis. Currently, JP-8 is being used as the standard for comparison of future fuels, including alternative fuels. Emerging issues of concern with jet fuels include naphthalene content, immunotoxicity and inhalation exposure characterization and modeling of complex mixtures such as jet fuels.

Irritant‐drinking behaviour can be modified by gravity‐stress loaded in developing but not in adult rats

AbstractIt is generally accepted that taste and taste‐related trigeminal chemical sensation bring up emotions that are essential for animal living and for a good quality of life, and that stress may modify sensory systems related to emotionality. The purpose of this study was to clarify (1) the effects of stress on taste and trigeminal irritant sensations, (2) effects of stress at a developing stage on these sensations. Male Wistar albino rats received 1G, 2G or 3G stimulation. Hyper‐gravity was applied with a centrifugal apparatus. The two‐bottle preference test was performed to measure chemical sensation. Adult rats received 1G (control), 2G (moderate) or 3G (strong) gravity loading every 10 min/day during 32 days. Developing rats received 3G gravity loading every 10 min/day during 45 days and were compared with 1G controls. As test solutions, taste solutions (sucrose, saccharin, citric acid, NaCl, monosodium glutamate, quinine and caffeine) and a trigeminal irritant solution (capsaicin) were used. In developing rats, but not in adult rats, hyper‐gravity stimulation increased the intake volume of sucrose, saccharin, NaCl, quinine and capsaicin, and the preference ratio for quinine, caffeine and capsaicin. It is suggested that the life stage where stress is loaded is critical for determining changes in emotionality as well as in emotion‐related sensory systems. Copyright © 2010 John Wiley & Sons, Ltd.