Journal of toxicology and environmental health
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J Toxicol Environ Health · Jun 1993
Effects of exposure to sulfuric acid-aerosol on airway responsiveness in guinea pigs: concentration and time dependency.
We investigated the concentration and time dependency of the effects of exposure to sulfuric acid (H2SO4) aerosol on airway responsiveness. Two hundred and sixteen male Hartley guinea pigs were used. The animals were divided into 3 groups (n = 72/group), with 1 group being exposed to filtered air and the other 2 to 1.0 mg/m3 or 3.2 mg/m3 H2SO4 aerosol. ⋯ Our results also showed that exposure to filtered air or 1 mg/m3 H2SO4 aerosol did not cause any significant change in airway responsiveness to inhaled histamine aerosol, expressed as the effective concentration of histamine (EC200His) that produced a doubling of SRawNaCl (SRaw after exposure to aerosol of 0.9% NaCl saline). On the contrary, exposure to 3.2 mg/m3 H2SO4 aerosol induced transient airway hyporesponsiveness after a 3-d exposure [EC200His prior to and after exposure: 1.35 +/- 0.28 and 2.23 +/- 0.22 mM (p < .01), respectively] and then transient hyperresponsiveness after a 14-d exposure [EC200His prior to and after exposure: 1.65 +/- 0.21 and 0.95 +/- 0.23 mM (p < .01), respectively]. Overall, the present results revealed that (1) 1.0 mg/m3 or 3.2 mg/m3 H2SO4 aerosol had no significant effect on SRaw0 during a 30-d exposure period, (2) a high concentration (3.2 mg/m3) of H2SO4 aerosol affected airway responsiveness during the 30-d exposure, while a low concentration (1.0 mg/m3) of H2SO4 aerosol did not, and (3) the effect of exposure to 3.2 mg/m3 H2SO4 aerosol on airway responsiveness was transient and stimulatory or inhibitory, depending on the duration of exposure.
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J Toxicol Environ Health · Nov 1992
Comparative StudyInduction of transient airway hyperresponsiveness by exposure to 4 ppm nitrogen dioxide in guinea pigs.
In the present study, we investigated (1) whether airway responsiveness to inhaled histamine-aerosol could be induced during 7-d exposure of guinea pigs to 4 ppm NO2 and, if so, (2) whether thromboxane A2 may be involved in such increase. Female Hartley guinea pigs were divided into 6 groups (n = 15/group). Three groups were exposed to filtered air and the other 3 groups were exposed to NO2 for 1, 3, or 7 d (24 h/d). ⋯ Exposure to air had no significant effect on the airway responsiveness. This transient hyperresponsiveness was inhibited by a specific inhibitor of thromboxane synthetase, OKY 046. These results indicated that (1) a lower concentration (4 ppm) of NO2 than that previously reported can induce transient hyperresponsiveness in guinea pigs during appropriate long-term exposure, and (2) thromboxane A2 may play an important role in this transient airway hyperresponsiveness.
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J Toxicol Environ Health · Jul 1992
Dermal absorption of the phenoxy herbicide 2,4-D dimethylamine in humans: effect of DEET and anatomic site.
Percutaneous absorption of the 14C-ring-labeled phenoxy herbicide 2,4-D-amine (2,4-dichlorophenoxyacetic acid dimethylamine) was examined following topical applications of the herbicide to the palm and forearm of human volunteers. The effect of two vehicles (water and acetone) and the mosquito repellent DEET (N,N-diethyl-m-toluamide) on dermal absorption of 2,4-D-amine also was investigated. The total percent dermal absorption was calculated from the mean percent urinary recoveries and was not corrected for nonurinary excretion. ⋯ Soap-and-water skin washes conducted at 24 h posttreatment removed up to 34% of the applied dose. Successive tape strips of skin taken at 24 h posttreatment demonstrated generally decreasing herbicide levels in the outer layers. The data bring into question the complete validity of the rhesus monkey model to predict human dermal absorption.
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J Toxicol Environ Health · Jul 1992
Percutaneous penetration of 2,4-dichlorophenoxyacetic acid and 2,4-D dimethylamine salt in human volunteers.
The percutaneous penetration of 2,4-dichlorophenoxyacetic acid (2,4-D) and 2,4-D dimethylamine salt (DMA) was evaluated separately in five male volunteers who participated in both experiments. Urine samples collected for 144 h following dermal applications of 10 mg to the dorsum of the hand (9 cm2) were analyzed for 2,4-D. Following the acid application, an average of 4.46 +/- 0.849% was recovered in the urine and a significantly lower amount of 1.76 +/- 0.568% following the DMA application. ⋯ Urinary excretion of 2,4-D was not complete in all volunteers 144 h following either application, but in all cases it was approaching the limit of detection. An average of 84.8 +/- 2.55% and 76.8 +/- 8.05% of the total recovered in 144 h was recovered in the urine 96 h following 2,4-D acid and 2,4-D DMA application, respectively. Average, approximated half-lives for excretion were 39.5 +/- 8.1 h for the acid application and 58.5 +/- 13.2 h for the DMA application.
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J Toxicol Environ Health · May 1992
Comparative StudyIn vivo percutaneous absorption and skin decontamination of alachlor in rhesus monkey.
The objectives of this study were to determine the percutaneous absorption of alachlor relative to formulation dilution with water, and to determine the ability of soap and water, and of water only, to remove alachlor from skin, relative to time. Alachlor is a preemergence herbicide. The in vivo percutaneous absorption of alachlor in rhesus monkeys was 17.3 +/- 3.3, 15.3 +/- 3.9, and 21.4 +/- 14.2% for 24-h skin exposure to Lasso formulation diluted 1:20, 1:40, and 1:80, respectively. ⋯ Continual successive washes (6-8 in sequence) recovered 80-90% of the skin-applied alachlor. These results suggest that simple washing with soap and water is appropriate for removing some chemicals from skin. Decontamination with only water was less effective than with soap and water.