Coexposure to toluene and p-xylene in man: uptake and elimination.

Abstract

Eight male subjects were experimentally exposed to toluene, p-xylene, and a combination of toluene and p-xylene in order to study the influence of coexposure and exposure to different levels of each solvent on their uptake and elimination. The exposures were performed for four hours at exposure levels equivalent to or lower than the Swedish threshold limit value for toluene, 300 mg/m3 (3.2 mmollm3). During and after the exposure, solvent concentrations were measured in blood and in expired air. In addition, the pulmonary ventilation rate was measured during the exposure. Decreases in the blood/end exhaled air concentration ratio were found for both toluene and p-xylene when given in combination compared with separate exposure. The total solvent uptake relative to the exposure level was decreased after exposure to the higher solvent concentrations, and the apparent clearance was also decreased after exposure to the higher concentrations of solvent. Finally, the blood solvent concentrations were lower at the end of the exposure compared with the maximal concentration during each exposure condition. In the kinetics of toluene and p-xylene the total amount of toluene or p-xylene, or both, seems to be of major importance. possible to replicate in man or in rats exposed to low doses of m-xylene.9 With this information to hand there seemed to be a need to study the effects on the uptake and elimination of commonly used organic solvents by simultaneous exposure to more than one solvent at a total level of exposure not exceeding the threshold limit value. In the present investigation subjects were exposed to toluene and p-xylene, both of which frequently occur in the industrial environment either singly or in combination as, for example, while working with thinners used for paints or in the printing trade. Furthermore, some metabolic interaction or dose dependent kinetics, or both, would be expected, especially at higher doses, since the main metabolic pathway is the same for toluene and xylenenamely, microsomal hydroxylation by cytochrome P-450 and further oxidation through alcohol and aldehyde dehydrogenases to the corresponding acid."0-'3 This metabolic pathway, like all enzymatically mediated processes, is limited by capacity. The main purpose of the present investigation was to study how the uptake and elimination of toluene and p-xylene in man were influenced by coexposure and by exposure to different levels of each solvent. 111

Real-time monitoring of respiratory absorption factors of volatile organic compounds in ambient air by proton transfer reaction time-of-flight mass spectrometry

“…However, toluene AFs from other studies were either much higher or much lower than the values reported here [41,42,45]. For C8-aromatics, while the mean respiratory AFs in many studies [29,46,49,50,[52][53][54] were lower than the 66.9% recorded in this study, other studies have reported much higher AFs [41,51]. Our results also indicated that the respiratory AFs of BTEX were much lower than 90%, which has been assumed to be the AF for toxic VOCs when assessing the human health risks of HAP exposure in many previous studies [6,[21][22][23][24]69].…”

“…However, compared with the mean respiratory AF in this study, Nomiyama and Nomiyama [37] reported significantly lower AFs (30%), while Yu and Weisel [40] reported much higher AFs (64%). For toluene, the results from this study were almost the same as the mean respiratory AFs of 55% and 54% reported by Wallen et al [44] and Wallen et al [46]. The mean respiratory AFs reported by Carlsson [43], Lof et al [47], and Lof et al [48] were all close to 50%, only slightly lower than the 55.9% recorded in this study.…”

Determinação simultânea dos ácidos hipúrico e metil-hipúrico urinários por métodos cromatográficos: comparação entre cromatografia líquida de alta eficiência e cromatografia gasosa capilar

“…O tolueno e o xileno são, atualmente, dois dos hidrocarbonetos aromáticos mais utilizados no meio ocupacional (Wallen et al, 1995).…”

“…

Determinação simultânea dos ácidos hipúrico e metil-hipúrico urinários Determinação simultânea dos ácidos hipúrico e metil-hipúrico urinários Determinação simultânea dos ácidos hipúrico e metil-hipúrico urinários Determinação simultânea dos ácidos hipúrico e metil-hipúrico urinários Determinação simultânea dos ácidos hipúrico e metil-hipúrico urinários por métodos cromatográficos: comparação entre cromatografia líquida de por métodos cromatográficos: comparação entre cromatografia líquida de por métodos cromatográficos: comparação entre cromatografia líquida de por métodos cromatográficos: comparação entre cromatografia líquida de por métodos cromatográficos: comparação entre cromatografia líquida de alta eficiência e cromatografia gasosa capilar alta eficiência e cromatografia gasosa capilar alta eficiência e cromatografia gasosa capilar alta eficiência e cromatografia gasosa capilar alta eficiência e cromatografia gasosa capilar Zelaine Lima Silva, Josianne Nicácio Silveira, Márcio Jacinto, Leiliane Coelho André Amorim, Zelaine Lima Silva, Josianne Nicácio Silveira, Márcio Jacinto, Leiliane Coelho André Amorim, Zelaine Lima Silva, Josianne Nicácio Silveira, Márcio Jacinto, Leiliane Coelho André Amorim, Zelaine Lima Silva, Josianne Nicácio Silveira, Márcio Jacinto, Leiliane Coelho André Amorim, Zelaine Lima Silva, Josianne Nicácio Silveira, Márcio Jacinto, Leiliane Coelho André Amorim, Edna Maria Alvarez-Leite* Edna Maria Alvarez-Leite* Edna Maria Alvarez-Leite* Edna Maria Alvarez-Leite* Edna Maria Alvarez-Leite*

INTRODUÇÃO INTRODUÇÃO INTRODUÇÃO INTRODUÇÃO INTRODUÇÃOO tolueno e o xileno são, atualmente, dois dos hidrocarbonetos aromáticos mais utilizados no meio ocupacional (Wallen et al, 1995).Estudos têm demostrado que a exposição conjunta a estes dois solventes pode resultar no aparecimento de interações toxicocinéticas importantes, uma vez que ambos são inibidores mútuos da biotransformação. Esta inibição poderá resultar em alterações nas concentrações urinárias dos metabólitos ácido hipúrico e metil hipúrico utilizados, respectivamente, como indicadores biológicos na exposição ocupacional ao tolueno e xileno (Alessio, 1996;Plaa et al, 1992).

Assim, a utilização de métodos analíticos que permitam a identificação conjunta destes biomarcadores é de grande importância para a melhor interpretação dos resultados da monitorização biológica da exposição.

A cromatografia líquida de alta eficiência (CLAE) e a cromatografia em fase gasosa (CG) são, atualmente, os métodos mais utilizados para a determinação urinária destes metabólitos (Kira, 1977;Poggi et al, 1982;Lundberg, Sollenberg, 1986;Ogata, Taguchi, 1988;Sakai et al, 1989; Carvalho, 1991; Inoue et al, 1991;Ukai et al, 1994;Ikeda, 1995;Kawamoto et al, 1995;Amorim, Alvarez Leite, 1997;Burini, 1998).

…”

Toxicokinetics of toluene in occupationally exposed volunteers.

“…The toxicokinetics of industrially used organic solvents in man have been focused upon in severallaboratory exposure experiment s (2,3,4,7,20,26,34,37,38,40,41). However, most of these stud ies were carried out with young health y volunteers with no history of occupational exposure to solvents or other agents that could affect the kinetics of the solvent studied.…”