Niveles urinarios de ácido trans, trans mucónico y orto cresol en una población infanto-juvenil residente en Ciudad Autónoma de Buenos Aires y Conurbano Bonaerense / Urinary levels of trans, trans muconic and ortho cresol in an infant-juvenile population resident in the Autonomous City of Buenos Aires and the Conurbano of Buenos Aires

Introducción: la exposición crónica al benceno y tolueno produce alteraciones sobre la médula ósea y el sistema nervioso central, entre otros. En orina, el ácido trans, trans mucónico (t, t-MA) es uno de los biomarcadores de exposición al benceno y el o-cresol (oCre) al tolueno. Objetivo: analizar los resultados de los niveles de t, t-MA y oCre urinarios en una población infanto-juvenil residente en Ciudad Autónoma de Buenos Aires y Conurbano Bonaerense potencialmente expuesta a benceno y tolueno ambiental. Materiales y métodos: se realizó un estudio retrospectivo de los resultados de t, t-MA y oCre urinarios. Las muestras de orina ingresaron al laboratorio con solicitud de t, t-MA (n=1519) y oCre (n=1447) durante el período 2011-2017 (rango etario entre 0 a 19 años). El t, t-MA se cuantificó por UFLC con detector de arreglo de diodos y el oCre por CG con detector de ionización por llama. Resultados: la edad promedio de los pacientes fue de 4,8 años y la mediana 4,6 años.Las concentraciones de t, t-MA urinario fueron: menor de 50 μg/l (44,8%); entre 50-500 μg/l (52,1%) y mayores de 500 μg/l (3,1%). Expresadas por gramo de creatinina: entre 15-163 μg/g creatinina (60,4%) y mayores de 163 μg/g creatinina (39,6%). El límite de cuantificación de t, t-MA fue de 50 μg/l. Las concentraciones de oCre urinario fueron: menor de 0,20 mg/l (97,7%) y entre 0,20-0,50 mg/l (2,3%) y mayor de 0,50 mg/l (0%). Expresadas por gramo de creatinina: menor de 0,30 mg/g creatinina en el 0,8% y mayores de 0,30 mg/g creatinina en el 1,5%. El límite de cuantificación de oCre fue de 0,20 mg/l. Conclusiones: los resultados del trabajo podrían indicar una contaminación ambiental persistente, en especial en el Conurbano Bonaerense, donde debería continuarse el monitoreo de algunas zonas. Pero, por otro lado, es de vital importancia tener en cuenta los factores de confusión, tales como la dieta, la exposición al humo de tabaco ambiental (fumador pasivo) y la tasa de excreción renal que llevarían a una sobre-estimación de los resultados y a una incorrecta toma de decisiones.

Introduction: Chronic exposure to benzene and toluene produces alterations in the bone marrow and the central nervous system, among other effects. In urine, trans, trans muconic acid (t, t-MA) is one of the biomarkers of exposure to benzene and o-cresol (oCre), to toluene. Objective: To analyze the results of urinary t, t-MA and oCre levels in an infant-juvenile population resident in the Autonomous City of Buenos Aires and the Conurbano Bonaerense, potentially exposed to environmental benzene and toluene. Materials and methods: A retrospective study of urinary t, t-MA and oCre results was performed. The urine samples entered the laboratory with the request of t, t-MA (n = 1519) and oCre (n = 1447) during the period 2011- 2017. The age range of the population was between 0 and 19 years. The t, t-MA was quantified by UFLC with diode array detector and the oCre by GC with flame ionization detector. Results: The average age of the patients was 4.8 years and the median age was 4.6 years. The urinary concentrations of t, t-MA were: below 50 μg/l (44.8%); between 50-500 μg/l (52.1%) and above 500 μg/l (3.1%). Expressed per gram of creatinine: between 15-163 μg/g creatinine (60.4%) and greater 163 μg/g creatinine (39.6%). The limit of quantification of t, t-MA was 50 μg/l. The urinary oCre concentrations were: less than 0.20 mg/l (97.7%) and between 0.20-0.50 mg/l (2.3%). Expressed per gram of creatinine: less than 0.30 mg/g creatinine in 0.8% and greater than 0.30 mg/g creatinine in 1.5%. The limit of quantification of oCre was 0.20mg/l. Conclusions: The results of the study could indicate persistent environmental contamination, especially in the Conurbano Bonaerense, where monitoring of some areas should be continued. However, it is of vital importance to take into account the confounding factors, such as diet, exposure to environmental tobacco smoke (passive smoking) and the rate of renal excretion, which would lead to an over-estimation of the results and to incorrect decision-making.

High performance liquid chromatography for determination of urinary metabolites of toluene, xylene and styrene and its application.

The purpose of this research was to determine mandelic, phenylglyoxylic, hippuric, o-, m- and p-methylhippuric acids, the six urinary metabolites of styrene, toluene and xylene by high performance liquid chromatography (HPLC). These metabolites were extracted in an acid medium, transferred into a basic solution and back extracted again using ethyl acetate, and the organic phase was evaporated to dryness under a compressed air flow at room temperature. The residue obtained was dissolved in 1 ml mobile phase solution of 0.01 M potassium orthophosphate in 0.3% acetic acid (adjusted to a pH of 2.5 with orthophosphoric acid):tetrahydrofuran:acetonitrile(87:5:8) and 100 microl was injected into a HPLC equipped with a 4.6 x 250 mm ODS3-C18 reversed phased column and ultraviolet (UV) detector at a wavelength of 254 nm. All metabolites were clearly separated within 21 minutes. The detection limits of the method were 1.1 ng/ml for PGA, 4.9 ng/ml for HA, 17.0 ng/ml for MA, 2.5 ng/ml for o-MHA, 1.7 ng/ml for p-MHA and 2.0 ng/ml for m-MHA. The percent recoveries of the six metabolites were 99.2-101.8% with percent coefficients of variation of less than 2%. The method was applied to the analysis of urine samples of twelve workers exposed to toluene, xylene and styrene in a paint factory. The 5-day post-shift urinary excretions of the six metabolites in these workers are presented. The metabolites were found at levels greater than the Biological Exposure Index (BEI) recommended by the American Conference of Governmental Industrial Hygienists (ACGIH).

Valores de referência do ácido hipúrico urinário na regiäo metropolitana de Belo Horizonte / Urinary hippuric acid reference values in Belo Horizonte metropolitan area, Brazil

Objetivando estabelecer a faixa de valor referência para o ácido hipúrico na regiäo metropolitana de Belo Horizonte, urinas de indivíduos näo expostos ocupacionalmente ao tolueno foram analisadas por cromatografia em fase gasosa, utilizando-se detector de ionizaçäo de chama. Os valores encontrados experimentalmente (n=281) variaram de <0,1 a 2,79 g/L, mas a aplicaçäo de estudo estatístico delimita como faixa de referência,a nível de significância de 95 porcento, os valores de 0,361 a 0,481 g/L. Säo descritas, também, as condiçöes analíticas padronizadas para a determinaçäo cromatográfica do ácido hipúrico urinário

Determinacao de orto-cresol urinario por cromatografia em fase gasosa utilizando-se detector de ionizacao de chama / Gas-chromatographic determination of orto-cresol in urine using flame ionization detector

O tolueno e um solvente aromatico com larga utilizacao industrial, sendo usado na fabricacao de varios produtos como cola, tiner, tintas e outras. Sua acao neurotoxica constitui-se no principal risco a saude dos trabalhadores, tornando-se indispensavel medidas de controle e avaliacao da exposicao ocupacional. A monitorizacao biologica do tolueno e realizada frequentemente, atraves da determinacao de seu principal produto de biotransformacao na urina, o acido hipurico, que esta tambem, presente em urina de individuos nao expostos ao solvente. Pequena fracao do tolueno absorvido e oxidado a compostos aromaticos incluindo o orto-cresol, o qual nao e encontrado significativamente, em urina de nao expostos. objetivando padronizar metodologia analitica para a determinacao deste metabolito em urina de individuos expostos e nao expostos ocupacionalmente ao tolueno, foi elaborado o presente trabalho. A tecnica selecionada foi a cromatografia em fase gasosa acoplada a detector de ionizacao de chama (CG/DIC). O metodo analitico apresentou boa precisao (CV intra e interensaio na faixa de 2,4 a 5,4 por cento) e recuperacao media de 98,0 por cento. O metodo apresentou linearidade na faixa de 0,2 a 3,0 micragrama/mL, sendo o limite de quantificacao o valor de 0,2 micragrama/ml