RESUMEN
N,N-dimethylformamide (DMF) is a solvent that is widely used in industry. The major occupational sources of exposure results from production of synthetic leather. The main metabolite formed in both man and animals is N-hydroxymethyl-N-methylformamide. Demethylation leads to N-methylformamide (NMF) and formamide and also to a small extent to hydroxy-methylformamide. All the metabolites are excreted in urine, as are very small amounts of the unchanged substance. N-acetyl-S-(N-methyl-carbamoyl)-cysteine can be determined in urine as a further metabolite. We conducted this biomonitoring study with the aim of evaluating the correlation between the excretion of N-methylformamide (mainly from N-hydroxymethylformamide) and levels of exposure to N,N-dimethylformamide among occupationally exposed people. The mean time-weighted average (TWA) exposure was about half (13.5 mg/m3) of the current threshold limit value, the range of the values varying from 0.4 to 75.2 mg/m3. A linear equation existed between urinary NMF concentration and DMF concentration in the environment. The findings show that the urinary NMF concentration can be used as an appropriate biological exposure index. The authors suggest for occupationally exposed subjects, a urinary NMF concentration corresponding to the time-weighted average of the threshold limit value of 39.9 mg/l (37.2 mg/g creatinine) and a 95% lower confidence limit (biological threshold) of 23.4 mg/l (22.2 mg/g creatinine).
Asunto(s)
Dimetilformamida/efectos adversos , Formamidas/análisis , Exposición Profesional/análisis , Curtiembre , Adulto , Humanos , Masculino , Persona de Mediana Edad , Solventes , Valores Limites del UmbralAsunto(s)
Gases/toxicidad , Salud Laboral , Humanos , Italia , Salud Laboral/legislación & jurisprudenciaRESUMEN
Work goal is a critical analysis of the possibility of using TTCA as a future marker for next environmental limit values which will be probably fixed to much lower levels. Four metabolites have been identified in the urines of CS2 exposed subjects, exactly: thiocarbamide, 2-mercaptothiazolinone, 2-thiothiazolidine-4-carboxylic acid (TTCA), 2-oxothiazolidine-4-carboxylic acid. TTCA represents about the 6% of absorbed CS2 during occupational exposure. TTCA discovery in the urines of CS2 exposed workers (an heterocyclic compound which develops in vivo through direct reaction between CS2 and Glutatione) allowed a more specific approach to exposure assessment. The end-shift urine TTCA concentration seems to be in strict relationship with CS2 absorbed amount. In 1998 ACGIH maintained the 1997 limit value (TLV-TWA 10 ppm). In the 1997 DFG cut down the limit value in half (MAK 5 ppm), while, until 1996, it accepted the ACGIH value.