Determinación y estandarización de plomo en sangre en operarios de estaciones de servicio del Estado Mérida / Blood lead determination and standardization in petrol station workers in the State of Merida

En este trabajo se ha determinado el contenido de plomo (Pb) en sangre en operarios de estaciones de servicio de la ciudad de Mérida (Venezuela) y en un grupo de personas no expuestas ocupacionalmente. Las muestras de sangre provenientes de sujetos de ambos sexos n=21 (controles) y n=65 (personal expuesto) fueron procesadas por absorción atómica con atomización electrotérmica (ETAAS). Las concentraciones obtenidas de 15,27±9,62 y 83,74±28,95 µg/L para los grupos denominados como control y expuesto respectivamente, muestran diferencias altamente significativas que evidencian una exposición directa al Pb, por cuanto los valores del grupo expuesto ocupacional son más de 5 veces superiores a los del grupo control. Los resultados obtenidos también muestran que valores iguales o superiores a 54,79 µg/L son indicadores de exposición directa al Pb, permitiendo establecer valores de tolerancia entre los intervalos de 24,89 y 112,69 µg/L. Estos valores de referencia se encuentran por debajo de lo descripto por Burguera y cols. (1997), lo cual podría atribuirse al reemplazo gradual de la gasolina con plomo, en los últimos años, que ha llevado a una disminución de un 27% en los niveles de plomo en sangre, en comparación con un estudio similar realizado en esta misma ciudad en el año 1997.

In this work the lead (Pb) content in blood was determined in petrol station workers in the city of Merida-Venezuela and in a group of people not occupationally exposed. The blood samples coming from subjects of both sexes n=21 controls and n=65 exposed workers were processed by atomic absorption with electrothermal atomization (ETAAS). The 15.27±9.62 and 83.74±28.95 µg/L concentrations obtained for the group referred to as control and exposed respectively show highly significant differences that evidence a direct exposure to Pb, since the values of the occupationally exposed group are more than 5 times higher than those of the control group. The results obtained also show that values equal to or higher than 54.79 µg/L are indicative of direct exposure to Pb, making it possible to establish tolerance values between the 24.89 and 112.69 µg/L intervals. These reference values are below what was reported by Burguera et al (1997) which could be attributed to the gradual substitution of gasoline for lead that has originated a 27% decrease in lead levels in blood, if compared with a similar study carried out in the same city in 1997.

Relationship between lead in breast milk and lead in blood of urban and rural mothers

Lead levels in breast milk and maternal blood of 60 lactating women were determined using Perkin-Elmer 2380 atomic absorption spectrophotometer. The mean lead concentration in breast milk was 4.13 +/- 0.89 micro g/dl and 3.06 +/- 0.76 micro g/dl for urban and rural mothers respectively. The mean lead concentration in blood was 6.19 +/- 1.09 micro g/dl and 4.61 +/- 0.93 micro g/dl for urban and rural mothers respectively. Urban women showed higher lead concentrations of both breast milk lead and blood lead than that of rural women [P < 0.0001]. In this study, lead concentrations in both milk and blood were affected by maternal age and exposure to smoking. The most important factors used to predict lead concentrations of breast milk in the studied samples were maternal age and maternal blood lead concentration. According to the daily permissible intake value established by WHO which is 5.0 micro g/kg/day in mother's milk, the mean value for lead in breast milk of urban and rural mothers was higher than the permissible level [6.3 micro g/kg/day and 6.1 micro g/kg/day respectively]