Impact of lead on serum paraoxonase 1 (PON1)‎ and atherosclerosis in occupationally-exposed Egyptian workers

Abstract EN

Objectives : The aim of the present study is to study whether lead exposure has any effects on serum PON1 activity and lipid profile levels and, in addition to, understand the possible interaction between lead and polymorphisms of genes that encode proteins known to be involved in the regulation of atherosclerosis.

Subjects and methods : This study was carried out on 90 male workers in a lead-acid battery manufactory.

Full medical history and clinical examination were performed with special emphasis on blood pressure measurement.

Blood samples were withdrawn from every selected worker for the estimation of blood lead levels, and the separated serum was used for estimating lipid profile as well as liver and renal function tests, in addition to blood glucose levels and PON1 activity assay.

Buffy coat, isolated from EDTA-treated blood, was used for genomic DNA preparation for genotyping.

According to the obtained blood lead level, subjects are classified into 3 groups : Group I with blood lead level < 40 Μg /dl, group II with a level ranged between 40 and 60 μg / dl, and group III with a level above 60 μg / dl.

Results : No statistically significant difference was found in systolic and diastolic blood pressure between the different groups.

Only the total cholesterol and LDL-C levels were the highest-exposure group.

Although, the average paraoxonase activity of the high exposure group was lower than the low-exposure group, it didn’t reach any statistical significance.

Simple linear correlation analysis revealed that blood lead was positively correlated with the total cholesterol and LDL C (P = 0.04).

In addition, a highly significant negative correlation was found between paraoxonase and both ages of workers and their duration of exposure (P = 0.002, 0.005, respectively).

A significant negative correlation was found between paraoxonase and blood lead in all groups studied as one.

Blood lead was found to be an independent factor affecting serum PON1 activity P = 0.05.

In our study, we found that the homozygous subjects for the R allele are more susceptible to lead toxicity than are subjects of other genotypes.

Conclusion and recommendations : Increasing the duration of occupational lead exposure is associated with decreased serum PON1 activity, which has a protective role against the development of atherosclerosis, predisposing these workers to premature atherosclerosis.

Serum PON1 activity could be used as a bio-marker to monitor the cardiovascular health among lead workers.