Aging and smoking increase the frequency of sister-chromatid exchanges (SCE) in man.

The frequency of SCE was determined in lymphocytes of 88 healthy human subjects, not occupationally exposed to known genotoxic agents, who were uniformly distributed in several classes of age (from 16 to 70 years), including an equal number of smokers and non-smokers, and of males and females. Our results indicate that the frequency of SCE increases linearly with age and that smoking enhances the frequency of SCE independently of age and sex.

Cytogenetic damage in workers exposed to ethylene oxide.

Sister-chromatid exchanges (SECs) and chromosomal aberrations (CAs) were detected in the peripheral lymphocytes of 41 sanitary workers exposed to ethylene oxide (EO) in the sterilizing units of 8 hospitals in the Venice Region. The first group (19 workers) was exposed to 10.7 +/- 4.9 ppm EO, expressed as the time-weighted average concentration for an 8-h working day (TWA/8 h conc.), and the second group (22 workers) to 0.35 +/- 0.12 ppm. Each exposed worker was paired with a control of similar age and smoking habits. A highly significant (P less than 0.001) increase in the mean frequency of SCEs was found in the higher exposure group, 14 (74%) exposed subjects having significantly increased levels of SCEs compared to their matched controls. In the lower exposure group, the increase in mean frequency of SCEs was lower, though still significant (P less than 0.05): 7 (33%) exposed subjects had higher and 1 (5%) had a lower SCE level than the matched controls. From the first group, 10 subjects, 7 of whom had increased SCE levels, were reanalysed 12-18 months after their exposure had been lowered or interrupted: in only 2 of them the SCE level was significantly decreased. A statistically significant correlation between SCE frequency and level of EO exposure (TWA/8 h conc.), as well as a multiple correlation between SCE level and EO exposure, smoking and age were found. However, no interaction could be detected between EO exposure and smoking in the induction of SCEs. In controls, SCE frequency was correlated with smoking and age. In the higher exposure group, the number of both chromatid- and chromosome-type aberrations, independent of gaps, was significantly increased, whereas in the lower exposure group only the frequency of chromosome-type aberrations, excluding gaps, was statistically higher than in controls. The level of CAs remained to a great extent unchanged in the 10 subjects re-examined at a later stage after lowering or halting exposure. Taking the group as a whole, the frequency of cells with total CAs was found to be weakly (P = 0.05) correlated with EO exposure, and was not correlated with smoking, age or SCE frequency.

A cytogenetic study on workers exposed to low concentrations of benzene.

A cytogenetic study was performed on 22 healthy workers engaged in benzene production and exposed to low concentrations of benzene, ranging from 0.2 to 12.4 p.p.m. (threshold limit value 10 p.p.m.). Workers were divided into two groups according to the different levels of exposure, inferrable also from the concentration of benzene in the alveolar air and the levels of urinary phenols. Each exposed subject was paired with a suitable control, living in the same area and of similar smoking habits and age. No statistically significant increase of sister chromatid exchange (SCE) frequency was observed in the exposed groups. In controls, SCE frequency was positively correlated with age and smoking habits. Among structural chromosomal aberrations, only the chromosome-type ones were significantly higher in exposed than in control subjects, and their increase was still significant when gaps were discarded.

Workers exposed to ethylene oxide have increased incidence of sister chromatid exchange.

We have determined the frequencies of sister chromatid exchange (SCE) in 41 workers engaged in the sterilization of medical equipment. Each exposed subject was paired with a control matched for age, smoking habits and sex. The frequencies of SCE were markedly higher in the exposed than the control workers. The exposed subjects were divided into two groups according to time-weighted average concentrations of ethylene oxide (EtO) in the air, that were determined at the work place of each worker during the 5 min following the sterilizer opening, during the entire sterilization cycle or during the 8-h working day. One group (19 subjects) was exposed to a range of 3.7-35.5 ppm (mean, 15.8 +/- 9.8 for a sterilization cycle) and showed a mean of 13.0 +/- 1.8 SCE compared to 10.2 +/- 1.2 in controls (variance, F = 31.2; p less than 0.001). The second group (22 subjects) was exposed to 0.3 - 2.6 ppm (mean, 1.1 +/- 1.0) and had a mean of 11.0 +/- 1.6 SCE compared to 9.8 +/- 1.4 in controls (F = 4.7; p less than 0.05). Statistical evaluation of the SCE frequencies correlates SCE induction with the level of EtO exposure and also with smoking and age. Our data show that EtO can induce human chromosomal damage at very low environmental exposure levels, lower than the present Italian official limits and lower than those found even in the most technologically advanced hospitals.

Increased incidence of chromosomal aberrations and sister chromatid exchanges in workers exposed to chromic acid (CrO3) in electroplating factories.

Chromosomal aberrations in cultured lymphocytes obtained from workers occupationally exposed to chromic acid (CrO3) were detected. Four separate groups of workers were examined, two of which were engaged in plating factories employing nickel in addition to chromium, and two coming from plating factories where only chromium was used. In the latter groups the frequency of sister chromatid exchanges (SCEs) were also detected in the cultured lymphocytes. A statistically significant increase of chromosomal aberrations, mostly of the chromosome-type, was found in two of the exposed groups of workers compared to the level observed in control donors. The frequency of SCEs in the exposed groups was higher than in controls, particularly in the factor which employed the younger workers. Besides the negative correlation with the age of workers, a positive correlation between the frequency of SCEs and the level of urinary chromium was found and such a correlation was strongly enchanced by smoking. The present data support the view that CrO3, like other soluble hexavalent chromium compounds, is genetically active in vivo.