Cytogenetic effects among workers exposed to formaldehyde. The possible role of some polymorphisms

Background

Formaldehyde (FA) is a human carcinogen. It is commonly used in diluted form as formalin. The purpose of this work was to evaluate the frequencies of chromosomal aberrations (CAs) and sister chromatid exchanges (SCEs) as a consequence of the exposure to FA in a hospital setting, taking into account the role of some polymorphisms in developing genotoxic damage.

Methods

CAs and SCEs assays were performed on peripheral blood lymphocytes of 57 pathologists enrolled in Turin hospitals (Italy) and 48 unexposed enrolled as controls. All subjects were genotyped for CYP1A1 exon 7 (A>G), CYP1A1*2A (T>C), CYP2C19*2 (G>A), GSTT1 (Positive/Null), GSTM1 (Positive/null), GSTP1 (A>G), XRCC1 (G399A), XRCC1 (C194T), XRCC1 (A280G), XPD (A751C), XPC exon 15 (A939C), XPC exon 9 (C499T), TNFα -308 (G>A), IL10 -1082 (G>A), IL10 -819 (C>T) and IL6 -174 (G>C) gene polymorphisms. Due to the little number of recessive homozygotes, we compared the dominant genotype with the combined group of heterozygotes and recessive homozygotes.

Results

Among pathologists, the mean value of personal air-FA was 64.2 µg/m3, mean significantly higher (p = 0.000) than controls (19.1 µg/m3). Similarly, pathologists showed significantly higher values of SCEs (p = 0.009) and CAs (p = 0.000) with respect to controls. In the same group, CYP2C19*2 (p = 0.011), XRCC1 (G399A) (p = 0.007), and IL10 (-1082) (p = 0.042) gene polymorphisms influenced the CAS levels, as well as those of CYP1A1 exon 7 (p = 0.010), XPD A751C (p = 0.002), XPC C499T (p = 0.040), and IL10 (-819) (p = 0.005) the levels of SCEs. In control group, CAs resulted significantly lower in CYP1A1 exon 7 dominant homozygotes (p = 0.001).

Conclusions

Our study confirms the role of FA as an inductor of genotoxicity, even when, daily, workers are exposed to low FA levels. Some genetic polymorphisms seem to have an influence in modulating the effect of FA exposure, highlighting, in occupational health studies, the role of the individual susceptibility.

Key messages

FA exposure is confirmed to be a genotoxicity inductor even at low concentrations. Some genetic polymorphisms seem to have a role in the modulation of FA exposure-related damage.

Formaldehyde in hospitals can still represent a risk factor. Oxidative stress and GSTT1 polymorphism

Background

Nurses employed in operating theatres and pathologists are workers professionally exposed to some environmental xenobiotics, such as drugs and formaldehyde (FA). Through experimental and epidemiological studies, both acute and chronic inhalation of FA has been associated with various health effects, including toxicity in the respiratory tract and cancer. The purpose of this study was to evaluate the relationship between occupational exposure to FA and the intensity of oxidative stress (OS).

Methods

87 female hospital workers were enrolled in a Turin hospital in Italy. Each subject filled a questionnaire and provided biological samples to measure OS biomarkers: 15-F2t-Isoprostane, malondialdehyde (MDA) and total glutathione content (GSX) in urine and inflammatory mediators and receptors (sIL-6R, VEGF-R2, TNFR1, TNFa, FGF2, CD30, CD27) in blood. All individuals were genotyped for CYP1A1, GSTT1, GSTM1, TNFa, and IL-6 polymorphisms. A personal passive air sampler, worn for a working shift (8h), assessed personal FA exposure.

Results

Subjects exposed to FA (27%) resulted to have a significant higher amount of 15-F2t-Isop (p = 0.000), MDA (p = 0.000), GSX (p = 0.001) compared with non-exposed workers. FA concentration was positively correlated with prevalence of reported respiratory symptoms (p = 0.004), 15-F2t-Isop (p = 0.044), GSX (p = 0.000), MDA (p = 0.000), FGF2 (p = 0.000), CD27 (p = 0.000) and negatively with sIL-6R (p = 0.001), VEGF-R2 (p = 0.000). A significant reduction was found in GSTT1 positive subjects concerning MDA levels (p = 0.000). The same relationship was found in the control group (b=-2.25; C.I. 0.21 - 0.516; p = 0.06).

Conclusions

FA exposure is confirmed to be an OS inductor and to be correlated with inflammatory response, highlighting how daily occupational exposure to this air pollutant can result in measurable biological outcomes.

Key messages

Daily occupational exposure to FA results in a disruption of oxidative status and inflammatory profile. GSTT1 gene polymorphism is able to influence the MDA levels in the control group.

Clastogenic effects of bisphenol A on human cultured lymphocytes

Bisphenol A is an endocrine disrupting compound widely used in the production of polycarbonate plastics and epoxy resins. It is ubiquitously present in the environment, mostly in aquatic environments, with consequent risks to the health of aquatic organisms and humans. In the present study, we analysed the cytogenetic effects of bisphenol A on human lymphocytes using in vitro chromosomal aberrations and micronuclei assays. Lymphocyte cultures were exposed to five different concentrations of BP-A (0.20, 0.10, 0.05, 0.02 and 0.01 μg/mL) for 24 h (for chromosomal aberrations test) and 48 h (for micronuclei test). The concentration of 0.05 µg/mL represents the reference dose established by United States Environmental Protection Agency (US EPA); 0.02 μg/mL represents the higher concentration of unconjugated BP-A found in human serum and 0.01 μg/mL represents the tolerable daily intake established by European Union. Data obtained from both assays showed significant genotoxic effects of the bisphenol A at concentrations of 0.20, 0.10 and 0.05 μg/mL, whereas at the concentration of 0.02 μg/mL, we observed only a significant increase in the micronuclei frequency. Finally, at the concentration of 0.01 μg/mL, no cytogenetic effects were observed, indicating this latter as a more tolerable concentration for human health with respect to 0.05 μg/mL, the reference dose established by US EPA.

Chromosomal damage in peripheral blood lymphocytes from nurses occupationally exposed to chemicals

In the present study, we evaluated the induced genome damage in peripheral blood lymphocytes from a sample of nurses occupationally exposed to low doses of different chemicals. A comprehensive multi-biomarker approach using cytogenetic endpoints was employed for analyzing chromosomal aberrations (CAs) and sister chromatid exchange (SCE) assay. The study included 20 nurses and 20 control subjects matched in age, gender and smoking habits. Nurses were exposed to different chemicals, such as cytostatic drugs, anaesthetics, formaldehyde and other sterilizing gases. Significant differences were found between exposure group and control group in terms of SCEs frequency (p < 0.001) but not in terms of replication index value (p = 0.845) and CAs (p = 0.236). Regression analyses indicated that the age and the exposure years did not influence the amount of the chromosomal damage among nurses. Vice versa, among controls, a positive correlation was found between the number of SCEs and age. In conclusion, our results suggest that a continuous long-term exposure to low doses of chemicals could result in increased levels of SCEs among nurses. This data emphasize the importance of biomonitoring nurses and other hospital workers handling drugs.

Demographic structure and microevolution of an Italian alpine isolated population

The isonymic method has been generally accepted in population genetic studies and surnames have been successfully used to investigate human populations as if they were genetic markers associated to the Y chromosome. In this study we analysed the microevolution dynamics of Postua, a mountain village of North Western Italy, by means of demographic methods. The uniqueness of this community is due to its past geographical and cultural isolation and to the high frequency of marriage between relatives. During the study period considered (1640-1989) the population underwent several fluctuations in size and other demographic parameters such as the endogamy, isonimy and consanguinity rates. Until the first half of the XIX century Postua appears to be a village characterised by a closed and isolated community, with high endogamy (80-90%) and isonimy (up to 34.4%). Only at the beginning of the XX century, when the population started to be subjected to significant immigration fluxes, data show a progressive reduction of the isolation. The population showed two demographic peaks, the first around the second half of the XVIII century (1639 inhabitants) and the second at the end of the XIX century (1464 inhabitants). The S/Nratio was low (0.2-0.3) and relatively constant until the beginning of the last century, and only in the last three decades of the XX century, when the population was subjected to immigration, Postua showed a significant increase in the S/Nratio values (to about 0.9). The surname frequency was constant until the 1850 when almost all surnames were the same as those already present in the XVII century. From the first half of the XIX century, the founder surnames decreased, whereas new surnames started to increase and became persistent in the population.

Erythrocyte polymorphisms in five ethnic groups of Northern Côte d'Ivoire

Distribution of some erythrocyte polymorphisms was investigated in five Northern Côte d'Ivoire ethnic groups. For the ABO blood group system, the frequencies of alleles p, q and r were 0.119, 0.150 and 0.731, respectively, while the frequencies of alleles D and d of the Rh blood group system were 0.726 and 0.274, respectively. These values are consistent with published data, while the high incidence of HbAS genotype could result from microevolutionay trends acting on this relatively small population. No 27-bp Southeast Asian ovalocytosis gene deletion was found in the sample.

COL1A2 gene deletion polymorphism in an Italian and an Ivorian populations

The COL1A2 gene is one of the two genes encoding for the polypeptides of type I collagen, that represent the major constituent of skin, bone, tendons, ligaments, blood vessels, dentin, and many interstitial tissues. The COL1A2 gene deletion polymorphism has been considered as an informative anthropological marker for describing geographically distinct human populations. Aim of the present study was to investigate the genetic variability at COL1A2 locus in two populations, one belonging to Ouangolodougou (N = 133), a village placed in Northern Ivory Coast, and one belonging to Lecco (N = 70), a village placed in a Northern Italy region called Lombardy. For each sampled population no data are available in literature. We reported, for the first time, the presence of the deleted allele among Ivorians (0.06), confirming the low deletion frequency of this polymorphism found in Sub Saharan Africa by other authors. For Italians, frequency analysis of this gene polymorphism (0.28 for the deleted allele) did not show any significant level of differentiation with respect to other Italian and European populations.

ACE and LRPAP1 insertion-deletion polymorphisms in a northern Ivory Coast population

The ACE and the LRPAP1 gene insertion-deletion polymorphisms were determined in 133 healthy individuals sampled from Ouangolodougou, a village located in northern Ivory Coast. No sex differences were found in ACE and LRPAP1 gene frequencies. The ACE insertion and deletion alleles had frequencies of 0.346 and 0.654, respectively. The ACE gene was not in Hardy-Weinberg equilibrium because of an excess of heterozygote genotypes and a deficiency of I/I genotypes compared to the expected values. Statistical analysis showed a significantly lower frequency of I/I genotypes in the Ivory Coast population compared to Sudan, Kenya, African Americans, and African Brazilians (p < 0.05), whereas no differences were found with respect to Somalia. Conversely, the frequencies of the insertion and deletion alleles in the Ivorian population did not differ from those of other African populations. The LRPAP1 insertion and deletion allele frequencies found in our study (0.192 and 0.808, respectively) did not differ significantly from the Czech and Spanish populations, the only two populations previously characterized for this polymorphism. However, the frequency of the I/I genotype was significantly lower than the frequencies observed in the European samples. Because of the limited information on the LRPAP1 gene polymorphism distribution in worldwide populations, it was not possible to draw any conclusion.

Glutathione S-transferase T1 (GSTT1) and M1 (GSTM1) polymorphisms in a sample of the population in Northern Italy

Glutathione S-transferase is a group of multifunctional enzymes important in the metabolism of xenobiotics. GSTT1 and GSTM1 are polymorphic in human populations. Since a relation between polymorphism and cancer susceptibility has been found, their distribution in human populations is of great interest. In the present study the distribution of GSTT1 and GSTM1 genotypes was studied in a total sample of 252 individuals of three localities of north-west Italy (Postua, Cavaglià and Biella) by PCR test. The frequencies of GSTT1 and GSTM1 "null" genotypes were respectively 7.94% and 34.92%. There are no significant differences between the populations studied in the GSTT1 "null" genotypes. On the other hand, for GSTM1 the frequency of gene deletion in Postua (25.5%) differs significantly (p < 0.01; chi-square test) from that of Biella (46.32%), which approaches the values indicated by most studies for Europeans (about 50%). The analysis of the frequencies of GSTT1 and GSTM1 polymorphisms among different age groups showed a lower frequency of negative genotypes in the older group, although not statistically confirmed.

Polymorphic Alu insertions in five North-West Italian populations

We analyzed the frequencies of eight human polymorphic Alu insertion loci in population samples from five towns in North-West Italy: Postua, Cavaglià, Biella, Torino, and Genova. All loci under scrutiny were found to be polymorphic in all samples, with the two exceptions of locus A25 in Postua, which was fixed for the absence of the Alu element, and APO in Genova, where the Alu insertion was fixed. Heterozigosity values were highly variable in all loci. F(ST) values for all loci indicate that most of the variability is found within populations, while between population variability is lower. In the multidimensional scaling (MDS) analysis plot, the studied populations are separated from the main group represented by European populations. The Postua sample is set apart also from neighboring towns as Cavaglià and Biella, confirming previous observations of the demographic isolation of this population.

Clinical usefulness of a new portable oxygen concentrator

Thirty chronic, hypoxaemic patients with a mean arterial oxygen tension (PaO2) of 6.81 kPa (SD 0.56) in air were tested using the Travelair. The study was performed at rest, allowing the patients to breathe in the following conditions: a) compressed air; b) continuous oxygen flow from the concentrator; c) oxygen from the concentrator in demand-valve mode (DV) with an activation time (AT) of 375 ms; d) DV with AT of 750 ms; e) DV with AT of 1,125 ms; f) DV with AT 1,500 ms; and g) continuous oxygen from the hospital outlet at 2 l.min-1. The mean (SD) SaO2% values at each consecutive step were: a) 87.2 (5.0)%; b) 93.0 (3.0)%; c) 93.9 (2.8)%; d) 94.2 (2.5)%; e) 94.0 (2.7)%; f) 94.1 (2.7)%; and g) 94.8 (2.4)%, respectively. Each of the results obtained with DV (b-f) was statistically different from those obtained breathing air (a) or oxygen (g). The mean (SD) respiratory rates at each consecutive step were: a) 21.2 (4.1); b) 21.0 (4.0); c) 21.3 (4.0); d) 21.0 (3.6); e) 20.7 (3.4); f) 21.0 (3.8); and g) 21.2 (3.8) breaths.min-1, respectively. No relationship was found between the mean oxygen saturations and the mean respiratory frequencies of the patients in each condition tested. With the concentrator on demand, the average of the best SaO2% obtained by the patients in whatever of the four DV activation time modes (conditions c-f) was 94.8 (2.4)%, and no statistical difference was detected between this result and the SaO2% obtained with 2 l.min-1 of continuous oxygen.