Persistence of Breakage in Specific Chromosome Bands 6 Years after Acute Exposure to Oil.

BACKGROUND: The identification of breakpoints involved in chromosomal damage could help to detect genes involved in genetic disorders, most notably cancer. Until now, only one published study, carried out by our group, has identified chromosome bands affected by exposure to oil from an oil spill. In that study, which was performed two years after the initial oil exposure in individuals who had participated in clean-up tasks following the wreck of the Prestige, three chromosomal bands (2q21, 3q27, 5q31) were found to be especially prone to breakage. A recent follow-up study, performed on the same individuals, revealed that the genotoxic damage had persisted six years after oil exposure. OBJECTIVES: To determine whether there exist chromosome bands which are especially prone to breakages and to know if there is some correlation with those detected in the previous study. In addition, to investigate if the DNA repair problems detected previously persist in the present study. DESIGN: Follow-up study performed six years after the Prestige oil spill. SETTING: Fishermen cooperatives in coastal villages. PARTICIPANTS: Fishermen highly exposed to oil spill who participated in previous genotoxic study six years after the oil. MEASUREMENTS: Chromosome damage in peripheral lymphocytes. For accurate identification of the breakpoints involved in chromosome damage of circulating lymphocytes, a sequential stain/G-banding technique was employed. To determine the most break-prone chromosome bands, two statistical methods, the Fragile Site Multinomial and the chi-square tests (where the bands were corrected by their length) were used. To compare the chromosome lesions, structural chromosome alterations and gaps/breaks between two groups of individuals we used the GEE test which takes into account a possible within-individual correlation. Dysfunctions in DNA repair mechanisms, expressed as chromosome damage, were assessed in cultures with aphidicolin by the GEE test. RESULTS: Cytogenetic analyses were performed in 47 exposed individuals. A total of 251 breakpoints in exposed individuals) were identified, showing a non-uniform distribution in the human ideogram. Ten chromosome bands were found to be especially prone to breakage through both statistical methods. By comparing these bands with those observed in certain exposed individuals who had already participated the previous study, it was found in both studies that four bands (2q21, 3q27, 5q31 and 17p11.2) are particularly sensitive to breakage. Additionally, the dysfunction in DNA repair mechanisms was not significantly higher in oil-exposed individuals than in non-exposed individuals. LIMITATIONS: The sample size and the possibility of some kind of selection bias should be considered. Genotoxic results cannot be extrapolated to the high number of individuals who participated occasionally in clean-up tasks. CONCLUSION: Our findings show the existence of at least four target bands (2q21, 3q27, 5q31 and 17p11.2) with a greater propensity to break over time after an acute exposure to oil. The breaks in these bands, which are commonly involved in hematological cancer, may explain the increase of cancer risk reported in chronically benzene-exposed individuals. In addition, a more efficiency of the DNA repair mechanisms has been detected six years after in fishermen who were highly exposed to the oil spill. To date, only this study, performed by our group on the previous and present genotoxic effects, has analyzed the chromosomal regions affected by breakage after an acute oil exposure.

Follow-Up Genotoxic Study: Chromosome Damage Two and Six Years after Exposure to the Prestige Oil Spill.

BACKGROUND: The north-west coast of Spain was heavily contaminated by the Prestige oil spill, in 2002. Individuals who participated in the clean-up tasks showed increased chromosome damage two years after exposure. Long-term clinical implications of chromosome damage are still unknown. OBJECTIVE: To realize a follow-up genotoxic study to detect whether the chromosome damage persisted six years after exposure to the oil. DESIGN: Follow-up study. SETTING: Fishermen cooperatives in coastal villages. PARTICIPANTS: Local fishermen who were highly exposed (n = 52) and non-exposed (n = 23) to oil seven years after the spill. MEASUREMENTS: Chromosome damage in circulating lymphocytes. RESULTS: Chromosome damage in exposed individuals persists six years after oil exposure, with a similar incidence than those previously detected four years before. A surprising increase in chromosome damage in non-exposed individual was found six years after Prestige spill vs. those detected two years after the exposure. LIMITATIONS: The sample size and the possibility of some kind of selection bias should be considered. Genotoxic results cannot be extrapolated to the approximately 300,000 individuals who participated occasionally in clean-up tasks. CONCLUSION: The persistence of chromosome damage detected in exposed individuals six years after oil exposure seems to indicate that the cells of the bone marrow are affected. A surprising increase in chromosome damage in non-exposed individuals detected in the follow-up study suggests an indirect exposition of these individuals to some oil compounds or to other toxic agents during the last four years. More long-term studies are needed to confirm the presence of chromosome damage in exposed and non-exposed fishermen due to the association between increased chromosomal damage and increased risk of cancer. Understanding and detecting chromosome damage is important for detecting cancer in its early stages. The present work is the first follow-up cytogenetic study carried out in lymphocytes to determine genotoxic damage evolution between two and six years after oil exposure in same individuals.

Chromosomal bands affected by acute oil exposure and DNA repair errors.

BACKGROUND: In a previous study, we showed that individuals who had participated in oil clean-up tasks after the wreckage of the Prestige presented an increase of structural chromosomal alterations two years after the acute exposure had occurred. Other studies have also reported the presence of DNA damage during acute oil exposure, but little is known about the long term persistence of chromosomal alterations, which can be considered as a marker of cancer risk. OBJECTIVES: We analyzed whether the breakpoints involved in chromosomal damage can help to assess the risk of cancer as well as to investigate their possible association with DNA repair efficiency. METHODS: Cytogenetic analyses were carried out on the same individuals of our previous study and DNA repair errors were assessed in cultures with aphidicolin. RESULTS: Three chromosomal bands, 2q21, 3q27 and 5q31, were most affected by acute oil exposure. The dysfunction in DNA repair mechanisms, expressed as chromosomal damage, was significantly higher in exposed-oil participants than in those not exposed (p= 0.016). CONCLUSION: The present study shows that breaks in 2q21, 3q27 and 5q31 chromosomal bands, which are commonly involved in hematological cancer, could be considered useful genotoxic oil biomarkers. Moreover, breakages in these bands could induce chromosomal instability, which can explain the increased risk of cancer (leukemia and lymphomas) reported in chronically benzene-exposed individuals. In addition, it has been determined that the individuals who participated in clean-up of the oil spill presented an alteration of their DNA repair mechanisms two years after exposure.

Health changes in fishermen 2 years after clean-up of the Prestige oil spill.

BACKGROUND: In 2002, the oil tanker Prestige spilled more than 67,000 tons of bunker oil, heavily contaminating the coast of northwestern Spain. OBJECTIVE: To assess respiratory effects and chromosomal damage in clean-up workers of the oil spill 2 years after the exposure. DESIGN: Cross-sectional study. SETTING: Fishermen cooperatives in coastal villages. PARTICIPANTS: Local fishermen who were highly exposed (n = 501) or not exposed (n = 177) to oil 2 years after the spill. MEASUREMENTS: Respiratory symptoms; forced spirometry; methacholine challenge; markers of oxidative stress (8-isoprostane), airway inflammation (interleukins, tumor necrosis factor-α, and interferon-γ), and growth factor activity in exhaled breath condensate; and chromosomal lesions and structural alterations in circulating lymphocytes. RESULTS: Compared with nonexposed participants, persons exposed to oil were at increased risk for lower respiratory tract symptoms (risk difference, 8.0 [95% CI, 1.1 to 14.8]). Lung function did not significantly differ between the groups. Among nonsmoking participants, exposed individuals had higher exhaled 8-isoprostane levels than nonexposed individuals (geometric mean ratio, 2.5 [CI, 1.7 to 3.7]), and exposed individuals with lower respiratory tract symptoms had higher 8-isoprostane levels than those of exposed individuals without symptoms. Exposed nonsmoking participants also had higher levels of exhaled vascular endothelial growth factor (risk difference, 44.8 [CI, 27.9 to 61.6]) and basic fibroblast growth factor (risk difference, 16.0 [CI, 3.5 to 28.6]). A higher proportion of exposed participants had structural chromosomal alterations (risk difference, 27.4 [CI, 10.0 to 44.8]), predominantly unbalanced alterations. The risk for elevated levels of exhaled 8-isoprostane, vascular endothelial growth factor, and basic fibroblast growth factor and structural chromosomal alterations seemed to increase with intensity of exposure to clean-up work. LIMITATIONS: The clinical significance of exhaled biomarkers and chromosomal findings are uncertain. The association between oil exposure and the observed changes may not be causal. The findings may not apply to spills involving other types of oil or to different populations of oil spill workers. CONCLUSION: Participation in clean-up of a major oil spill was associated with persistent respiratory symptoms, elevated markers of airway injury in breath condensate, and chromosomal damage.