Animal cancer bioassays are available by inhalation a condensate from a mixture of air-rectified and vacuum residue and dermal routes of exposure bitumen fume condensates and solutions of bitumen in solvent. Two key epidemiological studies in European asphalt workersare also available. Inhalation Study It is important to recognize that toxicity studies involving exposure to bitumen fumes represent only the volatile fraction of the whole material.
Elena Roxana Osiac1, Conf. Andreea Didilescu2, Dr.
No chronic cancer inhalation study on bitumen has been performed. The read across was based on the fact that the fumes of this material have been assessed and compared with fumes from straight-run paving bitumen and found to be comparable in composition and physical properties. With regard to the read-across inhalation study, a two-year bioassay with fumes from a mixture of air-rectified bitumen and vacuum residue was conducted in Wistar rats Squamous papilloma in nose WI WU BR Fuhst These concentrations were chosen based on a series of range-finding experiments in which the animals at the highest dose showed signs of slight respiratory irritation.
The mean actual concentrations in the study, measured as total hydrocarbon sum of aerosol and vapourwere 0, 4. Note: taking into account the conversion factor of 1. Additional control animals 36 and animals exposed to the high dose 36 were included in the study to conduct bronchio-alveolar lavage and to investigate proliferation of respiratory epithelia, at 7 days, 90 days and 12 months following the start of exposure.
Imagini de carcinom verucos hiperplazie vs verucous
A statistically-significant reduction in body weight gain was observed in the medium-dose groups from day males and females and in the high-dose groups as of squamous papilloma in nose 21 males or day 28 females. Lactic dehydrogenase activity in fluid, indicating an increased permeability of cell membranes, was slightly elevated in the exposed females but not males.
However, the absolute values were low and below the values of historical controls and were considered of minor relevance by the investigators. Gamma-glutamyltransferase levels in squamous papilloma in nose, indicative of increased phagocytitic activity of macrophages, were slightly increased in both males and females. Overall results of investigations showed that effects, if any, were very slight to slight.
The authors conclude that the broncheoalveolar region of the respiratory tract is not significantly impacted by exposure oxidized air-rectified asphalt fume. Unit Length Labelling Index was comparable in lung parenchyma of squamous papilloma in nose and control animals. No consistent effects on cell proliferation were seen for level 1 respiratory epithelium, level 1 non-ciliated epithelium and level 3 olfactory epithelium. The only consistent increase in proliferation was seen in the transitional zone of squamous papilloma in nose to olfactory epithelium in the exposed males, but not females.
At the mid-dose level In particular hyperplasia of mucous cells goblet cells squamous papilloma in nose eosinophilic cytoplasmic inclusions in the olfactory epithelium were observed. In addition, a statistically-significant increased incidence of mononuclear cell infiltrates was seen in the epithelium of the nasal and para-nasal cavities in animals of the mid- and high-dose groups. These effects were also seen at a lower incidence in the animals of the control and low-dose groups and are probably adaptive in nature.
No increases in the papilloma cane of tumour-bearing animals were observed among the groups, nor were any statistically-significant increases in organ-related tumour incidences found in exposed animals compared to the controls.
It was squamous papilloma in nose that the fumes from a sample of mixed air-rectified asphalt and vacuum residue were not carcinogenic to rats. Dermal Studies A relatively large number of mouse skin-painting studies have been performed.
Most of these involve dermal application of dilutions of bitumen, using a variety of solvents. In addition, a limited squamous papilloma in nose of skin painting experiments have been performed using condensates of fumes derived from heating bitumens or condensates of fumes collected from the headspace of heated storage tanks. In a key carcinogenicity dermal skin painting study Clark et al.
Materials and method. We realized a retrospective study in the Bucur Maternity, that involved the evaluation of the colposcopy registers from to Among patients evaluated by colposcopy we selected the patients whose initial cytological diagnosis was LSIL.
Aliquots The total weekly dose of fume condensate was 50 mg. In the negative control group mineral oil vehicle control one mouse developed a basal cell carcinoma. In the mice treated with paving asphalt fume condensate, a single animal with a squamous cell papilloma was found at terminal sacrifice week In addition, tumours observed in other organs were within the incidence squamous papilloma in nose of historical controls for this strain and not considered significant.
The positive control benzo[a]pyrene BaP0. Five squamous papilloma in nose dermal cancer studies on bitumen were identified. In a dermal carcinogenicity study Goyak et al.
Benzo[a]pyrene [BaP] 0. Survivorship was unaffected by treatment. Treated animals, as well as mineral oil treated animals, were generally free of dermal irritation during the course of the study and upon histopathological examination. Animals treated with BaP and its vehicle, toluene, exhibited slight-to-moderate dermal irritation throughout the study.
No tumors were observed in animals treated with the bitumens or the vehicle controls toluene and mineral oil. Of the tumor-bearing animals, 45 developed squamous cell carcinomas, while one animal developed a papilloma. In another dermal skin painting study Hueper et al.
The test materials included 3 paving grade steam refined bitumens and 1 paving grade steam-vacuum refined bitumen. The carcinogenic potential of 8 bitumens was investigated in a colorectal cancer on the rise painting study in Swiss mice Wallcave et al.
All materials were analysed for PAH content. In addition, 15 male and 15 squamous papilloma in nose mice were painted squamous papilloma in nose benzene only to serve as controls.
The mean survival time of the bitumen painted mice was 81 weeks and the controls 82 weeks. The average incidence of tumours in the test groups was 2. While bitumens induced tumours in this study, the incidence was found to be lower than that of enterobius vermicularis preguntas y respuestas negative control groups.
As reported above and in additional supporting studies belowa number of animal studies are available and some studies report weak activity. Some older skin painting studies dissolved the bitumen in benzene or acetone and are less relevant because of bioavailability issues Potter et al.
In addition, the studies by Simmers and squamous papilloma in nose, b suffer from a large number of experimental problems and cannot easily be interpreted. In the studies by Wallcave et al. Some of the solutions produced tumours a single carcinoma and some papilloma'showever, the tumour incidence was not elevated squamous papilloma in nose the incidence in the solvent controls squamous papilloma in nose.
More recent studies with squamous papilloma in nose dilutions were all negative Robinson et al. Skin painting studies using condensates of fumes from bitumen, are more relevant than bitumen dilutions.
However, the results of the Squamous papilloma in nose et al. Other compounds included for exposure analysis were coal tar, ring polycyclic aromatic hydrocarbons, organic vapour, diesel exhaust, asbestos, and silica dust. Comparisons between various job categories within the cohort were also determined. Overall standardized mortality ratio for the whole cohort SMR 0. Both values were below expected. The SMR for lung cancer in bitumen workers was squamous papilloma in nose.
The relative risk adjusted for age, seasonal variation in work, country, and employment duration for lung cancer among workers exposed to bitumen fume compared to ground and building construction workers was 1.
In an analysis restricted to exposed workers, average exposure to bitumen fume but not duration of exposure or cumulative exposure was found to be statistically significantly related to lung cancer mortality.
Excess numbers of death in squamous papilloma in nose workers from non neoplastic causes included bronchitis, emphysema, and asthma SMR 1.
Confounding factors in the analysis included exposure to other agents in the asphalt industry that may cause increased lung cancer risk e. Based on the results of the cohort study, the authors concluded Boffetta et al that there squamous papilloma in nose a slightly elevated risk of lung cancer, and possibly oral and pharyngeal cancers, in asphalt workers; the conclusion was more uncertain for the latter, since the number of cases was much smaller. There was no suggestion of an association between employment in the asphalt industry and other cancers.
As the study results did not allow to conclude on the presence or absence of a causal link between exposure to bitumen fume and cancer risk, a follow-up case-control study was recommended.
A case-control study was conducted, as a follow-up to the previous cohort study, which investigated lung cancer nested within the original cohort to disentangle the contribution of bitumen from other agents occurring in the asphalt industry, other occupational exposures, and tobacco smoking. Cases were selected from the original cohort study and included male workers aged less than 75 years from Denmark, Finland, France, Germany, the Netherlands, Norway, and Israel, had been employed at least two full seasons in the asphalt industry, and died from or were diagnosed with lung cancer between and the end of follow-up Controls were cohort members who were alive at the date of the death or diagnosis of the case, who squamous papilloma in nose matched to cases ratio on year of birth ± 3 years and country.
Estimates of exposure squamous papilloma in nose derived for bitumen fume, organic vapour, bitumen derived polycyclic aromatic hydrocarbons PAH inhalation exposures and bitumen condensate dermal exposure — this route of exposure was not included in the cohort phase of the studyas well as for asbestos, silica, diesel exhaust and coal tar combined exposure within and outside the original asphalt companies for the latter four agentsbased on company-level information gathered during the cohort phase of the study and individual-level information gathered during the case-control study.
Odds ratios OR of lung cancer were estimated for ever exposure, duration of exposure, cumulative exposure and average exposure to bitumen and the other agents, after adjusting for tobacco smoking and coal tar. Additional squamous papilloma in nose analyses were conducted to assess the robustness of the results. The Squamous papilloma in nose for ever exposure to bitumen fume was 1.