João Prista

Genotoxicity biomarkers in occupational exposure to formaldehyde: the case of histopathology laboratories

Formaldehyde, classified by the IARC as carcinogenic in humans and experimental animals, is a chemical agent that is widely used in histopathology laboratories. The exposure to this substance is epidemiologically linked to cancer and to nuclear changes detected by the cytokinesis-block micronucleus test (CBMN). This method is extensively used in molecular epidemiology, since it provides information on several biomarkers of genotoxicity, such as micronuclei (MN), which are biomarkers of chromosomes breakage or loss, nucleoplasmic bridges (NPB), common biomarkers of chromosome rearrangement, poor repair and/or telomere fusion, and nuclear buds (NBUD), biomarkers of elimination of amplified DNA. The aim of this study is to compare the frequency of genotoxicity biomarkers, provided by the CBMN assay in peripheral lymphocytes and the MN test in buccal cells, between individuals occupationally exposed and non-exposed to formaldehyde and other environmental factors, namely tobacco and alcohol consumption. The sample comprised two groups: 56 individuals occupationally exposed to formaldehyde (cases) and 85 unexposed individuals (controls), from whom both peripheral blood and exfoliated epithelial cells of the oral mucosa were collected in order to measure the genetic endpoints proposed in this study. The mean level of TWA(8h) was 0.16±0.11 ppm (<detection limit until 0.51 ppm) and the mean of ceiling values was 1.14±0.74 ppm (0.18-2.93 ppm). All genotoxicity biomarkers showed significant increases in exposed workers in comparison with controls (Mann-Whitney test, p<0.002) and the analysis of confounding factors showed that there were no differences between genders. As for age, only the mean MN frequency in lymphocytes was found significantly higher in elderly people among the exposed groups (p=0.006), and there was also evidence of an interaction between age and gender with regards to that biomarker in those exposed. Smoking habits did not influence the frequency of the biomarkers, whereas alcohol consumption only influenced the MN frequency in lymphocytes in controls (p=0.011), with drinkers showing higher mean values. These results provide evidence of the association between occupational exposure to formaldehyde and the presence of genotoxicity biomarkers.

Biomarkers of occupational exposure do anticancer agents: A minireview

The majority of anticancer agents has in common DNA-damaging properties and affects not only target-cells but also non-tumour cells. Its genotoxicity has been demonstrated in experimental models and in cancer patients treated with chemotherapy. Health care personnel involved in the preparation and administration of chemotherapy is therefore at risk for adverse health effects, since most environmental sampling studies demonstrated that there is widespread contamination of work surfaces and equipments with anticancer drugs. Adherence to safety guidelines and proper use of personal protective equipment are insufficient to prevent significant absorption, as evidenced by the presence of detectable amounts of drugs in urine samples and increased frequency of genotoxicity biomarkers. In this minireview, a critical appraisal of the most important biomarkers used for the evaluation of occupational exposure to anticancer agents as well as a summary of the key findings from several studies published in this field is performed.

Genotoxic effects of occupational exposure to lead and influence of polymorphisms in genes involved in lead toxicokinetics and in DNA repair

Lead is still widely used in many industrial processes and is very persistent in the environment. Although toxic effects caused by occupational exposure to lead have been extensively studied, there are still conflicting results regarding its genotoxicity. In a previous pilot study we observed some genotoxic effects in a population of lead exposed workers. Thus, we extended our study analysing a larger population, increasing the number of genotoxicity endpoints, and including a set of 20 genetic polymorphisms related to lead toxicokinetics and DNA repair as susceptibility biomarkers. Our population comprised 148 workers from two Portuguese factories and 107 controls. The parameters analysed were: blood lead levels (BLL) and δ-aminolevulinic acid dehydratase (ALAD) activity as exposure biomarkers, and T-cell receptor (TCR) mutation assay, micronucleus (MN) test, comet assay and OGG1-modified comet assay as genotoxicity biomarkers. Lead exposed workers showed markedly higher BLL and lower ALAD activity than the controls, and significant increases of TCR mutation frequency (TCR-Mf), MN rate and DNA damage. Oxidative damage did not experience any significant alteration in the exposed population. Besides, significant influence was observed for VDR rs1544410 polymorphism on BLL; APE1 rs1130409 and LIG4 rs1805388 polymorphisms on TCR-Mf; MUTYH rs3219489, XRCC4 rs28360135 and LIG4 rs1805388 polymorphisms on comet assay parameter; and OGG1 rs1052133 and XRCC4 rs28360135 polymorphisms on oxidative damage. Our results showed genotoxic effects related to occupational lead exposure to levels under the Portuguese regulation limit of 70 μg/dl. Moreover, a significant influence of polymorphisms in genes involved in DNA repair on genotoxicity biomarkers was observed.

Biomonitoring of a population of Portuguese workers exposed to lead

Lead is a heavy metal that has been used for many centuries and it is still used for various industrial purposes thanks to its physical and chemical characteristics. Human exposure to lead can result in a wide range of biological effects depending upon the level and duration of exposure. Despite the fact that lead has been found capable of eliciting genotoxic responses in a wide range of tests, not all studies have been conclusive. Although several experimental studies have shown that lead may modulate immune responses, data in exposed humans are still preliminary. The purpose of our study was to evaluate the genotoxic and immunotoxic effects of lead exposure in a group of 70 male workers from two Portuguese factories. The control group comprised 38 healthy males. The exposed individuals showed significantly higher levels of lead in blood and zinc protoporphyrin, and significantly lower δ-aminolevulinic acid dehydratase activity than the controls, suggesting a relatively high lead exposure. Nevertheless, the limit of 70 μg/dl for lead in blood established by the Portuguese regulation was never reached. Results of the comet assay were not modified by the exposure, but a significant increase in the mutation frequency in the exposed workers was obtained in the T-cell receptor mutation assay. Furthermore, data obtained in the analysis of the different lymphocyte subsets showed a significant decrease in %CD8+ cells and a significant increase in the %CD4+/%CD8+ ratio in exposed individuals with regard to the controls. No clear effect was observed for vitamin D receptor genetic polymorphism on the parameters evaluated. In view of our results showing mutagenic and immunotoxic effects related to lead exposure in occupational settings, it seems that the Portuguese biological exposure limit for lead needs to be revised in order to increase the safety of exposed workers.

Formaldehyde in indoor air: a public health problem?

Formaldehyde was the first air pollutant, which already in the 1970s emerged as a specifically non-industrial indoor air quality problem. Yet formaldehyde remained an indoor air quality issue and the formaldehyde level in residential indoor air is among the highest of any indoor air contaminant. Formaldehyde concentrations in 4 different indoor settings (schools, office buildings, new dwellings and occupied dwellings) in Portugal were measured using Photo Ionization Detection (PID) equipment (11,7 eV lamps). All the settings presented results higher than the reference value proposed by Portuguese legislation. Furthermore, occupied dwellings showed 3 units with results above the reference. We could conclude that formaldehyde presence is a reality in monitored indoor settings. Concentration levels are higher than the Portuguese reference value for indoor settings and these can indicate health problems for occupants.

Exposure and genotoxicity assessment methodologies: the case of formaldehyde occupational exposure

Formaldehyde (FA) ranks 25 th in the overall U.S. chemical production, with more than 5 million tons produced each year. Given its economic importance and widespread use, many people are exposed to FA occupationally. Recently, based on the correlation with nasopharyngeal cancer in humans, the International Agency for Research on Cancer (IARC) confirmed the classification of FA as a Group I substance. Considering the epidemiological evidence of a potential asso- ciation with leukemia, the IARC has concluded that FA can cause this lymphoproliferative disorder. Our group has devel- oped a method to assess the exposure and genotoxicity effects of FA in two different occupational settings, namely FA- based resins production and pathology and anatomy laboratories. For exposure assessment we applied simultaneously two different techniques of air monitoring: NIOSH Method 2541 and Photo Ionization Detection Equipment with simultane- ously video recording. Genotoxicity effects were measured by cytokinesis-blocked micronucleus assay in peripheral blood lymphocytes and by micronucleus test in exfoliated oral cavity epithelial cells, both considered target cells. The two exposure assessment techniques show that in the two occupational settings peak exposures are still occurring. There was a statistical significant increase in the micronucleus mean of epithelial cells and peripheral lymphocytes of ex- posed individuals compared with controls. In conclusion, the exposure and genotoxicity effects assessment methodologies developed by us allowed to determine that these two occupational settings promote exposure to high peak FA concentrations and an increase in the micronucleus mean of exposed workers. Moreover, the developed techniques showed promising results and could be used to confirm and extend the results obtained by the analytical techniques currently available.

Exposição ocupacional a formaldeído: avaliação da exposição e efeitos genotóxicos

Since 2004, formaldehyde (FA) has been classified by the International Agency for Cancer Research as a carcinogen. The FA ranks 25th in the overall United States chemical production, with more than 5 million tons produced each year. Due to its economic importance and varied use, many individuals are exposed to FA at their occupational settings. This study aimed to assess the exposure to FA in two occupational settings – FA production factory and pathology anatomy (PA) laboratories – and relate it to possible health effects by comparing frequency of micronuclei (MN) in peripheral bloodIntroducao: As desigualdades em saude sao reconhecidamente um problema de saude publica. A relacao entre determinantes sociais e as desigualdades em saude sao um achado robusto. Enquanto nos adultos e claro que estas desigualdades socioeconomicas se manifestam no seu estado de saude, a situacao e menos clara nas criancas e adolescentes. Foi entao efetuada uma revisao da literatura sobre a influencia dos determinantes sociais na saude na idade pediatrica. De forma a contribuir para um melhor conhecimento sobre a materia. Metodologia: A pesquisa foi efetuada segundo as normas PRISMA, com base nos termos MeSH: Social Class, Pediatric, Hospital, Emergency Treatment, Socioeconomic factor e Healthcare Disparities, na PubMed, Scielo e nas bases de dados da Cochrane. Foram excluidos artigos de revisao, opiniao bem como artigos que tratavam de questoes de acesso aos cuidados. Foi efetuada uma descricao quantitativa e qualitativa dos resultados. Resultados: Foram selecionadas 17 publicacoes, exceto uma do tipo descritiva, todas referentes a estudos observacionais analiticos, a maioria usando dados retrospetivos. Encontrou-se forte evidencia na relacao entre desigualdades em saude e os fatores socio economicos na idade pediatrica. Conclusao: Apesar de nenhuma das publicacoes selecionadas apresentar dados colhidos em Portugal, e seguro afirmar que e possivel encontrar a mesma relacao na idade pediatrica. E importante estudar mais esta area, identificar os determinantes sociais mais importantes bem como as populacoes mais vulneraveis, para melhor poder planear os cuidados de saude e combater as desigualdades. Palavras-Chave: Desigualdades em Saude, Determinantes Sociais da Saude, Fatores Socio-economicos, Pediatria

Genotoxic Effects of Exposure to Formaldehyde in Two Different Occupational Settings

Aleksandr Butlerov synthesized the chemical in 1859, but it was August Wilhelm von Hofmann who identified it as the product formed from passing methanol and air over a heated platinum spiral in 1867. This method is still the basis for the industrial production of formaldehyde today, in which methanol is oxidized using a metal catalyst. By the early 20th century, with the explosion of knowledge in chemistry and physics, coupled with demands for more innovative synthetic products, the scene was set for the birth of a new material– plastics (Zhang et al., 2009).

Exposure assessment: the influence of environmental monitoring methodology

Exposure assessment is an important step of risk assessment process and has evolved more quickly than perhaps any aspect of the four-step risk paradigm (hazard identification, exposure assessment, dose-response analysis, and risk characterization). Nevertheless, some epidemiological studies have associated adverse health effects to a chemical exposure with an inadequate or absent exposure quantification. In addition to the metric used, the truly representation of exposure by measurements depends on: the strategy of sampling, random collection of measurements, and similarity between the measured and unmeasured exposure groups. Two environmental monitoring methodologies for formaldehyde occupational exposure were used to assess the influence of metric selection in exposure assessment and, consequently, in risk assessment process. In one of the methodologies, environmental samples were obtained by personal air sampling, and formaldehyde levels were measured by GC analysis and time-weighted average (TWA8) estimated according to the NIOSH 2541 method. The second methodology aimed to measure ceiling values of formaldehyde using Photo Ionisation Detection equipment with simultaneously video recording. The NIOSH method data showed that exposure can be considered low, while results Environmental Health Risk V 353

Aspects to consider for selection of chemical risk assessment methodology: the case of formaldehyde occupational exposure.

There are several risk assessment methodologies available that can be applied in contexts where occupational exposure to chemical agents occur. However, there are some aspects that should be considered for selecting a more suitable and accurate risk assessment methodology. A study was carried out where two different risk assessment methodologies in ten anatomy and pathology laboratories were applied. One of the methodologies is propose by the Environmental Protection Agency (EPA) and the other methodology was based on the risk assessment methodology of Queensland University and defined by the authors to study this specific occupational setting. The two risk assessment methodologies obtained different results. Application of EPA methodology for risk assessment provides data that classifies this occupational setting similar to others where occupational exposure to formaldehyde occurs. However, differences and particular characteristics of this occupational setting are not possible to know due to the fact of relying only on TWA8h values. The proposal methodology ranks with high risk 30% of the activities studied in the ten laboratories and, 70% of the laboratories had at least one activity classified as high risk. The activities that were classified with very high risk and high risk were macroscopic exams developed always by the pathologist. www.witpress.com, ISSN 1743-3541 (on-line) WIT Transactions on Ecology and the Environment, Vol 132,