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- Anticona Huaynate, Cynthia, 1983-
(författare)
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Lead exposure in indigenous children of the Peruvian Amazon : seeking the hidden source,venturing into participatory research
- 2012
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Introduction. In 2006, a Peruvian environmental agency reported the presence of elevated blood lead levels (BLLs) in indigenous communities of the Corrientes river basin. This is a territory in the Peruvian Amazon where oil activity has been associated with serious environmental effects, with impact on an ongoing social conflict. This PhD project aimed to determine the lead sources, risk factors and pathways in children of these communities and to suggest control and prevention strategies. Given the arguments attributing the lead source to the oil activity pollution, the second objective was to clarify any potential connection between the two. This project was conducted by a collaborative research partnership with the regional health authorities and the community-based organization. The third objective was to characterize the challenges, facilitating factors and the lessons learned from the research process.Methods. Two epidemiological studies were conducted. Study I (2009) was carried out in three communities and study II (2010) in six communities with different levels of exposure to oil activity. The participants were children 0–17 years old. Data collection included: determination of BLLs, hemoglobin levels and anthropometric indicators, a risk factor questionnaire, an environmental assessment and a risk map. Data analysis included univariate, bivariate and multivariate logistic regression. Data for the third objective came from field notes, documents, interviews and a process of collective reflection.Results. Study I (n= 221) found no significant difference in the geometric mean(GM) BLLs between the communities exposed and not exposed to oil activity. Older age and being a boy were found as risk factors for BLLs ≥ 10 μg/dL. In study II (n= 346), age stratified logistic regression models indicated that children 0–3 years whose mothers had BLLs ≥ 10 μg/dL, children 0–6 years who played with pieces of lead and children 7–17 years who fished 3 times or more per weekor chewed pieces of lead to manufacture fishing sinkers had a significant increased risk of having BLLs ≥ 10 μg/dL. Children who lived in communities near oil battery facilities also had a significant increased risk of having BLLs ≥ 10 μg/dL. In both studies, environmental samples showed lead concentrations below reference levels. The challenges and facilitating factors identified focused on five interrelated themes: i) mutual trust, ii) multiple agendas, iii) equal participation, iv) competing research paradigms and v) complex and unexpected findings.Conclusions. Metal lead appeared to be the main source of exposure. Playing with pieces of lead and chewing pieces of lead to construct fishing sinkers appeared to be pathways of exposure for children aged 0–6 years and 7–17 years, respectively. Mothers’ BLLs > 10 μg/dL was a risk factor for BLLs > 10 μg/dL in children aged 0–3 years. Living in a community with high exposure to oil activity was a risk factor for BLLs > 10 μg/dL. The identified connection with oil activity was the proximity of communities to oil battery facilities and thus greater access to lead from cables and other industrial waste. Despite the numerous challenges, participatory research appears to be the most appropriate approach for this type of context. The study findings led us to recommend:i) a comprehensive community-based lead control and prevention plan,ii) the introduction of substitute non-harmful material(s) for fishing sinkers and iii) secure containment of the oil company’s waste deposits.
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| 2. |
- Späth, Florentin, 1980-
(författare)
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Molecular epidemiology approach : nested case-control studies in glioma and lymphoid malignancies
- 2019
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- BACKGROUND: Nested case-control studies aim to link molecular markers with a certain outcome. Repeated prediagnostic samples may improve the evaluation of marker-disease associations. However, data regarding the benefit of repeated samples in such studies are sparse. We aimed to assess the relationship between blood levels of various proteins and risk of glioma, B cell lymphoma, and multiple myeloma to gain further understanding of disease etiology and to evaluate the clinical relevance of the studied markers. To this end, marker-disease associations were evaluated considering the natural history of the studied disease and the time between blood sample collection and diagnosis using both single (I-II) and repeated prediagnostic blood samples (III-IV).PATIENTS AND METHODS: We conducted four nested case-control studies and one meta-analysis using samples from three prospective cohorts: the Janus Serum Bank, the Northern Sweden Health and Disease study, and the European Prospective Investigation into Cancer and Nutrition study. The following studied endpoints and relationships were included: I) glioma risk and the association with the receptor tyrosine kinases (soluble) sEGFR and sERBB2; II) B cell lymphoma risk and the association with the immune markers sCD27 and sCD30; III) B cell lymphoma risk and the association with immune markers (CXCL13, sTNF-R1, sCD23, sCD27, and sCD30) and their trends over time; and IV) multiple myeloma risk and the association with ten immune markers and growth factors (MCP-3, MIP-1α, MIP-1β, VEGF, FGF-2, fractalkine, TGF-α, IL-13, TNF-α, and IL-10) and their trends over time.RESULTS: Risk of developing I) glioma was weakly associated with high blood levels of sERBB2. In addition, high levels of both sEGFR and sERBB2 assessed 15 years before diagnosis were associated with glioblastoma risk.Risk of II) B cell lymphoma was associated with high levels of sCD30, whereas high levels of sCD27 were particularly associated with risk of chronic lymphocytic leukemia. Meta-analyses showed consistent results for sCD30 across cohorts and lymphoma subtypes, whereas results for sCD27 were less consistent across cohorts and subtypes.In addition, III) B cell lymphoma risk was associated with levels of CXCL13, sCD23, sCD27, and sCD30 assessed in samples collected 17 years before diagnosis. Marker levels increased in cases closer to diagnosis, particularly for indolent lymphoma with a marked association for chronic lymphocytic leukemia and sCD23. Increasing marker levels closer to diagnosis were also observed for CXCL13 in future diffuse large B cell lymphoma patients.Risk of IV) multiple myeloma was associated with low levels of MCP-3, VEGF, FGF-2, fractalkine, and TGF-α. Levels of these markers decreased in myeloma cases over time, especially for TGF-α. TGF-α assessed at time of the prediagnostic repeated sample seemed to help predict progression to multiple myeloma.CONCLUSIONS: Both the natural history of the studied disease and the time between sample collection and diagnosis are crucial for the evaluation of marker-disease associations. Using repeated blood samples improves the understanding of marker-disease associations and might help to identify useful biomarker candidates.
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