Publications by authors named "Jacques Gardon"

Exposure to particulate matter (PM) pollution is a significant health risk, driving the search for innovative metrics that more accurately reflect the potential harm to human health. Among these, oxidative potential (OP) has emerged as a promising health-based metric, yet its application and relevance across different environments remain to be further explored. This study, set in two high-altitude Bolivian cities, aims to identify the most significant sources of PM-induced oxidation in the lungs and assess the utility of OP in assessing PM health impacts.

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Background: Ingestion of flakes of Pb-based paint by infants remains a global health hazard with life-long consequences. Pb-based paint was banned for residential use in the US and Western Europe decades ago but is still sold in many countries. This study evaluates the performance of a new kit for detecting exposed Pb-based paint relying on the formation of Pb-halide perovskite that fluoresces bright green under a UV flashlight after spraying a non-toxic reagent.

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Elevated concentrations of arsenic, lithium and boron in drinking water have already been reported in Bolivia. Arsenic is known to cause genotoxicity but that caused by lithium and boron is less well known. The aim of the present cross-sectional study was to evaluate potential genotoxic effects of exposure to arsenic, while considering exposure to lithium and boron and genetic susceptibility.

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Article Synopsis
  • - French Polynesia (FP) has a high incidence of differentiated thyroid cancer (DTC), and this study examined the genetic factors contributing to DTC risk in the native population, particularly due to past nuclear tests from 1966-1974.
  • - Researchers analyzed over 300,000 single nucleotide polymorphisms (SNPs) in 283 DTC cases and 418 controls, discovering genetic links associated with DTC at three specific regions on chromosomes 6, 10, and 17, indicating an increased risk.
  • - The findings suggest that these genetic loci could influence DTC risk, but the study recommends further investigation using whole genome sequencing to better understand these factors, as the current methods may not fully capture the
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Importance: Due to the amount of iodine 131 released in nuclear tests and its active uptake by the thyroid, differentiated thyroid carcinoma (DTC) is the most serious health risk for the population living near sites of nuclear tests. Whether low doses to the thyroid from nuclear fallout are associated with increased risk of thyroid cancer remains a controversial issue in medicine and public health, and a misunderstanding of this issue may be associated with overdiagnosis of DTCs.

Design, Setting, And Participants: This case-control study was conducted by extending a case-control study published in 2010 that included DTCs diagnosed between 1984 and 2003 by adding DTCs diagnosed between 2004 and 2016 and improving the dose assessment methodology.

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Background: The elimination of onchocerciasis requires increasing ivermectin treatment coverage in communities hypoendemic for onchocerciasis. In areas where loiasis is co-endemic, this approach is complicated by the risk of serious adverse events following treatment with ivermectin in individuals with a high Loa loa microfilarial density (MFD). We aimed to evaluate the extent to which the pre-treatment MFD can be inferred from post-treatment MFDs.

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Humans living in the Andes Mountains have been historically exposed to arsenic from natural sources, including drinking water. Enzymatic methylation of arsenic allows it to be excreted more efficiently by the human body. Adaptation to high-arsenic environments via enhanced methylation and excretion of arsenic was first reported in indigenous women in the Argentinean Andes, but whether adaptation to arsenic is a general phenomenon across native populations from the Andes Mountains remains unclear.

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Background: Women living in the Bolivian Andes are environmentally exposed to arsenic, yet there is scarce information about arsenic-related effects in this region. Several biomarkers for telomere length and oxidative stress (mitochondrial DNA copy number, mtDNAcn; 8-Oxo-2'-deoxyguanosine, 8-oxo-dG; and 4-hydroxy nonenal mercapturic acid, 4-HNE-MA) have been previously linked to arsenic, and some of which are prospective biomarkers for cancer risk.

Objective And Hypothesis: To evaluate associations between arsenic exposure and telomere length, mtDNAcn, 8-oxo-dG, and 4-HNE-MA in Bolivians.

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Indigenous people living in the Bolivian Andes are exposed through their drinking water to inorganic arsenic, a potent carcinogen. However, the health consequences of arsenic exposure in this region are unknown. The aim of this study was to evaluate associations between arsenic exposure and changes in cancer-related proteins in indigenous women ( = 176) from communities around the Andean Lake Poopó, Bolivia.

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Background: Implementation of onchocerciasis elimination programmes has been delayed in Central Africa because of the risk of ivermectin-related serious adverse events (SAEs) in individuals with high microfilarial densities (MFD). We developed the first statistical models enabling prediction of SAE risk in individuals with a given MFD.

Methods: We used individual participant data from two trials conducted in loiasis-onchocerciasis co-endemic areas in Cameroon.

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Thyroid doses were estimated for the subjects of a population-based case-control study of thyroid cancer in a population exposed to fallout after atmospheric nuclear weapons tests conducted in French Polynesia between 1966 and 1974. Thyroid doses due to (1) intake of I and of short-lived radioiodine isotopes (I, I, I) and Te, (2) external irradiation from gamma-emitting radionuclides deposited on the ground, and (3) ingestion of long-lived Cs with foodstuffs were reconstructed for each study subject. The dosimetry model that had been used in 2008 in Phase I of the study was substantially improved with (1) results of radiation monitoring of the environment and foodstuffs, which became available in 2013 for public access, and (2) historical data on population lifestyle related to the period of the tests, which were collected in 2016-2017 using focus-group discussions and key informant interviews.

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Background: Little information is available on the effect of ivermectin on the third- and fourth-stage larvae of Onchocerca volvulus. To assess a possible prophylactic effect of ivermectin on this parasite, we compared the effects of different ivermectin regimens on the acquisition of onchocercal nodules.

Methods: We analyzed data from a controlled randomized clinical trial of ivermectin conducted in the Mbam Valley (Cameroon) between 1994 and 1998 in a cohort of onchocerciasis infected individuals.

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Background: Ivermectin is a key anthelmintic for the control of neglected tropical diseases. The main indications for population-level control with ivermectin through mass drug administration are onchocerciasis and lymphatic filariasis; however, there is interest in using higher, fixed-dose regimens for the control of scabies, soil-transmitted helminths and malaria. Safety data for these higher-dose regimens are needed.

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Background: Reconstruction of radiation doses to the thyroid for a case-control study of thyroid cancer in French Polynesians exposed to radioactive fallout from atmospheric nuclear weapons tests during childhood and adolescence faced a major limitation on very little availability of information on lifestyle of French Polynesians in the 1960s-1970s.

Method: We use the focus group discussion and key informant interview methodology to collect historical, for the 1960s-1970s, data on behavior and food consumption for French Polynesia population exposed to radioactive fallout from nuclear weapons tests conducted between 1966 and 1974.

Results: We obtained archipelago-specific data on food consumptions by children of different ages and by pregnant and lactating women during pregnancy and breastfeeding and behaviour, including time spent outdoors and type and construction materials of residences.

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Background: In central Africa, millions of individuals infected with have received the anthelminthic drug ivermectin (IVM) as part of mass drug administration (MDA) campaigns targeting onchocerciasis control or elimination. Nonetheless, the parasitological surveys that are occasionally conducted to evaluate the impact of IVM treatments on do not include an assessment of the extra benefits of those MDA campaigns on .

Methods: We conducted a systematic review of trials on the effect of a single standard (150-200 μg/kg) dose of IVM on microfilarial density (MFD).

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Article Synopsis
  • French Polynesia has the highest thyroid cancer incidence and mortality rates globally, potentially linked to high levels of non-essential trace elements (nETE) like mercury, lead, arsenic, and cadmium found in foods.
  • The study involved 229 cases and 373 controls, analyzing food contamination and correlating it with nETE levels in fingernails among Polynesian participants.
  • Results indicate that while lead and mercury were common pollutants in food and fingernail clippings, dietary exposure to nETE did not directly correlate with an increased risk of differentiated thyroid cancer, although certain factors like family cancer history influenced risks related to lead and arsenic intake.
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Elevated concentrations of inorganic arsenic, one of the most potent environmental toxicants and carcinogens, have been detected in well water around Lake Poopó, Bolivia. This study aimed to assess human exposure to arsenic in villages around Lake Poopó, and also to elucidate whether the metabolism and detoxification of arsenic in this population is as efficient as previously indicated in other Andean areas. We recruited 201 women from 10 villages around Lake Poopó.

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Background: Mass drug administration (MDA) with ivermectin is the cornerstone of efforts to eliminate human onchocerciasis by 2020 or 2025. The feasibility of elimination crucially depends on the effects of multiple ivermectin doses on Onchocerca volvulus. A single ivermectin (standard) dose clears the skin-dwelling microfilarial progeny of adult worms (macrofilariae) and temporarily impedes the release of such progeny by female macrofilariae, but a macrofilaricidal effect has been deemed minimal.

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Rationale: The highest burden of liver cancer occurs in developing countries, where the use of herbal medicine (HM) is still widespread. Despite this trend, few studies have been conducted to report HM practices of patients with a hepatic tumor in the developing world. Hence, this study aimed to document the use of HM among patients with liver cancer in Peru.

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Refined exposure assessments were realized for children, 7-9yrs, in the mining/smelting city of Oruro, Bolivia. Aerosols (PM>2.5, PM1-2.

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Article Synopsis
  • * A total of 467 pregnant women were recruited, with blood samples taken to measure heavy metal concentrations using advanced lab techniques, revealing significant correlations between maternal and cord blood for lead levels.
  • * Higher levels of toxic elements in maternal blood were linked to factors like maternal smoking, lower education levels, and having a partner involved in mining activities.
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Mining industries are known for causing strong environmental contamination. In most developing countries, the management of mining wastes is not adequate, usually contaminating soil, water and air. This situation is a source of concern for human settlements located near mining centers, especially for vulnerable populations such as children.

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Objectives: This study aims to (1) follow up and characterize infant growth patterns during the first year of life in Bolivia, and (2) determine whether there exists an association between weight gain and cognitive development in children living near contaminated mining industries.

Methods: Data on 175 children participating to the ToxBol (Toxicity in Bolivia) birth cohort were analyzed. Rapid-growth during the first 6 months was defined as a change in weight z-score > 0.

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The control of onchocerciasis or river blindness by mass treatment of the population with ivermectin (IVM) has been a great success until now, so that in certain foci its elimination has become feasible. However, after more than 20 years of repeated IVM mass treatment, the disease still persists in many endemic countries. Sub-optimal responses and genetic changes have been reported in Onchocerca volvulus populations under high IVM pressure but more work is needed to determine whether resistance is developing.

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Article Synopsis
  • * Pregnant women’s socioeconomic status and medical histories were assessed, and prenatal exposure to various trace elements was measured through blood tests; most levels were below control limits, except for slightly elevated antimony levels.
  • * Interestingly, despite concerns about contamination, the children's development scores on the Bayley Scales of Infant Development did not show abnormalities, with low lead levels surprisingly correlating positively with better performance.
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