Combining crop-exposure matrices and land use data to estimate indices of environmental and occupational exposure to pesticides.

BACKGROUND: Exposure assessment represents a major challenge for studies on the relation between pesticides and health. OBJECTIVE: We developed a method combining information from crop-exposure matrices (CEMs) and land use data, in order to compute indices of environmental and occupational pesticide exposure. We illustrate our approach using French data (1979-2010). METHODS: We used CEMs for five crops (straw cereals, grain corn, corn fodder, potatoes, vineyards) that describe use (annual probability, frequency, intensity) of pesticide subgroups, chemical families, and active substances by region and time since 1960. We combined these data with land use data from agricultural censuses (1979, 1988, 2000, 2010) to compute indices of environmental and occupational pesticide exposure in cantons (small French administrative units). Indices of environmental exposure were calculated based on the area of each crop in the cantons, while indices of occupational exposure depended on combinations of crops in each farm from the cantons. To illustrate our approach, we selected a pesticide group (herbicides), chemical family of herbicides (phenoxyacetic acids), and active substance from the phenoxyacetic acids chemical family (2,4-D). RESULTS: The estimated proportion of the area of crops with CEMs and of farms sprayed with herbicides was close to 100% between 1979-2010, but the estimated average annual number of applications increased. There were decreasing time-trends for phenoxyacetic acids and 2,4-D over the same period for all indices of exposure. There was a high use of herbicides throughout France in 2010, except in the South coast. For phenoxyacetic acids and 2,4-D, the spatial distribution was heterogeneous for all indices of exposure, with the highest values in the Centre and North regions. IMPACT STATEMENT: Assessment of pesticide exposure is a key issue for epidemiological studies on their association with health outcomes. However, it presents some unique challenges, particularly for retrospective exposure and the investigation of chronic diseases. We present a method to compute indices of exposure by combining information from crop-exposure matrices for five crops and land use data. Specificities of environmental and occupational exposure are addressed using different methods. These methods are applied to pesticides used in agriculture in France for five crops (3 groups, 91 chemical families, 197 active substances) to produce indices at a small geographic scale from 1979 to 2010 for the whole metropolitan France. Besides using these indices in French epidemiological studies, our approach could be relevant for other countries.

Qualitative and Semiquantitative Assessment of Exposure to Engineered Nanomaterials within the French EpiNano Program: Inter- and Intramethod Reliability Study.

The relatively recent development of industries working with nanomaterials has created challenges for exposure assessment. In this article, we propose a relatively simple approach to assessing nanomaterial exposures for the purposes of epidemiological studies of workers in these industries. This method consists of an onsite industrial hygiene visit of facilities carried out individually and a description of workstations where nano-objects and their agglomerates and aggregates (NOAA) are present using a standardized tool, the Onsite technical logbook. To assess its reliability, we implemented this approach for assessing exposure to NOAA in workplaces at seven workstations which synthesize and functionalize carbon nanotubes. The prediction of exposure to NOAA using this method exhibited substantial agreement with that of the reference method, the latter being based on an onsite group visit, an expert's report and exposure measurements (Cohen kappa = 0.70, sensitivity = 0.88, specificity = 0.92). Intramethod comparison of results for exposure prediction showed moderate agreement between the three evaluators (two program team evaluators and one external evaluator) (weighted Fleiss kappa = 0.60, P = 0.003). Interevaluator reliability of the semiquantitative exposure characterization results was excellent between the two evaluators from the program team (Spearman rho = 0.93, P = 0.03) and fair when these two evaluators' results were compared with the external evaluator's results. The project was undertaken within the framework of the French epidemiological surveillance program EpiNano. This study allowed a first reliability assessment of the EpiNano method. However, to further validate this method a comparison with robust quantitative exposure measurement data is necessary.

Impact of subsequent screening episodes on the positive predictive value for advanced neoplasia and on the distribution of anatomic subsites of colorectal cancer: A population-based study on behalf of the French colorectal cancer screening program.

BACKGROUND: The anatomic distribution of advanced colorectal neoplasia is increasingly important for choosing screening strategies and treatment options. We sought to evaluate the impact of repeated screening on the positive predictive value (PPV) for advanced colorectal neoplasia (advanced adenoma, AA, and colorectal cancer, CRC) and their distribution according to anatomic subsite distribution in average-risk adults. METHOD: The study included 98,031 men and women aged 50-74 who had a positive g-FOBT in 2010 and 2011 and underwent total colonoscopy. The PPV for detection of AA and CRC and the relative risks were determined with log-binomial models, and the distribution of anatomic subsites was estimated according to screening history. RESULT: The median age was 61 years (62 years for participants with AA and 64 for those with CRC). The PPV for detection of advanced neoplasia was 24.5%, substantially higher in men than women (30.7% vs 17.7%), and it increased with age. It also fell at all screening episodes after the first. Subsequent screening episodes were associated with an increased RR for proximal AA (RR 1.13, 95% CI 1.16-1.20). Advancing age (RR 1.28, 95% CI 1.19-1.39 for every 10-year increase in age), female gender (RR 1.31, 95% CI 1.19-1.44), and subsequent screening (RR 1.15, 95% CI 1.04-1.27) were significantly and independently associated with detection of proximal adenocarcinoma. The latter was also detected at an advanced stage more often (RR, 1.24, 95% CI: 1.09-1.42). Early stages of invasive adenocarcinoma (stages I and II) was more likely to be detected in a subsequent than an initial screening (RR 1.07, 95% CI 1.01-1.13). CONCLUSION: This study found that subsequent screening episodes using g-FOBT were associated with an increase in the detection rate of proximal AA and CRC, especially among women. The more frequent detection of proximal invasive adenocarcinoma at an advanced stage in subsequent screenings suggests that some of these tumors may well not be real incident lesions, but are likely to include lesions that were missed on the previous screens. Although modest, the increase in the rate of detection of invasive adenocarcinoma at early (and more curable) stages from the first to subsequent screenings, together with this potential for missed diagnoses on initial screening and the increased detection rate for proximal or rectal AA in subsequent screening episodes, underlines the need to reinforce the population's awareness of the importance of regular consistent screening, after negative results.

Colorectal cancer screening by guaiac faecal occult blood test in France: Evaluation of the programme two years after launching.

BACKGROUND: The French national screening programme for colorectal cancer (CRC) was rolled out nationwide from 2008. It targets men and women aged 50-74 who are invited every 2 years to perform a guaiac faecal occult blood test, followed, if positive, by a colonoscopy. This paper presents the evaluation of the programme for the 46 French districts that conducted a comprehensive screening campaign during 2008-2009, targeting 9.7 million people. METHODS: National database gathering information on people who were screened was used to estimate indicators reflecting the programme performance. RESULTS: Participation was 34.3%, with nearly three million people being tested. The percentage of positive tests was 2.8%. Completion of colonoscopies following a positive test was 88%. For men, 36.8% of the results of colonic explorations were normal, 40.1% were adenomas, and 9.0% were CRC, based on the most pejorative lesion. For women, corresponding figures were 55.9%, 25.7% and 5.8%. A CRC was detected for 7.5% of people who had a colonic exploration. The advanced adenoma detection rate among those screened was 4.9‰ and the CRC detection rate was 1.9‰. The description of CRC could only be made for 21 districts, for which 1441 invasive colonic adenocarcinomas were diagnosed; of these, 43% were stage I, 23% stage II, 25% stage III and 9% stage IV. CONCLUSION: This first evaluation since the programme was rolled out provides an inventory of CRC screening in France and points out some improvements expected, especially in terms of participation which is below the European recommendations. Future evaluations will analyse trends in these indicators.