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BackgroundPesticide exposure is associated with many long-term health outcomes; the potential underlying mechanisms are not well established for most associations. Epigenetic modifications, such as DNA methylation, may contribute. Individual pesticides may be associated with specific DNA methylation patterns but no epigenome-wide association study (EWAS) has evaluated methylation in relation to individual pesticides.ObjectivesWe conducted an EWAS of DNA methylation in relation to several pesticide active ingredients.MethodsThe Agricultural Lung Health Study is a case-control study of asthma, nested within the Agricultural Health Study. We analyzed blood DNA methylation measured using Illumina's EPIC array in 1,170 male farmers of European ancestry. For pesticides still on the market at blood collection (2009-2013), we evaluated nine active ingredients for which at least 30 participants reported past and current (within the last 12 months) use, as well as seven banned organochlorines with at least 30 participants reporting past use. We used robust linear regression to compare methylation at individual C-phosphate-G sites (CpGs) among users of a specific pesticide to never users.ResultsUsing family-wise error rate (p

BACKGROUND: Growing evidence suggests that pesticide use may contribute to respiratory symptoms. Objective: We evaluated the association of currently used pesticides with allergic and non-allergic wheeze among male farmers. METHODS: Using the 2005-2010 interview data of the Agricultural Health Study, a prospective study of farmers in North Carolina and Iowa, we evaluated the association between allergic and non-allergic wheeze and self-reported use of 78 specific pesticides, reported by [greater than or equal to] 1% of the 22,134 men interviewed. We used polytomous regression models adjusted for age, BMI, state, smoking, and current asthma, as well as for days applying pesticides and days driving diesel tractors. We defined allergic wheeze as reporting both wheeze and doctor-diagnosed hay fever (n = 1,310, 6%) and non-allergic wheeze as reporting wheeze but not hay fever (n = 3,939, 18%); men without wheeze were the referent. RESULTS: In models evaluating current use of specific pesticides, 19 pesticides were significantly associated (p < 0.05) with allergic wheeze (18 positive, 1 negative) and 21 pesticides with non-allergic wheeze (19 positive, 2 negative); 11 pesticides were associated with both. Seven pesticides (herbicides: 2,4-D and simazine; insecticides: carbaryl, dimethoate, disulfoton, and zeta-cypermethrin; and fungicide pyraclostrobin) had significantly different associations for allergic and non-allergic wheeze. In exposure-response models with up to five exposure categories, we saw evidence of an exposure-response relationship for several pesticides including the commonly used herbicides 2,4-D and glyphosate, the insecticides permethrin and carbaryl, and the rodenticide warfarin. Conclusions: These results for farmers implicate several pesticides that are commonly used in agricultural and residential settings with adverse respiratory effects., Introduction Worldwide, more than 5 billion pounds of pesticide active ingredients are used annually (U.S. EPA 2011a). Pesticides represent a diverse group of chemical and physical agents that have varying [...]

Purpose: During MR scans, abandoned leads from active implantable medical devices (AIMDs) can experience excessive heating at the lead tip, depending on the type of termination applied to the proximal contacts (proximal end treatment). The influence of different proximal end treatments (ie, [1] freely exposed in the tissue, [2] terminated with metal in contact with the tissue, or [3] capped with plastic, and thereby fully insulated, on the RF‐induced lead‐tip heating) are studied. A technique to ensure that MR Conditional AIMD leads remain MR Conditional even when abandoned is recommended. Methods: Abandoned leads from three MR Conditional AIMDs ([1] a sacral neuromodulation system, [2] a cardiac rhythm management pacemaker system, and [3] a deep brain stimulator system) were investigated in this study. The computational lead models (ie, the transfer functions) for different proximal end treatments were measured and used to assess the in vivo lead‐tip heating for four virtual human models (FATS, Duke, Ella, and Billie) and compared with the lead‐tip heating of the complete MR Conditional AIMD system. Result: The average and maximum lead‐tip heating for abandoned leads proximally capped with metal is always lower than that from the complete AIMD system. Abandoned leads proximally insulated could lead to an average in vivo temperature rise up to 3.5 times higher than that from the complete AIMD system. Conclusion: For the three investigated AIMDs under 1.5T MR scanning, our results indicate that RF‐induced lead‐tip heating of abandoned leads strongly depends on the proximal lead termination. A metallic cap applied to the proximal termination of the tested leads could significantly reduce the RF‐induced lead‐tip heating. [ABSTRACT FROM AUTHOR]

Purpose: To assess RF‐induced heating hazards in 1.5T MR systems caused by body‐loop postures. Methods: Twelve advanced high‐resolution anatomically correct human body models with different body‐loop postures are created based on poseable human adult male models. Numerical simulations are performed to assess the radiofrequency (RF)‐induced heating of these 12 models at 11 landmarks. A customized phantom is developed to validate the numerical simulations and quantitatively analyze factors affecting the RF‐induced heating, eg, the contact area, the loop size, and the loading position. The RF‐induced heating inside three differently posed phantoms is measured. Results: The RF‐induced heating from the body‐loop postures can be up to 11 times higher than that from the original posture. The RF‐induced heating increases with increasing body‐loop size and decreasing contact area. The magnetic flux increases when the body‐loop center and the RF coil isocenter are close to each other, leading to increased RF‐induced heating. An air gap created in the body loop or generating a polarized magnetic field parallel to the body loop can reduce the heating by a factor of three at least. Experimental measurements are provided, validating the correctness of the numerical results. Conclusion: Safe patient posture during MR examinations is recommended with the use of insulation materials to prevent loop formation and consequently avoiding high RF‐induced heating. If body loops cannot be avoided, the body loop should be placed outside the RF transmitting coil. In addition, linear polarization with magnetic fields parallel to the body loop can be used to circumvent high RF‐induced heating. [ABSTRACT FROM AUTHOR]

Purpose: The paper presents a novel method to reduce the RF‐induced heating of active implantable medical devices during MRI. Methods: With the addition of an energy decoying and dissipating structure, RF energy can be redirected toward the dissipating rings through the decoying conductor. Three lead groups (45 cm‐50 cm) and 4 (50 cm‐100 cm) were studied in 1.5 Tesla MR systems by simulation and measurement, respectively. In vivo modeling was performed using human models to estimate the RF‐induced heating of an active implantable medical device for spinal cord treatment. Result: In the simulation study, it was shown that the peak 1g‐averaged specific absorption rate near the lead‐tips can be reduced by 70% to 80% compared to those from the control leads. In the experimental measurements during a 2‐min exposure test in a 1.5 Telsa MR system, the temperature rises dropped from the original 18.3℃, 25.8℃, 8.1℃, and 16.1℃ (control leads 1‐4) to 5.4℃, 6.9℃, 1.6℃, and 3.3℃ (leads 1‐4 with the energy decoying and dissipation structure). The in vivo calculation results show that the maximum induced temperature rise among all cases can be substantially reduced (up to 80%) when the energy decoying and dissipating structures were used. Conclusion: Our studies confirm the effectiveness of the novel technique for a variety of scanning scenarios. The results also indicate that the decoying conductor length, number of rings, and ring area must be carefully chosen and validated. [ABSTRACT FROM AUTHOR]

Purpose: This paper studies the RF‐induced heating for modular external fixation devices applied on the leg regions of the human bodies. Through numerical investigations of RF‐induced heating related to different patient orientations, landmark positions, and device positions under 1.5T and 3T MRI systems, simple and practical methods to reduce RF‐induced heating are recommended. Methods: Numerical simulations using a full‐wave electromagnetic solver based on the finite‐difference time‐domain method were performed to characterize the effects of patient orientations (head‐first/feet‐first), landmark positions (the scanning area of the patient), and device positions (device on left or right leg) on the RF‐induced heating of the external fixation devices. The G32 coil design and three anatomical human models (Duke model, Ella model, and Fats model) were adopted to model the MRI RF coil and the patients. Results: The relative positions of the patient, device, and coil can significantly affect the RF‐induced heating. With other conditions remaining the same, changing the device position or patient orientation can lead to a peak 1‐g averaged spatial absorption ratio variation of a factor around four. By changing the landmark position and the patient orientation, the RF‐induced heating can be reduced from 1323.6 W/kg to 217.5 W/kg for the specific scanning situations studied. Conclusion: Patient orientations, landmark positions, and device positions influence the RF‐induced heating of modular external fixation devices at 1.5 T and 3 T. These features can be used to reduce the RF‐induced heating during MRI simply and practically. [ABSTRACT FROM AUTHOR]

Literature suggests that early exposure to the farming environment protects against atopy and asthma; few studies have examined pulmonary function. We evaluated associations between early-life farming exposures and pulmonary function in 3061 adults (mean age=63) from a US farming population using linear regression. Childhood raw milk consumption was associated with higher FEV1 (β=49.5 mL, 95% CI 2.8 to 96.1 mL, p=0.04) and FVC (β=66.2 mL, 95% CI 13.2 to 119.1 mL, p=0.01). We did not find appreciable associations with other early-life farming exposures. We report a novel association between raw milk consumption and higher pulmonary function that lasts into older adulthood. [ABSTRACT FROM AUTHOR]

Objective. A bone-inclusive ASTM phantom is proposed to improve the assessment of radiofrequency electromagnetic field (RF-EMF) power deposition near orthopedic device under 1.5 T and 3 T magnetic resonance imaging (MRI). Approach. A phantom is created by introducing a cylindrical bone structure inside the American Society for Testing and Materials (ASTM) phantom. Four orthopaedic implant families-rod, nailing system, plate system, and hip replacement-are used in the study. RF-EMF power deposition (in terms of peak averaged specific absorption rate over 1 gram) near these implants are evaluated by placing these implants inside the standard ASTM phantom, the developed bone-inclusive ASTM phantom, and two anatomically representative human body phantoms, known as Duke and Ella. Numerical simulations are performed to calculate the RF-EMF power deposition near various orthopaedic devices within these phantoms. Main Results. For devices implanted inside or near bone tissue, the evaluation of RF-EMF power deposition using the developed bone-inclusive ASTM phantom shows better correlations to the human body phantoms than the ASTM phantom. This improvement is attributed to the portion of the devices implanted within the bone tissue. Significance. The bone-inclusive ASTM phantom has the different tissue of interests surrounding the implants compared to the ASTM phantom. This variation can lead to the different resonance frequency under RF-EMF exposure. This leads to better correlation of RF-EMF power deposition near orthopaedic implants inside human body, making the bone-inclusive ASTM phantom more suitable for evaluating RF-EMF power deposition than ASTM phantom in MRI scans., (© 2024 Institute of Physics and Engineering in Medicine.)