VALIDATING SILICONE WRISTBANDS TO MEASURE PESTICIDE EXPOSURES AMONG OLDER ADULTS -- PROOF-OF-CONCEPT STUDY

Silicone wristbands have been used to measure exposure to pesticides and other chemicals among children and younger farm workers, but not in older adults. Thus, we aimed to examine exposure to pesticides using silicone wristbands in a small cohort of older adults living on agricultural land, with variable contact with fields and pesticides. We also investigated correlations between pesticide levels on wristbands and urinary pesticide metabolites. Organophosphate (OPH) pesticides and several organochlorines were measured in wristbands worn by 15 males age 70+ (10 farmers using pesticides and 5 non-farmers with no recent pesticide use). Wristbands were worn continuously for 5-days. End-of-day urine samples were collected on days 1-3-5. Spearman correlations and Wilcoxon Scores were calculated. Five pesticides were quantified in the wristbands and detection frequencies ranged from 40-90%. In urine,12 OPH metabolites were quantified, but only 5 were detected in >50% of the samples. None of 5 urinary herbicides were detected. Imputation was performed by dividing minimum-detect by square-root-2. Malathion was only detected in farmers compared to non-farmers. Correlations between OPH urinary metabolites and wristband were examined but only two were significant and were negative in direction. Notably, organochlorine DDE on the wristbands was significantly correlated with 3 OPH metabolites. These unexpected relationships, based on small numbers, suggest a need to replicate this work in a larger study sample to explore potential for confounding or mixtures in future studies of pesticides and health in older farmers.

Abstract 4115: QT Response to Exercise Maneuvers Predicts Genotype in Long QT Syndrome

Genotyping of patients with suspected LQTS may influence prognosis and response to therapy. It remains expensive and difficult to access in many settings. The resting QT interval is normal or borderline in up to half of genetically affected patients, making expert directed genotyping important in the management of LQTS patients. We examined the use of provocative postural and exercise testing as a tool to diagnose LQTS and predict genotype. Patients with suspected LQTS based on a history of syncope or cardiac arrest, with an affected first-degree relative, or a borderline or prolonged QT interval underwent exercise testing. 117 genotyped patients underwent provocative testing consisting of resting supine and standing ECGs, and exercise testing using a modified Bruce protocol. ECGs were obtained during exercise and at 1-minute intervals during recovery. Medians and IQRs are presented, and compared with Wilcoxon scores. 57 Of the 117 patients had an LQT mutation (LQT+) identified by genetic testing (LQT1=29, LQT2=38). The resting and standing ECGs were most useful in discriminating LQT+ patients from LQT− patients, with a prolonged resting supine QTc that underwent exaggerated prolongation compared to unaffected family members (Table ). Genotype prediction in the LQT+ patients was best achieved using a combination of exercise QT and QTc changes that were most abnormal in LQT1 patients, along with hysteresis that was abnormal in LQT2 patients. Postural QTc changes are useful in identifying mutation positive LQTS patients. In patients with abnormal findings, LQT1 is associated with impaired QT and QTc shortening at peak exercise, and LQT2 patients have exaggerated hysteresis. Exercise testing is a useful simple tool in the diagnosis of LQTS that helps direct genetic testing.