RT Journal Article SR Electronic T1 Longitudinal investigation of haematological alterations among permethrin-exposed pesticide applicators in the Biomarkers of Exposure and Effect in Agriculture study JF Occupational and Environmental Medicine JO Occup Environ Med FD BMJ Publishing Group Ltd SP 467 OP 470 DO 10.1136/oemed-2018-105559 VO 76 IS 7 A1 Shearer, Joseph J A1 Beane Freeman, Laura E A1 Liu, Danping A1 Andreotti, Gabriella A1 Hamilton, Jennifer A1 Happel, Julie A1 Lynch, Charles F A1 Alavanja, Michael C A1 Hofmann, Jonathan N YR 2019 UL http://oem.bmj.com/content/76/7/467.abstract AB Objectives Permethrin use has been associated with an increased risk of multiple myeloma (MM) among pesticide applicators. However, the biological plausibility and mechanisms underlying this association are not fully understood. The aim of this study was to assess whether exposure to permethrin is related to haematological alterations among occupationally exposed pesticide applicators.Methods We conducted a longitudinal study among 33 pesticide applicators in the Biomarkers of Exposure and Effect in Agriculture study comparing haematological parameters in the offseason with the day after permethrin exposure and, for 27 participants, approximately 3 weeks postexposure. Complete blood counts with white blood cell differential and lymphocyte subsets were measured at each visit. Multivariate linear mixed effects models were used to assess the relationship between natural log-transformed haematological parameters and exposure to permethrin.Results The adjusted geometric mean immature granulocyte count was elevated among pesticide applicators following permethrin exposure compared with their offseason levels (37% increase, 95% CI 6% to 76%). Modest but statistically significant (p<0.05) alterations in red blood cell (RBC) parameters (eg, decreased RBC count and haemoglobin and increased mean corpuscular volume and RBC distribution width-SD) were also observed the day after permethrin use compared with offseason levels; decreases in RBC count and haemoglobin and increases in RBC distribution width-SD persisted approximately 3 weeks after permethrin use.Conclusions Altered haematological parameters could be indicative of disrupted haematopoiesis, providing insights into the biological plausibility of the observed association between permethrin use and MM risk among pesticide applicators.