Corresponding author: M A Dalvie (aqiel.dalvie@uct.ac.za) Background. Rural residents in the Western Cape (WC), South Africa (SA) are highly exposed to agricultural pesticides that could impact their reproductive development. However, epidemiological evidence of the effect of pesticides on pubertal growth is contradictory. Objective. To investigate the effect of pesticide exposure measured using indices of environmental exposure to pesticides on the pubertal growth of boys in rural WC, SA. Methods. A cross-sectional study of 269 boys (177 of whom gave a history of residing on farms) was conducted. A questionnaire was administered, height and weight were measured and body mass index was calculated. A proximity index (PI) and spraying index (SI) was developed, measuring the lifetime average home distance from pesticide spraying and average frequency of spraying pesticides on a farm, respectively. Results. Median age of boys was 12.4 years (interquartile range 9.5 -13.3). More than 60% boys had height and weight <50th percentile for age. After adjusting for confounders, PI was significantly associated with shorter stature and lower weight (-1.7 cm/10-fold decrease, p=0.02 and -1.24 kg/10-fold decrease, p=0.04; respectively) and SI was non-significantly associated (-1.4 cm/10-fold increase, p=0.05 and -1.1 cm/10-fold increase, p=0.06; respectively). Associations were stronger for boys aged <11 years and were weaker when excluding nonfarm boys. There were no other associations between outcome and exposure. Conclusions. The use of quantitative exposure indices showed that lower heights and weights might be associated with pesticide exposure in farm boys v. non-farm boys, but not among farm boys. Lower anthropometric measurements among farm boys v. non-farm boys appear stronger at a younger age. The indices of environmental exposure to pesticides require further development.

Objectives Many contemporary pesticides used for spraying on agricultural crops have been shown to be hormonally active. This study investigated the effect of pesticide exposure, measured by means of environmental exposure indices, on pubertal growth of boys residing in the rural Western Cape. Methods A cross-sectional study of 269 boys including 176 boys residing on farms and 93 not residing on farms was conducted in the rural Western Cape. Tests included a questionnaire (items on demographics, birth weight, general and reproductive health, diet, residential history, pesticide exposures and mother's exposures during pregnancy) and height, weight and BMI of boys. A proximity, spraying intensity and a combined proximity-spraying index was calculated, respectively measuring the lifetime average distance of home from spraying, lifetime average frequency of spraying on farm and both. Results The median age of the boys was 11 years (range: 7-19 years). More than 60% boys had height & weight measurements < 50th percentile for age (according to CDC growth charts). The median distance of home to nearest spraying area was 100 m (range: 17.5-974.5 m) and median number of spraying days per annum on farm was 90 (range: 50-180). The proximity index was also associated with shorter stature (β = 0.0032, p = 0.03) adjusting for household income and alcohol intake during pregnancy. Further analysis is underway exploring the relationships between exposure indices and outcomes. Conclusions Preliminary results indicate that lifetime environmental exposure to pesticides have adverse effects on the height of boys.