Learning and recall of Worker Protection Standard (WPS) training in vineyard workers.

Worker Protection Standard (WPS) training is one of the U.S. Environmental Protection Agency's (EPA) primary methods for preventing pesticide exposure in agricultural workers. Retention of the knowledge from the training may occasionally be tested by state Occupational Safety and Health Administrations (state OSHAs) during a site visit, but anecdotal evidence suggests that there is no consistent testing of knowledge after WPS training. EPA's retraining requirements are at 5-year intervals, meaning the knowledge must be retained for that long. Vineyard workers completed a test of their baseline WPS knowledge, computer-based training on WPS, a post-test immediately after training and a re-test 5 months later. Pre-test performance suggested that there was a relatively high level of baseline knowledge of WPS information on two-answer multiple choice tests (74% to 75%) prior to training. Training increased the knowledge to 85% on the post-test with the same questions, a significant increase (p < .001, 1-tailed) and a large effect size (d) of .90. Re-test performance (78%) at 5 months revealed a return towards but not back to the pre-test levels. Better test performance was significantly correlated with higher education and to a lesser extent with younger ages. Whether this level of knowledge is sufficient to protect agricultural workers remains an open question, although an increase in the proportion of people in a work group who know the critical WPS information may be the most important impact of training.