Pesticide companies and regulators in developing countries use the United Nations Food and Agricultural Organization (FAO) recommended pictograms on pesticide labels to communicate risk information based on toxicological and environmental risk assessment data. The pesticide label not only is often the only access people have to pesticide risk information, but also in many countries is a legally binding document. As a result of the crucial role pesticide labels play in protecting health and the environment and as a legal instrument, pictograms are used to overcome literacy challenges in transmitting pesticide risk information. Yet, this risk communication tool is often prone to misinterpretations of the risk information which results in hazardous exposures to pesticides for farm workers and end-users generally. In this paper, results are presented from a study with 115 farm workers on commercial vineyards in the Western Cape, South Africa, assessing their interpretations of 10 commonly used pictograms. A standardized questionnaire based on four commonly used pesticide labels was administered. Overall, 50% or more of the study farm workers had misleading, incorrect and critically confused interpretations of the label pictograms. Interpretations often reflected farm workers' social and cultural frames of reference rather than the technically intended risk information. For example, the pictogram indicating a pesticide's toxicity requires boots must be worn, evoked interpretations of "dangerous to pedestrians" and "don't walk through pesticides". Furthermore, there was a gender variation in pictogram comprehension whereby males generally had more correct interpretations than females. This is a result both of a lack of training for women who are assumed to not work with pesticides, as well as a lack of pictograms relevant for female exposures. These findings challenge the viability of the United Nations current initiative to globally harmonize pictograms used on all chemical labels under the new Globally Harmonized System for the Classification and Labelling of Chemicals (GHS). Particularly as the GHS pictograms were not piloted prior to adoption of the system and represent complex risk assessment data such as chronic hazards. Public health and pesticide policy, backed by relevant research, need to address developing applicable and effective pesticide risk communication tools, particularly for developing country populations. Merely providing risk assessment derived information in a pictogram does not ensure that an end-user will interpret the message as intended and be able to make risk decisions which mitigate risks from exposures to pesticides or chemicals in general.