three northern governorates of Nineveh, Kirkuk and Erbil together received more than half the shipments. Contributing factors to the epidemic included the fact that distribution started late, and much grain arrived after the October–November planting season. Farmers holding the poisoned grain instead offered it to their families as food, since their own planting had been completed. Distribution was hurried and open, with grain being distributed free of charge or with payment in kind. Some farmers even sold off their own grain, lest this new grain's harvest devalue their old varieties. This left them dependent on tainted grain for the winter. Many Iraqis were either unaware of the significant health risk posed, or chose to ignore the warnings. Initially, farmers were to certify with a thumbprint or signature that they understood the grain was poison, but according to some sources, distributors did not ask for such an indication. Warnings on the sacks were in Spanish and English, not at all understood, or included the black-and-white skull and crossbones design, which meant nothing to Iraqis. The long, asymptomatic latent period of mercury poisoning may have granted farmers a false sense of security when animals fed the grain initially appeared to be fine. The red dye washed off the grain; the mercury did not. Hence, washing may have given only the appearance of removing the poison. Mercury was ingested through the consumption of homemade bread, meat and other animal products obtained from livestock given treated barley, vegetables grown from soil contaminated with mercury, game birds that had fed on the grain and fish caught in rivers, canals, and lakes into which treated grain had been dumped by the farmers. Ground seed dust inhalation was a contributing factor in farmers during sowing and grinding. Consumption of ground grain in homemade bread is thought to have been the major source of toxicity, since no cases were reported in urban areas, where government flour supplies were commercially regulated. Symptoms, outbreak and treatment The effect of mercury took some time – the latent period between ingestion and the first symptoms (typically paresthesia – numbness in the extremities) was between 16 and 38 days. Paresthesia was the predominant symptom in less serious cases. Worse cases included ataxia (typically loss of balance), blindness or reduced vision, and death resulting from central nervous system failure. Anywhere between 20 and 40 mg of mercury has been suggested as sufficient for paresthesia