Produce grown without the use of synthetic chemicals or materials. Foods claiming to be organic must be free of artificial food additives, and processed with fewer artificial methods, materials and conditions, such as chemical ripening, food irradiation, and genetically modified ingredients. Pesticides are allowed so long as they are not synthetic. For most of human history, food has been grown organically, but 20th century agriculture began to introduce pesticides and fertilizers using man-made chemicals. Organic food labeling is strictly regulated in the US by the US Department of Agriculture (USDA). The USDA carries out regular inspections of organic farmers and producers, spot testing their products for traces of pesticides or chemical fertilizers. Different countries have minor variances in defining what constitutes a product as being organic or naturally-grown. Organic products generally have less environmental impact and are considered healthier for consumption.