Some pesticides can be harmful to humans, but beer may be an organic solution to that problem, suggests a study published in Frontiers in Sustainable Food Systems. A team of researchers, led by Maite Gandariasbeitia from NEIKER-BRTA Basque Institute for Agricultural Research and Development in Spain, has investigated organic by-products of used beer grains (called bagasse) and canola (rapeseed oil) cakes, to find that they make a useful pesticide when mixed with cow manure.