However, for GM crops used in the production of pharmaceuticals, or in other cases in which absolutely no outcrossing is permitted, the researchers recommend the combination of chloroplast transformation with other biological containment methods, such as cytoplasmic male sterility or transgene mitigation strategies. This study showed that whilst transplastomic plants do not have absolute gene containment, the level of containment is extremely high and would allow for coexistence of conventional and genetically modified agricultural crops.[14]