In "The Biotech Century", Rifkin argues that 'Genetic engineering represents the ultimate tool.' 'With genetic technology we assume control over the hereditary blueprints of life itself. Can any reasonable person believe for a moment that such unprecedented power is without substantial risk?' Some of the changes he highlights are: replication partially replacing reproduction; and 'Genetically customized and mass-produced animal clones could be used as chemical factories to secrete—in their blood and milk—large volumes of inexpensive chemicals and drugs for human use.'