Rose in greenhouses, and in warmer countries they may also be grown under cover in order to ensure that the flowers are not damaged by weather and that pest and disease control can be carried out effectively. Significant quantities are grown in some tropical countries, and these are shipped by air to markets across the world. Some kind of roses are artificially coloured using dyed water, like rainbow roses. Rose perfumes are made from rose oil (also called attar of roses), which is a mixture of volatile essential oils obtained by steam distilling the crushed petals of roses. An associated product
Essential oil may contain impurities and additives that may be harmful to pregnant women. Sensitivity to certain smells may cause pregnant women to have adverse side effects with essential oil use, such as headache, vertigo, and nausea. Pregnant women often report an abnormal sensitivity to smells and taste, and essential oils can cause irritation and nausea when ingested. Always consult a doctor before use. The following table lists the or median lethal dose for common oils; this is the dose required to kill half the members of a tested animal population. LD is intended as a guideline only, and reported values can