Safety concerns have been raised about Ayurveda, with two U.S. studies finding about 20 percent of Ayurvedic Indian-manufactured patent medicines contained toxic levels of heavy metals such as lead, mercury and arsenic. Other concerns include the use of herbs containing toxic compounds and the lack of quality control in Ayurvedic facilities.
At an early period[when?], Ayurveda adopted the physics of the "five elements" (Devanāgarī: [महा] पञ्चभूत); earth (Pṛthvī), water (Jala), fire (Agni), air (Vāyu) and space (Ākāśa) that compose the universe, including the human body.[9] Ayurveda describes seven types of tissues of the body, known as thesaptadhātu (Devanāgarī: सप्तधातु). They are plasma (rasa dhātu), blood (rakta dhātu), flesh (māṃsa dhātu), adipose (medha dhātu), bone (asthi dhātu),marrow and nervous (majja dhātu), and reproductive (semen or female reproductive tissue) (śukra dhātu).[10] Ayurvedic literature deals elaborately with measures of healthful living during the entire span of life and its various phases. Ayurveda stresses a balance of three elemental energies or humors:Vāyu / vāta (air & space – "wind"), pitta