What are 5 negative effects of the Columbian Exchange?

The Columbian Exchange is the name given to a number of cultural and biological exchanges between the Old and New Worlds after Columbus' discovery in 1492. While this exchange brought many benefits to both sides; for example, through the greater variety of food, it also had many negative effects which can be summarised here:

1. Many plants brought to the New World damaged the environment. Plants like dandelion and couch grass, for example, disrupted the availability of sunlight to existing flora and aggravated the hooves and teeth of New World livestock. 


2. Similarly, the introduction of some animals upset the balance of life in the New World. Rats, for example, were accidentally brought to America and from Europe. Not only did they cause disease, rats also wiped out some smaller animals. 


3. The exchange brought diseases, like smallpox, measles and typhus, to the New World population.


4. The relationship between the natives and the settlers was fraught with tensions, particularly with regard to land. The Europeans often stole land from the natives to colonise and farm on.  


5. The natives became dependent on guns brought to America from Europe. They used these to hunt larger animals but the settlers, seeing this new reliance, overcharged the natives, therefore financially exploiting them.