List the disadvantages of production of genetically modified crops.

Explanation

1. Environmental hazards. These are as follows:-
(i) Unintended harm to other organisms. Last year a laboratory study was published in "Nature showing that pollen from Bt corn caused high mortality rates in monarch butterfly caterpillars. Monarch caterpillars consume milkweed plants, not corn, but the fear is that if pollen from Bt com is blown by the wind onto milkweed plants in neighbouring fields, the caterpillars could eat the pollen and perish. Although the .Nature. study was not conducted under natural field conditions, the results seemed to support this viewpoint..
(ii) Reduced effectiveness of pesticides. Just as some populations of mosquitoes developed resistance to the now-banned pesticide DDT, many people are concerned that insects will become resistant to Bt or other crops that have been genetically modified to produce their own pesticides.
(ii) Gene transfer to non-target species. Another concern is that crop plants engineered for herbicide tolerance and weeds will cross-breed, resulting in the transfer of the herbicide resistance genes from the crops into the weeds. These "superweeds" would then be herbicide tolerant as well. Other introduced genes may cross over into non-modified crops planted next to GM crops.
2. Human health risks. GM food can lead the following health problems.
(i) Allergies. The transgenic food may cause toxicity and or produce allergies. The enzyme produced by the antibiotic resistance gene can cause allergies, because it is a foreign protein.
(ii) Effect on Bacteria of Alimentary canal. The bacteria present in the human alimentary canal can take up the antibiotic resistance gene that is present in the GM food. These bacteria can become resistant to the concerned antibiotic and are difficult to manage.
(iii) Economic concerns. Bringing a GM food to market is a lengthy and costly process, and of course agri biotech companies wish to ensure a profitable return on their investment.