By Roland Pease
BBC Science correspondent
Genetically engineered rice crops can cut costs for poor farmers and improve health, a new Chinese study says.
GM companies promise higher yields from fields
In the study, published in the journal Science, Chinese and US researchers looked at the use of insecticides in small farm trials.
They compared normal strains of rice with varieties modified to have innate resistance to pests.
Chinese GM rice has been undergoing safety trials for nearly a decade now, but is not yet fully licensed.
One of the arguments against genetically engineered crops is that they benefit the seed companies, but not the farmers.
The authors of the new study disagree.
They found that Chinese farmers using rice engineered to resist insect pests made huge savings on insecticides, compared with their neighbours who had planted ordinary hybrid strains.
This had nothing to do with any specialist guidance the farmers received, because they were left to manage their crops as they saw fit.
As well as cutting costs, the researchers say, the farmers benefited from better health.
Pesticides in China are cheap and widely used, but poison an estimated 50,000 farmers a year, up to 500 fatally.
Dr Jikun Huang, who led the study, said he hoped it would help persuade the Chinese government to license the commercial use of GM rice.
If it does, the impact beyond China's borders would be substantial.
The world's largest country would be taking a lead in commercialising a major staple GM food developed in its own labs, which could transform the GM debate across the world.
But anti-GM campaigner Greenpeace expressed serious concern over the study.
Sze Pang Cheung, of Greenpeace China, commented: "The Science paper states that farmers cultivated the [genetically engineered - GE] rice without the assistance of technicians, and that quite a number of the randomly selected participants grew both [genetically engineered] and conventional varieties on their small family farms."
This month, Greenpeace found that GM rice that had not been approved for consumption was on sale in China and could have contaminated exports. It said the Science study provided further evidence of the failure to control GM rice trials in China.
"In other countries, GE field trials are tightly regulated, monitored and separated from conventional rice crops," Sze added.
"We should not be risking long-term health and environmental impacts, as well as international consumer rejection of Chinese rice when we don't need [genetic engineering] in the first place."