The company wants the Environmental Protection Agency to pass an increase of 4.9 parts per million of thiamethoxan. The current allowable level is 0.1ppm, Syngenta wants it increased to 5.0ppm. You can read the details on the regulations.gov  website which published the request on September 5th. The request itself was filed on August 22nd.
Tiffany Stacker of E&E  reports:
“Neonicotinoid pesticides are one of many factors that scientists say have caused a dramatic decline in pollinators, insects and animals that help crop production by carrying pollen from one plant to another. More than half of the managed honeybee colonies in the US have vanished during the last decade, according to the Pollinator Partnership nonprofit group.”
“Scientists say neonicotinoids can suppress bees’ immune systems, making them more vulnerable to viruses and bacteria. The Fish and Wildlife Service agreed to phase out neonicotinoids on wildlife refuges nationwide starting in January 2016,”
The Ontario Ministry of the Environment, and the Ministry of Agriculture came to the same conclusion as Stacker last year.
From Global News: 
“The information evaluated suggests that planting of corn seeds treated with the nitro-guanidine insecticides clothianidin and/or thiamethoxan contributed to the majority of the bee mortalities that occurred in corn growing regions of Ontario and Quebec in Spring 2012…The unusual weather conditions in the spring of 2012 were likely also a contributing factor.”
Clothianidin and thiamethoxan are two types of insecticides. Part of the neonicotinoid (NNI) family, they are used on about 95 per cent of corn crops in Canada and the U.S., as well as about 70 per cent of soy. The report clearly identified the pesticide as contributing to the majority of bee losses in a key region of corn and soy production. But there was no ban.
Then in July 2014, the Ontario government made an unprecedented move: the Liberal government confirmed that it was seeking to restrict the use of these pesticides .
The European Union banned the use of these pesticides two years ago after a major study found that their use closely correlated with Colony Collapse Disorder in previously well established bee colonies. You can read more about that at The European Environment Agency. 
The EPA is accepting comments regarding the request up until October 6th.
To comment on the Syngenta request click on this link  and them hit the comments tab in the top right corner.