Monsanto Hawaii, a company specializing in biotech corn seed crops, has signed a 99-year lease that will expand its presence on Moloka'i.

Monsanto had been leasing 700 acres from Molokai Properties Ltd., and the new deal gives the company three agricultural parcels totaling 1,650 acres, of which about 1,200 acres are suitable for farming.

The expansion will result in more jobs for Moloka'i, but environmentalists are concerned about the growing presence of genetically modified crops on the rural island.

The groups say the modified crops have not been adequately tested for long-term effects and could cross-pollinate with organic crops.

"It's absolutely scary for us because these chemical companies, Monsanto and Dow, are becoming the main farmers on our island," said community activist Walter Ritte, speaking on behalf of the group Hui Ho'opakele Aina.

"We have no protection because the state and the feds are not regulating them to our satisfaction."

Peter Nicholas, chief executive of Molokai Properties, said Monsanto has agreed to agricultural easements in line with the Community-Based Land Use Master Plan for Moloka'i Ranch.

"Monsanto has always been a good neighbor and provides much-needed jobs for our community," he said. "We believe this will be tremendous for the island."

Monsanto, which has been on Moloka'i since the 1960s previously under the name Hawaiian Research, employs about 110 full-time and 80 seasonal employees on the island.