Ford discovered the contamination during an investigation at its Twin Cities assembly plant that's required as part of the company's preparations to sell the property.
Ford owns the land, but has allowed youth baseball organizations to run leagues at the site for decades.
Andy Hobbs directs Ford's Environmental Quality office. He says Ford sampled eight areas for contaminants. Readings from four of the areas exceeded Minnesota guidelines for recreational use.
"All of those levels are still extremely low levels. They are all six inches to six feet beneath the surface of the ball fields. None of the substances we believe pose a health risk," says Hobbs.
Iron levels in the soil ranged from roughly 13,000 to 20,000 parts per million. The state standard is 12,000 parts per million.
Copper levels ranged from 13 to 35 parts per million. The state standard is 11 parts per million.
Arsenic levels were barely above the state's standard of 5 parts per million. They ranged from 5 to 16 parts per million.
Minnesota Department of Health spokesman Buddy Ferguson says of the three contaminants, health officials probably would be most concerned about arsenic. In this case, he says, the levels are extremely low.
"And in fact it really is in a range that could be attributed to normal background levels of arsenic," says Ferguson. "It's quite common to find levels of arsenic in the range of 20 parts per million, both in urban areas and elsewhere in the state."
Ferguson says the department can't comment on any possible health risks related to the ball field site until agency officials get a chance to investigate the matter further.
But parent Megan Tarnow says based on what she has heard about the contamination, she's not worried about the health of her 11-year-old son who played there this summer.
"The kids that are old enough to be playing baseball are not licking the dirt, especially if it's six inches [down]. The kids are not digging down six inches into the dirt," says Tarnow.
Tarnow adds that kids have been using the ball fields for more than 50 years. She says if there was a major problem, she believes it would be obvious by now.
Ford officials say they're not sure how the contaminants got into the soil. Andy Hobbs says he doesn't think its associated with any manufacturing activities at the site.
"We suspect it could be from backfill that was used on the site, or even fertilizer," says Hobbs. "It's very common in fertilizer and backfill to find these contaminants."
Hobbs says Ford will take more soil samples in the weeks ahead to determine the scope of the contamination. He says the company hasn't decided yet whether it will remove the contaminated soil or cap it.
The Ford fields are used by dozens of youth baseball teams. The season is winding down for many, but some teams play in the fall. Ford says it will do what it can to help the teams find other locations to play.