For home gardeners, spring planting is just a few weeks away. But if you're planning to add fertilizer to the soil, reading the product's label won't always tell you whether it's safe. In most states, including Minnesota, manufacturers can sell fertilizer containing arsenic, lead, cadmium, and other heavy metals without disclosing those ingredients. In Minnesota, that means a product called Ironite is still on the market, despite high levels of contamination.

When Carl Rosen, now acting head of the Horticulture Department at the University of Minnesota, wanted to improve the soil around his blueberry bushes, he went to a local garden store and bought a 25-pound box of Ironite.

The label listed the product's beneficial plant nutrients, such as nitrogen, iron, and sulfur.

But it neglected to mention another ingredient - arsenic.

"I actually used some of this, not knowing that it had arsenic in it, and I put it in a small area where I was growing some cranberries and lingonberries, that are acid loving plants," Rosen says. "One of the cranberries died where I put it, and I actually went in and measured the amount of arsenic in the soil. And the native level of arsenic's about one part per million in soils around here, and it was 100 parts per million."

Since then, sample tests of Ironite by the Minnesota Department of Agriculture have found arsenic levels of more than 4,000 parts per million. That's 100 times higher than the EPA's limit for arsenic in sewage sludge used as fertilizer. Ironite also contains high levels of lead.

The Agriculture Department responded by making the company change its label for Ironite sold in Minnesota. The new label drastically reduces the recommended application rates. The Agriculture Department says if less product is used per square foot, contamination levels are also reduced.

But Rosen says that's an ineffective way of dealing with the problem. "The thing that bothers me a little bit about this whole thing is that it is used for homeowner use, and homeowners don't often follow the labels. They'll put, you know, if one cup's good, two cups are better, that's often the mentality."

Rosen says if homeowners use too much Ironite, its arsenic and lead can build up in the soil and pose possible danger to pets and children.

And he says if Minnesota consumers do follow the label, the product is ineffective. Used at rates low enough to keep contamination under control, Ironite provides such low levels of nutrients that it does virtually nothing to improve the soil. "It's one of these things that it amazes me, that's it's still sold the way it is."

Calls to Minnesota garden centers found at least one major chain that still carries the product. The Minnesota Department of Agriculture's Greg Reginbal estimates that several tons of Ironite are sold each year in Minnesota. Reginbal says under current regulations, the agency doesn't have the authority to take further action, but points out that the federal EPA is considering stronger standards for fertilizers. He says if Minnesota adopts them, that would effectively take Ironite off the market here. "At the levels that we're seeing for Ironite right now, that would mean that would be an adulterated fertilizer that would not be sold in the state."

This year in Maine, environmental groups tried to pass a bill that would have banned fertilizers containing more than 500 parts per million of arsenic and effectively outlawed Ironite in that state. That measure failed, but lawmakers did pass a weaker version this month that requires the Maine Department of Agriculture to regulate heavy metals in fertilizers. In the meantime, Maine has halted Ironite sales.

Still, Heinz Brungs, president and owner of Ironite Products Company, denies the product poses a hazard.

Ironite is made from tailings from a defunct zinc mine in Arizona. The tailings include both arsenic and lead-bearing ores. But Brungs says as long as the arsenic and lead are in the form of ore, they're harmless. "This [ore]is one of the most distributed minerals on this planet, but it is insoluble," he says.

But scientists at the University of Minnesota and say the toxic elements do dissolve in water. During manufacturing, the ore is ground up into powder. When that's applied to soil and exposed to the weather, the arsenic and lead can be released into the environment.

Environmental groups say the fact that a product like Ironite remains on the market nearly nationwide reflects the general lack of regulation in the fertilizer market. They say given the lax rules, the practice of recycling waste as fertilizer poses a particular threat. Under federal law, manufacturers can recycle industrial and even hazardous waste as fertilizer without disclosing toxic ingredients.

The Minnesota Agriculture Department says few recycled fertilizers are used in Minnesota. The EPA says in most fertilizers, contamination levels are very low. But Jackie Hunt Christensen of the Minneapolis-based Institute for Agriculture and Trade Policy says members of the public ought to be able to read the ingredients for themselves.

"As a gardener and a mom I think people have a right to know ALL of what's in the fertilizer," she says. "I think everybody has a right to know what they're putting on their field or their garden or their lawn." In the meantime, she says consumers have to take it on themselves to become informed.

Christensen's group has worked with the state Departments of Agriculture and Health to set up websites that disclose fertilizer ingredients. For its part, the Ironite website assures consumers the product is safe and natural. It encourages home gardeners to use extremely high rates of the product. For bulb planting, it calls for five pounds of Ironite for a 10-by-10-foot square patch - 33 times the rate recommended by the Minnesota Department of Agriculture.