If you’re trying to help the bees by planting vegetables and flowers in your garden, you may actually be doing more harm than good, according to a report released today by Friends of Earth, an international network of environmental organizations.

That’s because at least half of plants in the report bought at big home improvement stores were found to contain neonicotinoids, a class of pesticides that has been proven to be harmful, and sometimes fatal, to bees. In fact, some scientists believe that the pesticides' effects on bees is a warning sign that the chemicals may also pose health issues for people.

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The Friends of Earth report follows news of a huge, 4-year study on widely used pesticides by the International Union for Conservation of Nature (IUCN). That study, based on 800 peer-reviewed papers published in the past 20 years, found that neonicotinoid pesticides were damaging many helpful species and were one of the main causes of the sharp decline of pollinators, including bees.

“The evidence is very clear. We are witnessing a threat to the productivity of our natural and farmed environment equivalent to that posed by organophosphates or DDT," said Jean-Marc Bonmatin of The National Center for Scientific Research in France, one of the lead authors of the IUCN study, in a press release.

"Far from protecting food production, the use of neonics is threatening the very infrastructure which enables it, imperiling the pollinators, habitat engineers and natural pest controllers at the heart of a functioning ecosystem.”

Neonicotinoids, or neonics, are essentially nerve agents, in the same class as nicotine. Plants absorb the chemicals into their cells, making every part of the plant toxic to insects, from the roots, to the stem, to the leaves, to the flower and pollen, as well as to the fruit or vegetable produced by the plant.

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Neonics were adopted in the early 1990s as the pesticide of the moment because they worked so well and were thought to be worlds safer than DDT, the nightmarish pesticide used for about 30 years, from the 40s into the 70s, that seriously harmed organisms of every size and shape. And for humans, as far as we know at the moment, neonics are safer.

Tim Brown, of the Pesticide Research Institute and a co-author of the Friends of Earth report, told Discovery News: “Neonics are not acutely toxic to humans, which has allowed them to not go under very close investigation. But we need to understand the cumulative effects on humans.”

“We’re not only finding them in the plants, but also in the fruits and vegetables,” Brown said. “Those (amounts) are in parts per billion, but it’s cumulative when you consume them in so many things.”

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Indeed, there has not been much research that looks at the effects of neonics on humans and other mammals. The results so far suggest that certain neonics “may adversely affect human health, especially the developing brain,” according to a December study in PLoS ONE.

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The European Union has banned the use of neonics on flowering plants and crops, but the United States has no such ban. The White House last week announced a task force to look at causes of pollinator collapse in the country, but any legislation is likely years away.

Currently, it falls to concerned organizations to raise awareness in companies like Home Depot and Lowe’s in the hopes that they will take action without direct legislation.

In a statement to DNews, Lowe’s said, in part: “Lowe’s supports ongoing efforts by the EPA and USDA to promote pollinator health, including the recently established Pollinator Health Task Force, which will work to foster a better understanding of pollinator losses, develop an education plan and seek ways to increase and improve pollinator habitats. We expect all of our vendors to abide by EPA guidelines regarding application and labeling of all pesticides.”

It also noted that Lowe’s offers organic pest control products.

Ron Jarvis, Vice President of Sustainability at The Home Depot, told DNews, “We want to do the right thing for the environment, for our customers and for the plants themselves.”

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To that end, the company is working with suppliers to withhold neonics and test how well the plants survive at Home Depot stores. The company also is requiring its suppliers by end of 2014 to label plants that have been treated with neonics.

“Labelling is a great first step, but we would like them to move in the direction of getting neonics out of their plants altogether,” said Lisa Archer, Director of the Food and Technology Program at Friends of Earth and a co-author of the organization’s report.

So what can home gardeners do to help the critters who help them? Friends of Earth recommends planting bee-friendly flowers that you know come from a place that doesn’t use neonics on the plants or on the seeds they grow from.

Also, avoid products with neonics that go by the names Acetamiprid, Clothianidin, Dinotefuran, Imidacloprid and Thiamethoxam, it says.