Food safety organisations in the US have condemned a new law they say will allow food producers to obscure the labeling of genetically modified ingredients in their products, despite widespread health concerns over the effects of GMOs and the pesticides associated with them.

Signed into law on Friday by President Barack Obama, the legislation permits manufacturers to inform consumers of GMO content through the use of Quick Response or QR codes, which require a device - such as a smartphone - to read.

The law was passed despite opposition from environmental and food safety groups, as well as national polls which show that some 90 percent of Americans surveyed favoured clear labeling.

Davin Hutchins, a senior campaigner for Greenpeace International's Food For Life Campaign, said that many people, particularly low-income households and the elderly, don't have the necessary technology or possess the know-how to easily read QR codes.

That makes the "new law discriminatory in nature," Hutchins told Al Jazeera.

Hutchins also said there is a crucial lack of detail in the new law, which critics are calling the "DARK Act" - short for "Denying Americans the Right to Know".

"Unfortunately, the new law does not adequately use a broad definition of genetic modification; the law refers to foods that are "bioengineered", which doesn't include all forms of genetic modification," he said.

"Furthermore, the USDA [Department of Agriculture] will have the ultimate authority to decide what foods to include and which to exempt, even though the majority of corn, sugar beets, and soybeans are genetically modified varieties in the United States."

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Katherine Paul, an associate director of the Organic Consumers Association - one of the country's leading food safety organisations - told Al Jazeera that the new law violates consumer rights as all citizens have the right to know and choose what they are purchasing.

Certainty for farmers

Monsanto, a leading producer of genetically engineered seeds and one of the main companies that supported the law, said that it believes the legislation provides sufficient information to consumers and "certainty for farmers".

"We recognize the importance of finding common ground and collaborating for the coexistence of all types of farming practices," Monsanto's CEO Hugh Grant said in a statement sent to Al Jazeera.

"As the planet gets warmer and drier, it’s critically important that farmers have access to all agricultural solutions to nourish our growing world and that consumers have choices and access to a healthy, balanced plate.

“Monsanto believes this agreement provides certainty for farmers, consumers and anyone involved in how food is produced, marketed and sold."

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Asked to comment on concerns the law violates consumer rights by not providing clear GMO labels, the Department of Agriculture said: "We are committed to providing multiple opportunities for engagement, and will have more information about this very soon."

For Paul and Hutchins, the main issue with GMO crops are the many "harmful" pesticides and herbicides used in their cultivation.

Already around 80 percent of processed foods in the US contain GMOs.

"The verdict on whether GMOs are harmful to human health is still out," Hutchins said.

"But there are other considerations: First, genetically modified monocultures like corn and soy are modified primarily to be paired with herbicides like Monsanto's RoundUp. The active ingredient in RoundUp is glyphosate, which was classified as a probable carcinogen by the World Health Organization's International Agency for Research on Cancer (IARC)," Hutchins said.

Paul said that more than 300 food and pesticide makers spent nearly $400m over the last four years in lobbying efforts to defeat the mandatory labeling of GMOs.

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"We failed not because of lack of support from consumers - but because of the enormous amounts of money thrown by the industry," Paul said, adding that she was disappointed by Obama, who once vowed to enforce clear GMO labeling.

"Our best hope to get it done through the system was Obama and he just let us down," she said.

"The next step is to increase education around GMO labeling ... We have to boycott the companies that backed the legislation and support those that opposed it."

The Organic Consumers Association, which has long lobbied for clear GMO labeling, has created an app that lists companies it says people should avoid due to their support for the new legislation.

The app, titled Buycott, also lists companies that were in favour of clear GMO labelling.