The U.S. Environmental Protection Agency (EPA) knows that dozens of the chemicals used in fracking pose health hazards. The agency not only allows their use, but also lets the oil and gas industry keep the chemicals secret, according to a new report.

Between 2003 and 2014 the EPA identified health hazards for 41 chemicals used in fracking, according to a report from the Partnership for Policy Integrity and Earthworks, based on documents obtained through a Freedom of Information Act request. Fracking is the injection of a chemical slurry into drilling sites to free up underground oil and gas deposits. Hazards from the chemicals used included irritation to eyes and skin; harm to the liver, kidney and nervous system; and damage to the developing fetus.

Nonetheless, in most cases, the EPA allowed the chemicals to be manufactured and used without further testing. What's more, the identities of the chemicals are hidden from the public, even though federal law authorizes the EPA to require disclosure of so-called trade secrets if there is unreasonable risk of injury to health or the environment.

In response to the report, more than 100 scientists, health professionals and first responders wrote the EPA, asking that it make public the identities of the chemicals known to pose health hazards.

"Citizens have a right to know what health hazards we are being exposed to, especially when these hazards have been identified by government health assessments ... It is an unreasonable risk for people to be unknowingly exposed to chemicals that EPA, itself, has identified as potentially harmful," said the letter. Signers included Sandra Steingraber, author of Living Downstream and other acclaimed books on environmental health, and Wilma Subra, winner of a MacArthur "genius" award for her work to help vulnerable communities document the health risks of industrial pollution.

A recent investigation led by the nonprofit group Physicians, Scientists, and Engineers for Healthy Energy reported that 17.6 million Americans live within a mile of least one active oil or gas well, and could be exposed to toxic chemicals used in oil and gas production. Despite these risks, there are no federal requirements for disclosure of the names and types of toxic chemicals pumped into wells near citizens' backyards. At the state level, California has adopted a comprehensive disclosure program for chemicals used in oil and gas, but most other states still allow protection of trade secrets.

Without knowing what chemicals are used, it is impossible to protect the health of communities in the vicinity of oil and gas production fields, especially the health of local children. When families near wells experience health problems they are often concerned that the wells play a role, but lack enough information to be sure, Marketplace found.

Their concerns are well-founded.

• In 2014, a study by researchers from the Colorado School of Public Health examined data on more than 100,000 births in rural Colorado between 1996 and 2009. They found an association between the the proximity of the mother's residence to natural gas production sites and an elevated risk of birth defects, such as heart and neural tube defects.

• A recently published comprehensive analysis by a team of researchers from public health organizations and leading universities reported that chemicals used in oil and gas development—including fracking—can severely harm children's brains, causing life-long learning problems and developmental disorders.

• Of the chemicals the EPA disclosed in response to the Partnership for Policy Integrity's open records request, nearly a quarter can damage the nervous system, especially during the sensitive early development periods of fetuses and young children.

With the mounting evidence of links between fracking and health issues, it's time for the EPA to stop suppressing information about the health risks of oil and gas production. The message from health professionals and first responders is clear: Americans deserve answers when it comes to toxic chemicals that may be used in or near their communities.