On March 29, Scott Pruitt, the new head of the Environmental Protection Agency, denied a  petition asking for a ban on the use of an insecticide called Chlorpyrifos. The petitioners, Pesticide Action Network and the Natural Resources Defense Council, cited studies show that Chlorpyrifos can have serious health consequences, such as damaging the nervous system of infants and children.

Understanding why the EPA denied  this petition means focusing on two related factors: the relative powerlessness of the communities affected by Chlorpyrifos and the relative invisibility of the health problems associated with it.

What is Chlorpyrifos?

Chlorpyrifos is an insecticide used on corn, soybeans, broccoli, apples, and other row crops as well as on turf, in greenhouses, and other places. It has been in use since 1965, and by some estimates there are about 44,000 farms that use about  6-10 million pounds of Chlorpyrifos each year.

Chlorpyrifos belongs to the same chemical family as sarin nerve gas and works by attacking the nervous system. Under the Federal Food, Drug, and Cosmetic Act, the EPA is charged with establishing maximum limits for insecticide residues in food substances.  Given Chlorpyrifos’ toxicity, the EPA requires “workers handling and applying Chlorpyrifos to wear additional personal protective equipment (chemical resistant gloves, coveralls, respirators), and restricting entry into treated fields for 24 hours up to five days.”

Why were these groups calling for a ban?

Epidemiological evidence suggests that Chlorpyrifos can cause brain damage to children and even to the unborn. A California study found that pregnant women who lived near fields where Chlorpyrifos was sprayed “were three times more likely to give birth to a child who would develop autism.”

In 2000, Dow Agro Sciences and six other manufacturers of Chlorpyrifos reached an agreement with the EPA to voluntarily discontinue its use for most residential purposes. Carol Browner, then EPA Director, noted that “poison control centers received about 800 calls a year, many involving children, for exposure to products containing Chlorpyrifos.”

Nevertheless, these companies have lobbied the EPA to continue to use Chlorpyrifos in agricultural operations. This is why in 2007, environmental groups petitioned the EPA to ban its use in agricultural use as well. When the EPA dragged its feet, these groups approached the courts, which ordered the EPA to rule on the petition by March 2017.

What did the EPA do?

The EPA denied the petition to ban Chlorpyrifos. This is arguably part of the Trump Administration’s efforts to reduce the regulatory burden on companies.  As Pruitt noted: “we need to provide regulatory certainty to the thousands of American farms that rely on Chlorpyrifos, while still protecting human health and the environment … By reversing the previous Administration’s steps to ban one of the most widely used pesticides in the world, we are returning to using sound science in decision-making – rather than predetermined results.”

While Pruitt emphasized “sound science,” the EPA’s own internal research notes the harmful effect of this pesticide. Of course, there is a debate about how to balance protecting public health and putting additional regulations on industry. Pruitt’s decision suggests that a ban on Chlorpyrifos does not pass his  cost-benefit test.

Why did the EPA do this?

But this begs the question of how costs and benefits are calculated, and who bears these costs. As much scholarship has found, poor and marginalized communities tend to be disproportionately exposed to pollution. In part this is because areas with more pollution tend to have cheaper land and housing, which makes them more attractive to poor people. The poor and marginalized also have little political power and thus offer less resistance.

The same logic holds in this case. When the EPA banned the use of Chlorpyrifos for residential purposes, this benefited a wide cross-section of people whose health might suffer if this chemical were sprayed on their lawns.

By contrast, the use of Chlorpyrifos in agriculture primarily affects the people who live near farmland. These families are disproportionately Latino and some studies report that Latino children are disproportionately affected by pesticide exposure. Many of the people affected cannot vote because they are guest workers or undocumented. Consequently, they have less political power and this means that firms and the EPA may be less attentive to the harmful consequences of pesticide use on their health.

A second issue is that some of the health effects of Chlorpyrifos are not immediately visible. Less visible environmental problems tend to receive less attention from companies and regulators. This is one reason why water pollution gets neglected in relation to air pollution. The slow effort to remove lead from drinking water is a case in point. Without dramatic events like river catching fire or smog enveloping cities, it is easier for Americans to take a clean environment for granted and consider the environment a low-priority issue.

Of course, the politics surrounding Chlorpyrifos could change. The issue was discussed on a recent episode of Bill Maher’s television show, lending it greater visibility. But overall the Chlorpyrifos episode shows how mostly invisible problems affecting marginalized communities often get less attention — absent external publicity or political mobilization.

Nives Dolšak is professor in the School of Marine and Environmental Affairs at the University of Washington.

Aseem Prakash is professor of political science, the Walker Family Professor and the founding director of the Center for Environmental Politics at the University of Washington.