Last March, Scott Pruitt, newly appointed to head the Environmental Protection Agency, rejected the previous administration’s proposal to ban agricultural use of a Dow Chemical Company pesticide, chlorpyrifos. The agency’s scientific advisory panel had concluded in 2016 that children risked irreversible brain damage and neurodevelopmental problems from very low levels of exposure to food residues of the chemical, which continues to be widely used on fruits and vegetables.

In hopes of bolstering the coal industry, Mr. Pruitt, who has rejected established climate science, has also scrapped regulations in the Clean Power Plan put in place by the Obama administration to minimize heat-trapping pollution. A warming trend in sea surface temperatures in the North Atlantic in recent decades has been strongly associated with the spread of potentially deadly marine pathogens like Vibrio cholerae, the cause of cholera, and V. parahaemolyticus, a cause of food poisoning, and could lead to widespread outbreaks.

Food safety measures are also in jeopardy. Enforcement has been delayed indefinitely of crucial rules in the Food and Drug Administration’s Food Safety Modernization Act, enacted seven years ago with bipartisan support to protect consumers from exposure to dangerous pathogens like salmonella and E. coli. Some of those who harvest, package and store foods produced on farms are now exempt from the act’s rules to prevent contamination of the food supply. Yet, each year 48 million people in this country are sickened, 128,000 are hospitalized and 3,000 die from preventable food-borne diseases.

The lax food safety rules of the European Union should be a lesson to heed. France and its allies are currently reeling under massive recalls of baby formula and other products contaminated with salmonella, a crisis said to stem from weak regulations that allowed tainted products to make their way into supermarkets and pharmacies even weeks after the problem was discovered.

Nutritional depletion from rising concentrations of carbon dioxide, the main greenhouse gas in the atmosphere, is another risk to the healthfulness of the American food supply, according to some experts. Dr. Samuel S. Myers, principal research scientist at the Harvard T.H. Chan School of Public Health, and colleagues linked significant reductions in zinc, iron and protein in staple grain crops like rice and wheat and smaller reductions in protein in legumes to rising levels of carbon dioxide in the air.

The researchers demonstrated these effects by growing 41 different varieties of staple crops under conditions likely to exist by 2050 unless there is a major decline in carbon dioxide pollution.

In an interview, Dr. Myers explained that even a small reduction in the protein content of grains could increase carbohydrate consumption and raise the risk of metabolic diseases like diabetes and heart disease that already endanger our overweight population.