Cancer Alley is an 85-mile stretch along the Mississippi River between Baton Rouge and New Orleans, Louisiana, where more than 150 petrochemical plants and refineries sit alongside residential neighborhoods. The name reflects decades of elevated cancer risk tied to industrial air pollution, with the burden falling disproportionately on Black communities and low-income residents. The corridor spans 11 parishes and is one of the most concentrated zones of chemical manufacturing in the United States.
Where Cancer Alley Is and What’s There
Louisiana hosts over 300 manufacturing facilities, and a huge share of them are packed into this narrow river corridor. Refineries, plastics manufacturers, and chemical plants line the Mississippi on both banks, often within a few hundred yards of homes, schools, and churches. Parishes like St. James, St. John the Baptist, St. Charles, and Ascension sit at the center of this industrial cluster.
The region developed this way because the Mississippi River provides both water for industrial processes and a shipping route for raw materials and finished products. Louisiana has actively courted these companies through its Industrial Tax Exemption Program, which partially exempts new or expanded manufacturing facilities from local property taxes for up to 10 years. In 2021 alone, that program cost local governments $1.5 billion in lost property tax revenue statewide. Chemical manufacturers accounted for 80.7% of those exemptions. In St. Charles Parish, the exemption totaled $119.8 million that year. In Ascension Parish, it was $123.9 million.
How High the Cancer Risk Actually Is
A 2025 study published in the Proceedings of the National Academy of Sciences used mobile air-monitoring equipment to measure carcinogenic chemicals across 530 census tracts in the Baton Rouge-to-New Orleans corridor. The findings were striking: 97% of those tracts had cancer risk levels above the national median. Nearly a third (32%) ranked above the 95th percentile nationwide, and 7% were above the 99th percentile.
The median cancer risk the researchers calculated was 310 excess cancer cases per million people, compared to the EPA’s own estimate of 60 per million for the same area. The highest-risk tract hit 560 per million, far exceeding the EPA’s upper threshold of acceptable risk, which is 100 per million. In other words, the EPA’s existing screening tools have been significantly underestimating the danger.
The Chemicals Driving the Risk
Three airborne compounds account for the vast majority of cancer risk in the corridor. Ethylene oxide, a gas used in chemical manufacturing and sterilization, is the dominant threat. It contributed between 39.5% and 92.2% of total cancer risk depending on location, with a maximum tract-level risk of 515 excess cancer cases per million. The median airborne concentration researchers measured was 27.7 parts per trillion, with peaks reaching 57.2 parts per trillion.
Chloroprene, a chemical used to make synthetic rubber, was the second-largest contributor, responsible for up to 36.8% of risk in some tracts. Its maximum tract-level risk reached 68 per million. Formaldehyde, a well-known carcinogen, contributed between 4.1% and 14.6% of risk. Together, these three chemicals accounted for 63% to 97% of total cancer risk across all measured tracts. One additional industrial solvent, 1,2-dichloroethane, spiked to 174 per million in a single tract.
Who Lives in Cancer Alley
The demographics of Cancer Alley are central to why it has become a flashpoint for environmental justice. The region is 40% Black, compared to 32% statewide and 12% nationally. In Jefferson, St. John the Baptist, East Baton Rouge, and Orleans Parishes, 79 census tracts are at least 90% Black, and most of those tracts also report very low household incomes. The poverty rate across Cancer Alley is 18.6%.
This pattern is not coincidental. Many of these industrial facilities were built near historically Black communities, some of which trace their roots to former plantation lands. The result is that the people breathing the most contaminated air are overwhelmingly those with the fewest resources to move away or fight back through the legal system.
Health Problems Beyond Cancer
Cancer risk dominates the conversation, but the health picture is broader. Louisiana as a whole performs poorly on nearly every public health metric, and the industrial corridor concentrates many of those problems. Statewide, 22% of adults report fair or poor health, compared to 17% nationally. The rate of preventable hospital stays is 4,947 per 100,000 Medicare enrollees, well above the national rate of 3,767.
Air quality is measurably worse. Louisiana’s average fine particulate matter level is 9.4 micrograms per cubic meter, compared to 7.5 nationally. Low birthweight affects 11% of Louisiana births versus 8% nationally. Residents also report more physically and mentally unhealthy days per month than the national average. These numbers reflect the state overall, but the parishes within Cancer Alley sit at the intersection of poor air quality, poverty, and limited access to healthcare.
The Fight Over Regulation
In 2022, nonprofit environmental law groups filed complaints on behalf of residents in St. John the Baptist Parish, alleging that Louisiana’s Department of Environmental Quality and Department of Health had violated federal civil rights law by issuing air permits to facilities like the Denka Performance Elastomer plant (which emits chloroprene) and a proposed Formosa Plastics complex. The EPA opened a civil rights investigation and found preliminary evidence that these agencies’ permitting practices may have had “an adverse and disparate impact on Black residents.”
Louisiana’s government pushed back hard. In June 2023, the state sought a court injunction to block the EPA from enforcing its disparate-impact regulations. The EPA then closed its investigations, claiming the complaints had been resolved. In January 2024, a federal judge ruled in Louisiana’s favor, granting the injunction and finding the state had standing to challenge the EPA’s authority. The ruling was a significant setback not only for Cancer Alley but for environmental justice enforcement nationally. The EPA subsequently dropped similar investigations in Flint, Houston, Detroit, and St. Louis.
Community Resistance
Local organizing has produced real victories despite the regulatory setbacks. In October 2018, Sharon Lavigne founded RISE St. James with just 10 community members. The group mobilized against a proposed $1.25 billion Formosa Plastics manufacturing plant in St. James Parish. Working with environmental law organizations, civic groups, and churches, Lavigne’s coalition successfully stopped the facility from being built. As of 2026, RISE St. James continues to fight further industrial expansion in the parish.
The tension at the heart of Cancer Alley remains unresolved: the same industrial facilities that generate billions of dollars in economic activity are producing airborne carcinogens at levels that far exceed what federal regulators consider acceptable. The communities most exposed to those chemicals have the least political and economic power, and the legal tools available to protect them have been weakened by recent court rulings. For the roughly one million people living in the corridor, the name Cancer Alley is not a metaphor.