By Mihir Vohra.
The communities along the San Jacinto River in Harris County, Texas face many environmental health threats from industrial activity in the area. These threats expose residents to toxic chemicals in the air, water, and soil that are known to cause significant health problems.
The San Jacinto River Waste Pits Superfund Site has been contaminated since the 1960s with dioxin waste from the Champion Paper Mill. Dioxins are some of the most toxic chemicals on the planet, and exposure can cause liver damage, diabetes, immune system dysfunction, cancer, birth defects, and miscarriage. Much of the waste from this site has since washed into the San Jacinto River, potentially exposing people and wildlife in the area. Nearby residents have reported significant health conditions – including pregnancy complications, birth defects, maternal mortality, and childhood cancers. After years of community pressure, EPA has ordered full remediation of the site, but excavation and removal of all contaminated material has not been done.
There are also over 600 oil and chemical barges along a 6-mile stretch of the river. According to 2023 data from the Texas Commission on Environmental Quality (TCEQ) found that these barges contribute more pollution than the ExxonMobil Baytown Refinery, one of the largest refinieries in the United States. Despite their massive emissions, barges aren’t required to get air pollution permits from the state or to report their emissions to the state. Many of the chemicals released by these barges, such as benzene and toluene, are known to cause blood cancers, immune system dysfunction, and brain dysfunction. Furthermore, hurricanes and tropical storms have previously caused chemical leaks, fires, and structural damage involving these barges, but little is being done to prevent future harm to the public or the environment from these barges during natural disasters. The ongoing emissions and potential for disasters pose huge threats to the health of surrounding residents.
The area also has several industrial facilities that emit toxic chemicals into the air as well. In 2021 and 2022 TCEQ measured levels of benzene in the air up to three times the state’s hourly guideline limit. As reported by Public Health Watch, in some instances the benzene concentrations were so high that TCEQ scientists investigating the situation got headaches and had to leave the area. These benzene concentrations were the highest ever detected in the Channelview area. While many local industrial facilities may be responsible for these benzene concentrations, the highest measurements were detected near the chemical facility K-Solv. TCEQ’s response to this hasn’t been to curb emissions from K-Solv or mitigate residents’ exposure to benzene, but to move their air monitors further from the facility so they detect less benzene.
The cumulative impact of multiple toxic chemical exposures can be deadly
Exposure to chemicals like the ones emitted from industrial facilities, barges, and the Superfund site near the San Jacinto River can cause serious health problems, but the full extent of the risk to nearby residents is unknown. Traditionally, when government agencies estimate the risk to the public from toxic chemical exposures, they only consider the risk from a single chemical emitted from a single location for a defined period of time. However, residents in this area are in a much more complicated situation, where they are exposed to multiple chemicals simultaneously over long periods of time. The government needs to consider the cumulative impact of exposure to multiple chemicals over a long time in order to more fully understand how people living near the San Jacinto River may be affected.
When multiple toxic chemicals target similar organs or biological pathways, then simultaneous exposure to them can make their effects worse. This can cause health problems even if the doses of the individual chemicals are within ranges the government deems “safe”. A study from a group of 350 cancer scientists found that exposure to multiple chemicals that don’t cause cancer on their own could lead to biological changes that ultimately do cause cancer. It is clear that exposure to multiple chemicals – even at low doses – can have complex, unexpected impacts on human health and need to be considered when evaluating the risk to the public from chemicals in the environment.
These concerns of cumulative impact of multiple chemical exposures could have health implications for residents near the San Jacinto River. For example, a 2025 study by the Texas Department of State Health Services (DSHS) found that residents in some areas of east Harris County (including Channelview) may be at elevated risk for cancer. In particular, they found that rates of leukemia were three times higher than expected. While the state refuses to release data that would allow for more specific conclusions about the risk area and identification of potential cancer clusters, this study demonstrates that residents in the area have a serious risk of developing cancer. The cumulative impact of all the toxic sites in the area may be responsible.
The US Environmental Protection Agency (EPA) has acknowledged the need to consider the accumulation of risks from multiple environmental threats when evaluating the potential harm to human health, and it has even developed a framework to do so. This would allow for a more realistic estimate of what people are exposed to and how it may affect their health. However, it has proven difficult to implement this framework because crucial information is often missing, difficult to obtain, or impossible to obtain in situations where people are being exposed to toxic chemicals. Thankfully, there are solutions that would allow the government to take action and better protect public health.
The government can do more to protect public health
The best way for the government to protect public health is to prevent these environmental exposures to toxic chemicals in the first place. This strategy is called the precautionary principle. It dictates that if an industrial activity or facility has the potential to cause harm to human health or the environment and there isn’t scientific certainty about this potential harm, then action should be taken to prevent harm rather than waiting for scientific certainty. This means that the burden of proof would no longer be on impacted communities to show that chemical exposures have caused their health problems. Instead, potential polluters like the Champion Paper Mill, the San Jacinto River barges, and K-Solv would first have to prove that their activities don’t expose communities to toxic chemicals before they are allowed to conduct operations that use these chemicals. Applying the precautionary principle would be a crucial way to prevent communities from being exposed to toxic chemicals.
In situations where a community has already been exposed to toxic chemicals in the environment, the government can be more decisive in taking action to protect public health. The current government response model relies on scientific evidence to prove that health conditions were caused by the particular chemical exposure. However, critical information required to prove causation is rarely available, so the government often fails to adequately protect public health. A government response model based on presumptive association would allow for the government to take action to protect public health in the absence of data linking cause and effect. In this model, when a community is exposed to a toxic chemical, government agencies would review scientific information about the health effects of exposure to that chemical. If the evidence indicates the chemical could cause a certain health condition, then the government would take action to benefit exposed community members who have that condition. They would not have to prove that their health condition was caused by exposure to the chemical of concern. Adopting a presumptive association model for federal responses to chemical exposures would create a standardized and timely approach that better protects public health.
The communities near the San Jacinto River have been exposed to multiple chemicals for many decades without help from the government, but we don’t have to continue letting this happen. The complicated problem of how to evaluate the threat of cumulative effects of exposure to multiple chemicals can be addressed with better government approaches that prioritize protecting public health.
CHEJ is a national project of the Texas Health and Environment Alliance (THEA), continuing its mission under THEA’s leadership. Learn more at txhea.org.