By Abbas Nazil
Researchers at the University of California, Davis have found that even short-term exposure to crude oil and flame retardants can affect not only directly exposed organisms but also their offspring and later generations, raising new concerns for human and environmental health.
The findings, published in Environmental Science and Technology across three studies, were based on research involving Atlantic killifish, a small species with transparent embryos that allow scientists to observe developmental changes. Because killifish share many genetic and cellular processes with humans, they serve as a powerful model for understanding how pollutants can disrupt growth, heart function, and behavior.
Professor Andrew Whitehead, chair of the Department of Environmental Toxicology at UC Davis and senior author of the studies, explained that toxic exposures may have effects that extend far beyond the lifetime of individuals.
He emphasized that risk assessments must consider generational impacts rather than focusing only on immediate harm.
The research stems partly from studies launched after the 2010 Deepwater Horizon oil spill, which released millions of gallons of crude oil into the Gulf of Mexico. Killifish collected from the area revealed striking long-term changes.
Offspring of oil-exposed parents showed altered expression of genes linked to brain and nerve processes.
In the following generation, genes regulating heart function were affected, along with visible changes in growth and skeletal shape.
Whitehead noted that these alterations remained detectable many years and two generations after the initial exposure.
The studies also examined flame retardants, particularly polybrominated diphenyl ethers, or PBDEs, a class of chemicals once widely used but now largely phased out in the United States due to toxicity.
Despite restrictions, PBDEs persist in the environment and are still produced in parts of Asia.
They can be passed to offspring through the placenta, breast milk, or eggs, leading to early exposure during critical developmental windows.
In experiments, adult fish exposed to PBDEs through diet passed the chemicals to their young, while embryos placed in contaminated water were directly exposed.
In both cases, offspring displayed altered behaviors linked to brain function, along with molecular changes in neural pathways.
Even when exposed only briefly during development and later raised in clean water, fish produced offspring with inherited behavioral differences.
Nicole McNabb-Kelada, a UC Davis Ph.D. graduate and lead author on the PBDE papers, called the results eye-opening, noting that maternal and environmental exposures each created lasting impacts across lifetimes and generations.
Whitehead warned that the legacy of toxic exposures can be far longer than current regulatory frameworks consider.
He stressed that preventing exposure in the first place is the most effective intervention, as contamination from oil spills, air pollution, and flame retardants continues to threaten both wildlife and human health.
The studies were supported by the National Institute of Environmental Health Sciences, the National Science Foundation, and several UC Davis fellowships and endowments.
Scientists from Louisiana State University, the Bigelow Laboratory for Ocean Sciences, and the U.S. Environmental Protection Agency collaborated on the research, underscoring its broad significance for understanding long-term environmental risks.
