Cattle in southeast Texas have high incidence of DNA damage. Scientists have found a link to large factories that emit toxic substances. By Matthew Cimitile Environmental Health News March 9, 2009
For 200 years, Randy Mumme’s family has raised cattle on the same plot of southeast Texas land. Then, about 10 years ago, something began to change. His steers were losing weight. Cows were miscarrying; one gave birth to a calf with three legs. Many calves were stillborn.
The family’s ranching practices had not changed over the centuries, but the environment had:
His ranch is four miles downwind of large industrial plants that spew tons of carcinogens and other toxic substances into the air. Mumme and other ranchers in Point Comfort suspect the factories are contributing to the ill-health of their cattle.
Now scientists have found DNA evidence that suggests the ranchers’ suspicions might be true, heightening concerns about their cattle as well as their own health.
Tests have revealed that herds as far as six miles downwind of the factories have more DNA disturbances than other herds not downwind, according to scientists at Texas A & M University. The changes in chromosome structure and other genetic damage can increase the animal’s risk of cancer and reproductive damage.
At the request of local ranchers, the researchers collected white blood cell samples from 21 herds within an 11-mile radius of the industrial facilities. Because of the strong, steady wind from the southeast, researchers expected if Formosa Plastics Corp. was the main culprit, cattle located downwind or northwest from the industrial complex would show larger genetic disturbances.
The results “provided a strong indication of increased damage” in herds downwind of the industrial complexes, according to the study, published in January in the science journal Ecotoxicity.
Cattle with the DNA damage were “oriented around the [Formosa] facility, with the highest damage occurring with those nearby and those downwind,” said Wesley Bissett, lead study author and a veterinarian at Texas A & M’s College of Veterinary Medicine. Bissett reported damage to cattle both within close proximity of the facility and in areas where the prevailing winds would blow the toxic gases.
Formosa spokesman Jim Sheppard said there is no direct evidence that industry is to blame. “The highest evidence of DNA damage was some distance from the industrial plants, rather than close to them,” he said, adding that the scientists said in their report that other environmental conditions or cattle herd management might be to blame.
Formosa, which has operated a petrochemical manufacturing plant in Point Comfort for 25 years, has undergone two multi-billion-dollar expansions over the past 15 years. Alcoa Inc., an aluminum manufacturer, also has a large facility near the ranches but not downwind.
DNA damage occurs in every living thing, but in most cases, normal repair mechanisms can mend it, said Terry Clawson of the Texas Commission for Environmental Quality. For example, ultra-violet rays from sunlight break DNA chains but in most cases cause no health effects.
The Point Comfort cattle, however, have such a high prevalence of genetic damage across multiple herds that scientists say it suggests an environmental cause.
Toxic substances can either bind directly to DNA or indirectly damage it by affecting enzymes and causing mutations that lead to increased risk of certain diseases, scientists say.
Niladri Basu, an environmental toxicologist at the University of Michigan who was not involved in the study, said the findings indicate that living downwind of large industrial plants can harm DNA and perhaps harm the health of animals, ecosystems and people.
“These results validate the health concerns raised by area residents and a human study is warranted,” Basu said.
In 2002, when the cattle study began, 1.4 million pounds of 43 toxic chemicals were emitted from Formosa and Alcoa plants, according to the Environmental Protection Agency. Many of the chemicals are known carcinogens, including butadiene, used in the production of rubber, and dichloroethylene, an industrial solvent.
Texas state officials fined Formosa $150,000 in 2000 for air pollution violations, including vinyl chloride and hydrogen chloride emissions that exceeded health limits multiple times. Since then, the emissions have declined, Clawson said.
The area has long been known for other problems related to toxic substances. Point Comfort is on the eastern banks of Lavaca Bay, which was classified as a Superfund site in 1980 due to mercury contamination from Alcoa. A 2007 study conducted by the same Texas A & M researchers shows wastewater discharges into the bay may be associated with DNA damage in oysters.
Researchers say more studies are needed to confirm the link between the industrial emissions and the cattle’s DNA damage, and to see if there are any human health effects.
Currently, no one is studying health of the ranchers. Such studies are complex because people are exposed to a variety of chemicals and lifestyles, such as smoking, that can harm their health, Bissett said.
For now, many of the ranchers fear for their families’ health and hope that further tests will help them recoup the costs of the calves that have been aborted or died before reaching full term.
Mumme, who is 59, grew up on the ranch and began managing it for his uncle in 1986.
“The presence of that plant has negatively affected the quality and quantity of livestock production and I fully believe it has also affected human health,” Mumme said. “The most important question now is what long-lasting effects will this have on me and on my kids?”