DDX levels well above death threshold in St. Louis robins
By Malachi Barrett, mbarrett@michigannewspapers.
Posted: 07/20/14, 10:50 AM EDT |
Among other action, results of the 2013 dead bird collection in St. Louis were presented to the Pine River Superfund Taskforce in their July meeting.
Matt Zwiernik, a Michigan State University professor with a doctorate in environmental toxicology, gave a power point presentation to open the meeting. Tissue samples from 28 birds in the nine-block residential area contained DDX at levels that many times greater than those found to induce death in laboratory settings.
“We looked at the literature and concentrations in the brain that caused acute effects, usually death, ranged from 7.5 parts-per-million to around 300 ppm,” Zwiernik said.
Samples in American robins ranged from 155 ppm-to-1043 ppm. The mean level was 552 parts-per-million, and brain or liver abnormalities were found in 12 of the 28 sampled birds.
“A threshold for acute death within 10-to-15 days of exposure is likely between 20 and 100 ppm,” Zwiernik said.
DDX includes DDT, and the breakdown compounds of DDD and DDE.
Chronic toxicity at much lower levels can cause reproductive problems and death of hatchlings, which is a problem when robins usually return to their place of birth in migratory seasons. It is possible that St. Louis may see less robins if DDX levels continue to be high.
Chairperson Jane Keon said that robins having been found to die of DDT poisoning helped the Environmental Protection Agency raise money to excavate contaminants in neighborhoods.
Tom Alcamo, EPA project manager, gave an update on decontamination efforts. He said that due to a recent decision, roughly 150 trees located in the parkways in the neighborhood would be removed.
Alcamo reiterated that homeowners receive a letter confirming their property is protective of human health and the environment, and available for unrestricted use. If homeowners don’t accept the excavation remedy, their letter will say that their yard is contaminated.
Only one homeowner of the 60 has refused access to have their yard remediated. Alcamo said this home is not a threat to public health.
Dan Rockafellow, Michigan Department of Environmental Quality project manager, gave praise to the efforts of the EPA, DEQ and taskforce during his report.
“In October of 2012 we had the orange fences up in the neighborhoods still and here we are not even two years later with a major multi-million dollar remedial action going,” Rockafellow said.
Alcamo said bids are out for removing a sheet pile wall from the riverbed, with work expected to begin in August. St. Louis has applied for $9.8 million from EPA rather than the expected $6.5 million to continue to construct the new water system.
Keon reported that Gratiot County is considering the purchase of 10 acres located on the west side of the landfill, which contains a plume of contaminates underneath it. She said Gratiot County prefers to own the land in case of another breach, rather than having a private owner there who might sue the county.