Research show that carcinogenic oil-related PAH compounds are easily absorbed through skin
By Bob Berwyn
SUMMIT COUNTY — Two years after the Deepwater Horizon oil disaster, beaches along the northern Gulf of Mexico coastline are far from being clean, says University of South Florida researcher James “Rip” Kirby, who recently documented accumulations of remnant oil with “scary high” concentrations of carcinogenic oil-related compounds. Download the full report or a summary at the Surfrider website.
In fact, the weathered tar product from crude oil dispersed with Corexit were found to have PAH concentrations consistently in excess of limits set to identify danger to life and health — IDHL limits, as defined by NOAA’s Office of Response and Restoration.
In all, 32 sites were sampled; only three were free of PAH contamination. Samples at 26 of the sites exceeded the IDHL limits. Testing was done at beaches between Waveland, Miss. and Cape San Blas, Fla.
Mixed with the dispersant Corexit, the bits of tar are full of toxic polycyclic aromatic hydrocarbons (PAHs) that can easily be absorbed through wet skin. There are no “safe” levels for many of the compounds, including various benzene derivatives known to cause cancer at very low exposure levels.
Testing with UV lights suggested that the contaminated material was being absorbed by the skin of the test subjects immediately, contradicting findings by the Florida Department of Health that discounted dermal absorption early in the health threat assessment efforts.
Kirby’s study found that wet skin dermal absorption is “not only possible, but rapid and highly efficient.”
Based on those findings, two toxicologists recommended additional studies to determine what level of enhanced absorption might result from the presence of Corexit® dispersant bound to hydrocarbon molecules in tar product found in coastal beach sediments.
A Florida Department of Health toxicologist recommended no action and said the current risk assessment model was adequate.
“That’s the problem … it’s mixed in with shell material, right where the little kids who can’t swim, and the parents are right there, watching them in the swash zone,” Kirby said, describing the part of the beach where the materials are deposited on days with gentle waves.
Kirby used ultraviolet light to detect the weathered tar product on the beaches. The samples weren’t fingerprinted to trace them to a particular source, but the UV signature of the tar sample was used to visually identify the probability of the sample as having been treated with Corexit® brand dispersants. Kirby said the study was designed to determine the toxicity of tar product, and results showed levels of PAHs that were off the charts.
“Tar balls are the least of their concerns. They’ve been told over and over again, the beaches are clean, come on down. But that’s not exactly true. There is tar product that will accumulate under certain conditions,” he said.
Specifically, Kirby found the oil remnants building in the so-called swash zone, where wave action influences the beach, and exactly where small children might spend hours splashing and playing in warm Gulf waters.
“It’s just like a curb on a street,” he said, describing how, under the right conditions, the heavier debris will build up in that zone. “Heavier things will accumulate at the base of that plunge step.”
it’s not an issue of whether 100 square meters is non-detectable,” he said, referring to common sampling techniques that look for contaminants over a broad area. “There are places on the beach that are contaminated.”
For Kirby, a big part of the problem is that the oil remnants he found are mixed with Corexit, a dispersant used in unprecedented quantity and at unprecedented depths during the oil disaster two years ago.
Simply explained, the dispersant is chemically designed so that one side of the molecule bonds with water while the other side bonds with the oil, the idea being to pull the oil particles apart. The smaller they are, the more accessible they are to oil-eating bacteria.
But biologists also know that those smaller particles of oil and dispersant are more easily absorbed by organisms small and large; that’s why the substance Kirby found along the beaches poses a danger to people.
The research was funded primarily by the Surfrider Foundation from financial support by Patagonia, O’Neill, Norcross Foundation, and individual donors.