Dr David Obendorf Informed by science or spin?
Now the analysis has been posted on the DPIW website, www.dpiw.tas.gov.au . Detectible residues of persistent organic pollutants in devils can not – of themselves – confirm a causal association with the facial cancer. The detection of some animals with higher residues and assay results do suggest that some high contamination point-source exposure has occurred; this definitely warrants further investigation. After the release of analysis by Professor Moore and Dr Ross as well as the media release from the Tasmanian Government, it is encouraging to read quality investigative journalism ( Sensitive devils a pollutant risk ) that actually refers to the scientists’ analysis rather than just simplistically accepting the Government’s perception. At the top of the island’s terrestrial food web, the Tasmanian devil is well placed to be an important sentinel animal for monitoring chemical residues. Unfortunately there are no test results for devils from locations that State Government has claimed are the likely sites where the first (or index) devils with facial cancer originated.
North Central South-east North-west
IN JANUARY this year, the test results of an ecotoxicology study – first mooted in 2005 – were released after a Freedom of Information request submitted by The Australian newspaper in late 2007. The testing of persistent organic pollutants (POPs) was conducted at the Commonwealth’s National Measurement Institute. Heavy metals, triazines, organochlorines and fluroacetate (1080) tests were done at the Analytical Services Tasmania. Various formulations of herbicides, pesticides and potent biocides contain these chemicals either as active constituents or as additives to assist in broadacre application of crops & plantations. This panel of chemicals were selected for a number of reasons: (1) their capacity to persist for long periods in the environment, (2) their capacity to biomagnify & bioaccumulate up through plant and animal food chains, (3) their potential to be carcinogenic or cytotoxic and (4) because of concerns raised by the scientific & general community. Several of chemicals assayed in devil tissues are regularly used by Tasmania’s agriculture and forestry industries, despite widespread community concern about their environmental effects
Dioxins, dioxin-like polychlorinated biphenyls (PCBs), furans and polybrominated diphenyl ethers, (PBDEs) were tested in 16 devils, 8 of these were showing obvious facial tumour disease.
In late January a Tasmanian Department of Primary Industries and Water spokesman Warwick Brennan said the study involved a range of chemicals based on known human and possible animal, carcinogens, and it formed part of a broader investigation into possible causes of DFTD.
Since 2003 scientists had been calling for a proper investigation of any likely chemical triggers in the Tasmanian environment that might have been responsible for beginning the index (or first) cancer cluster that began the apparent cascade of transmission of this devastating facial cancer of devils.
As first reported in The Australian newspaper on 22 January 2008 ( Sensitive devils a pollutant risk ) the detection of persistent organic pollutant residues showed that Tasmanian devils were storing dioxins, furans, PCBs and PBDEs in their body fat. The results of what the Tasmanian Government called a ‘pilot study’ – particularly the detection of certain congeners and especially the higher residues found in certain devils – has raised the interest of wildlife biologists and toxicologists worldwide.
The Tasmania’s Liberal and Green parties, the state’s public health department expressed concern and called for further work given the potentially harmful implications these results could have for natural ecological processes and human health.
“These alarming results have implications for animal and human health, and the fact that these highly toxic compounds exist in such levels in this state is a strong argument for our government to take a global leadership role in having them banned,” said Greens environment spokesman Nick McKim.
Used commercially as a flame retardant, PBDEs are found extensively in products ranging from televisions, computers and mobile phones to carpets, structural plastics, soft furnishings and curtains, but because of their characteristic failure to bind with plastics, eventually these toxic chemicals leach into the environment. The synthetic polychlorinated and polybrominated organic chemicals are manufactured in large quantities and used in many commercial applications including as solubilizers, surfactants, wetting agents and solvent vehicles.
Limited data describing the adverse health effects of PBDEs in humans has been reported, but according to the United States of America’s Environmental Protection Agency evidence from animal tests has shown PBDEs to be powerful neuro-developmental toxins, disruptors of thyroid functions, and potential liver toxins. And while the specific effects of brominated flame retardants are only beginning to be investigated, public health officials are concerned about the now established association between low concentrations of PBDEs in laboratory and companion animals, and various nervous system and reproductive effects, such as impaired learning and development, hyperthyroidism, and some cancers.
An EPA study published in August 2007 found hyperthyroidism has become one of the leading causes of death in pet cats. Toxicologist and EPA veterinarian Janice Dye hypothesised that the increased incidence of hyperthyroid cats resulted from their prolonged contact with certain polyurethane foams, and components of carpet padding, furniture and mattresses. She believed their meticulous grooming habits caused cats to ingest the PBDEs present in household dust.
“We definitely found evidence that cats are being exposed to these compounds based on the level of compounds in their blood. Cats are in this perfect position to be near the products these chemicals were put in to reduce flammability. Our results showed that cats are being consistently exposed to PBDE. Because they’re endocrine-disrupting agents, cats may well be at increased risk for developing thyroid effects,” she said.
The potential for diet to be a risk was also considered by researchers, and following their analysis of several cat food brands, the PBDE content of canned fish and seafood flavours was revealed as being significantly higher than dry or non-seafood canned items. As a result researchers estimated cats fed predominantly on a canned fish diet could have PBDE levels 12 times as high as those fed dry food diets, and potentially be receiving as much as 100 times greater dietary PBDE exposure than American adults.
While Tasmanian devils’ capacity to bioaccumulate some persistent organic pollutants in their fat tissues should not be regarded as unexpected given they are predators & scavengers, as veterinary wildlife pathologist I am concerned that inadequate wildlife, food and environmental toxicological sampling is being undertaken in Tasmania. This has implications for safeguarding Brand Tasmania – especially for its pure-food, clean-green, residue-free marketing for its aquaculture, dairy and meat industries.
Of somewhat more interest perhaps [than devils] was the detection of PBDE residues found in a very small sampling of Tasmanian farmed salmonids. Tasmania – as a salmon producer – has not participated in international public health studies measuring the residues of persistent organic pollutants in farmed and wild salmon. The reported levels in three fillet samples of sea-cage Tasmanian Atlantic salmon and one fillet from a farmed rainbow trout indicate that more monitoring of both farmed and recreational trout and Atlantic salmon needs to take place; more sampling needs to be done.
Despite a range of chemicals detected in the NMI study in January Mr Brennan said DPIW scientists were reluctant either to speculate on its results, or broaden the investigation to include other animals. “Because this work was done specifically for devils, as part of the investigation into facial tumour disease, a lot will depend on what comes out of the review. Yes, the report does spark concern, but the reality is we don’t know at this stage if there is a link to DFTD until we have that expert analysis,” he said.
Now the analysis has been posted on the DPIW website, www.dpiw.tas.gov.au .
Detectible residues of persistent organic pollutants in devils can not – of themselves – confirm a causal association with the facial cancer. The detection of some animals with higher residues and assay results do suggest that some high contamination point-source exposure has occurred; this definitely warrants further investigation.
After the release of analysis by Professor Moore and Dr Ross as well as the media release from the Tasmanian Government, it is encouraging to read quality investigative journalism ( Sensitive devils a pollutant risk ) that actually refers to the scientists’ analysis rather than just simplistically accepting the Government’s perception.
At the top of the island’s terrestrial food web, the Tasmanian devil is well placed to be an important sentinel animal for monitoring chemical residues. Unfortunately there are no test results for devils from locations that State Government has claimed are the likely sites where the first (or index) devils with facial cancer originated.
Despite numerous public documents, media statements and newsletters prepared by the Tasmanian government-managed DFTD program indicated that this ‘pilot study’ into chemical residues was a priority. There were numerous calls from 2003 onwards for this chemical study to get underway and despite subsequent assurances that it was being progressed apart from freezing samples, no laboratory testing was done 2007.
The absence of detectable residues of triazines, organophosphates and 1080 is not unexpected, given the tendency of these chemicals not to be retained in body tissues after exposure, but the fact that dioxins and PCBs also been detected in fat samples from Tasmanian platypus; another animal that is experiencing an unusual disease pathobiology, the government is on notice not to dismiss the detection of accumulated chemical residues in Tasmanian devils as unconnected to the genesis of the facial cancer.
Veterinary pathologist Dr David Obendorf has written extensively on the plight of the devils (and pesticides): HERE