Camphor laurel Toxicology update

Correspondence received from Royal Botanic Gardens, Kew, Richmond, Surrey TW9 3AB, UK Camphorlaurel 2002


Joe A. Friend Greentree Management Box 1518 Lismore 2480 Australia

Our ref. M85/932/2002PG 14 November 2002

Dear Mr Friend

Thank you for your letters dated 15th and l8th October, addressed to me Director, Public Relations - Scientific, and myself respectively. I have read the enclosures with interest, and am very sorry to hear that Cinnamomum camphora has such a devastating effect on the native birds. I asked two colleagues to look at the two leafy branch samples that you enclosed. Dr Hazel Wilkinson is a plant anatomist, and has examined the anatomy of the stem and leaf samples. Dr Geoffrey Kite. a plant chemist, has used a GC.MS to compare the volatile compounds from the two samples Dr Wilkinson found the following:

The stem & leaf anatomy of the two samples (of Cinnamomum camphora (I..) Nees et Eberm.) seem to be more or less identical. The young stem was examined in Transverse Section (TS), Longitudinal Section (LS) and paradermal to the lenticels. In TS the secretory cells in the cortex do not appear to be any more abundant under the lenticels than in other areas of the stem. However, LS and paradermal seem to show more secretory cells than other areas of the cortex. The leafTSs show quite frequent, large secretory cells in both palisade and spongy tissues. I suggest that evaporation of the volatile oil may occur through lenticels, the cuticular surface of young stems, both adaxial and abaxial leaf surfaces and stomata on the abaxial leaf surface. I tried looking at old flower remains including the ovary for possible glands on the surface but was unable to .see any. The sepals and petals were rather hairy and had fungal hyphae in abundance. There was no sign of any glands on the leaves.

In addition to Dr Wilkinson's report above, I enclose a copy of pages 170-1 from Anatomy of the Dicotyledons 2nd edition volume 3. Under "Economic uses" camphor and camphor oil are mentioned, and the wood can cause dermatitis or serious irritation of the respiratory organs during processing

Dr Kite's GC-MS traces (enclosed) show that by far the most abundant volatile compound in both the deterrent and killer leaves is camphor. There are only negligible traces of other compounds. If naphthalene had been present, it should have been detected.



The NSW Scientific Advisory Committee has released a report indicating camphor laurel toxicity. The Introduction and conclusion to the report are reproduced here

Report on the Toxicity Assessment of Camphor Laurel and Forest Red Gum Leaf Leachates to Vibrio fischeri (Microtox®) and the cladoceran Ceriodaphnia dubia

Moreno Julli, Ron Patra, Fleur Pablo, RM Sunderam and John Chapman Ecotoxicology Section Centre for Ecotoxicology, NSW EPA 6 April 2001


The Centre for Ecotoxicology (CET) was contracted by the NSW Scientific Advisory Committee to conduct a series of ecotoxicity tests to assess the aquatic toxicity of camphor laurel (Cinnamomum camphora) leaves. It has been alleged that camphor laurel has a high toxicity to aquatic fauna and its presence around waterways may result in significant impacts on aquatic communities.

Forest red gum (Eucalyptus teretecornis} leaves were used to provide a comparison (as positive control) to the tests involving camphor laurel. Leaves of the two species individually and combined, were incubated in water for a period of time. The toxicity of the resulting leaf leachates was assessed in time series experiments using the luminescent bacterium Vibrio fischeri (within the acute Microtox® test) and the Australian cladoceran Ceriodaphnia dubia. The leachate containing a mixture of the two leaf species was tested to assess if synergistic interactions occurred.

This work was designed to provide an estimate of the toxicity of camphor laurel in comparison with that of forest red gum leaves. Prediction of ecological effects of camphor laurel is not within the scope of this work. Ecological effects may involve changes to aquatic community structure or function due to factors other than toxidty, such as leaf decay rates or leaf palatability which affect macroinvertebrate assemblages.


For acute Microtox® tests red gum leaf leachates generally exhibited higher toxicity than camphor laurel leaf solutions. During most sampling periods, antagonistic or additive effects on toxicity was evident in red gum/camphor laurel leaf leachates. The slight decrease in pH evident in leaf leachates contributed to the observed Microtox® toxicity.

Similarly for C. dubia acute tests (up to day 10 of leaf incubations), red gum leachates were generally more toxic than camphor laurel leachates. Post day 10 camphor laurel leachates often produced immobilization effects in C. dubia which did not have readily discernible concentration / response relationships. This effect appears to have occurred due to the presence of bacteria. The acute toxicity of the camphor laurel leaf leachates to C. dubia therefore did not appear to be directly due to the release of toxic cellular constituents. It was not possible from this work to determine if the presence of the bacteria was an artefact of the laboratory incubations.

Reproductive impairment tests with C. dubia (days 14-21 if incubations) showed that red gum leachates were more toxic relative to camphor laurel. The high within-treatment variability of treatments containing camphor laurel, reduced the power of the test to detect differences in reproductive impairments.


Recent results of further toxicological testing of the bark off roots of Camphor Laurel trees growing in the Northern Riveis region, using Cane Toad tadpoles as the test organism demonstrate that it is now possible to scientifically screen-test individual trees for their relative toxicity to amphibians.

The toxins in Camphor laurel tree parts come in 3 groups of chemicals, all of which are quite powerful 'killing compounds' or capable of causing cancers : these are Safrole, the mammalian liver carcinogen, two root/bark based alkaloids - one of which is a precursor/ helps form morphine, and the camphor molecule itself, which is known for decades to have caused the death of human infants, and incapacitated or toxified adult working humans. Additionally, it is well known that l,8-cineole exists in significant quantities in certain types of Camphor trees, and that this chemical is specifically removed due to its known toxic characteristics, from Tea tree oils made in Australia(and elsewhere).

Further research also demonstrates that natural saponins, or soap-like molecules exuded from neighbouring rainforest species' trees living near Camphor laurels can help ensure that Camphor toxins exuded from Camphor root glands- very visible along the roots- are made more soluble, or part-soluble, hence to dissolve into soil-water, thence into streams and waterways.

Analytical assessments of individual trees proves that certain types of Camphor laurel are predominantly made-up of Safrole, not Camphor itself, and that these trees now appear to be the most powerfully toxic, and the most capable of seriously impacting on Australian wildlife species - some of which have already disappeared from the Northern Rivers region!


Between 1999 and 2001, all mainland states and capital cities were surveyed to determine the relative seriousness of the Camphor Laurel infestations known across Australia; only in the desert regions, including most of South and Western Australia is there no recorded spread of the tree. Suburban spread, and infestation/s appear to be the most serious problem- in all capitals (excepting Hobart), due largely to:-


A telephone Survey of a representative sampling of key industry groups, including Apiarists, Farmers, Graziers, Naturopaths, Herbal specialists, and Retailers that may still market the occasional product containing camphor proves that an overwhelming majority of Australians no longer want the trees 'hanging around'; i.e. it IS TIME for the Camphors to be replaced, and CONTAINED to a sustainably-managed area in northeastern NSW.


Since Australian koala biology expert Phillips (1996, Lismore C-Council) proved that local Goonellabah-Lismore koalas do eat or seasonally browse Camphor laurel leaves (at nightime) one would naturally expect that BF koalas have adapted to the chemicals in those leaves, there should be a marked increase in both the population-numbers of koala and their health. However, this is not the case, as a Survey of Skyline Road residents, and koala habitat proves that there has been a serious decline in koala numbers over the past decade. This finding is supported by interview of key local 'longtime-resident' homeowners around Goonellabah - in areas where Eucalypts, Camphor and koalas are regularly and concsistently reported/seen, to the effect that individuals and whole familes state "nil young koalas sighted" over periods of time separately reported to be 3, 4, 5, and in one case 8 years since they were last commonplace or regularly sighted.

FOR MORE INFORMATION DETAILS OF NEW TESTING METHOD for Individual Camphor Tree Toxicity- Joe A Friend, Principal Researcher P/Fax 02 66. 886 150/66 886 329 / 66214 878.