Paper presented at the IFEAT International Conference in Barcelona, 6 - 10 November 2011 ‘Spain: Bridging Continents and Cultures’ Pages 155-169 in the printed Conference Proceedings.
THE ENVIRONMENTAL FOOTPRINT OF ESSENTIAL OILS AND SYNTHETIC CHEMICALS (AND CONSEQUENCES FOR THE ESSENTIAL OIL INDUSTRY) Jim Gobert Telmont Essentials Pty Ltd 1 The Crescent Vaucluse NSW 2030, Australia firstname.lastname@example.org BACKGROUND AND OVERVIEW In addition to the aesthetic enrichment of our lives by natural flavour and fragrance materials, humankind has traditionally drawn, from nature, the active ingredients to improve living conditions. Traditional Chinese medicine has its origins from the eras of the Three Emperors (Fu-hsi, Shen-nung and Huang-ti from 2852 – 2597 BCE) and in India from the Vedic age (1700 – 11 BCE). Traditional medicine was generally an amalgam of pharmaceutical actives which would show dose-response curves (e.g. ephedra), sympathetic magic and materials that were believed to interact with life forces such as “qi”. Natural materials were also used to control nature - in Mesopotamia around 2500 BCE, sulphur was used to control fungal diseases in plants; Egyptian fisherman burnt castor oil in lamps to repel mosquitoes from around 500 BCE and leguminous plants (such as Lonchocarpus nicou - a source of rotenone) were used by South American natives around 1600 CE to catch fish. Around 1700 CE tobacco extracts (as a source of the insecticide l-nicotine) were used to control cereal pests in Europe. Even animals employ natural materials as active ingredients to improve their living standards primates (such as wedge-capped capuchins) have been observed rubbing themselves with millipedes at times of high insect activity to apparently repel various feeding insects. From the mid-20th century, toxic heavy metal complexes of arsenic and a diverse range of synthetic chemicals, derived mainly from fossil fuels, were employed to control plant pests and human diseases and softer, less noxious, natural chemicals were made relatively obsolete. Climate change, and means to limit its consequences, is causing us to assess the atmospheric consequences of synthetic, fossil fuel derived materials in general. Concurrently, a range of other issues – such the development of pest resistance to synthetic chemicals, the depletion of natural resources used in production of synthetics (such as phosphate rock – used to produce a diverse range of pesticides) and concerns about toxic residues in food, waterways and farm workers – is driving new research into natural and naturally derived, efficacious ingredients. The presentation consists of three major components, which can be summarised as follows: A. Our world is changing: - plants supply diverse natural chemicals; - there is new demand for functional natural chemicals; - improved safety, low carbon footprint & reduced residues stimulating this demand. B. Nature has the solution: - plants supply us with functional ingredients (for example fungicides, insect repellents, herbicides, insecticides) – three examples will be presented; - additional new application areas will increase new demand for a range of natural chemicals.
C. Impact on our industry: - increasing demand, with existing supply problems, will significantly impact essential oil supply. A. OUR WORLD IS CHANGING THE ROLE OF PLANTS AND NATURAL CHEMICALS Plants supply us with a diverse range of natural chemicals, usually of some benefit to the plant. For example, in the Cinnamomum aromaticum, cinnamic aldehyde acts as a fungicide, protecting the plant from fungal infection; in the Melaleuca alternifolia, the diverse terpenoids protect the plant from a wide range of herbivores; Chrysanthemum coccineum produces the insecticide, pyrethrum and the Rafflesia cause production of putrescine and cadaverine, attractants for fly pollinators. In other plants chemicals are produced with no obvious benefit to the plant – for example, the opium poppy, Papaver somniferum, produces potent analgesics, the opiates; the Artemesia nulla (traditionally used in Chinese medicine to treat malaria) contains the most potent known anti-malarial, artemisinin and the broad bean, Vicia faba, contains L-dopa, used to treat Parkinson’s disease and Encephalitis lethargica. New demands for essential oils in functional plants There is interest in active ingredients of botanical, and, usually essential oil origin for a range of reasons: • Low carbon footprint – as natural chemicals are in one way or another derived from CO2, such materials are likely to be carbon sinks. Chemicals synthesised from fossil fuels are likely to liberate CO2 into the atmosphere. Additionally, the energy source for natural materials is predominantly sunlight (with inputs from fossil fuel for farm operations, transport, isolation etc.) whereas for synthetic materials the energy source is predominantly burning of fossil fuels. •
Simple low-tech production – the desired natural chemicals are often physically extracted (by steam distillation and fractional distillation or crystallisation) from the botanical source.
Diversified production sites – the botanical sources can be spread across countries or continents, wherever the climactic and economic conditions best suit – often production sites can be shut down within a short period of time without detriment to local labour (which is then just utilised on a different crop).
Normally lower risk, and quicker access to market – many active ingredients already have a long history of use and extensive toxicology due to use as a flavour or fragrance ingredient (for example eugenol or cinnamic aldehyde). In many countries (for example Australia, Canada) regulatory authorities have special reduced regulatory requirements for low risk actives ingredients (for example in crop protection). In the EU, the Plant Protection Products Directive (PPPD) requires more stringent consideration of residues, but where the active and residue are low risk materials, for example food ingredients, there is regulatory leniency including reduced withholding period. Consequently, essential oils as actives may have quicker access to market.
Diverse resistance to pure synthetic chemicals – we observe many examples of species rapidly developing resistance to pure synthetic chemicals as active ingredients, for example weeds to glyphosate, mosquitoes to DDT. Essential oils, with their complex chemistry, do not appear to have the same potential for resistance development. In fact some researchers have found resistance to many essential oils improbable (1)
In addition to essential oils and isolates, many plants contain useful additional secondary metabolites – for example: - Antioxidants - from Rosmarinus officinalis, two potent antioxidants, carnosic acid and rosmarinic acid, can be obtained by solvent extraction of spent biomass remaining from steam distillation. These natural antioxidants are more effective than BHT or BHA. -
Osmoprotectants – plants which inhabit drought prone areas often produce osmotic pressure regulators which reduce water loss, for example betaines found in many Myrtaceae. These osmotic pressure regulators can be applied as a foliar spray onto other plants (for example tomatoes) to improve drought tolerance. (2)
Immune stimulators – the stilbenoid, resveratrol, is produced by many plants under stress from pathogen attack. Applying resveratrol, or some anthraquinones such as emodin, as a foliar spray often acts as an immune stimulator in the treated plant. (3)
CARBON FOOTPRINT The accurate calculation of carbon footprint of natural materials is extremely complex for a range of reasons: •
Complexities in accounting for farm input, procedures and methods (for example how do you use urea?)
Dependency on country and energy source (do you use coal, recycled steam etc.? – are there utilised exothermic processes with recoverable energy?)
Calculation of fate of products and by products (for example does spent biomass ferment, releasing methane, or get burnt?)
Agricultural practices – all agricultural practices, including cultivation, sowing, harvesting, irrigation etc. conducted on a plantation, come with an atmospheric carbon cost. Lal (4) reviewed a wide range of publications on farm operations and summarised them into practice groups – for example:
Additionally, for the farm energy inputs (for example for powering the distillation facility, boiler etc.), the carbon equivalent of the energy used varies according to the regional energy sources. For example: CO2 Footprint for Fermentation vs Exothermic Synthesis for a Specific Chemical
The generation system used determines CO2 emission (figures in the table are derived from ⁽⁵⁾) – for example nuclear, thermal coal, hydroelectricity, wind etc. Hence, from the table above, Norway, which generates over 98% of its electricity from hydroelectric power, has extremely how CO2 emissions per kWh; Australia which generates its electricity mainly from thermal coal power stations has very high CO2 emissions per kWh. Consequently, a farm producing identical essential oils would have a different carbon footprint if located in Brazil compared with an identical farm in Australia (due to differences in fuel source for energy used in production). An accurate calculation of carbon footprint is practically impossible due to the huge variations in all the potential inputs. Calculation of carbon footprint In combination with industry partners, a range of carbon footprint assessments were conducted. These were done by measuring the actual energy input required to make an active ingredient (calculated from the calorific value of coal, gas, diesel and of any biomass used to fuel the production process – the actual source being fairly irrelevant in determining energy input) to conduct manufacture of a series of active chemicals: -‐ Natural – based upon the total energy to convert the harvested biomass into the essential oil or isolate – these are full scale production figures. The biomass was produced under a regime of high manual labour input and fertilisation with animal manure (so farm inputs are minimised). -‐ Synthetic – based upon estimate of energy input for synthesis of starting materials plus actual energy to synthesise the active ingredient from the starting materials – these are figures obtained from 50 – 100kg pilot batches. The energy input was calculated in GJ/MT and then converted to kWh/MT which was subsequently converted to CO2 (E)/MT by using OECD conversion averages appearing in “CO2 Emissions from Fuel Combustion” by the International Energy Agency (5). This assumes that the site of isolation or synthesis is geographically similarly located and probably favours synthesis over isolation because the OECD figures are skewed towards higher CO2 (E) emitting processes – such as those requiring electricity input – whereas much essential oil production is conducted under lower emission regimes (for example burning spent biomass as a boiler fuel). The active ingredients selected for these comparisons were similarly performing natural and synthetic chemicals. For example, the naturally derived insect repellent para-menthane-3,8-diol (CAS 4282286-6; “3,8PMD”) is arguably of comparable performance with the synthetic insect repellent Icaridin (CAS 119515-38-7) : they have typical usage levels of 10-15% and have comparable efficacy against a range of insect species. (6)
These carbon footprint estimates therefore are: • Derived from actual production measurements. • Calculated from energy input then converting to CO2 (E) using IEA data. • Ignoring environmental fate of the material (for example, biodegradation, mineralisation). • Rounded to the nearest 10% to two significant figures. B. NATURE HAS THE SOLUTION Three examples were calculated of natural active ingredients vs. a synthetic equivalent: an insect repellent, a herbicide and a fungicide: INSECT REPELLENTS Current world demand for personal insect repellents is greater than 25,000 MT per annum and is increasing for a range of reasons: (i) Distribution of insect disease vectors – due to climate change, the geographical distribution of insects is changing, bringing diseases to new population areas. (ii) Developing resistance of insects to insecticides – as resistance increases, repellents become more important. (iii) Increasing affluence in developing countries. (iv) Concerns regarding market leader, diethyltoluamide (DEET) - whilst DEET has some aesthetic concerns (it is sticky and is a plasticiser) and much of the toxicity concerns are unfounded, there are new developing concerns regarding neurotoxicity and insect resistance. (v) Market wanting naturally-based product for emotive reasons (similar to use of pyrethrum in insecticides despite much higher market price). The barriers to entry for new insect repellent actives are extremely high – mainly due to the toxicology required by regulatory authorities – and there are only four main insect repellents in current use: diethyltoluamide (DEET), Icaridin, p-menthane-3,8-diol and the less used IR3535. Icaridin is synthesised by reacting 2 –ethoxy Piperdine with sec-Butyl chloroformate; p-menthane-3,8diol (3, 8PMD) is produced by reacting citronellal with sulphuric acid & purifying the crude produced 3,8PMD. The two products have similar performance and typical usage levels around 10 – 15% (6)
Calculation of Carbon Footprint
HERBICIDES The current world demand for herbicides is greater than 900,000 MT per annum and is increasing significantly for a range of reasons: •
Wetter, warmer growing conditions – in many areas due to climate change and favouring greater, faster weed growth.
Increased CO2 levels – as atmospheric CO2 levels increase, there is likely to be greater stimulation of growth of weeds, rather than staple grain crops (due to C3 vs. C4 photosynthesis).
Increased resistance – due to overuse of pure chemicals, many plants have evolved herbicide resistance, requiring rotation of different actives. This is accentuated with use of GM plants (which are often glyphosate resistant, inducing the farmer to use higher levels and broader distribution of glyphosate).
Increased agriculture demand – changes in living standards in developing countries and population growth are increasing demand for food, especially meat (which requires high grain input for production).
There is a wide variety of herbicides in use globally with a diverse range of applications. For comparison, the carbon footprint of the natural herbicide 1,4 cineole was calculated compared with similar performing synthetic herbicide cinmethylin, a derivative of 1,4 cineole (although the starting material is terpinene-4-ol). Cinmethylin has reduced volatility and controlled IP compared with 1,4 cineole.
Calculation of Carbon Footprint
FUNGICIDES The current world demand for fungicides is greater than 250,000 MT per annum and is increasing significantly for a range of reasons: •
Wetter, warmer growing conditions in many areas due to climate change.
Virulent diseases – fungal diseases are becoming more virulent and are causing severe damage in food crops around the world – for example: rice blast (US$60 billion cost p.a.), soy bean rust (up to 80% yield loss in range legumes), wheat stem rust (40% yield loss). Black Sigatoka (first seen in 1964 in Fiji; now in Asia, Americas, Africa) is crippling the banana industry worldwide: yields drop up to 50% on infected plants; fruit from diseased trees can ripen prematurely during shipping, causing further losses; commercial plantations frequently apply cocktails of fungicides, often with aerial spraying, and hand removal of infected leaves at a cost of 15% to 50% of the fruit's final retail price.
Resistance and cross-resistance of diseases to “pure” fungicides; essential oils, in contrast, are very complex and resistance is less likely to develop.
Increased demand for agricultural produce and diets richer in meat due to improved standard of living.
Quick internationalisation of diseases – fungal diseases are often readily transmitted as wind born spores between diverse geographic regions, including between countries.
There is a diverse range of fungicides in use globally. The banana disease, Black Sigatoka, is efficiently treated with tea tree oil as well as the synthetic fungicide, captan (which we were not able to reproducibly synthesise).
Calculation of Carbon Footprint
Table 1 â€œMorphology of fungus C. albicans 10231 at 0 and 4 hours in the presence of TTO (%v/v)â€?, shows typical results for essential oils applied to fungi at differing concentrations. At levels far below cidal concentrations, essential oils will typically suppress the virulent germ tube morphology in favour of the far less virulent single cells and single buds. (7)
Table 1 Essential oils suppress virulent fungal morphology Note * SC: single cells; SB: single bud; MB: multiple bud; GT: germ tube; TTO: tea tree oil ADDITIONAL NEW APPLICATION AREAS FOR ESSENTIAL OILS Many trees produce strong defence chemicals to protect against insect attack, such as: Lagarostrobos franklinii (Methyl eugenol) Callitris columellaris (Citronellic acid) Eucalyptus olida (Methyl cinnamate)
- termiticide - general insecticide, muscacide - nematicide
These are species that have great potential as sources for specialised insecticides.
Many plants produce low efficacy insecticides. Insecticidal efficacy in these plants is attenuated when the insecticide halflife in the insect is increased. Many plants produce such attenuating molecules â€“ for example molecules with a â€œmethylenedioxyphenylâ€? group block the cytochrome P450 enzymes that detoxify insecticides within the insect, thus increasing the insecticide halflife.
Many essential oils contain molecules with methylenedioxyphenyl groups - for example the Cinnamomum camphora contains safrole (which has carcinogenicity concerns), which is usually used as a precursor for production of piperonyl butoxide in commercial insecticides (which has growing safety concerns regarding development toxicity).
There is a wide range of essential oils with cytochrome P450 inhibition potential, for example the essential oils of Anethum graveolans (containing Dillapiole), Piper angustifolium (containing Apiole), Myristica fragrans (containing Myristicin) Beilschmedia miersii (containing Sarisan). There is a high potential for exploiting these and other essential oils containing such synergists and utilising genetic research to optimise yield and propagation characteristics.
Increasing affluence in developing countries is stimulating demand for meat production. Additionally, damage to ocean fish stocks is causing increased international demand for farmed fish (especially transported live); escalating grain prices are stimulating demand for better food conversion ratios in animals and use of non-grains as animal feeds. Some major new uses of essential oils in food production (some already in commercial products) are summarised as follows:
Whilst some of these essential oils can be replaced with synthetic aroma chemicals, these are often still ultimately derived from some isolate, for example there will be a significant demand for carvacrol as a feed stimulant: for the organic market, this will be from oregano oil (and the customers will be able to pay for it) but from the general market this will be produced synthetically, typically ex carvone ex limonene.
C. IMPACT ON OUR INDUSTRY CONSEQUENCES FOR THE ESSENTIAL OIL INDUSTRY The demand for efficacious natural materials, especially essential oils or isolates with lower carbon footprints than synthetics, will impact in the following ways upon our essential oil industry: (i) (ii) (iii)
Stimulate research of innovative new natural substances, essential oils & isolates. Stimulate research into new uses of known compounds into novel applications â€“ for example isolates as agricultural or cosmetic active ingredients. Increase demand for functional natural actives due to reduced toxicity concerns, sustainability, low carbon footprint, diverse chemical palette and increasing barriers to entry for synthetics. Whilst many functional ingredients can be synthesised, the precursor is often an essential oil (for example carvacrol ex carvone ex limonene); the growing organic market will demand essential oils and isolates (and be willing to pay for it). Cause increasing demands on already problematical essential oil supplies. We already are experiencing tightening supply for many essential oils due to factors such as : - climate change - high agricultural CPI (around 13% per annum in China) - production costs (due to increasing farm input costs) - reduced available labour (due to population shifts to cities) - land competition from other crops Induce geographical shift in production areas â€“ for example from China to Mozambique.
REFERENCES 1. Hammer KA, Carson CF. Riley TV. 2008. Frequencies of resistance to Melaleuca alternifolia (tea tree) oil and rifampicin in Staphylococcus aureus, Staphylococcus epidermidis and Enterococcus faecalis. International Journal of Antimicrobial Agents. 32: 170-3 2. Scott D. McNeil, Michael L. Nuccio and Andrew D. Hanson 1999, Betaines and Related Osmoprotectants. Targets for Metabolic Engineering of Stress Resistance, Plant Physiology August 1999 vol. 120 no. 4 945-949 3. For example , the commercial product “Regalia” from Marrone Bio Innovations : http://marronebioinnovations.com/products/regalia/ 4. Lal R, 2004, Carbon Emissions from Farm Operations. Environment International 30 : 981 – 990 5. International Energy Agency CO₂ Emissions from Fuel Combustion, Highlights, 2011 Edition http://www.iea.org/co2highlights/co2highlights.pdf 6. Deddoun, Mustapha, Frances , Stephen P, Strickman Daniel, Insect Repellents, Principles, Methods and Uses, CRC Press, 2007 7. Hammer KA. Carson CF. Riley TV. 2000. Melaleuca alternifolia (tea tree) oil inhibits germ tube formation by Candida albicans. Medical Mycology 38 (5): 354 – 361 Molecular drawings by eMolecules software http://www.emolecules.com/ Jim Gobert is Director/Owner of Telmont Essentials Pty. Ltd, based in Australia. He has a B.Sc. in chemistry and geology from the University of New South Wales, Australia, where he also undertook postgraduate work in environmental chemistry, pharmaceutical and cosmetic technology. He has been working in the essential oils sector for more than two decades. This includes working at H&R for 8 years as marketing director fragrances and cosmetic ingredients for Australia and New Zealand; then for Dragoco Singapore for 4 years as sales director fragrances and cosmetic ingredients. For the past 6 years, he has developed his own business supplying specialty essential oils from China and Australia to customers in the USA, Europe and the Middle East. New plantations have been developed on a sustainable agriculture basis to replace wild harvested or high environmental impact agriculture. The essential oils and isolates are not only for the F&F sectors but also for use as efficacious active ingredients for agriculture, aquaculture and cosmetics.