Environmental life cycle analysis of potato sprout inhibitors1

Environmental life cycle analysis of potato sprout inhibitors1

Industrial Crops and Products 6 (1997) 187 – 194 Environmental life cycle analysis of potato sprout inhibitors1 R.P.V. Kerstholt a,*, C.M. Ree a, H.C...

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Industrial Crops and Products 6 (1997) 187 – 194

Environmental life cycle analysis of potato sprout inhibitors1 R.P.V. Kerstholt a,*, C.M. Ree a, H.C. Moll b b

a Uni6ersity of Groningen, Chemistry Science Shop, Nijenborgh 4, 9747 AG Groningen, The Netherlands Uni6ersity of Groningen, Centre for Energy and En6ironmental Studies, Nijenborgh 4, 9747 AG Groningen, The Netherlands

Received 1 April 1996; accepted 4 September 1996

Abstract Potato sprout inhibitors are generally applied to suppress sprouting during winter storage. This study presents the compared environmental profiles of the two sprout inhibitors available on the Dutch market: A traditional chemical product with isopropyl-3-chlorophenylcarbamate (CIPC) and isopropyl-phenylcarbamate (IPC) and a new agrification product with S-(+)-carvone derived from caraway seed (Carum car6i ), examining the common idea that natural products are less harmful to the environment than chemical products. Nine environmental effect scores are evaluated based on emissions and energy use during the entire life cycle (life cycle analysis, LCA). A substantial difference is found in the environmental profiles of the two sprout inhibitors. In seven environmental effects (C)IPC scores better than carvone. Carvone only scores better with regard to human toxicity and ozone depletion. This study has also produced a clear insight into the relevant factors in the life cycles determining the environmental profiles. Regarding carvone, the essential factors are the use of fertilizer in the cultivation of caraway and the relatively high amount of carvone used per ton of potatoes as compared to (C)IPC. It is recommended that environmental LCA’s be performed for other agrification products. © 1997 Elsevier Science B.V. Keywords: Sprout inhibitor; Potato; Isopropyl-phenylcarbamate; Isopropyl-3-chlorophenylcarbamate; S-( +)-carvone; Caraway; Environmental life cycle analysis

1. Introduction

* Correspondence author. Tel.: + 31 50 3634132; fax. + 31 50 3634200; e-mail: [email protected] 1 This article is a summary of: Kerstholt, Rene´, 1995. Milieugerichte levenscyclusanalyse van kiemremmingsmiddelen voor aardappelen, report C77, Chemistry Science Shop, University of Groningen.

Potato sprout inhibitors are generally applied to suppress sprouting during winter storage. Until 1994 only isopropyl-phenylcarbamate (IPC) and isopropyl-3-chlorophenylcarbamate (CIPC) were allowed in the Netherlands (IKC-AT/PD, 1993). Despite their relatively low toxicity, (C)IPC

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potato sprout inhibitors are under discussion because of possible residues of (C)IPC in the potato. Italy and the Scandinavian countries have restricted the use of (C)IPC as a sprout inhibitor by requiring low residue concentrations (Lodewijk, 1994). Recently BV Luxan introduced Talent, a liquid formula of S-(+ )-carvone (2-methyl-5-isopropenyl-2-cyclohexen-1-one), as a potato sprout inhibitor (Meijer and Oosterhaven, 1994). S-( + )carvone is derived from caraway seed (Carum car6i ). The production of S-( + )-carvone from caraway seed was stimulated by the Dutch Ministery of Agriculture in the National Caraway Research Programme. Due to its high costs the use of Talent will be limited to some specific applications (Lodewijk, 1994): Low residue potatoes for export to Italy and Scandinavian countries; Biologically grown potatoes for the internal Dutch market Seed potatoes (not allowed yet) The environmental profiles of S-( + )-carvone and (C)IPC are compared by the life cycle analysis (LCA) method, examining the common idea that natural products are less harmful to the environment than chemical products. Nine environmental effect scores, mentioned in Heijungs (1992) are evaluated: Abiotic exhaustion (1), global warming (2), ozone depletion (3), human toxicity (4), aquatic ecotoxicity (5), photochemical ozone creation (6), acidification (7), nutrification (8) and odoriferous pollution (9). In a first approach the nine effects are treated on an equal base. Given the results, a further discussion about the different weights of these effects appears afterwards not to be necessary.

tion of raw materials to the emission of waste materials. In this research the ‘Guide for Environmental Life Cycle Assessment of Products’ (Heijungs, 1992) is followed closely. This guide is considered as the state of the art of LCA at international level (e.g. by the Society of Environmental Toxicology and Chemistry) (SETAC, 1996) and is currently used as a starting point for international standardisation at European (CEN) and global (ISO) level (ISO/TC 207/SC 5, 1996). Fig. 1 shows the procedure of performing an LCA. First the functional unit is defined, describing the precise dosage of the products. Second, an inventory is made of the processes necessary to produce the functional unit. This inventory is schematically described in a ‘process tree’. Quantification of the processes results in a table of the total input and emission of the materials due to the production of the functional unit. The emissions are multiplied by classification factors to calculate the environmental effect scores. The final results are evaluated by a sensitivity analysis to evaluate the influence of assumptions and missing data (emissions as well as classification factors). An improvement analysis is carried out to evaluate the influence of some (fictitious) measures to improve a product.

2. Method/materials The environmental profiles of Talent and GroStop SC are obtained by using the LCA methodology. LCA provides a systematic framework which helps to identify, quantify and interpret the environmental impacts of a product in an orderly way. In this methodology both products are evaluated from ‘cradle to grave’ i.e. from the extrac-

Fig. 1. The procedure for performing an LCA.

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Table 1 Chemical composition of the functional unit Compound (g/t per season)

Gro-Stop SC


CIPC IPC Dichloromethane S-(+)-carvone Unknown

17.3 2.7 64.0 — 4.4

— — — 547.7 28.8




2.1. Functional unit The functional unit is defined according to the directions for potato storage (Rastovski and Van Es, 1987): The amount of sprout inhibitor needed to store 1 t of potatoes without sprouting in air cooled warehouses (4 – 10°C) during an entire storage season ( \6 months) by means of the ‘fog’ method. The advised doses per ton are 20 g. (C)IPC (IKC-AT/PD, 1993) and 600 ml. Talent (BV Luxan, undated). Talent is a 95% liquid formula of S-(+)-carvone. A typical liquid formula of (C)IPC is Gro-Stop SC (BV Luxan), containing 260 g/l CIPC and 40 g/l IPC. Dichloromethane is applied as a solvent. Table 1 shows the chemical composition of the functional unit. In both sprout inhibitors 5% of the mass is considered to correspond to unspecified additives.

Fig. 2. Lifecycle of Gro-Stop SC

pared to other parts of the life cycle. The application of the products, however, is an important process from an environmental point of view, because volatile compounds like dichloromethane and S-(+ )-carvone are directly emitted into air (estimated at 90%). (C)IPC is less volatile. It is assumed that more than 50% is absorbed by

2.2. In6entory of processes Fig. 2 describes the life cycle of Gro-Stop SC, while Fig. 3 describes the life cycle of Talent. Emission data on the industrial processes have been provided by the Bureau of Emission Inventory (DGM/HIMH, 1992). Many of the relevant industrial production processes are located in Germany. However, as data from these industries could not be obtained, Dutch data are applied. The energy data for the industrial processes are obtained from Habersatter (1991). The formulation processes of both Gro-Stop SC and Talent have not been studied in detail: These emissions are of minor importance com-

Fig. 3. Lifecycle of Talent


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materials in the storage area (Hartmans 1995, personal communication). Besides, (C)IPC may partly be washed out into the surface water when the storage area is cleaned (estimated at 10%). Only a small part of the administered amount of (C)IPC ends up as a residue in the stored potatoes. In the LCA this fraction is ignored.

2.3. In6entory of Gro-Stop SC The natural resources needed for the production of Gro-Stop SC are oil, gas, sulphur and sodium chloride. The industrial processes to produce (C)IPC involve a wide range of reaction types. The final intermediates in IPC production are aniline and isopropylchloroformate or alternatively phenylisocyanate (from aniline and phosgene) and isopropylalcohol (Cremlyn, 1991). Both processes require the same starting materials, however. The production of CIPC requires the reaction of nitrobenzene and chlorine as an additional step. Dichloromethane is produced by the addition of chlorine to methanol (Huizinga and Hoogenkamp, 1994).

2.4. In6entory of Talent The natural resources needed for the production of Talent are gas, sulphur, phosphate rock, potash and limestone. These resources are needed to produce the N-, P- and K- fertilizer applied in the cultivation of caraway. Typical fertilizers are K-fertilizer (KCl), N-fertilizer (NH4NO3/CaCO3, 80/20%) and P-fertilizer (Ca(H2PO4)2) (LEI-DLO/ CBS, 1993). The emissions of fertilizers into the soil were calculated by subtracting the plant’s fertilizer uptake from the recommended doses (PAGV/IKCAGV, 1994). Addition of the N-fertilizer to the soil has at least three consequences, for which data were corrected: Carbonate reacts with acids in the soil forming carbon dioxide. Due to (de)nitrification by micro-organisms nitrous oxide is formed, estimated at 1% of the N-dose (Bouwman, 1994). Ammonia is released into the air due to its equilibrium with ammonium, estimated at 2% of the N-dose (Asman, 1992).

Typical pesticides in the cultivation of caraway are insecticides (vamidothion, deltamethrin), fungicides (iprodion) and herbicides (prometryn/ propazin, linuron/monolinuron) (PAGV/IKCAGV, 1994). However, the production processes of these pesticides are excluded from this study as these processes are not relevant in this LCA because of the low dosage of the pesticides. Emissions during the application of pesticides are distinguished into air (20–22%), soil and ground water (2–4%) and surface water (1–3% of the applied dose), according to the general distribution for crops in the open field (Tweede Kamer, 1991). The average yield of Dutch caraway seed is 1500 kg/ha (PAGV/IKC-AGV, 1994). Straw is regarded as a by-product (yield 2000 kg/ha), so the input and emissions of the cultivation of caraway are distributed over the seeds and the straw. An allocation based on the market value offers the most realistic distribution in accordance with the LCA standards. The price of caraway seed is estimated at NLG 2.50/kg, caraway straw is estimated at NLG 65/t. Extraction of S-(+ )-carvone from caraway seed is a process involving two steps. Caraway oil is extracted by steam distillation, which requires a great deal of energy (Muntinga, 1985). Out of 1500 kg caraway seed 60 kg caraway oil can be distilled. A fractionated distillation is performed to obtain S-(+ )-carvone from the caraway oil. The yield of this process is 55% S-(+ )-carvone and 45% R-(+)-limonene, the other major component of caraway oil (Diepenhorst 1995, personal communication). R-(+)-limonene is not used widely, which results in a low price (NLG 4/kg) as compared to S-(+ )-carvone (NLG 125/ kg). After extraction of the oil, the seeds can be sold for human consumption, the usual application of caraway seed (Diepenhorst 1995, personal communication). Allocations are based on market values. The price of caraway oil was estimated at NLG 85/kg. The price of the caraway seed after extraction of the oil was estimated at maximum as 90% of the price of untreated caraway seed.

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Fig. 4. Comparison of environmental profiles.

3. Results In Table 2 the chemicals and processes determining the environmental profiles of Gro-Stop SC and Talent are listed. Classification factors are from Heijungs (1992). The production and application of P-fertilizer in the cultivation of caraway is the most important factor explaining the highest scores for Talent. The application of Nfertilizer and pesticides also contributes considerably to the high scores. Fig. 4 presents a comparison of Talent (T) and Gro-Stop SC (G) by calculating T/G ratios. The figure demonstrates that Gro-Stop SC is less harmful than Talent (i.e. T/G\ 1) for seven environmental effect scores (out of nine). The common idea that a natural product would be better for the environment than a chemical product cannot be confirmed by the results of this case study.

4. Discussion

4.1. Sensi6ity analysis According to the LCA method a sensivity analysis was performed to evaluate the lack of some

emission and classification data and the allocation of data to the various products. Due to assumptions the quantitative LCA results are rather rough. However, sensivity analysis showed that the qualitative results of the LCA are very solid. Quantification of the processes showed a lack of data on the emissions from nine out of twenty industrial processes concerning Gro-Stop SC. 70% of the mass of the products is covered by this study. Sensitivity analysis indicates that the remaining 30% doesn’t change the environmental profile qualitatively. Evaluation of the missing classification factors consolidates the results of the LCA. The ozone depletion effect of Talent is underestimated, as nitrous oxide (mostly related to Talent) is neglected although it plays a role in ozone depletion. Quantitative data on nitrous oxide are absent (Guicherit 1994, personal communication). The human toxicity of Gro-Stop SC is overestimated, as for (C)IPC a general classification factor for carbamates is used. This factor is too large, considering the relatively low toxicity of (C)IPC (Worthing and Hance, 1983). In this study allocations are based on market values. The most crucial allocation concerns the extraction of caraway oil from caraway seed. An





9: Odoriferous pollution (m3)

8: Nutrification (kg PO3− 4 )

7: Acidification (kg SO2)







2.8×103 1.2×106









6: Photochemical ozone creation (kg C2H4) G

5: Aquatic ecotoxicity (m3)

0 0.27


4: Human toxicity (kg)



3: Ozone depletion (kg CFK-12)

1.1 39






Product Score

2: Global warming, 100 years (kg CO2)

1: Abiotic exhaustion (−)

Effect score

Class. factor

49 20 18 11 79 11 10 82 76 24 76 24 — 87

gas oil oil gas oil gas gas CH2Cl2 CO2 N2O CCl4 CFK-12

109326 m3 123559 M t 123559 M t 109326 m3 123559 M t 109326 m3 109326 m3 15 1 270 1.08 1.0 — CIPC 33 kg/kg 2.9 kg/kg 13 IPC 33/2.9 kg/kg 2.9 kg/kg 55 SO2 2.3 kg/kg 26 NOx 0.78 kg/kg 83 oil 0.05 m3/mg 17 Hg 500 m3/mg 38 linuron 20 m3/mg 25 Cd 200 m3/mg 21 Hg 500 m3/mg 16 deltamethrin 1000 m3/mg 62 CIPC 0.761 22 CH 0.377 76 S-(+)-carvone 0.443 24 CH 0.377 74 SO2 1.00 26 NOx 0.70 44 NH3 1.88 37 SO2 1.00 19 NOx 0.70 88 NOx 0.13 10 N2O 0.27 73 H2PO− 1.00 4 0.35 13 NH+ 4 13 NO− 0.09 3 97 H2S 0.00043 mg/m3 96 H2S 0.00043 mg/m3

Chemical (%)

Table 2 Chemicals and processes determining the environmental profile of Gro-Stop SC (G) and Talent (T)

69 40 37 16 8.7×103 8.3×102 7.8×102 58 (air) 3.0×104 (air) 35 (air) 2.9×10−2 (air) 9.9×10−3 (air) — 6.9 (air) 1.7 (water) 1.1 (air) 0.27 (water) 75 (air) 55 (air) 1.6×10−2 (water) 3.2×10−7 (water) 0.13 (water) 9.0×10−3 (water) 3.0×10−3 (water) 1.1×10−3 (water) 6.9 (air) 5.1 (air) 4.9×102 (air) 1.3×102 (air) 0.66 (air) 0.34 (air) 47 (air) 75 (air) 55 (air) 0.34 (air) 1.9×10−2 (air) 1.4×103 (soil) 7.3×102 (soil) 2.5×103 (soil) 1.2×10−3 (air) 0.52 (air)

Input or emission (g)

Combustion fossil fuels Combustion fossil fuels Recovery gas/oil Production dichloromethane Application pesticides Production P-fertilizer Production P-fertilizer Application pesticides Application Gro-Stop SC Combustion fossil fuels Application Talent Combustion fossil fuels Combustion fossil fuels Combustion fossil fuels Application N-fertilizer Combustion fossil fuels Combustion fossil fuels Combustion fossil fuels Combustion fossil fuels Application P-fertilizer Application N-fertilizer Application N-fertilizer Production (C)IPC Production P-fertilizer

Application Gro-Stop SC

Combustion fossil fuels Combustion fossil fuels Production chemicals Production chemicals Combustion fossil fuels Production N-fertilizer Combustion fossil fuels Application Gro-Stop SC Combustion fossil fuels Application N-fertilizer Production dichloromethane Production dichloromethane — Application Gro-Stop SC

Dominant process

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allocation based on market values results in a 54 – 46 distribution of input and emissions over the caraway oil and the caraway seed after extraction. When an allocation is based on mass the ratio would change rather dramatically into a 3 – 97 ratio. Most of the T/G ratios would then be divided by a factor of about 18. Such an allocation procedure, however, does not correspond to the main purpose of the cultivation of caraway in the present life cycle analysis, which is the recovery of S-(+)-carvone.

4.2. Impro6ement analysis Several scenarios are analysed to evaluate potential measures for improving the environmental profile of Talent. Firstly, a decrease of the high dosage of Talent is an effective measure: The effects of all the preceding processes decrease proportionally. In practice, however, this measure is not yet feasible. Secondly, a decrease of the application of fertilizer is necessary to reduce the highest T/G ratios. The application of clover as N-fertilizer and the application of basic slag as P-fertilizer is suggested. Finally, an energy efficient process for the extraction of caraway oil and an increase of the yield of S-(+ )-carvone may contribute to a better environmental score. The increase of the yield of S-( + )-carvone may be achieved by upgrading caraway resulting in both a better crop and a higher content of S-( +)-carvone. An increased yield is also achieved by the conversion of R-( +)limonene into S-(+ )-carvone. However, when suitable processes are available for this conversion, the entire life cycle might change in favour of extraction of R-( +)-limonene from citrus peels.

4.3. Green chemistry The high T/G ratios reveal the differences between industrial and agricultural processes. Generally industrial processes are more efficient in the utilization of raw materials and the control of emissions. Yet this does not mean caraway is not a good crop. On the contrary, when compared to


other crops the dose of fertilizer and pesticides is low. Even then, the potential common disadvantages for products of green chemistry (i.e. chemistry of agrification products) dominate the present LCA: “ Low efficiency (a large amount of product is needed to realize the aim) “ Low concentration of active ingredient in the crop (a large quantity of by-product arises) “ Extraction of the product requires a great deal of energy “ Cultivation of the crop requires a great deal of energy due to fertilizer use etc. These disadvantages also play a role in the cost of green products, which is generally higher than their chemical counterparts. Per ton of potatoes the use of Gro-Stop SC costs NLG 2–3, while Talent costs NLG 42–63 (Diepenhorst 1995, personal communication). The present disadvantages, however, are not a reason to reject the concept of green chemistry. This study aims to contribute to a better understanding of the environmental effects of green chemistry and the potential improvements in the life cycle of agrification products. It is recommended that environmental LCA’s be performed for other agrification products.

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Lodewijk, G., 1994. Met aardappel-ogen kijken naar carvon. Lecture during the Caraway and Carvoneday, Wageningen, 2 Juni 1994. Meijer, W.J.M., Oosterhaven, J. (Eds.), 1994. Karwij, Carvon en Biologische Kiemremming voor Aardappelen. DLO, Wageningen. Muntinga, B., 1985. Problemen rond de karwijteelt. Prof. H.C. van Hallinstituut, Groningen. PAGV/IKC-AGV, 1994. Teelthandleiding nr. 60: Teelt van karwij, Lelystad.


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