Environmental Impact Assessment of Toys Toward Sustainable Toy Production and Consumption in Japan
1
Faculty of Agriculture, Tokyo University of Agriculture and Technology, Tokyo 183-8509, Japan
2
Institute of Agriculture, Tokyo University of Agriculture and Technology, Tokyo 183-8509, Japan
*
Author to whom correspondence should be addressed.
Sustainability 2025, 17(6), 2351; https://doi.org/10.3390/su17062351
Submission received: 8 February 2025
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Revised: 1 March 2025
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Accepted: 6 March 2025
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Published: 7 March 2025
Abstract
:Japan’s toy market is the third largest in the world. However, the actual status of use and environmental impact of toys have not been fully studied. This study analyzes the environmental effects of wooden and plastic toys, considering their lifespan and disposal methods. A web-based survey of 1000 parents was conducted to determine the average lifespan and disposal method of toys. Additionally, a life cycle assessment was utilized to evaluate the environmental impact of common wooden and plastic toy cars across 14 environmental impact categories. Results showed that the average lifespans of wooden and plastic toys were estimated at 7.29 and 6.17 years, respectively; wooden toys had a slightly longer lifespan. Wooden toy cars had a smaller environmental impact than plastic toy cars in nine impact categories. Specifically, replacing plastic toy cars with wooden toy cars could reduce greenhouse gas emissions per toy car by 77%. However, wooden toy cars had a greater environmental impact than plastic toy cars in five categories. In a bid toward sustainable toy manufacturing by reducing environmental impact, it is important to use wooden materials made of logs from sustainably managed forests and decrease the utilization of plastic and metal parts and packaging materials.
1. Introduction
Toys are essential for children’s development. The scale of the global toy market is on the rise, reaching sales of $108.7 billion in 2023 [1]. However, the production and use of toys impact the environment considerably. The toy industry’s plastic intensity, as reported by the United Nations Environment Programme [2], is 48 tons per million dollars of revenue. This includes 37.5 tons of plastic in products, 2.9 tons in packaging, and 7.6 tons in the supply chain, making it the highest across all consumer goods sectors. Therefore, conducting a Life Cycle Assessment (LCA) to comprehensively quantify the environmental impact of toys is vital for the sustainability of toy production and consumption. However, limited studies have focused on this topic.
Muñoz et al. [3] and Margallo et al. [4] conducted an LCA to evaluate the environmental impact of toys with integrated electrical and electronic components. Across the environmental impact categories, the contribution of the toys’ use process was significant, mainly due to battery manufacturing. The environmental impact of the toy production process was also significant. Kovačič Lukman et al. [5] conducted an environmental LCA, life cycle costing, and social LCA of a monkey toy. They reported that the main environmental impacts are eutrophication, terrestrial eco-toxicity, acidification, and global warming. While these studies have focused on a single toy, some research has compared the environmental impact of multiple toys. Rangaswamy et al. [6] reported that locally produced traditional wooden toys in India are less toxic, consume less energy, and have less environmental impact than the poly-vinyl chloride (PVC) toys made in China. Levesque et al. [7] evaluated the environmental impact of eight different toys in the United States—three LEGO sets, one Barbie, one Jenga game, one plush dog, one plush dog with battery parts, and one Marble Frenzy game. The wooden Jenga was found to have only a small effect on global warming potential and eutrophication, but a large effect on acidification [7].
In addition to their different functions and sizes, different toys have different lifespans and disposal methods [8,9]. These differences affect the magnitude of environmental impacts. Therefore, it is important to conduct an LCA that reflects the actual situation of the toys.
Japan has the world’s third-largest toy market after the United States and China, and it is growing [10]. In recent years, Japan has been promoting the use of timber for climate change mitigation and the effective use of domestic artificial forests that are at the optimum age for harvesting. In this context, wooden toys are becoming increasingly popular and are attracting social interest [11,12]. However, to the best of the authors’ knowledge, no previous studies have examined the actual state of use, such as lifespans and disposal methods, and the environmental impact of toys in Japan.
To address this knowledge gap, this study conducted a questionnaire survey on the topic of wooden toys and common plastic toys in Japan to understand their actual use, including their lifespan and disposal methods. An LCA was used to elucidate their environmental impact to obtain insights toward sustainable production and the use of toys.
2. Materials and Methods
2.1. Questionnaire Survey
A questionnaire survey was conducted to determine the actual usage status of wooden and plastic toys. An online survey was conducted from 21 to 27 September 2023, and responses were received from 1000 parents (679 men and 321 women).
The questionnaire surveyed the number of years of use/ownership of the toys (considering their lifespan as the period of use/ownership [9]), disposal method, and reason for disposal after use/ownership. It was conducted using a multiple-choice format for each wooden and plastic toy. These questions examined the average use of toys made with each material. However, since the LCA target in this study is toy cars, the fact that they might have different characteristics from toys used for other purposes was considered. The study included a question limited to toy cars from respondents who used/owned toy cars. Thus, for each item, four responses were obtained—all wooden toys, all plastic toys, wooden toy cars, and plastic toy cars. The survey respondents’ basic information is presented in Data S1 in the Supplementary Materials.
2.2. Environmental Impact Assessment
2.2.1. Toys for Evaluation
The subjects of the LCA were wooden and plastic toy cars (Table 1). As wooden and plastic toy cars are widely used in Japanese society [12], and a single toy car can be used for the functional unit of both types, they were chosen as the study subject. For wooden toy cars, log and lumber production and product manufacturing are undertaken in Tokyo. Residues generated during the lumber production and toy manufacturing processes are used as fuel. As plastic toy cars vary in terms of their plastic material, metal parts, and countries of manufacture, three types were selected to avoid data bias.
2.2.2. Functional Unit and System Boundary
The functional unit was defined as one toy car per year of lifespan. The lifespan, that is, the number of years used/owned, was obtained from the questionnaire in Section 2.1 and integrated with the LCA. Additionally, toy cars of similar sizes were selected; however, their volumes were slightly different. The larger the volume, the greater the number of materials used, and the greater the environmental impact. Therefore, the results for plastic toy cars were divided by the volume ratio compared to wooden toy cars (Table 1) to evaluate the unified volume of wooden and plastic toy cars.
Figure 1 shows system boundaries. This study covered each process, from raw material procurement to the disposal/recycling of toy cars. “Log production” for wooden toy cars includes forestry operations (planting, weeding, harvesting, yarding, and hauling), and “other raw material procurement” includes the production of metal bolt/nut and oil-based paint. “Other raw material procurement” for plastic toy cars includes die-casts, metal rods, metal screws, and synthetic rubber. The manufacturing and disposal of packing materials used to transport the toy cars were also included in the scope of the evaluation. Since the toy cars in this study do not use batteries, the environmental impact in their use phase was assumed to be zero and excluded from the scope of the evaluation.
2.2.3. Inventory Analysis
As foreground data, Table 2, Table 3, Table 4 and Table 5 show the raw materials, energy consumption, and waste generation per toy car in each process of the system boundary. As background data, environmental load emissions, such as greenhouse gas (GHG) emissions, were calculated using the Inventory Database for Environmental Analysis (IDEA) Ver. 3.3 [13]. The IDEA is the most comprehensive inventory database available in Japan and uses a hybrid of both statistical and process-based data. The IDEA provides the environmental load intensity for each product, which traces back to the upstream processes, in other words, “from cradle to gate”. Environmental load emissions were calculated by multiplying the raw materials, energy consumption, and waste generation (Table 2, Table 3, Table 4 and Table 5) by the environmental load emission intensities in the IDEA database.
2.2.4. Impact Assessment
The environmental impact assessment was conducted using the Life Cycle Impact Assessment Method based on Endpoint Modeling (LIME) 2 [20]. The LIME2 produces impact assessment results using the following steps: characterization, damage assessment, and integration. Characterization assesses the potential impact caused by environmental load substances on each impact category obtained from the above-mentioned IDEA database. This study covered 14 environmental impact categories: climate change, ozone layer depletion, acidification, urban area air pollution, photochemical ozone, toxic chemicals (cancer), toxic chemicals (chronic disease), aquatic toxicity, biological toxicity, eutrophication, land use (occupation), land use (transformation), resource consumption, and water resource consumption. The environmental impact factors for each impact category for each product in the IDEA database were multiplied by the inventory data (see Section 2.2.3) in order to calculate the environmental impact. Damage assessment assesses potential damage quantities based on the following four endpoints: human health, social assets, biodiversity, and primary production. Integration calculates an integrated indicator with a monetary unit (Japanese yen, JPY) by weighting the importance among those impact categories in the LIME2 [20]. This study also covered the integrated indicator with a monetary unit.
The LIME 2 does not cover the absorption, storage, and emission of biogenic carbon in its impact on climate change. Therefore, this study supplementarily calculated the amount of biogenic carbon in the wooden toy cars, lumber and product residues, and packaging materials using conversion factors from volume or weight to carbon content (0.225 g-C/cm3 for the wooden toy cars and residues and 0.386 g-C/g for packaging materials) [21].
3. Results
3.1. Toy Lifespan
Figure 2 and Data S2 in the Supplementary Materials show the responses regarding the lifespan of wooden and plastic toys. Data S3 in the Supplementary Materials shows the results of the χ-square test to determine the differences in the lifespan based on the toy’s material and use. No statistically significant differences were found between the responses for all toys and toy cars for both wooden and plastic toys. Hence, no difference was observed in the lifespan of toy cars and other toys, irrespective of material. However, for both all toys and toy cars, a statistically significant difference was found between the responses for wooden and plastic toys, confirming a difference in lifespan. The results indicate that respondents use and own wooden toys for longer periods than plastic toys.
The average lifespan of wooden and plastic toys was estimated using the above-mentioned results. Since almost no differences were observed in the lifespan characteristics between all toys and toy cars for both materials, the results for all toys were used from this point onward. Among the responses regarding toy disposal, we used 0.5 years for “1 year or less”, 10 years for “10 years or more”, and the median for each of the other options (i.e., 2.5 years for “2–3 years”) to calculate the average lifespan. Among the respondents who never disposed of the toys, those with children aged 13 years or older were more likely to have used/owned toys for a long period; thus, the number of years they used/owned toys was set at 10 years. Respondents with children aged 12 years or younger were excluded because it was unclear how long they used/owned the toys. Under these assumptions, a weighted average of the duration the toys were used/owned was calculated, deriving 7.29 years for wooden toys and 6.17 years for plastic toys. A t-test confirmed a difference between the means at the 1% significance level, showing that the wooden toys had a mean lifespan of one year or more longer than that of the plastic toys. However, given that the “10 years or more” option in the questionnaire is assumed to be a minimum of 10 years, the above-average lifespans are considered conservative estimates and the actual lifespan may be longer.
3.2. Toy Disposal
Figure 3 and Data S4 in the Supplementary Materials show the responses regarding the most common methods and reasons for the disposal of toys. The χ-square test confirmed a statistically significant difference (disposal method: χ2 value 41.011, p-value 9.33 × 10−8; disposal reason: χ2 value 23.797, p-value 8.77 × 10−5) between wooden and plastic toys at the 1% significance level for both disposal method and reason. Several respondents chose “throw it away as trash” as a disposal method for both wooden and plastic toys; however, the percentage for wooden toys (53%) was lower than that for plastic toys (67%). This result indicates that a high percentage of wooden toys were reused (either given to acquaintances and friends or sold as second-hand items). The response of “broken” as the reason for disposal was more than 10 percentage points higher for plastic toys (42%) than for wooden toys (30%). In other words, plastic toys were found to be disposed of more frequently due to breakage.
3.3. Environmental Impacts
Figure 4 and Data S5 in the Supplementary Materials show the environmental impact per year of lifespan per wooden/plastic toy car. The lifespans were 7.29 years for wooden toys and 6.17 years for plastic toys. The most common response to the survey was “throw it away as trash” for both wooden and plastic toys. Therefore, considering the environmental impact, reuse after disposal was not included; instead, disposal and subsequent recycling were covered.
The impact of wooden and plastic toy cars on climate change (“W” and “P” in Figure 4a) shows that the total GHG emissions of the wooden toy cars are 0.45 kg-CO2eq/product/year and of the plastic toy cars are 0.79 kg-CO2eq/product/year; hence, emissions from wooden toy cars were smaller. The net emission, calculated by subtracting the total reduction amount (0.27 kg-CO2eq/product/year) from the total emission amount (0.45 kg-CO2eq/product/year) for wooden toy cars, is 0.18 kg-CO2eq/product/year, which is equivalent to 23% of the emissions from plastic toy cars.
The above results do not include biogenic carbon. The toy car product, lumber and product residues, and packaging materials (cardboard box and wrapping paper) store 0.30, 0.26, and 0.05 kg-CO2eq/product/year, respectively, of biogenic carbon for the wooden toy cars. The packaging materials (cardboard box) store 0.05 kg-CO2eq/product/year of biogenic carbon for the plastic toy cars. Although this carbon storage could have negative emissions until the disposal and recycling process, it would shift to significant positive emissions when the product, residues, and packaging materials are burned.
Wooden toy cars had a smaller environmental impact than plastic toy cars in nine of the 14 environmental impact categories. However, wooden toy cars had a greater environmental impact than plastic toy cars in five areas—ozone layer depletion, eutrophication, land use (occupation), land use (transformation), and resource consumption.
4. Discussion
4.1. Environmental Impacts
Regarding the impact of climate change, compared to plastic toy cars, wooden toy cars have particularly low GHG emissions in the raw material procurement and the disposal/recycling process (“W” and “P” in Figure 4a). In the raw material procurement process, the emissions related to the production of logs and lumber for wooden toy cars are smaller than the emissions related to the production of raw plastic materials for plastic toy cars, which influences the result. In addition, for wooden toy cars, the emission reductions in substituting kerosene with waste wood and residues for firewood are greater than the emissions associated with firewood production. Therefore, the net emission during the disposal/recycling process is negative. In contrast, for plastic toy cars, the emissions from burning waste plastics exceed the emission reductions achieved by replacing electricity with the power generated from waste plastic. Therefore, the net emission is positive. Due to this difference, the number of emissions generated during the disposal/recycling process for wooden and plastic toy cars differed greatly. From the difference in net GHG emissions between wooden and plastic toy cars, replacing plastic toy cars with wooden toy cars could reduce emissions by 77%. The magnitude of emission reduction was in line with that in previous studies [6,7] which reported emission reductions by 74% [6] and 80% [7] (see Section 4.3).
While wooden toy cars had a smaller environmental impact than plastic toy cars in nine categories, those had a greater environmental impact in five categories—ozone layer depletion, eutrophication, land use (occupation), land use (transformation), and resource consumption (“W” and “P” in Figure 4b,j,k,l,m). The influence of processes related to raw material procurement, product manufacturing, and packaging is particularly significant.
The influence of the raw material procurement process is evident in land use (occupation) and resource consumption. In land use (occupation), the production of wooden round rods (Table 1) increases the load in the form of forestry land for wood production. The logs and small-diameter wood used as raw materials for the wooden toy cars considered in this study were produced under sustainable forest management. Data on fuel and electricity consumption associated with the use of each machine during log and lumber production under forest management were collected, and the environmental impact was calculated by multiplying the fuel and electricity consumption by the environmental impact factors in the IDEA database. Since the wooden round rods were not produced in the lumber and toy manufacturing companies targeted in this study and were purchased from an external manufacturer, collecting detailed data on fuel and electricity consumption was difficult. Thus, the environmental impact factors for lumber from IDEA were used. This resulted in the occupation of land by forestry businesses for timber production being recorded as an environmental impact, leading to an increase in the impact of land use (occupation). Regarding resource consumption, the production of metal bolts/nuts is the main cause of increased environmental impact, suggesting that it is important to reduce the use of metals to reduce the environmental impact.
The product manufacturing process of wooden toy cars has a great impact on ozone layer depletion and resource consumption. This is because wooden toy cars consume more energy during production than plastic toy cars. Compared to plastic toy cars, which can be mass-produced, a single wooden toy car can take a longer time and more effort, which may lead to higher energy consumption during product manufacturing.
The environmental impacts of wooden toy car packaging were significant in ozone layer depletion, eutrophication, land use (occupation), and land use (transformation). The reason for this is that wooden toy cars use a large number of cardboard boxes and wrapping papers as packaging materials, which impose a high environmental burden. However, since the packaging materials are not part of the wooden toy car, this cannot be considered a drawback of wooden toy cars compared to plastic toy cars. To reduce the environmental impact of packaging for both wooden and plastic toy cars, reducing the amount and weight of packaging materials and using simplified packing is important.
Although wooden toy cars have a greater environmental impact in some areas, they have a smaller environmental impact in nine areas. Therefore, it can be concluded that they have an overall smaller environmental impact. The integrated result of the total environmental impact (“W” and “P” in Figure 4o) showed that wooden toy cars were 12.79 JPY/product/year and plastic toy cars were 18.19 JPY/product/year, with wooden toy cars proving to have a better environmental performance, with 70% of the total impact from plastic toy cars.
4.2. Sensitivity Analysis
The wooden toy cars in this study were made from logs produced, processed, and manufactured in Tokyo and sold in the region, and the waste wood was recycled after use. These conditions lead wooden toy cars to have a lower environmental impact. Therefore, conditions were set for cases where environmental impacts were likely to be higher (“Toy car (long trans)” in Table 2): the logs used to make the toy cars were imported (the United States, Japan’s largest log import partner), the toy cars were sold to distant locations (transported from Tokyo to Hokkaido, Japan’s northernmost island), and the waste wood after usage was incinerated instead of being used for energy.
The environmental impact of toy cars meeting these conditions (“W (long trans)” in Figure 4) was greater than that of wooden toy cars under the original condition (“W” in Figure 4) in all of the impact categories. Regarding climate change, the total GHG emissions of wooden toy cars increased to 0.70 kg-CO2eq/product/year, the total GHG reductions decreased to 0.12 kg-CO2eq/product/year, and net emissions were 0.58 kg-CO2eq/product/year. This is equivalent to 74% of the emissions produced by plastic toy cars; hence, the reduction effect of replacing plastic toy cars with wooden toy cars decreased. Similarly, the integrated result of wooden toy car (long trans) increased to 15.65 JPY/product/year, narrowing the gap with plastic toy cars. However, for overall environmental impact, the relationship between the magnitude of the environmental impact of wooden toy cars and plastic toy cars did not change between wooden toy cars (long trans) and the original wooden toy cars. This suggests that, even if the environmental impact of wooden toy cars varied with different conditions, the trend of environmental superiority over plastic toy cars would not change.
Since the volume of each toy car is different, the results for plastic toy cars were divided by the volume ratio compared to wooden toy cars (Table 1); they are presented in Data S6 in the Supplementary Materials. In three categories—ozone layer depletion, eutrophication, and land use (occupation)—wooden toy cars had a greater environmental impact than plastic toy cars. However, the impact of plastic became greater in land use (transformation) and resource consumption, and wood was seen to have a higher environmental performance.
4.3. Comparison with Previous Studies
Watkins and Mestre [8] found a lifespan of 0.5–5 years for low-priced toys and 1.5–7 years for high-priced toys. Tu et al. [9] found that about half of toy buyers reported an average lifespan of six months or less, and the other half reported an average lifespan of six months or longer. Levesque et al. [7] set the lifespan of toys at two years. This study’s questionnaire results revealed that the average lifespan of wooden toys was seven years and that of plastic toys was six years. This study assumes that the toys have been used/owned for 10 years if they have been used/owned for 10 years or longer and does not consider the extension of the lifespan through reuse. Therefore, the above lifespan is considered to be a conservative estimate. Nonetheless, the results of this study indicate a longer toy lifespan than previous studies.
Rangaswamy et al. [6] compared the environmental impacts of locally produced wooden toys in India and PVC toys made in China in seven impact categories—global warming potential, human toxicity potential, terrestrial eco-toxicity, freshwater aquatic eco-toxicity, photo-chemical oxidation, acidification, and eutrophication—and reported that the environmental impact of wooden toys was smaller in all seven categories. In this study, wooden toy cars had a smaller impact in six of the seven categories; however, they had a greater effect on eutrophication. However, eutrophication was mostly influenced by the packaging material; thus, the overall trends in this study are consistent with those found in Rangaswamy et al. [6]. Regarding the impact of climate change, previous research [6] reported that GHG emissions from wooden toys were only 26% of those from PVC toys, which indicates that replacing PVC toys with wooden toys could reduce emissions by 74%. The magnitude of reduction corresponded to the 77% reduction found in this study.
Levesque et al. [7] assessed the environmental impacts of LEGO sets, Barbies, Jenga Games, plush dogs, plush dogs with battery parts, and Marble Frenzy games on global warming potential, eutrophication, acidification, eco-toxicity, ozone depletion, photochemical ozone formation, and resource depletion. Wooden Jenga was reported to have a smaller environmental impact than plastic LEGO sets in several categories. However, wooden Jenga had a greater effect on acidification and ozone depletion. In this study, wooden toy cars had a greater effect on ozone layer depletion than plastic toy cars, which was consistent with the previous study. However, the effect on acidification was found to be small, which differed from the previous study. A simple comparison cannot be made between this study and Levesque et al. [7] because the toy types, functional units, system boundaries, and databases used are different. Additionally, while the impact of deforestation was included in acidification in the previous study, in this study, the impact of deforestation is included in the impact on land use. This difference may contribute to the difference in the effect on acidification. With regard to the impact on climate change, Levesque et al. [7] found that GHG emissions from wooden Jenga were only 20% of those from plastic LEGO sets, revealing that the substitution of LEGO sets with Jenga could reduce emissions by 80%. This reduction trend corresponded to that in this study (77% reduction).
4.4. Limitations and Future Prospects
For the questionnaire survey, the age distribution of respondents was concentrated in the range of 40s to 60s (see Data S1 in the Supplementary Materials) since the survey targeted people with children, who are thought to be able to answer items about the period of use/ownership and disposal methods of their children’s toys, amid the increasing trend in late marriages in Japan. Approximately 70% of the children of the respondents were aged 13 or older (Data S1 in the Supplementary Materials), which indicates that some respondents might be relying on their memories from more than ten years ago, leading to a decrease in the accuracy of responses. As a difference in lifespans or disposal methods of toys could significantly affect the environmental impact, a more detailed analysis by the categorization of respondents’ age should be considered for future research.
Although this work revealed that wooden toy cars were reused more often than plastic toy cars, the reuse option after disposal was not considered in the environmental impact assessment. The consideration of reuse is important for future research as it can contribute to extending the lifespan and curbing new toy production and waste generation, which leads to a reduction in the environmental impact. Since this study only evaluated the environmental impact of toy cars widely used in Japan, the results may change if other types of toys are targeted. It is important to expand the target types of toys for a more comprehensive evaluation.
5. Conclusions
This work was the first study to conduct a questionnaire survey pertaining to the use of wooden and plastic toys and an LCA to evaluate their environmental impact in Japan. The average lifespan (years used and owned) was estimated to be 7.29 years for wooden toys and 6.17 years for plastic toys, with wooden toys lasting more than 1 year longer than plastic toys. The most common disposal method for both wooden and plastic toys was to discard them as trash. However, wooden toys were reused more often than plastic toys, either by giving them to friends and acquaintances or by selling them as second-hand items. Plastic toys were disposed of more often because of damage.
The environmental impacts per year of a toy car’s lifespan were less for wooden toy cars than for plastic toy cars in nine categories—climate change, acidification, urban area air pollution, photochemical ozone, toxic chemicals (cancer), toxic chemicals (chronic disease), aquatic toxicity, biological toxicity, and water resource consumption. Regarding the impact of climate change, the net GHG emission of wooden toy cars is 0.18 kg-CO2eq/product/year and the emission of plastic toy cars is 0.79 kg-CO2eq/product/year. Thus, replacing plastic toy cars with wooden toy cars will reduce GHG emissions by 77% (0.61 kg-CO2eq/product/year).
However, wooden toy cars had greater environmental impacts than plastic toy cars in five categories—ozone layer depletion, eutrophication, land use (occupation), land use (transformation), and resource consumption. In the production of wooden toy cars, the production of wooden round rods, metal parts, and packaging materials contributed greatly to these environmental impacts. Hence, in order to reduce the environmental impact of wooden toy cars, procuring logs under sustainable forest management and reducing the use of metal parts and packing materials is important.
Since there were no statistical differences in lifespan, disposal method, or reasons for disposal between toy cars and all toys, the findings of the lifespan period and common disposal options and reasons obtained in this study are applicable to various toys other than toy cars. The environmental superiority of wooden toy cars remained consistent under unfavorable conditions for wooden toy cars. This suggests that, even if the environmental impact of wooden toy cars varied depending on conditions, the trend of environmental superiority over plastic toy cars would not change.
The findings obtained in this study can contribute to sustainable toy production and consumption, proposing the use of wooden materials made of logs produced from sustainable forest management and reduction in the use of plastic and metal parts and packaging materials.
Supplementary Materials
The following supporting information can be downloaded at https://www.mdpi.com/article/10.3390/su17062351/s1, Data S1: Basic information of survey respondents; Data S2: Lifespan of wooden/plastic toy; Data S3: Chi-square test for differences in toy lifespan; Data S4: Most common methods and reasons for disposing of toys; Data S5: Environmental impact per year of lifespan per wooden/plastic toy car; Data S6: Environmental impact per year of lifespan per wooden/plastic toy car with unified volume in the Supplementary Materials.
Author Contributions
Conceptualization, Y.Y. and C.K.; methodology, Y.Y. and C.K.; formal analysis, Y.Y.; investigation, Y.Y.; data curation, Y.Y.; writing—original draft preparation, Y.Y.; writing—review and editing, C.K.; funding acquisition, C.K. All authors have read and agreed to the published version of the manuscript.
Funding
This research was funded by the Japan Society for the Promotion of Science, grant number JP23H03596, JP24K03140, and the Institute of Global Innovation Research at the Tokyo University of Agriculture and Technology.
Data Availability Statement
The data presented in this study are available from the corresponding author on reasonable request.
Acknowledgments
We would like to thank the log and toy manufacturing company, Tokyo Chainsaws Co., Ltd., and the lumber companies for providing valuable information and data for this study.
Conflicts of Interest
The authors declare no conflicts of interest.
Abbreviations
The following abbreviations are used in this manuscript:
| LCA | Life cycle assessment |
| PVC | Poly-vinyl chloride |
| GHG | Greenhouse gas |
| IDEA | Inventory database for environmental analysis |
| LIME | Life cycle impact assessment method based on endpoint modeling |
| JPY | Japanese yen |
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Figure 1.
System boundaries.
Figure 2.
Lifespan of wooden/plastic toy. “Have disposed of a toy before: X years” indicates that the respondent has disposed of a toy after using/owning it and has used/owned the toy for X years. “Never disposed of a toy before: child aged Y or older/younger” indicates that the respondent never disposed of a toy after using/owning it and the child is Y years old or older or younger. The figure excludes respondents who have never used/owned a toy; thus, the number of respondents (n) varies depending on the material and toy usage.
Figure 2.
Lifespan of wooden/plastic toy. “Have disposed of a toy before: X years” indicates that the respondent has disposed of a toy after using/owning it and has used/owned the toy for X years. “Never disposed of a toy before: child aged Y or older/younger” indicates that the respondent never disposed of a toy after using/owning it and the child is Y years old or older or younger. The figure excludes respondents who have never used/owned a toy; thus, the number of respondents (n) varies depending on the material and toy usage.
Figure 3.
Most common methods and reasons for disposing of toys.
Figure 4.
Environmental impact per year of lifespan per wooden/plastic toy car. Panels (a–n) show the respective results of 14 environmental impact categories by each life cycle process. Panel (o) indicates the results integrated with a monetary unit (JPY) by weighting the importance among those impact categories. “W” indicates wooden toy cars in “Toy car” in Table 2. “W (long trans)” indicates wooden toy cars in “Toy car (long trans)” in Table 2 and assumes the import of logs as raw material from the United States, the long-distance transportation of toy car products (from Tokyo to Hokkaido), and the incineration of waste wood without energy use. “P” indicates the average value for three types of plastic toy cars. The “Net impact” was calculated by subtracting the reduction in environmental impact (− value) from the environmental impact (+ value). Biogenic carbon balance is not included in panel (a) climate change.
Figure 4.
Environmental impact per year of lifespan per wooden/plastic toy car. Panels (a–n) show the respective results of 14 environmental impact categories by each life cycle process. Panel (o) indicates the results integrated with a monetary unit (JPY) by weighting the importance among those impact categories. “W” indicates wooden toy cars in “Toy car” in Table 2. “W (long trans)” indicates wooden toy cars in “Toy car (long trans)” in Table 2 and assumes the import of logs as raw material from the United States, the long-distance transportation of toy car products (from Tokyo to Hokkaido), and the incineration of waste wood without energy use. “P” indicates the average value for three types of plastic toy cars. The “Net impact” was calculated by subtracting the reduction in environmental impact (− value) from the environmental impact (+ value). Biogenic carbon balance is not included in panel (a) climate change.
Table 1.
Toy car specifications.
| Type of Toy Car | Size (L × W × H) (in cm) | Material | Amount Used | Manufactured in | Volume Ratio |
|---|---|---|---|---|---|
| Wooden | 29 × 15 × 15.5 | Lumber | 1017.13 cm3 | Japan | 1.00 |
 | Small-diameter wood (forest residue) | 1564.80 cm3 | (Tokyo) | ||
| Wooden round rod | 53.90 cm3 | ||||
| Metal bolt/nut | 156.60 g | ||||
| Oil-based paint | 1.68 g | ||||
| Plastic (1) | 25.5 × 14 × 15.5 | Polypropylene | 446.00 g | Vietnam | 0.82 |
 | |||||
| Plastic (2) | 34 × 6 × 9.8 | Acrylonitrile-Butadiene-Styrene resin | 185.40 g | China | 0.30 |
 | Methyl Methacrylate Acrylonitrile Butadiene Styrene resin | 3.40 g | |||
| Polyoxymethylene | 0.20 g | ||||
| Die-cast | 109.10 g | ||||
| Metal rod | 4.00 g | ||||
| Metal screw | 6.60 g | ||||
| Synthetic rubber | 16.00 g | ||||
| Plastic (3) | 30.5 × 18 × 15 | Acrylonitrile-Butadiene-Styrene resin | 551.06 g | China | 1.22 |
 | Metal rod | 8.14 g | |||
| Metal screw | 0.60 g | ||||
Table 2.
Raw material, energy consumption, and waste generation per wooden toy car.
| Toy Car/Packaging | Life Cycle Process | Quantity | Unit | Data Source | |
|---|---|---|---|---|---|
| Toy Car | Raw Material Procurement | ||||
| Log production | Log (cedar/cypress) production | 3281.60 | cm3 | (a) | |
| Small-diameter wood (logging residue) production | 2180.32 | cm3 | (a) | ||
| Gasoline consumption | 0.005 | L | (a) | ||
| Engine oil consumption | 0.0001 | L | (a) | ||
| Diesel consumption | 0.02 | L | (a) | ||
| Log transportation | 3t truck (logging site → lumber site, Tokyo) | 10.00 | km | (a) | |
| Small-diameter wood transportation | 3t truck (logging site → product manufacturing site, Tokyo) | 11.00 | km | (a) | |
| Lumber production | Lumber production | 2297.12 | cm3 | (a) | |
| Electricity consumption (Japan) | 0.11 | kWh | (a) | ||
| Diesel consumption | 0.001 | L | (a) | ||
| Lumber transportation | 3t truck (lumber site → site for natural drying → product manufacturing site, Tokyo) | 16.00 | km | (a) | |
| Other raw material procurement | Wooden round rod production | 53.90 | cm3 | (a) | |
| Metal bolt and nut production | 156.60 | g | (a) | ||
| Oil-based paint production | 1.68 | g | (a) | ||
| Product manufacturing | Electricity consumption (Japan) | 4.65 | kWh | (a) | |
| Product transportation | 4t truck (product manufacturing site → site of use, Tokyo) | 62.00 | km | (a) | |
| Disposal and recycling of lumber residue | |||||
| Firewood production | Residue for firewood generated | 505.37 | cm3 | (a) | |
| Residue transportation, 3t truck (residue generated site → firewood production site, Tokyo) | 3.30 | km | (a) | ||
| Gasoline consumption | 0.001 | L | (b) | ||
| Firewood transportation, 3t truck (firewood production site → site of firewood use, Tokyo) | 10.00 | km | (a) | ||
| Kerosene replaced with firewood (thermal efficiency: firewood 0.72, kerosene 0.90) | 2.83 | MJ | (b), (c) | ||
| Firewood burning | 3.53 | MJ | (d) | ||
| Chip production | Residue for chips generated | 216.59 | cm3 | (a) | |
| Residue transportation, 3t truck (residue generated site → chip production site, Tokyo) | 14.30 | km | (a) | ||
| Diesel consumption | 0.0006 | L | (b) | ||
| Chip transportation, 3t truck (chip production site → site of chip use, Tokyo) | 10.80 | km | (a) | ||
| Kerosene replaced with chip (thermal efficiency: chip 0.85, kerosene 0.90) | 1.31 | MJ | (b), (c) | ||
| Chip burning | 1.39 | MJ | (d) | ||
| Incineration | Residue for disposal generated | 262.53 | cm3 | (a) | |
| Disposal and recycling of product residue | |||||
| Firewood production | Residue for firewood generated | 1279.99 | cm3 | (a) | |
| Gasoline consumption | 0.002 | L | (b) | ||
| Kerosene replaced with firewood (thermal efficiency: firewood 0.72, kerosene 0.90) | 7.16 | MJ | (b), (c) | ||
| Firewood burning | 8.95 | MJ | (d) | ||
| Disposal and Recycling | Waste wood for firewood generated | 2635.82 | cm3 | (a) | |
| Gasoline consumption | 0.01 | L | (b) | ||
| Kerosene replaced with firewood (thermal efficiency: firewood 0.72, kerosene 0.90) | 16.27 | MJ | (b), (c) | ||
| Firewood burning | 20.34 | MJ | (d) | ||
| Landfill of waste metal bolts and nuts | 156.60 | g | (a) | ||
| Toy car (long trans) | Log transportation | Container ship (Port of Los Angeles, USA → Port of Tokyo, Japan) | 9724.00 | km | (e) |
| Product transportation | 4t truck (product production site, Tokyo → site of use, Hokkaido) | 1135.00 | km | (f) | |
| Disposal | Incineration of waste wood | 2635.82 | cm3 | (a) | |
| Packaging | Packaging material manufacturing | Cardboard box (4725 cm2) production | 260.00 | g | (a) |
| Wrapping paper production | 19.50 | g | (a) | ||
| Production of flexible plastic film for packaging | 1.00 | g | (a) | ||
| Incineration of waste packaging material | Incineration of waste cardboard and paper | 279.50 | g | (a) | |
| Incineration of waste plastic film | 1.00 | g | (a) | ||
Note: Toy car (long trans) represents cases assuming log imports (from the United States) during the raw material procurement process, the long-distance transportation of the toy car product (from Tokyo to Hokkaido) during the product transportation process, and the incineration of waste wood (no energy use) during the disposal process. Data sources: (a) surveys conducted by this research on log, lumber, and toy manufacturing companies; (b) [14]; (c) [15]; (d) [16]; (e) [17]; and (f) the distance on Google Maps.
Table 3.
Raw material, energy consumption, and waste generation per plastic toy car (1).
| Toy Car/Packaging | Life Cycle Process | Quantity | Unit | Data Source | |
|---|---|---|---|---|---|
| Toy Car | Raw Material Procurement | ||||
| Raw material procurement for plastics | Polypropylene production | 446.00 | g | (a) | |
| Product manufacturing | Electricity consumption (Vietnam) | 3.30 | kWh | (b) | |
| Product transportation | Container ship (Hai Phong Port, Vietnam → Port of Tokyo, Japan) | 7141.00 | km | (c) | |
| 4t truck (Port of Tokyo, Japan → site of use, Tokyo) | 19.00 | km | (d) | ||
| Disposal and recycling | Incineration of waste plastic | 446.00 | g | (a) | |
| Electricity replaced with power generation from waste plastic | 0.57 | kWh | (e) | ||
| Packaging | Packaging material manufacturing | Cardboard box production | 222.00 | g | (a) |
| Cellophane tape production | 144.00 | cm2 | (a) | ||
| Plastic zip tie production | 4.40 | g | (a) | ||
| Incineration of waste packaging material | Incineration of waste cardboard | 222.00 | g | (a) | |
| Incineration of waste plastic | 4.40 | g | (a) | ||
Table 4.
Raw material, energy consumption, and waste generation per plastic toy car (2).
| Toy Car/Packaging | Life Cycle Process | Quantity | Unit | Data Source | |
|---|---|---|---|---|---|
| Toy Car | Raw Material Procurement | ||||
| Raw material procurement for plastics | Acrylonitrile-Butadiene-Styrene resin production | 185.40 | g | (a) | |
| Methyl Methacrylate Acrylonitrile Butadiene Styrene resin production | 3.40 | g | (a) | ||
| Polyoxymethylene production | 0.20 | g | (a) | ||
| Other raw material procurement | Die-cast production | 109.10 | g | (a) | |
| Metal rod production | 4.00 | g | (a) | ||
| Metal screw production | 6.60 | g | (a) | ||
| Synthetic rubber production | 16.00 | g | (a) | ||
| Product manufacturing | Electricity consumption (China) | 1.40 | kWh | (b) | |
| Product transportation | Container ship (Port of Guangzhou, China → Port of Tokyo, Japan) | 6204.00 | km | (c) | |
| 4t truck (Port of Tokyo, Japan → site of use, Tokyo) | 19.00 | km | (d) | ||
| Disposal and recycling | Incineration of waste plastic | 205.00 | g | (a) | |
| Landfill of waste metal | 119.70 | g | (a) | ||
| Electricity replaced with power generation from waste plastic | 0.26 | kWh | (e) | ||
| Packaging | Packaging material manufacturing | Cardboard box production | 127.90 | g | (a) |
| Plastic tray production | 114.00 | g | (a) | ||
| Incineration of waste packaging material | Incineration of waste cardboard | 127.90 | g | (a) | |
| Incineration of waste plastic | 114.00 | g | (a) | ||
Table 5.
Raw material, energy consumption, and waste generation per plastic toy car (3).
| Toy Car/Packaging | Life Cycle Process | Quantity | Unit | Data Source | |
|---|---|---|---|---|---|
| Toy Car | Raw Material Procurement | ||||
| Raw material procurement for plastics | Acrylonitrile-Butadiene-Styrene resin production | 551.06 | g | (a) | |
| Other raw material procurement | Metal rod production | 8.14 | g | (a) | |
| Metal screw production | 0.60 | g | (a) | ||
| Product manufacturing | Electricity consumption (China) | 4.08 | kWh | (b) | |
| Product transportation | Container ship (Port of Guangzhou, China → Port of Tokyo, Japan) | 6204.00 | km | (c) | |
| 4t truck (Port of Tokyo, Japan → site of use, Tokyo) | 19.00 | km | (d) | ||
| Disposal and recycling | Incineration of waste plastic | 551.06 | g | (a) | |
| Landfill of waste metal | 8.74 | g | (a) | ||
| Electricity replaced with power generation from waste plastic | 0.70 | kWh | (e) | ||
| Packaging | Packaging material manufacturing | Cardboard box (4754 cm2) production | 323.00 | g | (a) |
| Plastic tray production | 4.60 | g | (a) | ||
| Cellophane tape production | 123.30 | cm2 | (a) | ||
| Plastic zip tie production | 2.60 | g | (a) | ||
| Incineration of waste packaging material | Incineration of waste cardboard | 323.00 | g | (a) | |
| Incineration of waste plastic | 7.20 | g | (a) | ||
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MDPI and ACS Style
Yamane, Y.; Kayo, C. Environmental Impact Assessment of Toys Toward Sustainable Toy Production and Consumption in Japan. Sustainability 2025, 17, 2351. https://doi.org/10.3390/su17062351
AMA Style
Yamane Y, Kayo C. Environmental Impact Assessment of Toys Toward Sustainable Toy Production and Consumption in Japan. Sustainability. 2025; 17(6):2351. https://doi.org/10.3390/su17062351
Chicago/Turabian StyleYamane, Yuina, and Chihiro Kayo. 2025. "Environmental Impact Assessment of Toys Toward Sustainable Toy Production and Consumption in Japan" Sustainability 17, no. 6: 2351. https://doi.org/10.3390/su17062351
APA StyleYamane, Y., & Kayo, C. (2025). Environmental Impact Assessment of Toys Toward Sustainable Toy Production and Consumption in Japan. Sustainability, 17(6), 2351. https://doi.org/10.3390/su17062351
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