Yijun Li†
a,
Kai Zhao†
a,
Chi Wanga,
Hang Fub and
Shanying Hu
*a
aDepartment of Chemical Engineering, Tsinghua University, Beijing 100084, P. R. China. E-mail: hxr-dce@tsinghua.edu.cn
bSchool of Resources and Environment, Nanchang University, Nanchang, 330031, P. R. China
First published on 24th July 2025
Plasticizers are among the most used additives in the plastics industry, widely applied to improve the flexibility and processability of plastics. Despite the complex ecological and health risks associated with their life cycle, there is still a lack of comprehensive analysis and forward-looking research on the environmental impacts of plasticizers during the production stage, leading to a gap in relevant scientific information. This study, based on life-cycle assessment (LCA) methodology, selects 12 representative plasticizers and establishes a unified “equivalent performance” functional unit to systematically quantify their environmental impacts in the production stage. Through structural, source, market and functional grouping analyses, this study reveals the structural differences in environmental impacts and potential driving mechanisms. Results show that benzene-based plasticizers perform well on most indicators but exhibit significantly higher toxicity, while some bio-based varieties, although advantageous in terms of toxicity, face challenges related to resource use and carbon emissions. Traditional plasticizers with higher maturity exhibit more robust performance and stronger consistency. Furthermore, prospective scenario modeling based on learning curves indicates that new plasticizers have significant reduction potential towards key indicators such as carbon footprint and toxicity, with reductions reaching 7%–12%. Based on these findings, this study reveals the trade-offs among production-related environmental impacts, toxicity during the usage phase, and economic factors. Among the evaluated plasticizers, di-2-ethylhexyl terephthalate stands out because of its excellent overall performance, demonstrating strong potential for green substitution. This research provides scientific support for the green design, alternative pathway selection, and policy formulation for plastic additives while advancing the application of life cycle assessment methods in other domains of plastic chemistry.
Green foundation1. This study systematically evaluates the environmental impacts of 12 typical plasticizers during the production stage by constructing a unified “equivalent performance” life cycle functional unit. It advances the standardized application of green chemistry evaluation methods in additives and provides scientific data support for the sustainable transformation of industry.2. Future scenario modeling based on learning curves shows that new plasticizers have a reduction potential of up to 12% towards key indicators such as carbon footprint and toxicity. A multidimensional comprehensive assessment reveals that di-2-ethylhexyl terephthalate performs well across environmental, health, and economic aspects, demonstrating outstanding potential for sustainable substitution. 3. This analytical framework and methodology will be extended to the study of other types of additives in the future to promote broader green transformation assessments. |
However, existing studies using life-cycle assessment (LCA)15–17 have quantitatively identified that the environmental impacts of plasticizers during the production stage are significant and cannot be ignored. (For instance, the contribution of diethylhexyl phthalate to carbon emissions in PVC films reached 7.14%.)18 Therefore, reducing the life cycle environmental burden of plasticizers is a key factor in the sustainable transformation of the plastics industry.
Currently, the plasticizer market is primarily dominated by traditional plasticizers such as diethylhexyl phthalate and dibutyl phthalate (accounting for 45% of the total plasticizer production in China),19 which benefit from mature processing technologies, abundant raw materials, and relatively low prices. However, the emergence of new additives (such as acetyl tributyl citrate and epoxidized soya bean oil) is breaking the traditional pattern and providing new options for plasticizer use. Notably, Fig. 1(b) illustrates that among the 25 LCA studies focused on the production stage of plasticizers, 80% focus on individual plasticizers in bio-based plastics (e.g., glycerol and polyethylene glycol).20–39 Only five studies focus on the unitary production processes (per ton) of typical plasticizers (mainly diethylhexyl phthalate and phthalic anhydride) used in petroleum-based general plastics,18,40–43 highlighting the lack of comprehensive LCA analysis for new plasticizers. Moreover, each of these five studies investigates no more than five plasticizers (Fig. 1(b)). These findings highlight a critical research gap. Despite the large production volume, wide application, and substantial environmental impacts of plasticizers, most existing LCA studies provide limited coverage of petroleum-based plasticizers and insufficient assessment of newer alternatives. Additionally, the strategy of substituting plastic additives under equivalent functional requirements has been proven to be the most effective mitigation approach for reducing the environmental impact of plastic additives during the production stage.18 However, the replacement of different types of plasticizers is not functionally equivalent. Fig. 1(b) shows that none of the existing studies has considered the differences in the amounts of additives required for achieving equivalent material performance (e.g., the amount of long-chain chlorinated paraffins required to achieve the same plasticizing effect is 1.6 times that of dibutyl phthalate).10 Furthermore, to explore the substitution potential of new plasticizers, it is necessary to consider the evolution of production processes, optimization of raw material paths, and progress in technological maturity, evaluating the potential of both traditional and new plasticizers in future green transformations. However, existing research remains at the static assessment stage, with insufficient forecasting of future emission reduction potential. Therefore, it is necessary to adopt prospective analysis to promote the updating of relevant scientific information, facilitate pollution control and green transformation, and provide support for policy formulation and resource allocation.
This study selects 12 widely used plasticizers based on their prevalence and typicality (covering multiple categories, accounting for over 95% of total production).19 It systematically collects key environmental emission data for these plasticizers during the production stage. Based on this, an LCA model is developed, and functional units are defined according to equivalent performance to quantify the environmental impacts of different plasticizers, with the results being analyzed from multiple perspectives. Additionally, future scenario modeling based on learning curves is conducted to identify the potential for resource and energy efficiency improvements and environmental emission reductions as these plasticizers evolve. The aim of this study is to reveal the environmental performance differences of various types of plasticizers and their key influencing factors, providing scientific information and data support for the green design of plastic-related chemicals and plasticizer substitution strategies, contributing to plastic pollution control and sustainable management.
Chemical name | Official abbreviations | Molecular formula | CAS | Substitution factors |
---|---|---|---|---|
Diethylhexyl phthalate | DOP (DEHP) | C24H38O4 | 117-81-7 | 1.0 |
Dibutyl phthalate | DBP | C16H22O4 | 84-74-2 | 0.86 |
Diisodecyl phthalate | DIDP (DPHP) | C28H46O4 | 26761-40-0 | 1.1 |
Diisononyl phthalate | DINP | C26H42O4 | 28553-12-0 | 1.06 |
Di-2-ethylhexyl terephthalate | DOTP (DEHTP) | C24H38O4 | 6422-86-2 | 1.03 |
Trioctyl trimellitate | TOTM | C33H54O6 | 3319-31-1 | 1.17 |
Phenyl alkyl Sulfonate | ASE (T50) | C21H36O3S | 91082-17-6 | 1.05 |
Dioctyl sebacate | DOS | C26H50O4 | 122-62-3 | 0.93 |
Dioctyl adipate | DOA | C22H42O4 | 123-79-5 | 0.93 |
Acetyl tributyl citrate | ATBC | C20H34O8 | 77-90-7 | 0.97 |
Epoxidized soya bean Oil | ESO (ESBO) | C57H98O12 | 8013-07-8 | 1.1 |
Long chain chlorinated paraffins | LCCPs | C15H26Cl6 | 63449-39-8 | 1.4 |
Here, SFx represents the substitution factor of plasticizer x, while mx and mDOP refer to the mass of plasticizer x and DOP added per 100 mass units of resin to achieve the same performance.
Based on this, this study uses “the mass of each plasticizer required to achieve the same plasticizing effect as 1 ton of DOP” as the functional unit. Compared to traditional methods that use a fixed mass as the basis, this approach enables a more practically meaningful comparison of environmental impacts. The substitution factors for various plasticizers and their corresponding masses in terms of the functional unit can be found in Table S3 of the SI.
Environmental impact type indicators | Abbreviation | Impact-type indicator unit |
---|---|---|
Global warming potential | GWP | kg CO2 eq. |
Resources consumption | RC | MJ |
Human health | HH | DALY |
Terrestrial ecosystems | TE | Species. year |
Freshwater ecosystems | FE | Species. year |
Comprehensive toxic potential (toxicity) | CTP | CTU |
The basic formula for modeling the input of the LCA process using the power law form of the experience curve is as follows:
b = −log2(1 − LR). |
To prevent the input from decreasing infinitely due to the learning curve, which would violate mass conservation or physical limits, this study introduces a minimum input threshold, , for constraint and adjustment:
Due to the difficulty in obtaining detailed historical data, this study follows the “learn-by-component” hypothesis proposed by Thomassen, combining the empirical learning rate ranges for raw materials (4%–7%) summarized by them.57 A classification-based setting strategy is adopted to reflect the differences in technical maturity and learning potential across different input types. Considering that new plasticizer products (such as ATBC) are still in the optimization and scaling-up phase within their industrial chains, and their upstream raw materials have not yet reached the resource utilization efficiency typical of mature products, a relatively higher learning rate is set for these inputs. In contrast, traditional plasticizers (such as DOP and DBP) have long-established production paths and stable experience with raw material usage, and thus a lower learning rate is set to reflect their limited improvement potential. Additionally, if the input value calculated by the learning curve falls below the theoretical limit, the learning rate is appropriately adjusted downward to ensure the physical plausibility of the simulation results.
For background energy inputs such as electricity and steam, this study follows the approach of Bergesen and Suh in prospective life cycle modeling,56 using a uniform learning index (b) of 0.15, corresponding to a learning rate of approximately 9.875%. This reflects the potential resource efficiency improvements achievable by emerging technologies such as combined heat and power (CHP) steam, wind power, and others in the future (specific input learning rates can be found in SI Table S31). By introducing such parameter settings, the prospective life-cycle assessment can reflect the evolution of input structures driven by technological learning. This ensures that the environmental impact results are time-dynamic and sensitive to future development trends.
To interpret the extent of environmental performance improvement under future scenarios, we define the concept of Environmental Impact Mitigation Potential as the relative reduction in each environmental impact indicator compared to the baseline scenario. For each plasticizer, the mitigation value of each indicator is calculated as
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Fig. 2 Environmental impact endpoint results of 12 typical plasticizer categories at the production stage. |
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Fig. 3 Contribution analysis of environmental impacts of 12 typical plasticizer categories at the production stage. |
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Fig. 4 Environmental impact results of plasticizer groups classified by structural, source, market, and functional categories. |
In the raw material source dimension (Fig. 4b), both the median and mean values indicate that bio-based plasticizers exhibit higher environmental loads on most indicators, except for resource consumption, with a particularly significant difference in the FE indicator. This result suggests that, although bio-based raw materials have advantages in terms of renewability, their raw material utilization rate is lower, and the energy inputs and indirect emissions associated with the agricultural supply chain are more complex (e.g., land-use change, pesticide application, etc.). Additionally, although DOS and ATBC are categorized as bio-based plasticizers, their upstream raw material structures still contain a certain proportion of petroleum-based components, and the environmental loads associated with this portion contribute significantly to the overall life cycle impact.
In the market entry time dimension (Fig. 4c), traditional plasticizers (such as phthalates) show small environmental performance differences across all indicators, demonstrating strong consistency. In contrast, the environmental impact values of new plasticizers exhibit greater variability, reflecting their diverse production pathways and varying levels of process maturity. Furthermore, the toxicity indicators for traditional plasticizers are generally higher than those for new types, as their core structures still rely on aromatic intermediates.
In the functional characteristics dimension (Fig. 4d), general-purpose plasticizers show comparable or even superior environmental performance across all six environmental indicators compared to non-general plasticizers. This indicates that general plasticizers, represented by DOP, DINP, and DOTP, not only have advantages in terms of production costs and process maturity but also that the robustness of their environmental impacts may be a key factor supporting their long-term dominance in the market.
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Fig. 5 Environmental impact mitigation potential of typical plasticizers driven by technological progress. |
Traditional plasticizers (including phthalate-based and LCCPs) exhibit limited mitigation potential overall, with average reductions across six endpoint indicators remaining below 6%. This is primarily due to the high technological maturity of their production processes and the limited room for energy efficiency improvements in key upstream inputs (such as phthalic anhydride and liquid chlorine), resulting in relatively low learning rates.
In contrast, new plasticizers such as ATBC, ESO, and ASE demonstrate greater mitigation potential, with average reductions typically between 7% and 10% and some indicators exceeding 12%. Among them, ATBC shows the highest average mitigation rate across all impact categories. ASE, however, displays significant variability in its mitigation potential across different indicators (e.g., a 4.8% reduction in land ecosystem impacts versus a 12.3% reduction in toxicity), which can be attributed to the varying contributions of its raw materials to different environmental dimensions.
Additionally, certain plasticizers (such as TOTM, DOS, and DOA) are already approaching the defined material efficiency limits under current assumptions, meaning that their environmental impact levels are nearing the optimal boundary achievable through existing pathways. Further reductions for these plasticizers would require structural innovation in upstream production routes, such as raw material substitution, synthesis route redesign, or fundamental adjustments to process energy systems.
On this basis, further grouping analysis and prospective LCA modeling reveal the driving mechanisms of plasticizer environmental performance and their future evolutionary pathways, ultimately providing scientific data support for promoting plasticizer substitution and the sustainable transformation of the industry. Additionally, the methodology used in this study is highly versatile and can be extended to the environmental assessment of other types of plastic resins and products, as well as to the evaluation of other additives such as thermal stabilizers and flame retardants. This provides a methodological reference and data support for life cycle management of plastic-related chemicals and the formulation of environmental policies for green chemical products (Fig. 6).
Given the central role of functional equivalence in this study, it is important to evaluate the applicability and limitations of the substitution factor approach. Previous studies and industrial practices have demonstrated that various plasticizers can be functionally interchangeable in specific polymer systems. For example, in flexible PVC, many plasticizers exhibit adequate compatibility in terms of molecular polarity and interactions with polymer chains and can effectively improve flexibility and processability.11 Additionally, the Handbook of Plasticizers by Wypych provides extensive guidance on the recommended use levels of different plasticizers in various polymer systems, further supporting the feasibility of functional substitution.58
Nevertheless, it should be noted that functional equivalence is typically established based on a specific performance criterion, such as achieving a Shore A hardness of 80 at room temperature, as used in this study. The SF approach inherently assumes that plasticizers with different chemical structures can be compared based on equal functional output. However, significant differences may exist in migration behavior, volatility, thermal stability, and compatibility with polymer matrices. Moreover, SF values are derived under standardized conditions, which may not fully reflect performance in actual processing or application environments. Despite these limitations, the substitution factor method provides a practical normalization strategy for life cycle assessment, enabling fair comparisons across plasticizers based on equivalent functionality. This is consistent with the core LCA principle of functional-unit-based comparison and strengthens the robustness and applicability of the results in this study.
In the typology-based analysis section, the sample distribution is relatively balanced across the grouping dimensions of structure, market entry time, and functional attributes. However, an imbalance exists in the raw material source dimension, with a 3:
9 ratio between bio-based and fossil-based plasticizers, which may affect the representativeness of inter-group comparisons for certain environmental indicators. To mitigate the influence of sample size differences, boxplots are used in Fig. 4 to visualize the environmental impact characteristics of each group. Compared to approaches that only present means or error bars, boxplots simultaneously display medians, quartiles, and outliers, providing a more comprehensive view of data distribution. This is particularly beneficial under unbalanced sample conditions, as the median serves as a robust statistic that reveals typical trends and minimizes the influence of outliers.
We also recognize that such bias cannot be entirely eliminated, as it stems from the limited availability of life-cycle data for bio-based plasticizers. This limitation reflects the fact that these products are still in the early stages of industrial scaling, with relatively low levels of data transparency and accessibility. Future research could address this issue by collaborating with industry stakeholders to supplement high-quality life-cycle data for a broader range of bio-based plasticizers, thereby improving the representativeness and generalizability of grouping analyses.
This study conducts a qualitative uncertainty analysis of data sources based on the criteria specified in Table S28 in the SI. The uncertainty assessment results for each process in the inventory are presented in Tables S5–S25 in the SI. All plasticizers performed well in terms of sample completeness, temporal representativeness, and geographical representativeness, which is mainly due to the relatively easy availability and strong consistency of the relevant data. In terms of source reliability, most data are sourced from irregularly updated literature or specialized books (such as environmental impact assessment reports). Some key processes, such as carbon dioxide emissions, rely on periodically updated data from authoritative sources, which are of higher quality. However, some data, such as the emissions from the three wastes of DOP and DBP, are based on estimates or expert judgments. In terms of technical representativeness, most data reflect the current level of mainstream companies or equivalent processes, with only a few cases where comparable data were used as substitutes due to missing information. Overall, some phthalate-based plasticizers (DOP, DBP, and DINP) still have room for improvement in certain direct environmental emission data, while the inventory data for other categories already have a solid quality foundation (Fig. 7).
To further assess the impact of database selection on LCA results, this study compares the carbon emission results for plasticizer production under the same model input structure using both localized Chinese background data and the Ecoinvent generic database. The results show that, for most plasticizers, the carbon emissions calculated using localized data are lower than those using the Ecoinvent version, with reductions ranging from 1% to 58%. This may be due to the lack of specific process data for some plasticizer raw materials (e.g., octanol used for DOTP) in the Ecoinvent database. The use of a generic production scenario, such as “chemical production, organic”, which represents the average production of many organic chemicals, has likely led to overestimated carbon emissions. A notable exception is DOS, where carbon emissions are higher (+13%) when using localized data. This is due to more detailed modeling of upstream agricultural inputs (such as fertilization and irrigation) related to castor oil in the Chinese context, indicating that the carbon emissions of bio-based pathways are more sensitive to agricultural inputs and regional modeling differences.
Overall, localized data better reflect the raw material structure and energy system characteristics within China, improving the representativeness of the assessment results for actual production scenarios. However, the relatively limited openness of the CLCD database presents certain limitations in applications requiring high academic transparency, reproducibility, and methodological consistency.59 In contrast, although the Ecoinvent database has some issues with process substitution, its complete data system and transparent methodology make it widely applicable in international life cycle research and comparative analysis (Fig. 8).
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Fig. 8 Comprehensive comparison of the global warming potential, chemical toxicity factors, and market prices of 12 plasticizers. |
Sections 3.1–3.3 focus primarily on the environmental impacts of plasticizers during the production phase, but this analysis is not exhaustive. To evaluate the development potential and mutual substitutability of different types of plasticizers from a more systematic and multidimensional perspective, this study selects three key dimensions for quantitative analysis: (i) environmental load during the production phase (represented by GWP), (ii) potential health risks during the use phase (i.e., the possible toxicological effects on human health due to exposure during the use phase, represented by chemical toxicity factor), and (iii) economic viability (represented by market prices). The calculation method for the toxicity factor and the selection criteria for market prices are detailed in the SI.
Phthalate-based plasticizers, as a class of products with mature processes and widespread applications, have relatively low carbon emissions during the production phase and cost advantages in terms of market prices. However, they not only cause residues in typical environmental media but also pose significant ecological and health risks in certain usage scenarios,60,61 thus necessitating the identification of feasible substitutes.
ATBC, as an emerging bio-based plasticizer, performs well in terms of use safety but has a relatively high carbon footprint due to its high production energy consumption. In addition, due to the incomplete scaling-up of its preparation route, its price remains high, limiting its large-scale market application (other new plasticizers such as TOTM, ASE, DOS, and DOA also face similar price issues). The bio-based plasticizer ESO (epoxidized soybean oil), with a similar positioning, performs well across all three dimensions and shows strong substitution potential. However, as noted earlier, ESO exhibits excessively high values in other environmental impact indicators, so its overall applicability still requires further evaluation in specific application scenarios.
DOTP, in terms of carbon emissions and market prices, is comparable to traditional phthalate-based plasticizers, but its chemical toxicity factor (CTF) is significantly lower. As indicated in section 3.1, its production process also has relatively low environmental impacts, making DOTP a promising alternative that balances environmental, health, and economic considerations. Chlorinated paraffins show low carbon emissions, low toxicity factors, and price advantages in this study, but it should be noted that short-chain chlorinated paraffins (SCCPs) have been included in the Stockholm Convention as persistent organic pollutants (POPs) that are banned from use.62 This ban focuses on the high persistence (P), bioaccumulation (B), and toxicity (T) exhibited by these chemicals in the environment, as well as their potential for long-range environmental transport (LRTP). The chemical toxicity factor used in this study is primarily based on publicly available toxicological test data, covering only some of the PBT characteristics but not systematically incorporating environmental behavior parameters (e.g., environmental half-life, bioaccumulation factor, and mobility),63 which may underestimate the high persistence risk of long-chain chlorinated paraffins after use. Given that LCCPs and SCCPs share certain structural and environmental behavior similarities, it is necessary to incorporate more external toxicological and environmental behavior research results for a comprehensive assessment.
Despite these limitations, valuable insights can still be drawn from the results. Based on the comprehensive results from the three-dimensional analysis and the forward-looking analysis in section 3.3, it can be concluded that although traditional phthalate-based plasticizers currently dominate the market due to their mature industrial systems and cost advantages, their potential for further improvement is limited, and their development is also constrained by potential health risks and regulatory trends. At the same time, emerging categories like DOTP, which have demonstrated outstanding performance, exhibit more balanced advantages in terms of environmental impact, health, and economics, providing a solid foundation to become the next generation of mainstream alternatives. With the optimization of future technological pathways and the expansion of market scale, more new plasticizers are expected to stand out in multi-dimensional sustainability evaluations, forming a more diverse and robust green substitution system.
The future sustainable development of plasticizers can be further advanced in several key areas. First, more precise environmental impact assessments should be conducted during the production stage, with continuous improvement of regional life cycle data and enhanced transparency and representativeness of background databases, enabling accurate identification of high-impact stages and the optimization of cleaner processes. Scenario analysis indicates that new plasticizers still have significant potential for transformative development. By optimizing raw material pathways and energy systems, promoting technological maturity, and scaling up production, both environmental benefits and unit costs can be improved, enhancing market feasibility. Moreover, considering the trade-offs among environmental friendliness, performance, and economics, future efforts should focus on building a sustainable design framework based on a full life cycle perspective and multi-criteria synergy, promoting the green substitution of traditional high-risk products with green plasticizers from the source. Regulatory bodies should also play a guiding role in accelerating the industry's green transformation, while companies should incorporate environmental performance into core decision-making alongside cost-effectiveness. Policy measures should include fiscal support and technological incentives to reduce barriers to the initial promotion of emerging green additives and enhance their accessibility and application in practical plastic systems. Ultimately, through the collaboration of industry, research, and regulation, the green transformation and high-quality development of the plasticizer system can be accelerated.
The Supplementary Information includes detailed life cycle inventory datasets, environmental impact assessment results, contribution analysis data, and comparative analysis with existing plasticizer studies. The SI also contains additional figures, tables, and methodological descriptions supporting the main text. See DOI: https://doi.org/10.1039/d5gc01960e.
Footnote |
† These authors contributed equally to this paper. |
This journal is © The Royal Society of Chemistry 2025 |