INTRODUCTION

Developed by Gunther von Hagens in 1977 (von Hagens et al., 1987), plastination is a highly effective preservation technique of biological tissue, replacing lipids and water with polymers (silicone, epoxy resin, or polyester). These polymers subsequently harden, creating durable, odorless specimens that are easier to store and safer to use than traditional wet prosected specimens (Hayat et al., 2018). Plastinated specimens have become an increasingly popular resource for the anatomical education of human and veterinary physicians, and also for the general public (Body Worlds Museum) (Sora et al., 2019).

A key advantage of plastinated specimens is their durability; with appropriate care, plastinates are made to last indefinitely (von Hagens et al., 1987), providing a more sustainable and robust alternative to wet specimens. Despite their longevity, scenarios arise in which the disposal of plastinates is required, for example, when the specimen is no longer in use, microbial degradation occurs due to improper storage conditions, or a failure occurs during the plastination procedure.

Anatomical material is disposed of in one of two ways: burial or thermal decomposition (cremation or incineration), with thermal treatment being the preferred and default method. Regarding plastinated anatomical material, because the plastination process permanently preserves the specimen, burial is not an appropriate disposition method, as decomposition is not achievable. This leaves cremation/incineration as the only viable disposal method for plastinated specimens.

However, because plastinated specimens are inherently plastic, this raises concerns about the safety and feasibility of their disposition by incineration. Equally, due to the extended durability of plastinates, few crematoria or incineration plants have experience with their disposition.

This study, therefore, aimed to determine if thermal decomposition is an appropriate and safe disposition method for plastinates through:

Part 1: Investigating the thermal disposability of three silicone or epoxy impregnated specimens

Part 2: Reviewing the legal compliance procedures within the UK and Germany.

Types of Plastinated Specimens

The three most widely used plastination techniques are silicone (S10), epoxy resin (E12), and polyester (P40). Preservation with silicone – the most common technique – is used for 3D specimens, whereas epoxy resin and polyester are used for sheet plastination, where the specimen has been thinly sliced (1-4 mm) (Sora et al., 2019). The three specimens used in this study were silicone- and epoxy resin-plastinated specimens. No P40 specimens were used due to their unavailability at the time of the experiment.

MATERIALS AND METHODS

Part 1: Thermal disposability investigations

Thermal disposability experiments were conducted by the Institute of Combustion and Power Plant Technology, Stuttgart University, Germany, in 2018 (Schmid and Ross, 2018).  Details of the specimens used in the experiment are shown in Table 1. All three specimens were sourced from Gubener Plastinate, Germany, and were unsuitable for teaching or display and therefore required disposition.

Figure 1. Photograph of specimens as provided to the Institute for Combustion and Power Plant Technology: Probe 1: S-nb. Probe 2: S-b. Probe 3: ER-b (see Table 1)

The samples had been plastinated following the silicone S10 standard technique or the E12 epoxy technique. All plastination chemicals had been sourced from BIODUR® Products, Heidelberg, Germany. The silicone plastination chemicals used were: S10, S3 (hardener), S6 (cross-linker); epoxy resin plastination chemicals were: E12 (resin), AE10 (additive), E1 (hardener), A-60 (additional thiochemical hardener, only available for internal use within BIODUR® Products). N.B. The additive AE10 has since been replaced with AE20, however there are no consequences for the interpretation of the results.

To understand how plastinates respond to heat for their final disposition, following thermal disposability investigations were conducted (Table 2):

Part 2: Compliance investigations for the thermal decomposition of plastinates in Germany and the UK

The German Crematorium “Krematorium am Limes” (Fig.2) and the UK waste management company “Stericycle” were interviewed in 2025 to assess the legal compliance of incinerating plastinated specimens.

Questions asked:

1. If approached, would you agree to cremate plastinated bodies or body parts? If not, why?
2. What are the regulations / technical rules / ordinances that you must observe for the operation of the incineration plant? With regard to:
   1. Incineration procedure
   2. Temperature regulation
   3. Specific limit values for pollutants in the exhaust air
3. Material flow: what kinds of remains go where? (ashes/ slag/ contaminated exhaust filters)
4. Which is your competent supervisory authority regarding the proper function of the incineration plant?
5. Are other accompanying materials also permitted during the incineration of anatomical material, even if only in small quantities?
   

   Figure 2. Photograph of Krematorium am Limes

RESULTS

Part 1: Thermal disposability investigation
The raw data for all the following graphs are available in the Appendix.

Figure 3. General composition of the incinerated samples

As can be seen in Figure 3, the combustible components made up the by far biggest portion of the samples. Ash content varied between 0.5% and 15.4% while water was present in portions of 1.5% to 3.8%.

1.2 Elemental composition

All three specimens show an overall similar elemental composition; carbon content varied between 36.90% – 59.30% and oxygen 25.80% – 46.20%. Hydrogen and nitrogen had the smallest variation, 6.61% - 7.84% and 2.14% - 3.75%, respectively (Fig. 4). Only the epoxy resin specimen contained sulphur, which originated from the thiochemical epoxy hardener used.

Figure 4. Elemental composition: only elements >1% included in analysis

1.3 Calorific Value

Figure 5. Calorific value: green shading shows the calorific value for plastics; the value for tires is given for reference

All specimens produced a calorific value typical of plastics (Fig. 5). Green indicates the range of calorific values for plastics, 21.90-43.20 MJ/Kg (Abdulyekeen et al., 2021). The calorific value for tires is given for reference.

1.4 Ash melting behavior

Table 3 shows the ash melting behavior of the samples examined. ‘Not recognizable’ temperatures indicate that the temperature was not high enough to achieve softening or flow of the ash. Flow temperature is the temperature at which ash flows like a liquid. All three specimens exhibited high ash-melting behavior.

1.5 Main ash elements

Figure 6. Main ash elements: only elements >1% included in analysis

As expected, the results shown in Figure 6 demonstrate that only the bone-containing specimens contained calcium and phosphorus, reflecting the presence of bone. The only element >1% for the S-nb specimen was silicone oxide at 92.5%. Cremated body results are provided for comparison (Rikhvanov et al., 2014).

1.6 Ash trace elements

*Incineration slag refers to ash from waste incineration plants.

The trace elements for all three specimens fell below the average incineration slag levels (Table 4). Only zinc levels in ER-b came within 90% of the lower boundary of the incineration slag range (purple). Tests also revealed high values of tin for all three specimens compared to incineration slag data (orange). Data for the Earth’s crust and incineration slag taken from Schmid and Ross (2018).

Part 2: Compliance investigations

Table 5 shows the answers provided by the UK company Stericycle and the German crematorium to the questionnaire. Both Stericycle and the crematorium agreed to cremate plastinated specimens, provided that the technical and legal requirements were met. Unfortunately, limited information was provided by Stericycle despite follow up.

DISCUSSION

Part 1: Technical report

General composition

This demonstrated the breakdown of non-combustible components (water and ash) and combustible components in the specimens (Fig. 3). These results are expected, given the high plastic content, and mirror the typical composition of common industrial polymers (Dai et al., 2023). Specifically, the high proportion of combustible content seen is attributed to the high carbon content seen in plastics (Dai et al., 2023).

Elemental composition

The only elements identified in all the plastinates with a content percentage greater than 1% were carbon, hydrogen, oxygen, and nitrogen (Fig. 4). The exception was the epoxy resin plastinate, which was found to contain sulfur; this can be attributed to the additional A-60 thiochemical epoxy hardener used during the plastination process for this particular plastinate. This type of thiochemical hardener is not a standard in the epoxy resin plastination process, but if applied during epoxy resin coating preparation, it can create a smoother, more uniform surface on sliced specimens and reduce the flammability of the epoxy resin (Shao et al., 2020).

Although not included in Figure 4, the chlorine levels for all three specimens were negligible (all <0.06% chlorine). All crematoria and incineration plants must operate at a minimum of 850 °C; this regulation, in part, is attributed to the need for a minimum temperature for disposing of waste with a chlorine content >1% (Trojan et al., 2023). Although the chlorine levels of the plastinates are of no consequence to thermal disposability procedures, it is important to highlight.

Both the general and elemental compositions of the plastinates indicate that plastinated specimens are suitable for thermal decomposition at the elemental level, as their results reflect those of typical industrial polymers.

Calorific value

Calorific value is the measure of heat produced during complete combustion and is a significant property in technical combustion (Mahmudul et al., 2017), as it informs incineration temperature requirements. The minimum calorific value of waste required to sustain the appropriate temperature of 850 °C is 5.043 MJ/Kg. All three specimens surpass this threshold (S-nb: 22.88 MJ/Kg, S-b: 22.62 MJ/Kg, ER-b: 26.1 MJ/Kg – Figure 5), indicating that no additional fuel is required to sustain combustion (Trojan et al., 2023). Additionally, the calorific value of each specimen fell within the expected range for plastics (21.90-43.20 MJ/Kg) (Abdulyekeen et al., 2021). However, institutions can dispose of plastinated material via incineration plants or crematoria; the feasibility of incinerating material with this calorific value must be explored to ensure that the permissible total energy output is not exceeded, for calorific value and energy output are directly proportional. This is most important for crematoria, as their combustion chambers are typically designed for bodies with a higher water content, which produce a lower calorific value, and thus a lower energy output. Plastinated bodies, on the other hand, undergo a crucial dehydration process, replacing water molecules with plastic polymers, which increases their calorific value and ultimately the total energy output produced. Therefore, to answer the question of whether crematoria can withstand the higher energy output, the following calculations explore the potential energy content for a 30Kg whole body plastinate (Table 6):

Step 1: Scale up the results

Equation used: Plastinate weight (Kg) x calorific value (MJ/Kg) = energy content (MJ)

Step 2: Combine with coffin energy output.

Data for the pine-wood coffin and the oak coffin were taken from Schmid and Ross (2018).

Calculations show that cremation of a whole plastinated body with a pine coffin produces a total energy output of 1138 MJ, which is still lower than that of an oak coffin alone (1208 MJ) (Table 6). This demonstrates that crematorium combustion chambers are suitable and safe for the thermal disposition of plastinated specimens, as it is unlikely that the permissible combustion heat output will be exceeded.

Ash melting behavior

Ash melting behavior is an important factor in thermal decomposition, as it indicates the likelihood of slag formation during incineration. Slag is the residue produced when softened or melted ash condenses upon contact with the lower-temperature inner wall of an incinerator, causing it to agglutinate. These deposits can ultimately damage equipment and reduce furnace efficiency (Chen et al., 2025), so slagging should be avoided. Therefore, for the biomass in question, the lower the ash melting point, the greater the likelihood of slag formation (Zhou et al., 2023).

The results in Table 3 demonstrate that all three specimens have a very high ash melting point, with the temperatures of the silicone plastinates being unrecognizable. This is due to the strong, irreversible covalent crosslinks found in both thermoset elastomers (silicone) (Luo et al., 2022), and thermoset duroplastics (epoxy resin) (Pieniak et al., 2023), which cause the plastics to not soften or melt with heat but decompose. This indicates that slag formation is highly unlikely with thermal decomposition of plastinated specimens, making them a favored biomass for incineration in both incineration plants and crematoria. These theoretical reflections are corroborated by the statement from the German crematorium operator that slag formation in the combustion chamber is rarely observed (Table 5).

Ash's main elements

Figure 6 highlights the main elements present in the ash of each plastinate, compared with those of a non-plastinated cremated body. The presence of calcium and phosphorus reflects the presence of bone in the specimen, which is consistent with the levels expected for a cremated body (Rikhvanov et al., 2014).

Ash trace elements

Trace elements found in the plastinates’ ash were compared with those in Earth’s crust and slag from incineration plants to determine whether the ash produced is typical and appropriate for incineration plants and crematoria. Importantly, all measurements with an incineration slag comparison are below the incineration slag readings, with only the zinc measurement for epoxy resin coming within 90% of the lowest incineration slag value (Table 4, purple). The outlier was the high quantities of tin (particularly for the silicone plastinates), for which no data for relative incineration slag quantities are available. The high tin content produced by the silicone plastinates can be attributed to the tin-based catalyst BIODUR® S3 (Chaynes & Mingotaud, 2004), which is used as the hardener during the curing process. The source of tin in the epoxy resin plastinates is harder to explain, as no tin is present in any of the chemicals. However, before E12 plastination, the specimen was injected with a red-pigmented polymer to highlight the blood vessels, so it could be theorized that the low tin presence was attributable to this. Verification of tin presence in epoxy resin plastinated specimens could be achieved through secondary incineration tests. Despite this, it can be confidently concluded that the chemical components of plastinated specimen ash are tolerable and pose no issues for incineration plants or crematoria.

Part 2: Compliance investigations

Interviews with Stericycle and a crematorium manager confirmed that it is permissible to incinerate plastinated specimens, as compliance regulations were upheld: in Germany it's the 27^th Ordinance on the Implementation of the Federal Emission Control Act (Twenty-seventh Ordinance on the Implementation of the Federal Emission Control Act, 1997), and for the UK it's the Industrial Emissions Directive regime (Industrial Emissions Directive, 2020)  and the Environmental Permitting Regulations (The Environmental Permitting (England and Wales) Regulations, 2016) (Table 5). The results were typical of plastics already incinerated by these companies (e.g., clinical waste bins, plastic coffin linings, etc.) (Abdulyekeen et al., 2021; Dai et al., 2023). This shows that plastinated specimens impregnated with silicone or epoxy resin are chemically suitable for disposition via cremation and incineration, despite the limited information provided by Stericycle.

Our findings indicate that both the technical and legal standards for incinerating anatomical material were met, demonstrating that plastinate specimens are safe and suitable for disposition by incineration in the UK and Germany. Comparisons against the legislation and operating procedures of other countries should be conducted to guarantee compliance and feasibility. Therefore, this paper can serve as a disposal guide for both UK and German crematorium operators and institutions housing plastinated specimens, and as a reference point for other countries, whilst their legislation is compared.

Limitations

A limitation of this study is that no investigations into the potential of flue gas pollutants were conducted; therefore, future chemical tests are necessary. These results would not affect the technical procedure for incineration but may affect the feasibility of plastination incineration, as the governing regulations regarding potential environmental impact must be met.

Furthermore, repeat thermal disposability investigations should be conducted to include polyester plastinated specimens (P40) to ensure they are also suitable and appropriate for thermal disposition. Nonetheless, as polyester is also a thermoset plastic (Loos, 2015), it can be hypothesized that it will yield results similar to those of silicone and epoxy resin.

CONCLUSION

Our findings demonstrate that crematorium combustion chambers and incineration plants are suitable and safe for the disposition of plastinated specimens, as the relevant technical and legal standards for the UK and Germany were met. Therefore, this paper can serve as a disposal guide for both crematorium and incineration plant operators, as well as for institutions housing silicone- and epoxy-resin plastinated specimens. Although, as aforementioned, this report should only serve as a reference point for other countries until their individual legislation is confirmed to align with its findings.

ACKNOWLEDGMENTS

The authors sincerely thank those who so generously donated their bodies to science, enabling anatomical research. Results from such research can increase mankind’s overall knowledge, which can then improve patient care. Therefore, these donors and their families deserve our deepest gratitude; their donations are invaluable gifts (Iwanaga et al., 2021). Appropriate consent was obtained for the use of cadaveric material. The human donor consented to image permission as documented in the Institute for Plastination’s body‑donation form, which is legally relevant under German law. Furthermore, the authors would like to thank Mr. Marc Oliver Schmid and Mr. Wolfgang Roß from the Institute for Combustion and Power Plant Technology, University of Stuttgart, Mr. Kevin Volk from the “Krematorium am Limes”, and the representatives from Stericycle.

Appendix

Raw data of the results are represented as graphs (Schmid and Ross, 2018).

General composition:

Elemental composition:

Calorific value: