Chemistry Chronicles

Embalming: A “Living” Rite HAROLD T. MCKONE

From natron to formaldehyde, preserving bodies “balsamic spirit”, which was produced by dissolving one pound of cream of tartar has been a chemical undertaking. and a half-pound of salammoniac in six pounds of water. The body was injected s you might expect, some of the confirmed the use of these three embalm- with this mixture and then immersed in earliest descriptions of embalming ing methods and provided substantial addi- this solution for six weeks. Afterward, Acome from the Egyptians, who are tional information on ancient Egyptian the body was placed in the sun to dry. credited with the development of the funeral practices. For example, research In the 18th century, William Hunter, a first recorded successful embalming. Preser- found that in the 21st dynasty (ca. 1000 Scottish anatomist, outlined a method of vation of the body was not a matter of B.C.E.), embalming in Egypt was at an apex, arterial and cavity embalming in which a choice among Egyptians. On the basis of and leather patches were added to the skin mixture of turpentine and camphor was their religious laws, it was compulsory, not to cover bed sores. used. His brother, John Hunter, used only for native Egyptians, but also for William’s methods to embalm the body strangers who died in their land. of the wife of Martin Van Butchel, a famous London citizen. Mr. Van Ancient Practices Butchel subsequently kept the body The Greek historian Herodotus of his wife on display, dressed in fine described three different embalming clothes, in a glass case in his sitting methods available to Egyptians in the room. As the news of his “exhibit” fifth century B.C.E. The most elabo- spread, Van Butchel was so inundat- rate of these procedures involved ed by curiosity seekers that he was the removal of all brain tissue through forced to announce: “No stranger the nostrils, eviscerating of the inter- can see my embalmed wife unless it nal organs through an incision in is between nine and one . . . Sunday the flank (often these organs were excepted.” When Van Butchel remar- stored in vases or jars), and anoint- ried, the body of his first wife was ing the interior of the body cavity before Ancient Persians preserved their dead removed to the Royal College of Surgeons reclosing the incision. The incision was then by immersing them in jars of honey and in London. covered with beeswax to produce a less wax, eliminating damaging air and By the beginning of the 19th century, obvious scar. Afterward, they used “natron” microbes. Embalming was also practiced embalming was becoming increasingly (a mixture of sodium chloride, sodium among the ancient peoples of Ethiopia, the common in the United States—primarily sulfate, sodium carbonate, and potassium Canary Islands, Peru, and North America. because it had become fashionable to have and sodium nitrate) to dehydrate the a proper mourning period before interment. body before the remains were wrapped in Further Advances In 1850, a patent was granted to Freder- many layers of linen cloths and resins. This Christianity gradually brought about ick and Trump for a “refrigerator for complex mummification process, including changes in burial customs in the Greco- corpses”. Although this invention helped the recitation of prayers from the Book of Roman worlds. Christians focused on the delay decomposition, it did nothing to the Dead took approximately 70 days. spiritual aspect of the funeral service rather destroy harmful bacteria. As smallpox, diph- A second, less complex embalming than on preservation of the body. Howev- theria, and other epidemics began to method involved injecting cedar oil into er, during the 15th century, interest in take their toll, sanitation became a matter the anus and stoppering the opening. body preservation was renewed, partly of concern. Accordingly, several patents The external body was then treated with because of a desire to discover more were issued for embalming fluid formula- natron to effect dehydration. After a about human anatomy. Leonardo da Vinci tions for use as a disinfectant and body period of time (which varied according to (1452–1519) described a method of venous preservative. These fluids contained salts the individual) the oil was drained, there- injection to preserve the cadavers he was of heavy metals (such as arsenic, antimo- by eluting the internal organs. studying. Early embalming fluids common- ny, lead, mercury, and copper) to inhibit The third and least costly embalming ly contained mixtures of turpentine, bacterial growth. method involved cleansing the body, drying camphor, lavender oil, vermilion (mercu- with natron, and wrapping with linen. ry sulfide), wine, rosin, and saltpeter. Formaldehyde Emerges In 1972, a Manchester (U.K.) museum In the late 17th century, German physi- By the early 1900s, laws prohibiting the project was undertaken to investigate cian Gabriel Clauderus published a book use of metal salts in embalming were passed.

PHOTO: COREL ancient Egyptian lifestyles. The study describing an embalming method using Formaldehyde soon became the compound

©2002 AMERICAN CHEMICAL SOCIETY DECEMBER 2002 TODAY’S CHEMIST AT WORK 33 of choice and continues to be the most formaldehyde, there are several major differ- common preservative in embalming fluids. Formaldehyde is ences. With glutaraldehyde, the reaction The ability of formaldehyde to act as a cell with protein end groups begins to occur preservative was discovered in the late still the embalming at a much lower pH. Also, protein binding 1800s. Its fixative properties were found by with glutaraldehyde is much greater and accident by a German physician named fluid of choice in stronger, and the number of cross-links is Ferdinand Blum (1865–1959) in 1893. Blum considerably larger. Because glutaraldehyde was involved in a research project on the the United States. is a dialdehyde, one or both functional antiseptic properties of formaldehyde. While groups may react with the protein end working with a 4% aqueous solution of group. This produces a more complex, more formaldehyde, Blum discovered that his wet that once a formaldehyde molecule reacts cross-linked product with a higher molec- fingers became stiff. He wrote a paper with a protein end group it will remain ular weight. The resulting protein–aldehyde describing his finding, and this was the there until it reacts with a second end system is more stable (i.e., less readily beginning of the widespread use of formalde- group, forming a bridged dimer. This process hydrolyzed) than the system produced when hyde as a cell preservative. continues until a firm, stable, cross-linked formaldehyde is used. The reasons for formaldehyde’s contin- substrate is formed. The small size of the In addition, glutaraldehyde diffuses and ued popularity include low cost, avail- formaldehyde molecule allows for rapid penetrates into tissue more evenly than ability in a usable form, and simplicity of tissue penetration. This is important formaldehyde. Thus, the body is more apt use. In addition, formaldehyde provides because rapid tissue penetration decreased to retain its natural texture and, through good cell preservation under a variety of autolysis (the self-destruction of cells the introduction of coloring agents into pH conditions. and tissues after death). the embalming mixture, a more “natural” The chemistry of formaldehyde as a Numerous health concerns are associ- and even coloration is produced. Glutaralde- preservative is complex. In aqueous solu- ated with exposure to embalming fluids. hyde firms body tissue more readily and tions, formaldehyde undergoes two reac- Formaldehyde is presumed to be a carcino- evenly and is a more efficient and effec- tions. The first involves the formation of gen and to cause “occupational asthma” tive disinfectant. methylene glycol, which preserves tissue and contact dermatitis. In addition, with In spite of the apparent advantages of by a pathway different from that of respect to embalming, formaldehyde has a glutaraldehyde, formaldehyde is still the formaldehyde. In the second reaction, tendency to dry out tissue and cause an embalming fluid of choice in the United formaldehyde reacts with oxygen to yield ashen-grey coloration of the skin. Numer- States. There are several reasons for this. formic acid. The presence of the latter in ous attempts have been made to improve First, formaldehyde is a well-accepted stan- any great amount in embalming fluid is the formulation of formaldehyde-based dard in the embalming industry. Second, unacceptable because it causes “formalde- embalming fluids and to discover a formaldehyde is approximately five to eight hyde pigments” on the body. Materials such formaldehyde replacement. times less expensive on a per-pound basis. as methanol, methyl salicylate, and a vari- In terms of toxicity, glutaraldehyde is a ety of buffers are added to embalming fluids Replacing Formaldehyde severe skin and eye irritant, and it irritates to prevent excess formic acid formation. In 1943 a patent was granted to Hilton the respiratory tract when inhaled. Howev- In addition to the above considera- Ira Jones for an embalming fluid contain- er, glutaraldehyde lacks the harsh odor of tions, the pH of the blood plays a role in ing a dialdehyde, glyoxal. However, glyox- formaldehyde, and thus is not as easily the embalming process. After death, the pH al was found to produce a yellow stain on detected. There is no firm evidence to date of the blood becomes increasingly acidic as tissues, and its use as an embalming fluid to indicate that long-term exposure to a result of the production of lactic and did not become widespread. glutaraldehyde can cause harmful effects. carbonic acids during rigor mortis. Blood pH Glutaraldehyde was first used as a The practice of embalming has a long changes from 7.4 in the living state to 6.3 formaldehyde substitute in 1955. This and interesting history. Analytical chem- during rigor mortis. This “acidic period” lasts dialdehyde was found to react with tissue istry, toxicology, and biochemistry will play for approximately 48 h after death and is proteins in a manner similar to formalde- increasingly important roles in this field the time when embalming is most likely to hyde but without significant tissue dehy- as embalmers attempt to meet new govern- occur. A neutral or slightly alkaline embalm- dration. The rate of cell preservation using ment regulations and address new health ing fluid is required to neutralize this acidic glutaraldehyde depended on several factors. issues related to body preservation. blood and optimize cell fixation. Boric acid • Concentration: The higher the concen- Adapted from Today’s Chemist at Work, April 1994, combined with borax (sodium tetraborate) tration, the more rapid the cell fixa- pp 68–70. or sodium bicarbonate combined with diba- tion. However, tissue dehydration sic sodium phosphate are among the more occurred at high concentrations. Opti- Acknowledgment common buffer pairs used in formaldehyde- mum concentrations were found to be I thank the Dodge Co. (Cambridge, MA), manu- facturer of embalming chemicals, for its assistance based embalming fluids to ensure an appro- in the range of 1.0–1.5% (aqueous). in obtaining information for this article. priate body fluid pH. • pH: A slightly alkaline, buffered solu- Formaldehyde preserves tissue by form- tion optimized fixation. Harold T. McKone is a professor of chem- ing cross-links among protein end groups •Temperature: Room temperature provid- istry at Saint Joseph College, West Hartford, to create a stable, complex matrix. The ed the most stable and uniform results. CT. Send your comments or questions regard- exact mechanism of this cell fixation is Although glutaraldehyde preserves body ing this article to [email protected] or to the unknown, but it is generally thought tissue in much the same manner as Editorial Office address on page 6. ◆

34 TODAY’S CHEMIST AT WORK DECEMBER 2002 www.tcawonline.org