Testing Procedures for Historic Cemeteries

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Christopher L. Borstel and Charles M. Niquette

ACRA Edition, Volume 6, Number 5. October 2000


In an effort to determine what hazards might be anticipated with respect to historic cemetery excavations, the junior author contacted a number of different people who had experience in this kind of work. Specific questions to be addressed centered on diseases that might survive for long periods of time and that might pose a health hazard to employees. Curiously, the results of these contacts were mixed and often conflicting. Attempts to find a resolution to the matter through the Center for Disease Control also failed to generate any useful information. Instead, inquiries to the CDC prompted only generic responses. Despite these poor results, the senior author responded to an email plea for help on ACRA-L. Not only had Chris and his firm, The Louis Berger Group, Inc., considered the hazards associated with cemetery excavation but also they had developed a draft protocol for insuring the health and safety of Berger crews engaged in this activity. Chris was more than willing to share this document as well as a relevant paper that he and his colleagues presented at the Fall 1998 meeting of the Archaeological Society of Virginia (Meyers et al. 1998).

Somewhat surprisingly, biological hazards do not appear to be the real health and safety risk associated with historic cemetery excavations (Crist 2000) except in very special circumstances (e.g. sealed metal coffins or frozen corpses); instead, one needs to be keenly aware of chemical dangers – especially arsenic. This paper represents revised version of Berger’s protocol. Following a brief background concerning the use of arsenic in embalming the dead, we outline (1) those steps necessary to complete a site assessment, that is to determine the presence or absence of arsenic in historic graves; and, (2) provide interpretive guidelines to be followed if arsenic is found to be present. Use of the protocol is dependent upon the level of toxicity encountered and documented as part of the site assessment. In the conclusions to the paper, we describe personal protective equipment, universal safety precautions, and basic hygiene practices to be used during historic cemetery excavation whether or not arsenic is found to be present.


Arsenic, an embalming agent in common use between 1850 and 1910, is a highly toxic substance. According to Kones and McGee (1996:15), six patents for embalming fluid issued between 1856 and 1873 included as little as four ounces to as much as 12 pounds of arsenic per body. Because arsenic does not breakdown over time, it can be expected to move into the surrounding soil or leach into the ground water below cemeteries. Due to inadequate records kept concerning the numbers of people embalmed in the second half of the nineteenth century, it is nearly impossible to predict how much arsenic might be expected in any given cemetery dating to this period.

Meyers et al. (1998) report that

…prior to the usage of arsenic, there were few embalming alternatives for preserving the body beyond keeping it on ice. During the Civil War, many families were given the option of requesting that the body of their loved one be shipped home for burial. Dr. Thomas Holmes was in charge of setting up battlefield embalming stations for the Union Army (see Habenstein and Lamers 1955). Arsenic was an ideal embalming agent because it preserved the body well, and Holmes instructed multiple embalmers in this technique. After the Civil War ended, these embalmers returned to their hometowns and utilized this new procedure. By the 1890′s, arsenic embalming was the primary embalming method utilized by the funeral home industry, although other methods used mercury and other chemicals as well… Arsenic was banned from usage as an embalming agent by the federal government in 1910, because of the large number of deaths in embalmers due to their overexposure to the chemical.

Even if arsenic is absent from the grave, there is the possibility that other chemical hazards (e.g., mercury or formaldehyde) may be present if the interment post-dates ca. 1850. There is also a slight possibility that pathogens may be present (depending upon type and soil conditions). At a minimum, therefore, good basic hygiene should be practiced. Care should be taken avoid excess contact with soil. Hands should be washed thoroughly before smoking or eating. Wear latex gloves when toweling or screening soil from vicinity of body.

According to Dana Kollmann, a forensic archaeologist, arsenic in a grave is indicated by the presence of vivid blue or blue-green (copper oxide-like) crystal formations on bones. Such formations and staining are evidently more extensive than the restricted stains that may be left on bones by copper shroud pins or other cuprous artifacts near the skeleton. Arsenic compounds also apparently leave larger crystals than the extensive staining produced by vivianite, a hydrated iron phosphate, which sometimes forms on bones in moist, acidic soil conditions (Shackley 1975). According to rock and mineral field guides, arsenic minerals have a noticeable garlic-like odor when broken (Pough 1960). Another obvious indicator suggesting that arsenic or some other preservative was used as an embalming medium would be the presence of tissue remains in the grave. Extreme caution should be used if unusual odors, soil colors, lusters, or staining, or unfamiliar materials (particularly in finely divided or crystalline form) are noted.

The potential hazards of arsenic are both acute and chronic. Acute effects include dermatitis and irritation of mucous membranes and poisoning, most typically through ingestion, but also possible through skin contact or inhalation of dust. Chronic effects include lung cancer because of exposure to arsenic dust. Archaeological excavation of graves where arsenic contamination is present involves the potential for exposure to this material through skin contact, ingestion, and breathing of dust unless appropriate personal protective equipment and hygiene standards are followed. Worker exposure to inorganic arsenic compounds is specifically regulated by OSHA under 29 CFR 1929.1018.

An assessment of the presence or absence of arsenic in burials is necessary prior to excavation of historic cemeteries. Arsenic is classified by NIOSH as a carcinogen and has strict recommendations for personal protective equipment that would be required for any disinterment. Moreover, at least one field supervisor with 40-hour OSHA certification is required to participate in any effort to excavate historic graves where arsenic is present.

Site Assessment

A protocol for testing historic cemeteries, especially those containing unmarked graves, should be followed prior to any archaeological excavations:

1. Prior to any archaeological excavations on an unmarked cemetery, the history of the cemetery should be thoroughly researched and every attempt should be made to determine its age.

2. If the age of the cemetery is determined to fall within the 1850-1910 range, then steps must be taken to ensure that arsenic is not present in any of the grave shafts. Although the primary concern is arsenic, there is also the possibility of mercury and formaldehyde contamination if the graves date to the twentieth century.

3. To evaluate the potential occurrence of arsenic in the soil, a program of soil testing will be conducted before the grave is excavated. Sampling procedures and interpretive guidelines have been developed. These guidelines allow excavation of a grave if soil samples yield less than 100 ppm. If samples are over 100 ppm, then consultation with HAZMAT experts is required. All data should be reviewed during development of Phase III work plan and budget.

4. The Site Safety Plan must address the potential presence of arsenic in the soil. In addition, the Principal Investigator is responsible for preparing and discussing with the crew.

Soil Sampling Procedure

The person collecting soil samples should wear a facemask, respirator, tyvek coveralls and booties, and latex gloves. The tyvek booties will eliminate the need to decontaminate work boots and to prevent tracking of soil into vehicles. After taking these samples, the coveralls and gloves should be placed in a garbage bag and disposed of properly. The sampler should wash hands and face before eating or performing other work. See Konefes and McGee (1996), 29 CFR 1929.1118, and the conclusions of this paper for further details about personal protective equipment.

1. Identify the soil anomaly (grave shaft) to be excavated.

2. Assuming the initial sampling is designed to confirm or eliminate the presence of elevated levels of arsenic, a soil sample should be collected from the area that has the probability of the highest contamination, that is the center of the anomaly at a depth of where the body was interred. Burial depth may vary with local conditions and sampling depth should be adjusted accordingly. To determine the depth of the interment, use a small bucket auger in an attempt to recover a small amount of bone or coffin wood. Alternatively, one might try to determine the depth of the grave shaft using a solid steel probe. Duplicate samples should be obtained from the same interval or depth for quality control.

For a more fine grained approach, collect the following soil samples using a small bucket auger: one (1) from upper third of feature soil column, one (1) from middle third of feature soil column, one (1) from base of feature soil column, and one (1) from approximately 1 foot below base – a total of four samples. Collect a duplicate soil sample from near the base of the grave shaft in a general auger hole. Again, it is recommended that samples be extracted near the center of the anomaly on the assumption that this would be where the thorax of the body would have been located and that soil in this area would have the highest concentrations of arsenic since this is where the largest quantity of soft tissue would be located. Use appropriate procedures to decontaminate soil corer between samples. Begin a chain of custody for the samples. An 8-ounce jar of soil is required for each sample. The lab can provide you with appropriate sample jars and chain of custody forms. Samples should be labeled with date, time, sample I.D. and sample depth, placed in an ice filled cooler maintained at 4 degrees C for delivery to the lab. Enter the requested test method on the COC that would be 6010 for total arsenic. Turn around time for this analysis is typically around 10 working days.

3. To establish the naturally occurring arsenic levels, collect soil samples from a nearby off-site area. Drill three auger holes to the same depth as the sample interval in the anomaly. Collect a sample from the same depth in each hole and composite them together into one sample to establish background. This may mean each control sample will be larger than those you take from the soil anomaly.

4. Submit the two samples from the lowest level within the grave and the aggregated samples to a testing laboratory for analysis. Given the limited schedule of most projects of this type, it is likely that testing will need to be done on an expedited or priority basis. The cost for laboratory analysis of the samples is modest. In checking with local laboratories, EnviroData Group here in Lexington provided the following figures: Arsenic is $20, Mercury $28 and formaldehyde is $100. Unless you are working on a very recent burial, there shouldn’t be any formaldehyde left. It is very volatile and in its pure form is a gas. An aqueous solution using methanol and formaldehyde is used for embalming. Both are very volatile and should dissipate quickly.

5. Unless the potential presence of arsenic can be ruled out based on archaeological or historical data available during Phase II fieldwork, collect additional soil samples from other graves. Collecting these samples while you’re in the field will provide you with the basic material for developing data later if there is a need to plan for further work. It is recommended that a minimum of 5-10 samples, selected from among the grave shafts chosen at random. (With more than 20 anomalies, you’ll want to increase the number of graves sampled, if possible. A good sample size would be 30 to 50 graves for a cemetery of 100-300 graves).

Interpretive Guidelines Analysis of Arsenic in Features Fill Soils

1. VALUE RANGE: Arsenic in fill is similar to (or lower than) values for aggregated control samples and all values are less than 20 parts per million (ppm).

INTERPRETATION: Arsenic contamination is probably absent.

ACTION: Proceed with excavation of feature using standard health and safety procedures for historic burials.


A. The similarity of the values for feature and aggregated control samples suggests that the level of arsenic has not been increased in the feature soil due to the use of an arsenic- based embalming fluid.

B. The threshold of 20 ppm is that given by the New Jersey Department of Environmental Protection in its Cleanup Standards for Contaminated Sites (Tables 3-2 and 7-1, 1992 proposed rule, as amended). This threshold applied both to residential and non-residential sites and takes into account “natural background.” According to one source cited in reports available on the Internet, the average U.S. soil contains 5 ppm of arsenic (Lindsay 1979). We interpret the New Jersey threshold of 20 ppm to be the level at which long-term and repeated exposure to soil- and dust-borne arsenic should be avoided.

LIMITATION: Since the assessment of contamination will be based upon analysis of a single sample from an unknown location within the possible grave, and since the patterns of dispersion of arsenic in the soil are unknown, the possibility of arsenic contamination cannot be entirely dismissed at this early stage of the investigation. Therefore, careful observations should be made as excavation proceeds and the presumption of non-contamination should be revised if necessary. See general comments on grave excavation.

2.    VALUE RANGE: Arsenic in fill is noticeably (up to approximately 4 times in the 1-20 ppm range) higher than values for aggregated control samples, but all values are less than 20 ppm.

INTERPRETATION: Arsenic contamination is possibly absent.

ACTION: Proceed with excavation of feature using standard health and safety procedures for historic burials. Analysis of one or more additional soil samples from the feature fill would be appropriate.


A. We have no data on how much variation there is in the natural, background level of arsenic in the soil, and the number of samples being used to make decisions concerning the action to be taken at this site is so small as to make impossible to evaluate local variability. Given uncertainties about natural variability of arsenic concentrations, it is therefore possible that a higher value for arsenic in feature soil as compared to controls is the result of natural variability in the soil and not an indication of contamination. A hypothetical calculation suggests that minimum soil contamination resulting from the presence of an arsenic-embalmed body may be in the range of 100 to 300 ppm , substantially higher than the 5 ppm said to be characteristic of an average U.S. soil (Lindsay 1979). This computation would seem to indicate that arsenic contamination due to use of embalming fluids is likely to produce values far above usual background levels in most areas of the country (areas where bedrock is rich in heavy metals are a possible exception).

B. Regarding the 20 ppm threshold, see Justification B, Item 1.

LIMITATION: See comments on limitations under Item 1.

3.    VALUE RANGE: Arsenic in fill is greater than 20 but less than 100 ppm.

INTERPRETATION: Arsenic contamination may be present, particularly if value for fill soils is considerably greater (2-4 times or more) than for aggregated control samples.

ACTION: Verify level of arsenic in fill soil through additional analysis if difference between control samples and fill samples is large. Institute dust control measures and thorough excavator hygiene. Proceed with excavation using great caution.


A. Regarding the 20 ppm threshold, see Justification B, Item 1.

B. The 100 ppm threshold is set based upon the following analysis. At levels of less than 100 ppm, we believe that exposure to arsenic through ingestion, skin contact, and contact with mucous membranes can be readily controlled through the use of minimal personal protective equipment and rigorous washing with soap and water before smoking or eating and at the end of a work period. The principal hazard at these levels comes from arsenic in soil dust. NIOSH sets a 15-minute exposure limit for inorganic arsenic at 0.002 milligrams/cubic meter (mg/m3) (1994 NIOSH Pocket Guide to Chemical Hazards). According to a report prepared by Emilcot Associates, the lower limit for visible dust in the air is 2.5 mg/m3. In order to achieve an exposure of 0.002 mg/m3 arsenic at the point when dust is first visible in the air, there would need to be (0.002/2.5)(1,000,000) or 800 ppm in the soil. Our proposed threshold provides a safety factor of eight regarding the 15-minute exposure limits.

It should be stressed that the upper limit of 100 ppm is based on several critical assumptions. These are: (1) exposure will be limited to the excavation of a single feature over a period of 2-5 days, with no more than 3 workers involved in the excavation at any one time; (2) rigorous dust control measures will be practiced, so that use of respirators as a further safety measure will be unnecessary; and (3) a high standard of worker hygiene will be maintained.

LIMITATION: See comments on limitations under Item 1.

Since the only information we have on natural, background levels of arsenic in the soil is a single statement of unevaluated reliability (5 ppm for average U.S. soil-Lindsay 1979), we have no knowledge concerning the upper limit of naturally-occurring levels of arsenic in the soil, it would appear that if the control samples from this project area yield values much over 20 ppm, we should begin to suspect that there is widespread contamination and proceed using extreme caution for all further work.

The threshold guidelines herein apply only to the specific activity of opening one shaft feature for a limited period. Conditions should be reassessed if work beyond this is contemplated.

4.    VALUE RANGE: Arsenic in fill is greater than 100 ppm.

INTERPRETATION: Arsenic contamination is probable.

ACTION: Confirm arsenic level through additional testing. No excavation of grave shafts should be undertaken until further, expert assessment is completed.

JUSTIFICATION: Limits as defined above have been exceeded. Expert advice is necessary to assess hazards and to develop plans for dealing with them. It is probable that any excavation would need to be undertaken by qualified personnel working under a detailed health and safety plan.


When digging historic graves, your best course of action is to assume the worst sorts of chemical and biological hazards and take the necessary precautions to provide a safe and healthy working environment.  If you use universal safety precautions and exercise good basic hygiene practices, the chances for significant problems will be greatly diminished.  These universal safety precautions remain standard health and safety procedures for excavation of all historic burials.  They also apply in situations where 20-100 ppm arsenic is suspected to be present in the soil.  Vigilant care must be exercised to minimize exposure via skin contact, ingestion, or breathing dust.   Personal protective equipment to be employed and basic hygiene practices to be followed are as follows:

1.  Wear latex gloves when there is the potential for handling soil–e.g., when toweling or screening.  This means that if only shovels are being employed for excavation, and hands are not touching the soil, then bare hands, or preferably inexpensive cloth gloves that can be discarded at the completion of the excavation, are acceptable.

2.  Wear eye protection if your face is likely to be exposed to soil particles or dust (e.g.., when screening).

3.  Wash your hands and face thoroughly in water before eating or smoking.

4.  Keep drinking water and other beverage containers far enough from work area so that contamination from soil cannot happen.

5.  It is not necessary to wear tyvek coveralls during excavation, provided fresh clothing is worn daily.  Coveralls may be appropriate for very dirty jobs (e.g., continuous soil screening or extensive toweling).  Given the summer season, other means of minimizing contact, such as using clean plastic sheeting to kneel on when toweling, may be more suitable.

6.  Shoes or boots should be wiped down at the end of a work shift to remove adhering soil and dust using a damp paper towel or disposable cloth.

7.  DUST CONTROL IS ESSENTIAL.  Dust should be controlled by regularly spraying walls, floors, and back dirt piles with a light spray of water.  Under most conditions, it is not necessary (or desirable) to get the soil soaking wet.  Rather, only enough water should be used to keep the surface of the soil slightly moist.  Cover the excavation area and the back dirt piles with plastic when work is not going on to minimize moisture loss.  If possible, work early in the day or during cloudy weather.  If screening is necessary, care should be taken not to generate dust.  Means to do this include lightly spraying soil with water before screening and pushing soil through the screen with a gloved hand rather than shaking the screen.

8.  These precautions should be observed until the excavation is backfilled.


Susan Bush of Commonwealth Technology, Inc., provided substantive comments and suggestions to this paper.  We would like to thank Steve Creasman and Andrew Bradbury at Cultural Resource Analysts, Inc., for their thoughtful comments.  Mary Sayers at URS Greiner Corporation was also helpful in providing background information and useful advice.  Most of all, we hope that the paper is helpful to those who contemplate historic cemetery excavation and that future field crews are provided a safe and healthy working environment.  Archaeology is important but it is not so important that we should expect any employee to be put in harm’s way through our own ignorance.


Crist, Thomas A.J.
2000 Smallpox and other scourges of the dead.  Paper submitted for inclusion in Dangerous Places, Health Safety and Archaeology, edited by D.A. Poirer and K. Feder.  Greenwoood Press of Connecticut.

Habenstein, R.W. and W.M. Lamers
1955  The History of American Funeral Directing.  Buefin Printers, Milwaukee, Wisconsin.

Konefes, John L. and Michael K. McGee
1996 Old Cemeteries, Arsenic, and Health Safety.  CRM 19(10):15-18.

Lindsay, W.L.
1979 Chemical Equilibria in Soils.  Wiley, New York.  Cited in a document on the World Wide Web at http://www-orca.nos.noaa.gov/projects/wastesites/quantico.

Meyers, Maureen, Christopher L. Borstel, David Breetzke and Henry Holt
1998 Arsenic and Old Graves: Testing Procedures at Nineteenth-Century Cemeteries.  Paper presented at the  Fall 1998 meeting of the Archaeological Society of Virginia.

Pough, Edward H.
1960 A Field Guide to Rock and Minerals.  3rd ed.  Houghton-Mifflin, Boston.

Shackley, Myra L.
1975 Archaeological Sediments.  Wiley, New York.

One comment on “Testing Procedures for Historic Cemeteries
  1. Kathy Walker says:

    I found this article to be very interesting because I knew nothing of the history of embalming materials except formaldehyde. In addition, I had not considered the dangers of digging things up except for the usual microbes and fungi found in soil.

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