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Appendix A

The naturally occurring element radium has been well-studied. 226Ra decays by the emission of alpha particles and photon radiation (gamma rays) with a physical half-life of 1,602 years (11). With a biological half-life of 16,400 days (bone) and 900 days (total body),226Ra non-uniformly deposits within bone. The average U.S. daily intake of 226Ra is estimated to be 0.0851 Bequerels (Bq; 2.3 pico Curries, pCi) most individuals maintain a body burden of nearly 1.15 Bq (31 pCi). The estimated fraction of 226Ra transferred from the gastrointestinal tract after ingestion to the blood is 20% (12).

A member of the naturally occurring uranium series, 226Ra decays to produce the radioactive gas, radon-222 (222Rn). The 226Ra deposited within bone releases about 70 percent of the 222Rn produced into the blood system and this amount is ultimately exhaled. The EPA presently limits the amount of 226Ra and 228Ra in drinking water to 5 pCi/L (9) and there are no federal limits for radium contamination in buildings other than the surface contamination levels mentioned previously.

The radon gas produced also is radioactive and chemically inert and this radon is produced both outside the body as well as inside from the internally deposited 226Ra. There have been direct correlations between the exposure to radon and radon progeny and the appearance of lung cancer in humans. The initial epidemiological studies of radon exposure began in 1879 in Europe. Since then, these studies have spread worldwide and are still in progress. The studies involve uranium miners and show increasing risks of lung carcinomas as accumulated exposure to these products increased (4). 222Rn decays by the emission of an alpha particle and gamma rays. The half-life of 222Rn is 3.8 days (11). The decay products are also radioactive, emitting alpha particles, beta particles, and gamma rays. These radon progeny, with half-lives ranging from seconds to over 20 years, ultimately decay to a stable (non-radioactive) form of lead.

Because radon is chemically inert and does not attach to surfaces, the implications of its exposure are difficult to evaluate. However, the charged decay products can electrostatically attach to surfaces. Most progeny immediately attach to aerosols. The ratio of attached progeny to unattached progeny is important in dose calculations because as the ratio increases, the radiation dose to lung surfaces increases. Other factors affecting the lung dose include the ratio of 222Rn to its progeny, the breathing patterns, lung characteristics, gender, and age of the individual exposed. In a recent report from the National Academy of Sciences, the dose from the radon progeny was the greater risk compared to exposure to radon gas (4). Dose estimates have been published by the NCRP and include those factors (13). The NCRP estimates that the risk of developing lung cancer following a lifetime exposure to 222Rn is 2.1 in 1,000 per pCi/L exposure under environmental conditions. The NCRP also states that the dose to the bronchial regions of a typical working adult because of exposure to 222Rn is 0.27 rad per year per pCi/L. For a ten year old child (12 hours active, 12 hours resting), the dose estimate is 0.45 rad/year per pCi/L.


Gary D. Perlman, MPH
Environmental Epidemiology and Occupational Health
Connecticut Department of Public Health

ATSDR Radiation Support

Paul A. Charp, Ph.D.
Senior Health Physicist
Division of Public Health Assessment and Consultation
Agency for Toxic Substances and Disease Registry
Atlanta, GA

ATSDR Regional Representative:

Louise House, RN, MA
Agency for Toxic Substances and Disease Registry, Region 1
Boston, MA

ATSDR Technical Project Officer:

Tina Forrester, Ph.D.
Superfund Site Assessment Branch
Division of Public Health Assessment and Consultation
Agency for Toxic Substances and Disease Registry
Atlanta, GA

Greg Ulirsch
Superfund Site Assessment Branch
Division of Public Health Assessment and Consultation
Agency for Toxic Substances and Disease Registry
Atlanta, GA


  1. Correspondence from Thomas C., Condon (EPA On Scene Coordinator), to Lousie House (ATSDR Regional Representative), on June 12, 1998.

  2. Connecticut Department of Environmental Protection Data provided to Connecticut Department of Public health in May of 1998.

  3. Keane, A.T. and C.W. Mays. Mastoid Carcinoma 52 years after childhood intake of 226Ra in a man retaining 1k Bq: Estimation of skeletal Dose. Radiation Protection Dosimetry, 1987.

  4. National Research Council. Health Risks of Radon and Other Internally Deposited Alpha-emitters. BEIR IV. Washington, D.C.: National Academy Press, 1988.

  5. Stebbings, J.H., H.F. Lucas, and A.F. Stehney. Mortality from Cancers of Major Sites in Female Radium Dial Workers. Am. J. Indust. Medicine 5:435-459, 1984.

  6. Rundo, J., A.T. Keane, H.F. Lucas, R.A. Schlenker, J.H. Stebbings, and A.F. Stehney (1985). Current (1984) Status of the Study of 226Ra and 228Ra in Humans at the Center for Human Radiobiology. Strahlentherapie [Sonderb] 80:14-21.

  7. NCRP. Exposure of the population in the United States and Canada from natural background radiation. National Council on Radiation Protection and Measurements, 1987.

  8. NCRP. Recommendations on Limits for Exposure to Ionizing Radiation. NCRP Report 116. Bethesda: National Council on Radiation Protection and Measurements, 1994.

  9. 10 CFR 835. Occupational Radiation Protection. Code of Federal Regulations, Title 10, Section 835.

  10. EPA. Establishment of cleanup levels for Superfund sites with radioactive contamination. OSWER Directive 9200.4-18. August 22, 1997.

  11. DHEW U.S. Department of Health, Education and Welfare. Radiological Health Handbook. Washington, D.C.: 1970.

  12. ICRP. Limits for the Intake of Radionuclides by Workers. International Commission on Radiological Protection Publication 30, - Part 1. New York: Pergamon Press, 1979.

  13. NCRP. Evaluation of Occupational and Environmental Exposures to Radon and Radon Daughters in the United States. NCRP Report 78. Bethesda: National Council on Radiation Protection and Measurements, 1984.


The Public Comment section for the Former Clock Factories contains public comments received during the public comment period which began on September 23, 1998, and continued through December 1, 1998. Each comment and their respective responses are listed below.

            All points of exposures should be marked

RESPONSE to Comment No. 1
            The CT DPH and the Agency for Toxic Substances and Disease Registry (ATSDR) agree with this comment. This suggestion will be included in our recommendation section.

            The table on page 18 in the Recommendations section of the PHA should be modified to accurately reflect the limited areas of contamination on the fourth, fifth, and seventh floors of the facility. The text on page 15 states that radiation levels were above the EPA risk based clean-up levels only in "isolated areas." We insist that the PHA accurately reflect that only limited areas on the impacted floors are of concern. This treatment would be consistent with that given to other facilities on the PHA.

RESPONSE to Comment No. 2
            The CT DPH and the Agency for Toxic Substances and Disease Registry (ATSDR) agree with this comment. This clarification was incorporated as indicated.

            Tables 2 through 14 in the Discussion section of the PHA present an inconsistent picture of the "Measurement Description" associated with each Radiological Parameter for each site. Test and sampling procedures should be consistent for all sites and any remedial requirements should be based on consistent measurement and sampling methodologies for each radiologic parameter. The PHA should address whether all facilities were assessed in accordance with a consistent sampling and measurement methodology and should be more comprehensively present the associated data.

RESPONSE to Comment No. 3
            The radiologic surveys conducted to date were designed as "walk-through" investigation efforts. These investigations can be conducted relatively rapidly, and provide useful data for inclusion in Public Health Assessments. Additional sampling, including characterizations designed for remediation efforts, will be conducted at a later date.

            In the Summary section, paragraph 2, the first sentence should be revised to read "contamination was detected at levels that may pose a . . . " The addition of the word "may" will more accurately reflect the situation presented in the PHA and is consistent with the text throughout the document and in the conclusion.

RESPONSE to Comment No. 4
            The CT DPH and the Agency for Toxic Substances and Disease Registry (ATSDR) agree with this comment. This clarification was incorporated as indicated.

            It must be noted that there are countless innocent landowners who may be profoundly affected by this process. Accordingly, the PHA should clearly detail what additional assessments, studies, and actions can be expected. In addition, the relevant agencies should begin to notice potentially responsible parties so that the costs associated with any ongoing or future investigations and remedial measures may be directed to those responsible for the contamination.

RESPONSE to Comment No. 5
            The CT DEP and EPA are currently negotiating on remediation plans. These two agencies will notify the potentially responsible parties. The CT DPH and the ATSDR will review any additional data and remediation plans, and if necessary, will incorporate our findings in a separate report.

            Why wasn't Timex of Middlebury included in the report?

RESPONSE to Comment No. 6
            Timex of Middlebury has hired a consultant who is investigating chemical pollution at and near the site. The investigation and remediation are being performed under the oversight of the DEP. Timex has signed a consent order with the DEP to deal with the past contamination of this site. As part of this investigation radiation surveys were performed and split samples were taken in the presence of DEP Radiation Section Personnel. No radium contamination was found. Old record searches indicate that the use of radium paint was limited to the facilities we have recently been surveying.

COMMENT NO. 7,8, and 8
            Where are the dump sites of all these clock factories?
            The dump sites must be located and tested.
            I want all the grounds and dump sites located, tested and cleaned up by the clock companies responsible. Not by the Taxpayer!

RESPONSES to Comments No. 7,8, and 9
            There is no documentation to indicate that disposal of radioactive waste was occurring. The alpha and beta radiation emitted by radium will be stopped by a 1/4 inch of dirt. The gamma radiation would be reduced about 90% by one foot of dirt. Two feet of dirt would reduce it by 99%. Thus a landfill which might have 30-100 feet of dirt and debris on top of potentially radium contaminated waste from the 1920's, would not have any detectable radiation level over background. Digging into a closed, capped landfill for the purpose of sampling for radium would be a greater risk to the environment and nearby populations, than leaving it undisturbed. These are sampled routinely for the presence of chemicals and radium/radon.

COMMENTS NO. 10, 11, and 12
            Why wasn't testing done on all the dangerous chemicals used by the clock companies sooner?
            Why were the tests done for radium only? There should be testing done for all chemicals that could be hazardous or a pollutant to the environment.
            Why wasn't the testing for radium and all other dangerous and residual chemicals done long before this?

RESPONSES to Comments No. 10,11, and 12
            Since October 1, 1985, it has been common practice to perform environmental studies before the sale or transfer of industrial properties. These were done in the past when these properties changed hands. For example: Bender Plumbing had extensive testing done at the Benrus Factory, including the drilling of monitor wells, before purchase. Therefore facilities sold after 1985 have been tested for chemicals likely to have been used by the previous occupants. Many of these facilities are currently used as industrial sites and are subject to inspections by OSHA and other DEP departments. Because the use of radium occurred at very few facilities nationwide, and was mostly discontinued 50 to 60 years ago, routine testing for radium is not normally a part of a pre-sale environmental study. Radium contamination at most of the "affected" facilities is so low that it would have been difficult or impossible to detect with the instrumentation available in the 1960's and 1970's.

            There should be a cancer study done in the vicinity of each of the clock factories! Not the entire town!

RESPONSE to Comment No. 13
            Radioactive contamination has been identified at specific locations within the buildings listed in this public health assessment. Health studies of persons exposed to radium through their work have shown that the workers have a higher risk of some types of cancer. However, a person needs to be close to the source of the radioactivity in order for their health to be affected by any radiation. Since there is no evidence that there has been any contamination to the neighborhoods near the clock factories, persons living near the clock factories would not have been exposed to the radiation and a study of cancer incidence in the neighborhoods near the clock factories is not warranted.

COMMENTS NO. 14 and 15
            Timex of Middlebury used radium in their war contracts.
            Where are all the dump sites? Do they glow in the dark?

RESPONSES to Comments No. 14 and 15
The 'glow in the dark' effect is caused when radiation caused by the decay of radium strikes the florescent chemical mixed with it. Even if radium and the florescent chemical were disposed of together, a capped landfill would not allow the light to be visible. Three feet of dirt an/or other debris would also prevent more than 99% of the radiation from escaping.

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