InspectAPedia tolerates no conflicts of interest. We have no relationship with advertisers, products, or services discussed at this website.
Transite Asbestos Cement Pipes:
This article assists in the recognition of transite pipe used for water pipes, and discusses potential hazards of this material when it is
found in buildings.
Transite pipe is an asbestos-cement product which was used for both HVAC ducts and for chimney or flue material to vent gas-fired appliances as well as for water piping in some communities.
This article explains the potential health hazards (asbestos exposure by ingestion) as well as practical problems (fragility, collapse, expense of replacement) of cement asbestos transite pipe water piping and we provide citations to authoritative studies of this question. Among topics of discussion here are Vinyl-lined Transite Asbestos Pipe Hazards.
Practical Hazards & Risks of Transite Water Supply Piping Mains. Safety hazards associated with transite pipe cement asbestos materials in buildings. How to recognize asbestos transite pipe materials in building chimneys, air ducts, water pipes.
This document assists building buyers, owners or inspectors who need to identify asbestos materials (or probable-asbestos) in buildings by simple
We provide photographs and descriptive text of asbestos insulation and other asbestos-containing products
to permit identification of definite, probable, or possible asbestos materials in buildings.
Guide to Health Hazards of Transite Pipe Cement-asbestos Water Piping
Transite pipe or asbestos-cement pipes were used for water supply systems in some municipalities up into the 1970's in the U.S. and probably in other countries. In some cities (Ellwood PA for example), the transite water mains were found to be unable to reliably withstand high water pressures (up to 225 psi in Ellwood according to one of our readers) and the pipes were easily broken.
Asbestos fibers may be ingested from water supplied through transite water piping. Transite piping
deteriorates over time, releasing asbestos fibers from the interior of the pipe
into the drinking water flowing through that conduit. The level of health risk from ingested asbestos fibers is uncertain and probably low.
An NIH report prepared by industry experts concluded:
The work group believes that the cancer risk associated with asbestos ingestion should not be perceived as one of the most pressing potential public health hazards facing the nation.
However, the work group does not believe that information was sufficient to assess the level of cancer risk associated with the ingestion and therefore, this potential hazard should not be discounted, and ingestion exposure to asbestos should be eliminated whenever possible.
Cancer mortality for the population census tracts of Escambia County, FL, which use asbestos-cement (AC) pipe for public potable water distribution, was compared with cancer mortality data collected from census tracts in the same county where other types of piping materials are used. An analysis of covariance was run to test for differences in standard mortality ratios for seven cancer sites among three potential asbestos exposure groups based on AC pipe usage.
Twelve variables representing nonexposure-related influences on disease rates were combined in four independent factors and used as covariates in these analyses.
No evidence for an association between the use of AC pipe for carrying drinking water and deaths due to gastrointestinal and related cancers was found. The limitations on the sensitivity of the analysis are discussed.
ASBESTOS DUCTS, HVAC - Guide to Identification of Asbestos Materials On or In Heating and Cooling Duct Work: carbon monoxide hazards of transite chimneys and vents
While an expert lab test using polarized light microscopy may be needed to identify the specific type of
asbestos fiber, or to identify the presence of asbestos in air dust or water samples, many asbestos-containing building products
not only are obvious and easy to recognize, but since there were not other look-alike products that were not asbestos, a visual identification of this material can be virtually a certainty in many cases. Links to U.S. government and other authoritative research and advice are included.
Vinyl-lined Transite Asbestos Pipe Hazards
A more immediate water quality hazard has been detected in some vinyl-lined transite water pipes - Tetrachloroethylene. A report on the Sandwich water district on Cape Cod in Massachusetts reported that
"PCE was detected in the distribution system at an annual average of 0.8 parts per billion, which is below the limit set by the U.S. Environmental Protection Agency (EPA).
This substance leaches into the water from vinyl lined transite water pipe. In order to address this problem, in 2002 approximately 8,500 feet of water mains were sealed with an epoxy coating resulting in a dramatic decrease in PCE levels. "
Practical Hazards & Risks of Transite Water Supply Piping Mains
Leaks in transite water supply piping underground can result in substantial water losses in districts where this piping was used.
Locating transite water supply mains: We've been informed that excavators complain that its lack of metal makes locating transite water pipes difficult - one cannot use ordinary metal detectors.
Of course a buried pipe of non-metallic material might be located if it is possible to insert a sending probe inside its length but on a water main this procedure is impractical. Contractors joke that they find transite pipe by using the metal bucket of a backhoe as a pipe detector.
Replacement costs for transite water supply piping: because of its age, leaks, fragility, and difficulty of finding transite cement asbestos water supply mains and water piping without also damaging it at the same time, owners of properties and communities served by cement asbestos water pipes (transite) can expect to face increasing costs to replace that piping.
Incorrect spellings of transite piping or transite duct material that we've seen include transit pipe, transit ducts,
Transide pipe, transide ducts, tranisite pipe, and transight pipe. "Transite" is the correct spelling.
Research on the Hazards of Ingesting (eating) Asbestos - Mixed Arguments, Risk Assessments
Allen, Elizabeth M., Bruce H. Alexander, Richard F. MacLehose, Gurumurthy Ramachandran, and Jeffrey H. Mandel. "Mortality experience among Minnesota taconite mining industry workers." Occup Environ Med 71, no. 11 (2014): 744-749.
Objective To evaluate the mortality experience of Minnesota taconite mining industry workers.
Methods Mortality was evaluated between 1960 and 2010 in a cohort of Minnesota taconite mining workers employed by any of the seven companies in operation in 1983. Standardised mortality ratios (SMR) were estimated by comparing observed deaths in the cohort with expected frequencies in the Minnesota population. Standardised rate ratios (SRR) were estimated using an internal analysis to compare mortality by employment duration.
Results The cohort included 31 067 workers with at least 1 year of documented employment. Among those, there were 9094 deaths, of which 949 were from lung cancer, and 30 from mesothelioma. Mortality from all causes was greater than expected in the Minnesota population (SMR=1.04, 95% CI 1.02 to 1.04).
Mortality from lung cancer and mesothelioma was higher than expected with SMRs of 1.16 for lung cancer (95% CI 1.09 to 1.23) and 2.77 for mesothelioma (95% CI 1.87 to 3.96).
Other elevated SMRs included those for cardiovascular disease (SMR=1.10, 95% CI 1.06 to 1.14), specifically for hypertensive heart disease (SMR=1.81, 95% CI 1.39 to 2.33) and ischemic heart disease (SMR=1.11, 95% CI 1.07 to 1.16). Results of the SRR analysis did not show variation in risk by duration of employment.
Conclusions This study provides evidence that taconite workers may be at increased risk for mortality from lung cancer, mesothelioma, and some cardiovascular disease.
Occupational exposures during taconite mining operations may be associated with these increased risks, but non-occupational exposures may also be important contributors.
Berndt, Michael E., and William C. Brice. "The origins of public concern with taconite and human health: Reserve Mining and the asbestos case." Regulatory Toxicology and Pharmacology 52, no. 1 (2008): S31-S39. Abstract:
Asbestos first became an issue to Minnesota’s iron industry when it was revealed that mineral fibers similar to those in Reserve Mining’s tailings were being found in drinking water for several communities that used Lake Superior as their primary water source. This discovery turned what had largely been an environmental court battle into a case concerning public health.
The courts listened to much conflicting and uncertain scientific testimony on the size and distribution of the mineral fibers and on the potential health effects imposed by them. In April 1974, the plant was ordered to shut down by a federal judge but the company quickly appealed the decision. The appeals court granted a stay and ultimately ruled that the plant’s closure could not be justified based on the unknown health effects of the mineral fibers since the consequences of such an action would have immediate and severe social and economic impacts.
The plant was allowed to continue operation, but ordered to abate emissions to air around the plant and to switch to a land-based tailings disposal system. Much of the scientific uncertainty and public concern over mineral fibers in Minnesota’s taconite industry remain today.
Cunningham, H. M., and R. D. Pontefract. "Asbestos fibres in beverages and drinking water." Nature 232, no. 5309 (1971): 332-333.
Frumkin, Howard, and Jesse Berlin. "Asbestos Exposure and Gastrointestinal Malignancy Review and Meta‐Analysis." American journal of industrial medicine 14, no. 1 (1988): 79-95.
The epidemiologic literature linking asbestos exposure with gastrointestinal malignancy is reviewed. Problems in comparing studies are discussed, appropriate strategies for comparison are developed, and study results are pooled using a model which accounts for both intrastudy and interstudy variability.
Stratification of cohorts by dose reveals that significant asbestos exposure, as indicated by a lung cancer standardized mortality ratio (SMR) of at least 200, is associated with an elevated gastrointestinal cancer SMR for five or six end points examined.
Gross, Paul, Russell A. Harley, Layinka Margaret Swinburne, John MG Davis, and William B. Greene. "Ingested mineral fibers: Do they penetrate tissue or cause cancer?." Archives of Environmental Health: An International Journal 29, no. 6 (1974): 341-347. Abstract:
Three different laboratories independently investigated the ability of ingested mineral fibers to penetrate tissues in rats. All concluded that there was no evidence of tissue penetration by ingested mineral fibers.
These experimental observations are supported by the findings in coal and hard-rock miners who swallow, during their lifetime, nearly 100 times the amount of dust that is stored in their lungs. The intestinal wall or mesenteric lymph nodes of these people show no evidence of storage of the ingested dust particles.
Animals fed asbestos over much of their lifetime and allowed to live to the age of cancer production, failed to provide evidence of a cancerogenic effect.
Hallenbeck, W. H., and C. S. Hesse. "A review of the health effects of ingested asbestos." Reviews on environmental health 2, no. 3 (1977): 157-166.
Harries, P. G. "Asbestos hazards in naval dockyards." Annals of occupational hygiene 11, no. 2 (1968): 135-145. Abstract:
Occupational studies indicate that a human health hazard may exist for ingested asbestos since the death rates due to digestive system cancers are elevated in asbestos workers.
This finding may be related to the swallowing of asbestos that was inhaled and cleared from the respiratory system via the respiratory clearance mechanism.
Published animal ingestion experiments have serious shortcomings in their design and execution which make their interpretation very difficult. Animal ingestion and human autopsy studies suggest that asbestos fibers may penetrate the digestive tract and migrate to other locations in the body. A brief description is given of the types of asbestos materials, and their uses in shipbuilding and ship repairing in Naval Dockyards. An outline of the problems to be faced and a description of preventive methods is followed by a series of questions intended to stimulate practical solutions to the problems of using asbestos materials safely in the industry.
Langston, Nancy. "The Wisconsin Experiment." [PDF] Places Journal (2017). [Website article] retrieved 2017/08/12, original source: https://placesjournal.org/article/the-wisconsin-experiment/
Asbestos fibers can also contaminate the water. Beginning in 1956, an enormous taconite processing facility owned by Reserve Mining Company began dumping tailings directly into Lake Superior. After decades of lawsuits, the operation was shut down, but not before dumping 400 million tons of waste. Asbestiform fibers were dispersed throughout a third of the lake, eventually reaching Duluth, where the drinking water had over 100 billion fibers per liter.
Editor's Note: see Levy (1976) & Sigurdson (1981, 1983) giving results of long term health effects of asbestos fibers in the drinking water of Duluth MN.
LeFevre, M. E., R. Hammer, and D. D. Joel. "Macrophages of the mammalian small intestine: a review." RES, J. Reticuloendothel. Soc.;(United States) 26, no. 5 (1979). Abstract:
The present review resulted from questions concerning the fate in the intestine of ingested particulate pollutants such as asbestos and fly ash. These and other similar particulates are common contaminants of food and water, but little is known of the hazards associated with their ingestion. It is probable that they present some hazard if they penetrate the intestinal mucosa. In a recent study, fly ash from a coal-burning power plant was found to contain both organic and inorganic mutagens (34).
The dangers of asbestos ingestion have been widely discussed (20, 36a, 41, 56, 83, 100, 148, 172, 184), although the extent of asbestos penetration of the intestinal mucosa still uncertain (20, 69, 108, 181).
It seemed obvious that many of the particulate pollutants which penetrated the mucosal barrier would be phagocytized by macrophages residing in the lamina propria and that a study of the disposition of particulates within the gut wall should begin with a consideration of intestinal macrophages of lung, pertoneal cavity, spleen and liver have been discussed at length (25), little published work has dealt directly with the origin, abundance and activities of intestinal macrophages.
Nevertheless, considerable information on intestinal macrophages and their interactions with materials which reach them from the intestinal lumen is available in publications dealing primarily with other topics.
Such information is important in toxicologic studies as well as in studies of host defences to intestinal Ags. It is, therefore, appropriate to assemble and discuss findings on intestinal macrophages, even though at present more questions will be raised than can be answered.
Levy, Barry S., Eunice Sigurdson, Jack Mandel, Emaline Laudon, and John Pearson. "Investigating possible effects of asbestos in city water: surveillance of gastrointestinal cancer incidence in Duluth, Minnesota." American journal of epidemiology 103, no. 4 (1976): 362-368.
Abstract: The recent discovery of over one million asbestos-like fibers per liter of Duluth tap water and the suggestive evidence of a link between certain gastrointestinal (GI) cancers and work exposure to asbestos fibers in the air prompted this study. GI cancer incidence data were gathered for Duluth in the same manner as data previously gathered for comparison cities, Minneapolis and St. Paul
Although some differences in GI cancer incidence occurred among the three cities in 1969–1971, there was no consistent pattern of statistically significant differences observed.
The number of GI cancers diagnosed in Duluth residents in 1972 was similar to that in each of the previous three years. This study represents the start of ongoing cancer surveillance in Duluth.
McMillan, Lilia M., Roy G. Stout, and Benjamin F. Willey. "Asbestos in raw and treated water: an electron microscopy study." Environmental Science & Technology 11, no. 4 (1977): 390-394.
Olson, Harold L. "Asbestos in potable-water supplies." Journal-American Water Works Association 66, no. 9 (1974): 515-518.
Asbestos-cement pipe was developed in Italy approximately sixty years ago and its use rapidly spread around the world. The causes of the rapid acceptance are as follows: the pipe is resistant to corrosion, asbestos-cement pipe has a high enough strength to withstand high external forces, asbestos-cement pipe has contributed to high water quality, it is light weight and easy to install and has a permanently smooth wall so pumping costs are low.
Asbestos fiber is dangerous when inhaled but there is no evidence that asbestos from pipe endangers the health of humans.
Sigurdson, Eunice E. "Observations of cancer incidence surveillance in Duluth, Minnesota." Environmental health perspectives 53 (1983): 61. Abstract:
In 1973, amphibole asbestos fibers were discovered in the municipal water supply of Duluth, Minnesota. The entire city population of approximately 100,000 was exposed from the late 1950s through 1976 at levels of 1-65 million fibers per liter of water.
Because of previous epidemiologic studies that linked mesothelioma, lung and gastrointestinal cancers to occupational exposure to asbestos, surveillance of cancer incidence in residents of Duluth was initiated to determine the health effect from ingestion of asbestos.
The methodology of the Third National Cancer Survey (TNCS) and SEER Program was used. Duluth 1969-1971 rates were compared with TNCS rates for the cities of Minneapolis and St. Paul during 1969-1971; Duluth rates during 1974-1976 are compared with Duluth 1969-1971; Duluth rates during 1979-1980 are compared with Duluth 1969-1971 and with Iowa SEER; and a table of the occurrence of malignant mesothelioma is presented.
Statistically significant excesses are observed in several primary sites in Duluth residents.
However, lung cancer in Duluth females is the only primary site considered also of biological significance.
The mesothelioma incidence rate is no more than expected. This paper also describes the problems of long-term surveillance of exposed populations considered at risk of environment cancer, the need for improved study methodologies and the use of federal records for follow up of exposed individuals.
Sigurdson, Eunice E., Barry S. Levy, Jack Mandel, Richard McHugh, Leonard J. Michienzi, Helen Jagger, and John Pearson. "Cancer morbidity investigations: lessons from the Duluth study of possible effects of asbestos in drinking water." Environmental research 25, no. 1 (1981): 50-61. Abstract:
In 1973, 1 to 30 million asbestos-like fibers per liter of tap water were discovered in Duluth drinking water.
Previous studies had linked mesothelioma, lung, and gastrointestinal cancers with occupational exposure to asbestos, so surveillance of cancer morbidity in Duluth was initiated to investigate effects from ingestion of asbestos in drinking water.
Gastrointestinal and lung cancer incidence data for 1969–1974 were collected in the same manner as in the Minneapolis-St. Paul component of the Third National Cancer Survey; Duluth rates for 1969–1971 were compared with incidence rates for the cities of Minneapolis and St. Paul during the same time period; and Duluth rates for 1972–1974 were compared with Duluth rates for 1969–1971.
Duluth females and both sexes combined had statistically significantly higher rates of pancreatic cancer than in Minneapolis and St. Paul in 1969–1971. These rates subsequently decreased in 1972–1974 for both sexes combined in Duluth.
Duluth males and both sexes combined had similar excesses for gastrointestinal tract not specified in comparison with Minneapolis and St. Paul.
Duluth and Minneapolis cancer incidence rates yielded less-exaggerated differences between the two study areas compared with mortality rates. Resources required for morbidity surveillance are described.
Toft, Peter, and M. E. Meek. "Asbestos in drinking water: a Canadian view." Environmental health perspectives 53 (1983): 177.
For several years now, public health professionals have been faced with evaluating the potential hazards associated with the ingestion of asbestos in food and drinking water. In Canada, this is a subject of particular concern, because of the widespread occurrence of chrysotile asbestos in drinking water supplies.
The results of available Canadian monitoring and epidemiologic studies of asbestos in drinking water are reviewed and discussed in light of other published work.
It is concluded that the risk to health associated with the ingestion of asbestos, at the levels found in municipal drinking water supplies, is so small that it cannot be detected by currently available epidemiologic techniques.
Wedding, James B., Andrew R. McFarland, and Jack E. Cermak. "Large particle collection characteristics of ambient aerosol samplers." Environmental Science & Technology 11, no. 4 (1977): 387-390.
Also see MESOTHELIOMA doctors, organizations, treatment resources, legal advice.
Continue reading at CEMENT ASBESTOS PIPE or select a topic from closely-related articles below, or see our complete INDEX to RELATED ARTICLES below.
Try the search box below or CONTACT US by email if you cannot find the answer you need at InspectApedia.
Ask a Question or Search InspectApedia
Use the "Click to Show or Hide FAQs" link just above to see recently-posted questions, comments, replies, try the search box just below, or if you prefer, post a question or comment in the Comments box below and we will respond promptly.
Thanks to Roger Hankey & Cheryll Brown, www.hankeyandbrown.com, ASHI home inspectors in Minnesota, for the deteriorated transite pipe gas flue vent photograph and comments. Mr. Hankey is a past chairman of the ASHI Technical Committee, serves as co-chairman of ASHI legislative committee, and has served in other ASHI professional and leadership roles. 7/2007.
12/2008: thanks to an anonymous reader DG, GE Infra, Transportation, for editorial comments and suggestions about transite water supply piping.
That reader commented:
Transite pipe was used in fresh water supply piping in some communities, and we have it in our subdivision,
I remember playing on the pile of left over pipe (1970's). It was 4-6" dia. and was probably
1/2-1" thick, the ends looked to be belt sanded to a taper.
Recently I was talking with a digging contractor, he swears at the stuff, as it cannot
be found (underground) with a metal detector, only the metal bucket of the
excavator. He says the the Ellwood city (in western PA) water system ran it
at about 225 psi, and just looking at it would break it.
Notes on the Sandwich water district, Cape Cod, MA, water quality report were obtained online at www.sandwichwater.com/sandwich-pg2-08-corrected.doc - 12/09/2008
"Report on cancer risks associated with the ingestion of asbestos. DHHS Committee to Coordinate Environmental and Related Programs", Environmental Health Perspectives 1987 June; 72: 253-265. This article is available from NIH at pubmedcentral.nih.gov/articlerender.fcgi?artid=1474636 - the list of references for this study is extensive and quite useful.
Nicholson, WJ. Human cancer risk from ingested asbestos: a problem of uncertainty.Environ Health Perspect. 1983 Nov;53:111–113
Erdreich, LS. Comparing epidemiologic studies of ingested asbestos for use in risk assessment. Environ Health Perspect. 1983 Nov;53:99–104.
Millette, JR; Craun, GF; Stober, JA; Kraemer, DF; Tousignant, HG; Hildago, E; Duboise, RL; Benedict, J. Epidemiology study of the use of asbestos-cement pipe for the distribution of drinking water in Escambia County, Florida. Environ Health Perspect.1983 Nov;53:91–98. At PubMed via NIH www.ncbi.nlm.nih.gov/pubmed/6559131
"Epidemiology study of the use of asbestos-cement pipe for the distribution of drinking water in Escambia County, Florida,"
Millette JR, Craun GF, Stober JA, Kraemer DF, Tousignant HG, Hildago E, Duboise RL, Benedict J., Environmental Health Perspectives, 1983 Nov; 53:91-8.
June 1997 - Window Putty - OSHA case cites contractor for asbestos exposure during removal of window putty http://www.osha.gov/pls/oshaweb/owadisp.show_document?p_table=NEWS_RELEASES&p_id=1091
Asbestos Identification and Testing References
Asbestos Identification, Walter C.McCrone, McCrone Research Institute, Chicago, IL.1987 ISBN 0-904962-11-3. Dr. McCrone literally "wrote the book" on asbestos identification procedures which formed
the basis for current work by asbestos identification laboratories.
Stanton, .F., et al., National Bureau of Standards Special Publication 506: 143-151
Pott, F., Staub-Reinhalf Luft 38, 486-490 (1978) cited by McCrone
Asbestos in Your Home U.S. EPA, Exposure Evaluation Division, Office of Toxic Substances, Office of Pesticides and Toxic Substances, U.S. Environmental Protection Agency, Washington,D.C. 20460
Asbestos products and their history and use in various building materials such as asphalt and vinyl flooring includes discussion which draws on Asbestos, Its Industrial Applications, D.V. Rosato, engineering consultant, Newton, MA, Reinhold Publishing, 1959 Library of Congress Catalog Card No.: 59-12535 (out of print, text and images available at InspectAPedia.com).
"Handling Asbestos-Containing roofing material - an update", Carl Good, NRCA Associate Executive Director, Professional Roofing, February 1992, p. 38-43
EPA Guidance for Controlling Asbestos-Containing Materials in buildings, NIAST, National Institute on Abatement Sciences & Technology, [republishing EPA public documents] 1985 ed., Exposure Evaluation Division, Office of Toxic Substances, Office of Pesticides and Toxic Substances, U.S. Environmental Protection Agency, Washington,D.C. 20460
Books & Articles on Building & Environmental Inspection, Testing, Diagnosis, & Repair
Carson, Dunlop & Associates Ltd., 120 Carlton Street Suite 407, Toronto ON M5A 4K2. Tel: (416) 964-9415 1-800-268-7070 Email: firstname.lastname@example.org. The firm provides professional home inspection services & home inspection education & publications. Alan Carson is a past president of ASHI, the American Society of Home Inspectors. Thanks to Alan Carson and Bob Dunlop, for permission for InspectAPedia to use text excerpts from The Home Reference Book & illustrations from The Illustrated Home. Carson Dunlop Associates' provides extensive home inspection education and report writing material.
The Illustrated Home illustrates construction details and building components, a reference for owners & inspectors. Special Offer: For a 5% discount on any number of copies of the Illustrated Home purchased as a single order Enter INSPECTAILL in the order payment page "Promo/Redemption" space.
TECHNICAL REFERENCE GUIDE to manufacturer's model and serial number information for heating and cooling equipment, useful for determining the age of heating boilers, furnaces, water heaters is provided by Carson Dunlop, Associates, Toronto - Carson Dunlop Weldon & Associates Special Offer: Carson Dunlop Associates offers InspectAPedia readers in the U.S.A. a 5% discount on any number of copies of the Technical Reference Guide purchased as a single order. Just enter INSPECTATRG in the order payment page "Promo/Redemption" space.
The Home Reference Book - the Encyclopedia of Homes, Carson Dunlop & Associates, Toronto, Ontario, 25th Ed., 2012, is a bound volume of more than 450 illustrated pages that assist home inspectors and home owners in the inspection and detection of problems on buildings. The text is intended as a reference guide to help building owners operate and maintain their home effectively. Field inspection worksheets are included at the back of the volume.
Special Offer: For a 10% discount on any number of copies of the Home Reference Book purchased as a single order. Enter INSPECTAHRB in the order payment page "Promo/Redemption" space. InspectAPedia.com editor Daniel Friedman is a contributing author.
Special Offer: Carson Dunlop Associates offers InspectAPedia readers in the U.S.A. a 5% discount on these courses: Enter INSPECTAHITP in the order payment page "Promo/Redemption" space. InspectAPedia.com editor Daniel Friedman is a contributing author.
The Horizon Software System manages business operations,scheduling, & inspection report writing using Carson Dunlop's knowledge base & color images. The Horizon system runs on always-available cloud-based software for office computers, laptops, tablets, iPad, Android, & other smartphones