Dioxins

1.   What are dioxins?
2.   How can my child be exposed to dioxin?
3.   What are the health effects of dioxins?
4.   Is there a test to see if my family has been exposed to high levels of
      dioxins?
5.   How can I limit my family’s exposure to dioxins?
6.   References

What are dioxins?

Polychlorinated dibenzodioxins, commonly called dioxins, are a family of chemical compounds unintentionally produced by a variety of industrial processes, including:
  • PVC plastic manufacturing
  • Manufacturing of certain industrial chemicals and pesticides
  • burning of medical /city wastes
  • the chlorine bleaching process of pulp and paper mills
All members of this family are not equally toxic. Based on animal studies, the most toxic member of this family is considered to be 2,3,7,8-tetrachloro- dibenzodioxin, or dioxin. Perhaps the most publicized dioxin exposure was from Agent Orange. This was a chemical mixture heavily contaminated with dioxin that served as a defoliant agent during the Vietnam War.
How can my child be exposed to dioxin?

Dioxins are present at low levels in most sources of air, water, and soil. Exposure to higher levels of dioxins is possible through food, air, pesticides, soil, and the workplace:
  • In food

    The most common route of environmental dioxin exposure is from food, especially milk (breast and dairy), fish, and other meats. For the general population, more than 90% of dioxin exposures come from food. [4]

    Dioxins tend be found in fatty tissues and accumulate in the body. Fish caught from dioxin-contaminated waters tend to have higher levels of dioxins than the smaller fish or plant material they eat. When a pregnant mother eats these fish, these dioxins are poorly eliminated from the body. This phenomenon is called bioconcentration.

    Nursing infants may be exposed to relatively high dioxin levels in breast milk (due to high fat content).
  • In the air

    Very low background air levels of dioxins can be found in both urban and rural settings. However, urban settings tend to have higher dioxin levels than rural settings. [4]

    Also, air polluted by tobacco smoke may contain higher levels of dioxins than unpolluted air.

    Exposure to higher levels of dioxins from the air is possible near certain hazardous waste sites.
  • In pesticides

    Exposure to dioxins may occur by contact with pesticides that contain chlorine compounds. When this happens, the dioxins are usually absorbed through the skin.
  • In soil

    There may be high soil dioxin levels near some hazardous waste sites. Contact with soil may lead to exposure across the skin. This may be a problem for children due to their tendency to play in the dirt and eat dirt.
  • In the workplace

    Workers involved in the manufacturing PVC, paper/pulp products, and certain pesticides may be exposed to high levels of dioxins in the air or across the skin.

What are the health effects of dioxins?

Based upon acute high dose exposure to animals, dioxin is considered extremely toxic. Very low levels are necessary to kill certain lab animals. In general, the health effects in humans are more controversial.

The health effects of dioxins will depend on several factors:
  • particular dioxin species involved
  • level and time course of exposure
  • health status of the exposed individual
We will discuss the health effects of dioxins in terms of short and long term health effects:
  • Short term

    Short term health effects from exposure to dioxins have been largely gathered from a single industrial accident that occurred in Seveso, Italy in 1976. In this incident, many people were acutely exposed to high levels of dioxin. Exposure to dioxins may produce the following short term health effects:
    • Dermal
      Exposure to dioxins has been clearly linked to chloracne. This condition resembles regular acne, but may involve different body parts such as the trunk and arms. [14] Other skin findings from dioxin exposure include rashes, discoloration, and increased body hair. [14]
    • Liver
      Some exposed children had abnormal liver tests. This may have been due to the dioxin exposure. [14]
    • Bladder
      One human case report outside of Seveso suggests that exposure to dioxin may have contributed to a case of hemorrhagic cystitis (irritation of the bladder accom- panied by bleeding). [10]
  • Long-term effects

    These information concerning the health effects of long-term exposure to dioxins have been largely gathered from people exposed during the Seveso incident and Vietnam veterans exposed to Agent Orange. Another source of information was an accidental exposure to dioxin among residents of Times Beach, Missouri. There is considerable controversy regarding the long term health effects from dioxin exposure. Exposure may be associated with the following health outcomes:
    • Cancer
      One study of Seveso cases linked exposure to dioxins with rectal cancer in males and liver and stomach cancer in females. [20]

      This same study suggests that exposure to dioxins may cause blood and lymphatic cancers. [20]

      One study of workers exposed to dioxin in an industrial accident suggests that dioxin exposure may increase the risk of cancers of the digestive tract. [15]

      One occupational study suggests that dioxin exposure may increase the risk of lung cancer, cancer of the oral cavity, and non-Hodgkin’s lymphoma (cancer of the lymphatic system). [18]

      Several human studies suggest that dioxin exposure increases risk of soft tissue sarcoma (cancer of connective tissues). [19][35]

      The link between dioxins and cancer is still very controversial. Not all studies have demonstrated associations between dioxin exposure and cancer. One study of Vietnam veterans shows no such association. [25]

      Some studies suggest that dioxins may actually prevent certain forms of cancer. [32][33]

      Many animal studies strongly suggest that dioxins cause various types of cancer. [36-39]
    • Endocrine System
      Two studies, one from Seveso and the other from Vietnam veterans, linked dioxin exposure with increased [risk of diabetes mellitus. [24][28]

      One occupational study links dioxin exposure with thyroid disease. [31]
    • Cardiovascular System
      One study of Seveso cases suggests dioxin may increase risk of death in patients with heart disease. [20] However, these results may have been due to the psychological trauma of the incident. [14]

      One occupational study suggests that exposure to dioxins may increase risk of ischemic heart disease. [16]

      These findings are controversial. Other studies do not support this association. [21]
    • Immune system
      One occupational study suggests that TCDD exposure increases risk of developing infectious and parasitic disease. [31] This might imply damage to the immune system.

      Other studies do not support this association. One study of Vietnam veterans who sprayed Agent Orange revealed no immune system changes among exposed veterans. [27]
    • Lungs
      One study of Seveso cases suggests that dioxin may increase risk of death in patients with chronic obstructive pulmonary disease. [28] However, these results may have been due to the psychological trauma of the incident. [14]
    • Reproductive System
      One study has suggested that men exposed to dioxins may have an altered ratio of male to female children. [7]

      However, this finding is controversial. Several studies of Vietnam veterans show no association between dioxin exposure and reproductive changes in exposed fathers or poor pregnancy outcomes in their children.
    • Child Development
      There is little human evidence that TCDD exposure is associated with birth defects or other developmental problems in children. Several studies of Vietnam veterans who sprayed Agent Orange have failed to demonstrate an increased risk of birth defects or other developmental problems. [11][22]

      Though human studies have not demonstrated developmental problems from dioxin exposure, several animal studies have given us reason for concern. One study suggests that monkeys exposed to TCDD levels in their mother’s milk within the range of human contam- ination had learning deficits. [8]

      One human study suggests that mothers exposed to background environmental levels of both dioxins and PCBs (another group of chemicals that often accompany dioxin) may have children with adverse health effects. These include decreased birth weight, hormonal changes, learning deficiencies, and behavioral problems. [13]

      Another animal study suggests that dioxins may alter thyroid function. [12]

Is there a test to see if my family has been exposed to high levels of dioxins?

There are medical tests that can detect the amount of dioxins in the blood, breast milk, or body fat. However, these tests are mainly used in research settings, not in clinical practice. These tests cannot tell how long the exposure has gone on.

Furthermore, even if the test reveals high levels of dioxins, this finding cannot be used to predict potential health problems.
How can I limit my family’s exposure to dioxins?

Don’t burn construction materials such as treated lumber or PVC pipes near the home.

Children should avoid playing in soils near uncontrolled hazardous waste sites.

All household members should wash their hands before meals.

Discourage children from eating dirt or putting toys or other objects in their mouths.

Check with your local health, environmental, or conservation department for fish advisories in local waters. Women of childbearing age, pregnant women, nursing mothers, and young children should pay special attention to local fish advisories. [2]

If you eat fish, try to eat fewer fatty fish (carp, trout, catfish), especially those caught from waters contaminated with dioxins. Also, trim skin and fatty areas before eating the fish. [2]

Do not smoke. This may decrease exposure to inhaled dioxins.
References

[1] Ellenhorn's Medical Toxicology, 2nd Edition. Pesticides. Williams & Wilkins 1997: 1639-42.

[2] Etzel R, Balk, S. Handbook of Pediatric Environmental Health. American Academy of Pediatrics Committee on Environmental Health Affairs, 1999.

[3] Schettler T, Stein J, et al. In Harm’s Way: Toxic Threats to Child Development. Greater Boston Physicians for Social Responsibility 2000

[4] ATSDR Toxicological Profile for chlorinated dibenzo-p-dioxins (CDDs). Update 1998:1-18, 27-67.

[5] EPA. Health Assesment Document for 2,3,7,8 Tetrachlorodibenzo-p-Dioxin and other Related Compunds, 1994. p. IX-81.

[6] Bowman R, Schantz S, et al. Chronic Dietary Intake of 2,3,7,8 TCDD at 5 or 25 ppt in the monkey: TCDD kinetics and dose-effect estimate of reproductive toxicity. Chemosphere 1989;18:243-52.

[7] Mocarelli P, Gerthoux PM, et al. Paternal concentrations of dioxin and sex ratio of offspring. Lancet 2000;355(9218):1858-63.

[8] Schantz S, Ferguson S, et al. Effects of 2,3,7,8 TCDD on behavior of monkey in peer groups. Neurotoxicology and Teratology 1992;14(6):433-46.

[9] Feeley M, Brouwer A. Health risks to infants from exposure to PCB’s, PCDD’s and PCDF’s. Food Additives & Contaminants 2000;17(4)325-33.

[10] Carter C, Kimbrough R, et al. TCDD:an accidental poisoning episode in horse arenas. Science 1975;188:738-40.

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[12] Sewall C, Flagler N, et al. Alternation in thyroid function in female Sprague-Dawley rats following chronic treatment with 2,3,7,8-tetrachlorodibenzodioxin. Toxicology & Applied Pharmacology 1995;132(2):237-44.

[13] Patandin S, Lanting C, et al. Effects of environmental exposures to polychlorinated biphenyls and dioxins on cognitive abilities in Dutch children at 42 months of age. Journal of Pediatrics 1999;134(1):33-41.

[14] Bertazzi P, Bernucci I, et al. The Seveso studies on early and long-term effects of dioxin exposure: a review. Environmental Health Perspectives 1998;106 Suppl 2:625-33.

[15] Ott M, Zober A. Cause specific mortality and cancer incidence among employees exposed to 2,3,7,8-TCDD after a 1953 reactor accident. Occupational & Environmental Medicine 1996;53(9):606-12.

[16] Vena J. Boffetta P, et al. Exposure to dioxin and nonneoplastic mortality in the expanded IARC international cohort study of phenoxy herbicide and chlorophenol production workers and sprayers. Environmental Health Perspectives 1998;106 Suppl 2:645-53.

[18] Becher H, Flesch-Janys D, et al. Cancer mortality in German male workers exposed to phenoxy herbicides and dioxins Cancer Causes & Control 1996;7(3):312-21.

[19] Kogevinas M, Kauppinen T, et al. Soft tissue sarcoma and non-Hodgkin's lymphoma in workers exposed to phenoxy herbicides, chlorophenols, and dioxins: two nested case-control studies. Epidemiology 1995;6(4):396-402.

[20] Bertazzi P, Zocchetti C, et al. Ten-year mortality study of the population involved in the Seveso incident in 1976. American Journal of Epidemiology 1989;129(6):1187-200.

[21] Wolfe W, Michalek J, et al. Health status of Air Force veterans occupationally exposed to herbicides in Vietnam. I. Physical health. JAMA 1990;264(14):1824-31.

[22] Wolfe W, Michalek J, et al. Paternal serum dioxin and reproductive outcomes among veterans of Operation Ranch Hand. Epidemiology 1995;6(1):17-22.

[23] Henriksen G, Michalek J, et al. Serum dioxin, testosterone, and gonadotropins in veterans of Operation Ranch Hand. Epidemiology 1996;7(4):352-7.

[24] Henriksen GL. Ketchum NS. Michalek JE. Swaby JA. Serum dioxin and diabetes mellitus in veterans of Operation Ranch Hand. Epidemiology 1997;8(3):252-8.

[25] Ketchum N, Michalek J, Burton J. Serum dioxin and cancer in veterans of Operation Ranch Hand. American Journal of Epidemiology 1999;149(7):630-9.

[26] Michalek J, Akhtar F, Kiel J. Serum dioxin, insulin, fasting glucose, and sex hormone-binding globulin in veterans of Operation Ranch Hand. Journal of Clinical Endocrinology & Metabolism 1999; 84(5):1540-3.

[27] Michalek J, Ketchum N, Check I. Serum dioxin and immunologic response in veterans of Operation Ranch Hand. American Journal of Epidemiology 1999;149(11):1038-46

[28] Pesatori A, Zocchetti C, et al. Dioxin exposure and non-malignant health effects: a mortality study. Occupational & Environmental Medicine 1998;55(2):126-31.

[29] Calvert G, Hornung R, et al. Hepatic and gastrointestinal effects in an occupational cohort exposed to 2,3,7,8-tetrachlorodibenzo-para-dioxin. JAMA 1992;267(16):2209-14.

[30] Suskind R, Hertzberg V. Human health effects of 2,4,5-T and its toxic contaminants. JAMA 1984;251(18):2372-80.

[31] Zober A, Ott M, Messerer P. Morbidity follow up study of BASF employees exposed to 2,3,7, 8-tetrachlorodibenzo-p-dioxin (TCDD) after a 1953 chemical reactor incident. Occupational & Environmental Medicine 1994;51(7):479-86.

[32] Greenlee WE, Hushka LJ, Hushka DR. Molecular basis of dioxin actions: evidence supporting chemoprotection. Toxicologic Pathology 2001;29(1):6-7, 2001.

[33] Safe S. Molecular biology of the Ah receptor and its role in carcinogenesis. Toxicology Letters 2001;120(1-3):1-7.

[35] Viel JF, Arveux P, et al. Soft-tissue sarcoma and non-Hodgkin's lymphoma clusters around a municipal solid waste incinerator with high dioxin emission levels. American Journal of Epidemiology 2001;152(1):13-9.

[36] DeVito MJ, Birnbaum LS, et al. Comparisons of estimated human body burdens of dioxinlike chemicals and TCDD body burdens in experimentally exposed animals. Environmental Health Perspectives 1995;103(9):820-31.

[37] IARC. International Agency for Research on Cancer. Polychlorinated dibenzo-para-dioxins and polychorinated dibenzofurans. IARC Monographs 1997;69.

[38] Davis BJ, Mccurdy EA., et al. Ovarian tumors in rats induced by chronic 2,3,7,8-tetrachlorodibenzo-p-dioxin treatment. Cancer Research 2000;60(19):5414-9.

[39] Walker NJ, Tritscher AM, et al. Hepatocarcinogenesis in female Sprague-Dawley rats following discontinuous treatment with 2,3,7,8-tetrachlorodibenzo-p-dioxin. Toxicological Sciences 2000;54(2):330-7.