## Public Health Assessments & Health Consultations

Page last reviewed: October 15, 2009 Page last updated: October 15, 2009 Content source: Agency for Toxic Substances and Disease Registry

Agency for Toxic Substances and Dise ase Registry, 4770 Buford Hwy NE, Atlanta, GA 30341 Contact CDC: 800-232-46 36 / TTY: 888-232-6348 HEALTH CONSULTATION

MARTIN CREEK LAKE HENDERSON, RUSK AND PANOLA COUNTIES, TEXAS

Se ptember 17, 1998

Pre p ared b y

: Texas Department of Health Under Cooperative Agreement with the Ag enc y

for Toxic Substances and Disease Registry

TABLE OF CONTENTS

BACKGROUND AND STATEMENT OF ISSUES

DISCUSSION

A

TSDR's CHILD HEALTH INITIATIVE

CONCLUSIONS

RECOMMENDATIONS

REFERENCES

PREPARERS OF REPORT

CERTIFICATION

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## Public Health Assessments & Health Consultations

HEALTH CONSULTATION

MARTIN CREEK LAKE HENDERSON, RUSK AND PANOLA COUNTIES, TEXAS

BACKGROUND AND STATEMENT OF ISSUES The Texas Department of Health (TDH) Seafood Safety Di vision (SSD) requ ested that the Health Risk Assessment and Toxicology Program evaluate the potential health risks associated with consumption of fish taken from Martin Creek Lake, a 5,000 acre cooling reservoir operated by Texas Ut ilities Electric Service Compan y (TU Electric). Martin Creek Lake is located 17 miles northe ast of Henderson, on the border of Rusk and Panola Counties. During the late 1970's, Martin Creek Lake received discharg es from ash ponds containing elevated selenium leve ls, resulting in increased selenium concentrations in fish. In 1979, selenium concentrations in bass ranged from 7.1 to 8.3 parts per mi llion (ppm). Elevated levels of selenium in water and fi sh tissue were implicated in a se ries of fish kills during this time.
Since the fish kills, TDH, the Texas Parks and Wildlife Depart ment (TPWD), and TU Electric have worked cooperatively to monitor selenium le vels in fish tissue. In 1992, TDH issued a fish consumption advisory for the lake after it was determined that the levels of selenium in fish from the lake could pose a potential health risk. The advi sory recommended that adults consume no more than one eight-ounce meal each week an d children seven years of age and older consume no more than one four-ounce meal each week. Chil dren six and under, pregnant women, or women wh o may soon become pregnant we re advised not to consume the fish. Additionally, person s consuming fish from the re servoir were advised not to consume mineral dietary supplem ents with selenium exceed ing 50 micrograms per day. In 1996 and 1997, TDH collected 34 fish (17 ba ss, 10 channel catfish, 4 black crappie, 1 white crappie, and 2 flathead catfish) for a re-evaluation of the pres ent fish consumption advisory. The concentration of selenium in the fish ranged from 0.7 to 4.0 ppm wi th an overall average concentration of 2.3 ppm (Table 1). Although selenium levels in fish from Martin Creek Lake continue to be above reported na tional averages (0.1 to 1.5 ppm [1]), the concentration of selenium in fish from Martin Creek Lake has been decreasing over the 19 years of investigation (Figure 1).

Table 1. Selenium in Martin Creek Lake Fish

November 1996 Species # collected Size Selenium Range (ppm) Selenium Average (ppm) Largemouth Bass 13 15-21" 2.17 - 4.0 3.06

Channel Catfish 8 15-26" 0.996 - 1.79 1.35 Pa g e 1 of 6 ATSD R -PHA-HC-Martin Creek Lake-p1

10/5/2010 htt p ://www.atsdr.cdc. g ov/HAC/ p ha/ p ha.as p ?docid=117& pg =1White Crappie 1 16" 2.74 2.74 Black Crappie 2 12-14" 4.18 - 4.23 4.2 All Fish (1996) 2.6 March 1997 Largemouth Bass 4 15-21" 1.67 - 2.42 1.9

Black Crappie 2 14" 2.28 - 2.77 2.5 Channel Catfish 2 22" 0.743 - 0.839 0.79 Flathead Catfish 2 23- 25" 1.11 - 1.17 1.14

All Fish (1997) 1.6 All Fish (1996-97) 2.3

Figure 1. Average Selenium Concentr ations in Martin Creek Lake Bass

DISCUSSION

Selenium Selenium is a naturally occurring substance that is widely, but unevenly distributed in rocks andsoils of the earth's crust. It is rarely found in pure fo rm in the environment. When rocksdecompose into soils, selenium often combines with sodium and oxygen to form sodiumselenate, or with water to form sodium selenite, both of which are water soluble. Plants easilytake up inorgani c selenium compounds from wate r and change them to organic seleniumcompounds such as sele nomethionine. The major man-ma de source of selenium in theenvironment is coal burning, es pecially the fly ash that resu lts from burning coal. Persons livingnear industrial sites may be exposed thro ugh ingesting the soil or water, breathing the dust, eatingplants that may have taken up selenium from soil, or ingesting fish that may have taken upselenium from high concentrations in water [2]. The esti mated bioaccumulation factor forselenium in fish ranges from 485 to 1,746, depending on the species [3]. In general, the moresoluble and mobile forms of seleni um (selenite and sele nate) dominate under aerobic (highoxygen concentrations) an d alkaline (high pH) conditions [2]. Humans and animals are both capable of absorb ing and utilizing both organic or inorganic formsof selenium from food or water sources. Most of the sele nium that enters the body is excreted inthe urine within 24 hours. Selenium can build up in the body if exposure is high and occurs overa long period of time. Body burd ens of selenium primaril y occur in the liver, kidneys, hair, andnails. Selenium is an essential dietary elem ent for both human and animals in either theinorganic or orga nic form. Selenium has antioxid ant effects which help prevent damage totissues caused by oxyg en. A selenium deficient diet ca n result in Keshan disease, Pa g e 2 of 6 ATSD R -PHA-HC-Martin Creek Lake-p1

10/5/2010 htt p ://www.atsdr.cdc. g ov/HAC/ p ha/ p ha.as p ?docid=117& pg =1the signs andsymptoms of which may include mu scle pain, cardiomyopathy, enlargement of the heart,increased red bl ood cell fragility, and pancreatic degeneration.

The human recommended daily allowance (RDA) of seleni um for maintenance of good health is55 micrograms per day (ug/day) fo r women and 70 microgra ms per day for men. Estimates ofthe average intake of selenium from food for the U.S. population range from 71 to 152micrograms of selenium pe r person per day [2]. Welsh et al. reported that about three percent ofMaryland residents consumed diets wh ich contained over 200 Âμg of selenium per day [4]. TheFood and Nutrition Board of the National Research Coun cil has estimated the safe and adequatedaily dietary intake of sele nium in adults to be 50 to 200 Âμg [5]. However, when eaten inamounts th at are not much higher than required for good nutrition, selenium becomes harmful tohuma ns and animals [2] (Figure 2) . Signs and symptoms of sub -acute and chronic toxicity inhumans include bri ttleness and loss of hair and nails; blisters, eruptions and skin mottling; pi ttingand excessive decay of the teeth; a garlic or sour-milk breath odor; periodic episodes of nauseaand vomiting; and increased fatigue. No human populations in the U.S. have be en reported to have chronic selenium toxicity,including populations in the western part of the country with naturally hi gh levels of selenium inthe soil and water. In a study of 142 subjec ts living in a seleni ferous area of South Dakota andWyoming, there was no evidence of toxicity from selenium in subjects whose intake was as highas 724 ug per day [6]. There have been a limi ted number of case reports of individuals whodeveloped minimal signs of se lenium toxicity follo wing chronic dietary intakes of 850-900 ugper day. In areas of China with selenium intakes of 3,200 to 6,690 ug per day, clinically apparentsele nium toxicity was observed, wh ile persons with daily intakes in the range of 42-750 ug perday did not produce any signs of to xicity or other adverse health effects [7]. The Agency for Toxic Substances and Disease Registry (ATSDR) rece ntly has established achronic oral Minimum Risk Le vel (MRL) for selenium of 5 Âμ g/kg/day [2]. For a 70 kg adult thisis equivalent to an intake of 350 Âμg/day. The MRL is an estimate of the daily human exposure toa haza rdous substance that is likely to be without appreciable risk of noncancer health effectsover a specified durati on of exposure. The MRL was derived from a study involving a Chinesepopulation with high selenium inta ke. Blood selenium concentrations and degree of se lenosiswere determined for 349 adults. The endpoint used to derive the MRL was nail disease,specifically bri ttleness of nails. By re gression analysis the corresponding selenium dietaryi ntakes were determined. A "n o observable adverse effects level" (NOAEL) of 15 ug/kg/da y,was determined. The NOAEL is the highest dose at which no statistically or biologicallysignificant adverse effects were observed. For a 70 kg adult this dose is equivalent to a seleniumintake of 1,050 Âμg/day. To esta blish the MRL, ATSDR divided the NOAEL by a factor of threeto account for human vari ability. It is important to note that the MRL based on th e Chinese studymay be conser vative because only dietary exposure was considered and it has been sugges ted thatinhalation exposure to selenium in smoke was significant. The population studie d cooked theirmeals on open fires of coal containing high concentrations of selenium.
Carcinogenicity
The EPA and the National Toxicology Program have determined that selenium is not classifiableas a carcinogen and it is rated as a Group D chemical. In fact, studies of cancer in humanssuggest that lower than no rmal selenium levels in the di et may increase the risk of cancer. Thismay be due to the fact that selenium is used in th e body in enzymes that protect Pa g e 3 of 6 ATSD R -PHA-HC-Martin Creek Lake-p1

10/5/2010 htt p ://www.atsdr.cdc. g ov/HAC/ p ha/ p ha.as p ?docid=117& pg =1against oxidativedamage to ti ssues which may be responsibl e for cancer promotion. One specific form ofselenium, called selenium sulf ide, is a probable huma n carcinogen. Selenium sulfide is notfound in foods, and is a very di fferent chemical from th e organic and inorganic seleniumcommonly found in the environment. Because it is no t absorbed through the skin, its primary usein the anti-dandruff shamp oo Selsun Blue, is considered safe [2].

Figure 2. Health Effects of Selenium

Toxicological Evaluation In 1992, when TDH estimated th e risks associated with eating selenium contaminated fish, anMRL for this contaminant was not available. Using availabl e information, TDH estimated 400Âμg/day (5.71 Âμg/kg/day assuming a 70 kg adult) to be a safe and acceptable dietary seleniumintake. This estimated safe daily intake is remark ably similar to the MRL (5 Âμg/kg/day)established by AT SDR and provided approximatel y a 2.6-fold safety factor below the currentNOAEL of 1,050 ug/day, or the lowest level reas onably expected to result in signs or symptomsof toxicity . In performing the risk as sessment, TDH determined the acceptable daily intake ofsele nium from fish by subtractin g an assumed daily intake of selenium from other sources (2 00Âμg/day [2.86 Âμg/kg/day assu ming a 70 kg adult]) from the estimated safe and acceptable dailyintake. Thus, for a 70 kg adult, TDH estimated that 200 Âμg (2.86 Âμg/kg/day) was an acceptab ledaily intake of selenium from fish.

To evaluate the current risks associated with eating fish from Martin Creek Lake we used thesame paradigm used in the previous risk assessment except that we used the MRL established byATSDR. Assuming a background daily intake of selenium from other sources of 200 Âμg, weestimate that approximately 15 0 Âμg/day (2.14 Âμg/kg/d ay assuming a 70 kg adult) is an acceptabledaily in take of selenium from fish.

To determine the actual number of meals that could be consumed without exceeding the MRL weused two values for th e concentration term; the arithmetic average and the 95 th percent upperconfidence interval (95% UCL) of the arithmet ic average. The 95% UCL is defined as a valuethat wh en calculated repeatedly for random ly drawn subsets of site specific data, equals orexceeds the true average 95 percent of the time. We estimated the 95% UCL by de fining the distribution of se lenium in fish tissue from MartinCreek Lake using the 1996- 97 data and then randomly drawing 1,000 samples of 34 fish fromthat distribution. Averages were ob tained for each of the 1,000 samples and the 950 th

rankordered average was defined as the 95 th

percentile. The arithmetic average should be mostrepresentative of the con centration that would be cont acted over time; however, the 95% UCL ofthe average provides a conservative estimate of the average concentration and is useful toaccount for sampling va riations and suspected seasonal variations in fish tissue concentrations. Figure 3 provides a graphical representation of the relationship between the sample distributionan d the 95% UCL of the arithmetic average. Using these assumptions we esti mate that adults could consu me approximately two (eight ounce) meals per week and ch ildren (body weight 10-30 kg ) could consume approximately Pa g e 4 of 6 ATSD R -PHA-HC-Martin Creek Lake-p1

10/5/2010 htt p ://www.atsdr.cdc. g ov/HAC/ p ha/ p ha.as p ?docid=117& pg =1one to two (four ounce) meals per week of Mart in Lake fish before ex ceeding the MRL (Table 2). Individuals would have to consume appr oximately three times these amounts before exceeding the lowest level reason ably expected to result in si gns or symptoms of toxicity.
Figure 3. Probability Density Distribution for Selenium Concentration in Fish from Martin Lake

Table 2. Recommended Limi tations on Long-Term Fish Consumption by body weight

Body Weight Estimates Based on Average Seleni um Level of 2.3 ppm for the 34 fish samples collected (kg) (lb) (a) Baseline exposure (Âμg/day) (BW x 2.86 ug/kg/day) (b) Minimum Risk Level (Âμg/day) (BW x 5 ug/kg/day) Acceptable Daily Intake

From Fish

(ug/day) ((b) - (a)) Quantity of fish that can be consumed without exceeding MRL
Meals per week Average (2.3 ppm) 95% UCL (2.65 ppm) Assumes a child body weight and an average meal size of 4 ounces each
10 22 29 50 21 0.6 0.54
20 44 57 100 43 1.2 1.1
30 66 86 150 64 1.9 1.6 Assumes an adult body weight and an average meal size of 8 ounces each
40 88 114 200 86 1.2 1.1
50 110 143 250 107 1.6 1.3
60 132 172 300 128 1.9 1.6
70 154 200 350 150 2.2 1.9
80 176 229 400 171 2.5 2.2
90 198 257 450 193 2.8 2.4
100 22 286 500 214 3.1 2.7

ATSDR's CHILD HEALTH INITIATIVE The TDH has prepared this co nsult under a Cooperative Agre ement with the Agency for ToxicSubstances and Disease Registry (A TSDR). TDH has incl uded the following information inaccordance with AT SDR's Child Health Initiative.

ATSDR's Child Health Initiati ve recognizes that the unique vulnerabilities of infants andchildren demand special emphasis in commu nities faced with contamination of their water, soil,air, or food. Children are at grea ter risk than adults from certain kinds of exposures to hazardoussubstances emitted from waste sites and emergency events. They are more likely to be exposedbec ause they play outdoors and they often bring food into Pa g e 5 of 6 ATSD R -PHA-HC-Martin Creek Lake-p1

10/5/2010 htt p ://www.atsdr.cdc. g ov/HAC/ p ha/ p ha.as p ?docid=117& pg =1Page last reviewed: October 15, 2009 Page last updated: October 15, 2009 Content source: Agency for Toxic Substances and Disease Registry

Agency for Toxic Substances and Dise ase Registry, 4770 Buford Hwy NE, Atlanta, GA 30341 Contact CDC: 800-232-46 36 / TTY: 888-232-6348 contaminated areas. They are sh orterthan adults, which means they breathe dust, soil, and heavy vapors close to the ground. Childrenare also smaller, resulting in higher doses of chemical exposure per body weight. The deve lopingbody systems of children can sustain permanent damage if toxic exposures occur duri ng criticalgrowth stages. Most importantly, children depend completely on adults for risk identificati onand management decisions, housing decisions, and ac cess to medical care. Special consideration was given to children's he alth in this consultation. Children consuming one to two meals per week (4 ou nces each) would not exceed mi nimal risk levels for adverse health effects from selenium in fish.

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## Public Health Assessments & Health Consultations

HEALTH CONSULTATION

MARTIN CREEK LAKE HENDERSON, RUSK AND PANOLA COUNTIES, TEXAS

CONCLUSIONS

The levels of selenium in Martin Creek Re servoir have decreased significantly during the period of invest igation (1979 - 1998). 1.

Estimated exposures to selenium from eating fish from Martin Creek do not exceed minimum risk levels for adverse health effe cts for children consumi ng one to two meals per week (4 ounces each) or for adults consuming approximately two meals per week (8 ounces each). Approximatel y three times these amounts wo uld be required to exceed the lowest levels reasonably expected to result in signs and sy mptoms of toxicity, therefore, ingestion of fish from Martin Creek Reservoi r poses no apparent public health hazard. 2.

RECOMMENDATIONS The fish consumption advisory issued for Martin Creek Lake in 1992 should be reevaluated based on the cu rrent recommended limitati ons on long-term fish consumption. 1.

REFERENCES IRIS, 1998. Integrated Risk Information System. U.S. Environmental Protection Agency, Office of Health an d Environmental Assessment, Environmental Criteria and Assessment Office. Cincinnati, Ohio. 1.

ATSDR, 1996. Agency for Toxic Substances and Disease Registry. Toxicological Profile for Selenium. Atlanta: ATSDR, Aug. 1996. 2.

Lemly, 1985. Toxicology of se lenium in a freshwater re servoir: Implications for environmental hazard evaluati on and safety. Ecotoxicol. En viron. Safety 10:314-338. 3.

Welsh, et al., 1981. Selenium in self-selecte d diets of Maryland re sidents. J. Am. Diet Assoc. 79-277-85. 4.

FNB, NRC, 1980. Food an d Nutrition Board, Nation al Research Council: Recommended dietary allowances, 9th ed. Washington, D.C: National Academy of Sciences. 5. Pa g e 1 of 3 ATSD R -PHA-HC-Martin Creek Lake-p2

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necker, et.al., 1991. Selenium in diet, bl ood, and toenails in relation to human health in a seleniferous area. Am. J. Clin. Nutr. 53:1288-94. 6.

Y an g

, et.al., 1983. Endemic seleni um intoxication of humans in China. Am. J. Clin. Nutr. 37:872-81. 7.

PREPARERS OF THE REPORT
Lisa R. Williams, M.S. Toxicologist Health Risk Assessment and Toxicology Program
John F. Villanacci, Ph.D. Director Health Risk Assessment and Toxicology Program

A TSDR REGIONA L REPRESENTATIVE

Geor g

e Petti g rew, P.E. Senior Regional Representative A

TSDR - Region 6

A TSD R TECHNICAL PROJECT OFFICE R

W illiam Greim Environmental He alth Scientist Division of Health Asse ssment and Co nsultation Superfund Site Assessment Branch

CERTIFICATION

The Martin Creek Lake Health Consultation was p re p ared b y

the Texas De p artment of Health under a cooperative agr eement with the Agency for To xic Substances and Disease Registry (ATSDR). It is in accordance with approved methodology and procedures existing at the time the Health Cons ultation was initiated.

Technical Pro j ect Officer, SPS, SSAB, DHAC

The Division of Health Assessment and Consultation, ATSDR, has reviewed this Health Consultation and concurs with its findings.
Chief, SPS, SSAB, DHAC, ATSDR

Table of Contents Pa g e 2 of 3 ATSD R -PHA-HC-Martin Creek Lake-p2

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Agency for Toxic Substances and Dise ase Registry, 4770 Buford Hwy NE, Atlanta, GA 30341 Contact CDC: 800-232-46 36 / TTY: 888-232-6348 Pa g e 3 of 3 ATSD R -PHA-HC-Martin Creek Lake-p2

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