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 Disease Registry, 4770 Buford Hwy NE, 

Atlanta, GA 30341 

Contact CDC: 800-232-4636 / TTY: 888-232-6348

HEALTH CONSULTATION

MARTIN CREEK LAKE 

HENDERSON, RUSK AND PANOLA COUNTIES, TEXAS

September 17, 1998

Prepared by:

Texas Department of Health 

Under Cooperative Agreement with the 

Agency for Toxic Substances and Disease Registry

TABLE OF CONTENTS

BACKGROUND AND STATEMENT OF ISSUES

DISCUSSION

ATSDR's CHILD HEALTH INITIATIVE

CONCLUSIONS

RECOMMENDATIONS

REFERENCES

PREPARERS OF REPORT

CERTIFICATION

Next Section

 

ATSDR-PHA-HC-Martin Creek Lake-p-toc Page 1 of 1

http://www.atsdr.cdc.gov/HAC/pha/PHA.asp?docid=117&pg=0 10/5/2010
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 Division (SSD) requested 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 Utilities Electric Service Company (TU Electric). Martin Creek 

Lake is located 17 miles northeast of Henderson, on the border of Rusk and Panola Counties. 

During the late 1970's, Martin Creek Lake received discharges from ash ponds containing 

elevated selenium levels, resulting in increased selenium concentrations in fish. In 1979, 

selenium concentrations in bass ranged from 7.1 to 8.3 parts per million (ppm). Elevated 

levels of selenium in water and fish tissue were implicated in a series of fish kills during this 

time.

Since the fish kills, TDH, the Texas Parks and Wildlife Department (TPWD), and TU Electric 

have worked cooperatively to monitor selenium levels 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 advisory recommended that adults 

consume no more than one eight-ounce meal each week and children seven years of age and 

older consume no more than one four-ounce meal each week. Children six and under, 

pregnant women, or women who may soon become pregnant were advised not to consume 

the fish. Additionally, persons consuming fish from the reservoir were advised not to 

consume mineral dietary supplements with selenium exceeding 50 micrograms per day.

In 1996 and 1997, TDH collected 34 fish (17 bass, 10 channel catfish, 4 black crappie, 1 white 

crappie, and 2 flathead catfish) for a re-evaluation of the present fish consumption advisory. 

The concentration of selenium in the fish ranged from 0.7 to 4.0 ppm with an overall average 

concentration of 2.3 ppm (Table 1). Although selenium levels in fish from Martin Creek Lake 

continue to be above reported national 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

ATSDR-PHA-HC-Martin Creek Lake-p1 Page 1 of 6

http://www.atsdr.cdc.gov/HAC/pha/pha.asp?docid=117&pg=1 10/5/2010
White 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 Concentrations 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 form 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 inorganic selenium compounds from water and change them to organic 

seleniumcompounds such as selenomethionine. The major man-made source of selenium in 

theenvironment is coal burning, especially the fly ash that results from burning coal. Persons 

livingnear industrial sites may be exposed through 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 estimated bioaccumulation 

factor forselenium in fish ranges from 485 to 1,746, depending on the species [3]. In general, 

the moresoluble and mobile forms of selenium (selenite and selenate) dominate under 

aerobic (highoxygen concentrations) and alkaline (high pH) conditions [2]. 

Humans and animals are both capable of absorbing and utilizing both organic or inorganic 

formsof selenium from food or water sources. Most of the selenium 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 burdens of selenium primarily occur in the liver, 

kidneys, hair, andnails. Selenium is an essential dietary element for both human and animals 

in either theinorganic or organic form. Selenium has antioxidant effects which help prevent 

damage totissues caused by oxygen. A selenium deficient diet can result in Keshan disease, 

ATSDR-PHA-HC-Martin Creek Lake-p1 Page 2 of 6

http://www.atsdr.cdc.gov/HAC/pha/pha.asp?docid=117&pg=1 10/5/2010
the signs andsymptoms of which may include muscle pain, cardiomyopathy, enlargement of 

the heart,increased red blood cell fragility, and pancreatic degeneration. 

The human recommended daily allowance (RDA) of selenium for maintenance of good 

health is55 micrograms per day (ug/day) for women and 70 micrograms per day for men. 

Estimates ofthe average intake of selenium from food for the U.S. population range from 71 

to 152micrograms of selenium per person per day [2]. Welsh et al. reported that about three 

percent ofMaryland residents consumed diets which contained over 200 Âμg of selenium per 

day [4]. TheFood and Nutrition Board of the National Research Council has estimated the 

safe and adequatedaily dietary intake of selenium in adults to be 50 to 200 Âμg [5]. 

However, when eaten inamounts that are not much higher than required for good nutrition, 

selenium becomes harmful tohumans and animals [2] (Figure 2). Signs and symptoms of sub

-acute and chronic toxicity inhumans include brittleness and loss of hair and nails; blisters, 

eruptions and skin mottling; pittingand 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 been reported to have chronic selenium 

toxicity,including populations in the western part of the country with naturally high levels of 

selenium inthe soil and water. In a study of 142 subjects living in a seleniferous 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 limited number of case reports of 

individuals whodeveloped minimal signs of selenium toxicity following 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 apparentselenium toxicity was observed, while persons with daily intakes 

in the range of 42-750 ug perday did not produce any signs of toxicity or other adverse health 

effects [7].

The Agency for Toxic Substances and Disease Registry (ATSDR) recently has established 

achronic oral Minimum Risk Level (MRL) for selenium of 5 Âμg/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 hazardous substance that is likely to be without appreciable risk of 

noncancer health effectsover a specified duration of exposure. The MRL was derived from a 

study involving a Chinesepopulation with high selenium intake. Blood selenium 

concentrations and degree of selenosiswere determined for 349 adults. The endpoint used to 

derive the MRL was nail disease,specifically brittleness of nails. By regression analysis the 

corresponding selenium dietaryintakes were determined. A "no observable adverse effects 

level" (NOAEL) of 15 ug/kg/day,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 establish the MRL, ATSDR 

divided the NOAEL by a factor of threeto account for human variability. It is important to 

note that the MRL based on the Chinese studymay be conservative because only dietary 

exposure was considered and it has been suggested thatinhalation exposure to selenium in 

smoke was significant. The population studied 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 normal selenium levels in the diet may increase the risk of 

cancer. Thismay be due to the fact that selenium is used in the body in enzymes that protect 

ATSDR-PHA-HC-Martin Creek Lake-p1 Page 3 of 6

http://www.atsdr.cdc.gov/HAC/pha/pha.asp?docid=117&pg=1 10/5/2010
against oxidativedamage to tissues which may be responsible for cancer promotion. One 

specific form ofselenium, called selenium sulfide, is a probable human carcinogen. Selenium 

sulfide is notfound in foods, and is a very different chemical from the organic and inorganic 

seleniumcommonly found in the environment. Because it is not absorbed through the skin, 

its primary usein the anti-dandruff shampoo Selsun Blue, is considered safe [2].

Figure 2. Health Effects of Selenium

Toxicological Evaluation

In 1992, when TDH estimated the risks associated with eating selenium contaminated fish, 

anMRL for this contaminant was not available. Using available 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 remarkably similar to the MRL (5 

Âμg/kg/day)established by ATSDR and provided approximately a 2.6-fold safety factor 

below the currentNOAEL of 1,050 ug/day, or the lowest level reasonably expected to result in 

signs or symptomsof toxicity. In performing the risk assessment, TDH determined the 

acceptable daily intake ofselenium from fish by subtracting an assumed daily intake of 

selenium from other sources (200Âμg/day [2.86 Âμg/kg/day assuming 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 acceptabledaily 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 150 Âμg/day (2.14 Âμg/kg/day assuming a 70 kg 

adult) is an acceptabledaily intake of selenium from fish. 

To determine the actual number of meals that could be consumed without exceeding the 

MRL weused two values for the concentration term; the arithmetic average and the 95th

percent upperconfidence interval (95% UCL) of the arithmetic average. The 95% UCL is 

defined as a valuethat when calculated repeatedly for randomly drawn subsets of site specific 

data, equals orexceeds the true average 95 percent of the time. 

We estimated the 95% UCL by defining the distribution of selenium 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 obtained for each of the 1,000 samples and the 

950th rankordered average was defined as the 95th percentile. The arithmetic average should 

be mostrepresentative of the concentration that would be contacted over time; however, the 

95% UCL ofthe average provides a conservative estimate of the average concentration and is 

useful toaccount for sampling variations and suspected seasonal variations in fish tissue 

concentrations. Figure 3 provides a graphical representation of the relationship between the 

sample distributionand the 95% UCL of the arithmetic average.

Using these assumptions we estimate that adults could consume approximately two (eight 

ounce) meals per week and children (body weight 10-30 kg) could consume approximately 

ATSDR-PHA-HC-Martin Creek Lake-p1 Page 4 of 6

http://www.atsdr.cdc.gov/HAC/pha/pha.asp?docid=117&pg=1 10/5/2010
one to two (four ounce) meals per week of Martin Lake fish before exceeding the MRL (Table 

2). Individuals would have to consume approximately three times these amounts before 

exceeding the lowest level reasonably expected to result in signs or symptoms of toxicity.

Figure 3. Probability Density Distribution for Selenium Concentration in Fish from Martin 

Lake 

Table 2. Recommended Limitations on Long-Term Fish Consumption by body 

weight

Body 

Weight

Estimates Based on Average Selenium 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 consult under a Cooperative Agreement with the Agency for 

ToxicSubstances and Disease Registry (ATSDR). TDH has included the following 

information inaccordance with ATSDR's Child Health Initiative. 

ATSDR's Child Health Initiative recognizes that the unique vulnerabilities of infants 

andchildren demand special emphasis in communities faced with contamination of their 

water, soil,air, or food. Children are at greater risk than adults from certain kinds of 

exposures to hazardoussubstances emitted from waste sites and emergency events. They are 

more likely to be exposedbecause they play outdoors and they often bring food into 

ATSDR-PHA-HC-Martin Creek Lake-p1 Page 5 of 6

http://www.atsdr.cdc.gov/HAC/pha/pha.asp?docid=117&pg=1 10/5/2010
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 Disease Registry, 4770 Buford Hwy NE, 

Atlanta, GA 30341 

Contact CDC: 800-232-4636 / TTY: 888-232-6348

contaminated areas. They are shorterthan 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 developingbody systems of children can sustain 

permanent damage if toxic exposures occur during criticalgrowth stages. Most importantly, 

children depend completely on adults for risk identificationand management decisions, 

housing decisions, and access to medical care.

Special consideration was given to children's health in this consultation. Children consuming 

one to two meals per week (4 ounces each) would not exceed minimal risk levels for adverse 

health effects from selenium in fish.

Next Section Table of Contents

 

ATSDR-PHA-HC-Martin Creek Lake-p1 Page 6 of 6

http://www.atsdr.cdc.gov/HAC/pha/pha.asp?docid=117&pg=1 10/5/2010
Page 1 of 1

http://www.atsdr.cdc.gov/HAC/PHA/reports/martincreek_09171998tx/images/figure1.gif 10/5/2010
Page 1 of 1

http://www.atsdr.cdc.gov/HAC/PHA/reports/martincreek_09171998tx/images/figure2.gif 10/5/2010
Public Health 

Assessments & 

Health Consultations

HEALTH CONSULTATION

MARTIN CREEK LAKE 

HENDERSON, RUSK AND PANOLA COUNTIES, TEXAS

CONCLUSIONS

The levels of selenium in Martin Creek Reservoir have decreased significantly during 

the period of investigation (1979 - 1998).

1.

Estimated exposures to selenium from eating fish from Martin Creek do not exceed 

minimum risk levels for adverse health effects for children consuming one to two meals 

per week (4 ounces each) or for adults consuming approximately two meals per week 

(8 ounces each). Approximately three times these amounts would be required to exceed 

the lowest levels reasonably expected to result in signs and symptoms of toxicity, 

therefore, ingestion of fish from Martin Creek Reservoir 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 current recommended limitations on long-term fish 

consumption.

1.

REFERENCES

IRIS, 1998. Integrated Risk Information System. U.S. Environmental Protection 

Agency, Office of Health and 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 selenium in a freshwater reservoir: Implications for 

environmental hazard evaluation and safety. Ecotoxicol. Environ. Safety 10:314-338.

3.

Welsh, et al., 1981. Selenium in self-selected diets of Maryland residents. J. Am. Diet 

Assoc. 79-277-85.

4.

FNB, NRC, 1980. Food and Nutrition Board, National Research Council: 

Recommended dietary allowances, 9th ed. Washington, D.C: National Academy of 

Sciences.

5.

ATSDR-PHA-HC-Martin Creek Lake-p2 Page 1 of 3

http://www.atsdr.cdc.gov/HAC/pha/pha.asp?docid=117&pg=2 10/5/2010
Page last reviewed: October 15, 2009

Page last updated: October 15, 2009

Longnecker, et.al., 1991. Selenium in diet, blood, and toenails in relation to human 

health in a seleniferous area. Am. J. Clin. Nutr. 53:1288-94.

6.

Yang, et.al., 1983. Endemic selenium 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 

ATSDR REGIONAL REPRESENTATIVE

George Pettigrew, P.E.

Senior Regional Representative 

ATSDR - Region 6

ATSDR TECHNICAL PROJECT OFFICER

William Greim

Environmental Health Scientist 

Division of Health Assessment and Consultation 

Superfund Site Assessment Branch

CERTIFICATION

The Martin Creek Lake Health Consultation was prepared by the Texas Department of 

Health under a cooperative agreement with the Agency for Toxic Substances and Disease 

Registry (ATSDR). It is in accordance with approved methodology and procedures existing at

the time the Health Consultation was initiated.

Technical Project 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

 

ATSDR-PHA-HC-Martin Creek Lake-p2 Page 2 of 3

http://www.atsdr.cdc.gov/HAC/pha/pha.asp?docid=117&pg=2 10/5/2010
Content source: Agency for Toxic Substances and Disease Registry 

Agency for Toxic Substances and Disease Registry, 4770 Buford Hwy NE, 

Atlanta, GA 30341 

Contact CDC: 800-232-4636 / TTY: 888-232-6348

ATSDR-PHA-HC-Martin Creek Lake-p2 Page 3 of 3

http://www.atsdr.cdc.gov/HAC/pha/pha.asp?docid=117&pg=2 10/5/2010