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HEALTH CONSULTATION

GROUNDWATER WELLS EAST MOUNT HOUSTON
HOUSTON, HARRIS COUNTY, TEXAS


BACKGROUND AND STATEMENT OF ISSUES

The Texas Department of Health, Health Risk Assessment and Toxicology Program received a request from a citizen to evaluate whether the barium and manganese in her drinking water could be responsible for depression, obsessive-compulsive disorder (OCD), and seizures in family members who grew up drinking the water. The citizen receives her water from two private wells in the 7700 block of East Mount Houston Drive in the Dyersdale Field area in northeast Harris County. Shallow groundwater in this area reportedly has been affected by brine from oil and gas development operations. One well was drilled in 1984 and the other in January 1998. For the purposes of this report we have designated the 1984 well as Well #1 and the 1998 well as Well #2. Well #1 was sampled by the Railroad Commission of Texas in May 1996, November 1996, and July 1997. Well #2 was sampled and analyzed for barium and manganese in February and June of 1998.

To address the citizen’s concerns TDH first compared the barium concentrations found in water taken from the residential wells to EPA’s Maximum Contaminant Level (MCL); manganese levels were compared to EPA’s Secondary Drinking Water Standard (SDWS) for this contaminant. MCLs are chemical-specific maximum concentrations allowed in water delivered to the users of a public water system. MCLs are considered protective of public health over a lifetime (70 years) at an exposure rate of two liters per day; however, they also may be based on available technology and economic feasibility. Although MCLs apply to public water systems, they can be used as a guide when assessing the public health implications of contaminants found in water from private water wells. EPA’s SDWS for manganese in drinking water is not directly analogous to an MCL as it was set for aesthetic reasons and is not health based. Thus, exceeding the SDWS should not be interpreted to mean that a health hazard exists.

In addition to comparing the measured concentrations to published drinking water standards, we reviewed toxicological data from the Agency for Toxic Substances and Disease Registry’s (ATSDR’s) Toxicological Profiles for barium [1] and manganese [2], EPA’s Integrated Risk Information System (IRIS) [3], Patty’s Industrial Hygiene and Toxicology [4], and other toxicology references. Below we have summarized the toxicological information available for these contaminants. We were not able to find any information associating exposure to barium or manganese via ingestion of drinking water with depression, OCD, or seizures.

Barium concentrations in Well # 1 ranged from 2.2 to 3.6 mg/L and manganese concentrations ranged from 0.85 to 1.3 mg/L (Table 1). Both contaminants exceeded their respective drinking water standards in this well. The maximum reported concentration of barium in Well #2 was 0.8 mg/L, a concentration below EPA’s MCL (Table 2). Manganese concentrations in Well #2 exceeded EPA’s secondary drinking water standard in 4 of 6 samples (Table 2).

Table 1.

Well #1 Sampling Data East Mount Houston, Harris County, Texas
Constituent Sampling
Interval
 Date of Sample Units Comparison Values  Source of Comparison Value
  (Minutes) 5/30/96 11/22/96 7/29/97      
Barium mg/L

2.0

 EPA’s MCL

0 2.6 2.2 3.2
30   2.3  
40     3.2
120 2.87 2.2 3.6
240 2.87

2.2

 
    mg/L 0.05 EPA’s secondary drinking water standard
Manganese 0 1.00 0.85 1.1
  30   0.89 1.1
40 1.13 0.86 1.3
120 1.1 0.85 1.3

Table 2.

Well #2 Sampling Data East Mount Houston, Harris County, Texas
Constituent Sampling
Interval
 Date of Sample Units Comparison Values  Source of Comparison Value
  (Minutes) 2/4/98 6/30/98      
Barium 5   0.35 mg/L 2.0  EPA’s MCL
  40 0.15 0.28
  120 0.29 0.810
Manganese 5 <0.05 0.20 mg/L 0.05 EPA’s secondary drinking water standard
  40 <0.05 0.19
  120 0.16 0.19


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