Intestinal effects of sulfate in drinking water on normal human subjects.
Uncontrolled observations implicate sulfate in drinking water at concentrations exceeding 500-700 mg/liter as a cause of diarrhea, but controlled studies have not been reported. We conducted a controlled study in normal adults to determine the effect of various drinking water sodium sulfate concentrations on bowel function. Ten healthy subjects were given a constant diet and fluid intake. Fluid consisted of 36 ml/kg/day of drinking water of various known sulfate concentrations and 500 ml of other fluid. In a dose-ranging study, four subjects received drinking water with sulfate concentrations of 0, 400, 600, 800, 1000, and 1200 mg/liters for six consecutive two-day periods. In a single-dose study, six other subjects received water with sulfate concentrations of 0 and 1200 mg/liter for two consecutive six-day periods. Stool mass, frequency, and consistency and mouth-to-anus appearance time of colored markers were measured. In the dose-ranging study, the only significant linear trend was decreasing mouth-to-anus appearance time with increasing sulfate concentrations. In the single-dose study, 1200 mg/liter sulfate caused a significant but clinically mild increase in mean stool mass per six-day pool from 621 g to 922 g (P = 0.03). When all 10 subjects were used to compare effects of 0 mg/liter and 1200 mg/liter sulfate, significant differences in stool consistency (P = 0.02) and transit time (P = 0.03) were observed. None of the subjects reported diarrhea or passed more than three stools per day. In 10 normal adult subjects, sulfate in drinking water at a concentration of 1200 mg/liter, which is higher than reported to occur in US municipal water sources, caused a measurable but clinically insignificant increase in stool mass and decrease in stool consistency and appearance time, but no change in stool frequency and no complaint of diarrhea.
Heizer
W D
WD
Department of Medicine, and General Clinical Research Center, University of North Carolina, School of Medicine, Chapel Hill 27599-7080, USA.
Sandler
R S
RS
Seal
E
E
Murray
S C
SC
Busby
M G
MG
Schliebe
B G
BG
Pusek
S N
SN
D000328:Adult; D002400:Cathartics / Q000008:administration & dosage / Q000493:pharmacokinetics / Q000494:pharmacology*; D003967:Diarrhea / Q000139:chemically induced; D004305:Dose-Response Relationship, Drug; D005260:Female; D005772:Gastrointestinal Transit; D006801:Humans; D007408:Intestinal Absorption; D008297:Male; D013431:Sulfates / Q000008:administration & dosage / Q000493:pharmacokinetics / Q000494:pharmacology*; D014867:Water / Q000737:chemistry; D014881:Water Supply / Q000592:standards*
D002400:Cathartics; D013431:Sulfates; D014867:Water; C012036:sodium sulfate