L in Water Used for Preparation of Dialysate

Relatively Low Al Levels (50-75 fig/L) in Water Used for Preparation of Dialysate 

Davidson et al. found that the cumulative risk of death due to dialysis dementia in patients whose water supply had a mean Al concentration 200 pg/L was significantly greater (27.9% deaths in the first 40 months) than the risk in patients whose mean water Al content was 200 pg/L (2.1% deaths in the first 490 months). The relation between the mean Al concentration in the dialysate and time to death was given in the formula [24] The time in months from the first symptoms of dialysis dementia to death = 65—0.081 x [mean Al concentration (pg/L) in dialysis water]. 

It may be postulated that the severity of exposure to Al determines the pattern of morbidity. Normally, Al in plasma is bound and transported by transferrin. However, when plasma Al levels exceed 500 to 600 pg/L, transferrrin s capacity for binding Al is exceeded, and Al probably exists in plasma in combination with citrate or as a hydroxide in association with phosphate. Thus, acute severe exposure may be more likely to produce the neurological disorder and increased sensitivity to flicker, whereas chronic moderate exposure may manifest primarily as bone disease and the other less dramatic symptoms [27, 125-128]. In any case, considering the fact that there have been only two reports of outbreaks of acute Al encephalopathy in dialysis centers [17, 43-45], and s-Al levels of 1200 pg/L [44] to 1700 pg/L (Table 1) have been reported (Table 6), acute Al encephalopathy due to water contamination probably only develops when the Al level in the tap water is well above 1000 pg/L. 

There are several possible reasons for the fact that some patients remain relatively symptom-free while others develop serious neurological symptoms in cases with apparent similar exposure. 

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