Seasonal lead release to drinking water and the effect of aluminum

Monitoring lead in drinking water is important for public health, but seasonality in lead concentrations can bias monitoring programs if it is not understood and accounted for. Here, we describe an apparent seasonal pattern in lead release to orthophosphate-treated drinking water, identified through point-of-use sampling at sites in Halifax, Canada, with various sources of lead. Using a generalized additive model, we extracted the seasonally-varying components of time series representing a suite of water quality parameters and we identified aluminum as a correlate of lead. To investigate aluminum’s role in lead release, we modeled the effect of variscite (AlPO4 · 2H2O) precipitation on lead solubility, and we evaluated the effects of aluminum, temperature, and orthophosphate concentration on lead release from new lead coupons. At environmentally relevant aluminum and orthophosphate concentrations, variscite precipitation increased predicted lead solubility by decreasing available orthophosphate. Increasing the aluminum concentration from 20–500 µg L-1 increased lead release from coupons by 41% and modified the effect of orthophosphate, rendering it less effective. We attributed this to a decrease in the concentration of soluble (<0.45 µm) phosphorus with increasing aluminum and an accompanying increase in particulate lead and phosphorus (>0.45 µm).

Intoxications by lead and its inorganic compounds

Lead belongs to the group of blood poisons that impair the synthesis of porphyrins and heme. Under industrial conditions, only chronic lead poisoning can develop. Lead belongs to the poisons that have the effect of material cumulation. The half-life of lead is 20 years. Once in the body, it is deposited in many organs in the form of the insoluble tribasic lead phosphates. A significant part of the lead is deposited in the trabeculae of the bones. Under the influence of provoking factors, an intensive lead release from the depot can be observed. In such cases, the amount of lead in the circulating blood increases sharply, and remission is replaced by an exacerbation. There is a wavy course of chronic lead intoxication. Lead and its inorganic compounds belong to the group of poisons that have a polytropic effect on the body, affecting many organs and systems. The blood system (anemia with specific characteristics) and the nervous system (polyneuropathy and encephalopathy) are primarily affected. A number of other organs and systems are also affected. The most severe specific syndrome of gastrointestinal tract damage is lead colic. Due to the impaired synthesis of porphyrins and heme in certain biological substrates of the body — in the blood, erythrocytes and urine, substances unused in the synthesis of heme are accumulated. They are markers of chronic intoxication caused by lead, in the presence of a relevant clinical picture. The diagnosis is based on data from a professional history, sanitary and hygienic characteristics of working conditions, clinical and objective characteristics of the disease and data from laboratory examination. The main thing is to stop contact with lead and remove it from the body. Antidotes for lead poisoning are chelators: tetacinum-calcium, pentacinum, D-penicillamine. In combination with technical and sanitary-hygienic measures to prevent chronic intoxication caused by lead, preliminary and periodic medical examinations of persons in contact with lead are of great importance.