Food contamination from toxic products is an issue particularly close to the public opinion, who is not willing to run any risk, compelling the legal authorities to make rules stricter and obtain the widest safety warranties from manufacturers. 

Heavy metal release coming from items used for conserving and distributing potable water is part of this issue and obliges manufacturers to adjust their technological processes to the new norms. 

States impose a limit to the daily global quantity of contaminating assimilable material and leave the certificating organizations the task of defining materials, methods and release rates for satisfying the above-mentioned limits, which are often quite different among the various countries. 

The metals object of control in the field of yellow or coated brass used to contain potable water, are those making part of the alloy composition or those used for the decorative or protective galvanic processes.

The most famous are: 

Copper, Zinc, Lead, Molybdenum, Nickel, Selenium, and Arsenic.

Amongst these metals, lead is the most observed, since it is a non-secondary component in brass faucets, being technically needed for speeding-up machining operations and reducing production costs. Unfortunately, during machining the lead is brought to the surface of the metal part and will enter into contact with the water.

Now in Europe there are no EC regulations unifying the procedures for the release tests but a specific commission is working on this matter. In the meantime, each country establishes arbitrarily rules and limits. In the Czech Republic, even before its entry in the European Community there were definite and strict regulations.

At present, one of the most required verification methods is the Protocol 61 of American NSF, also recognized by the UL certification. In Australia and New Zealand, they follow methods provided by AZ/NZS 4020 regulations, who have own procedures and limits.

TOXICOLOGICAL AND REGULATORY ASPECTS

Metals are the man’s best-known toxicological agents. You can find them in the environment through the geological and biological cycles and as a consequence of  industrial processes. 

In the past, only acute cases of metal intoxication were considered and only recently  the long-term exposure effects have been taken into consideration.

The effects caused by the exposure to a toxic agent are related to the quantity of the  agent itself and its relation to the exposure time and to the metal concentration in the environment.

A critical factor within the presence of metal in the organism is the biological half-life, i.e. the time needed by the organism to eliminate half of the absorbed metal quantity. For example, the biological half-life of lead is of 20-30 years, while for other metals as chrome  is of only a few days.

The molecular targets are different according to the type of metal and the involved body area; normally they are enzymes, membrane and/or cellular organisms that will bind according to their chemical type and binding affinity.

Blood, urine and hair are the most accessible for measuring the exposure to a metal and  they are therefore used as biological indicators. Factors related to the individual influence the toxic effects of a metal too: children and old people are more sensitive to poisoning and some metals such as lead easily cross the placenta, revealing metal haematic levels in the fetus equal to the ones of the mother. A diet poor in vitamin C can increase the lead absorption too.

LEAD TOXICITY

Lead is the commonest metal, detectable in every environmental cycle and in all biological systems.
Children at a very early age or in the fetal period are the most sensitive  target within the population.
Food is the main assumption way, but other environmental issues such as lead-based paints on old houses, car exhausting combustion, etc. must not be underestimated.
The assumption of lead has decreased, decreasing the use of it in food tins, water mains and petrol.
Adults absorb 15% of the ingested lead and, as a rule, they accumulate less than 5%; the values increase in children as they absorb 41% of the ingested lead and accumulate 32%.
The inner organism compartments where we can find lead are two: the bone system, with an half-life of more than 20 years and the more instable compartment of soft tissues, in particular the Central Nervous System. Within children and babies, the most critical effects are on the Central Nervous System and show-up with vomit, irritability, loss of appetite  and learning problems. Within adults, the most evident effects are hypertension, nephropathies and anemia caused by an increased fragility of the red globules membrane and to the fact that lead replaces Iron in the hemoglobin synthesis.
The blood pressure increases when the quantity of lead in the organism reaches 10 μg/dl of blood, while higher concentrations of around 100 μg/dl, cause mental retarding. 

REGULATION ASPECTS

Since long time the United States have been committed for limiting the lead level in waters meant for human consumption. At first by reducing the lead contents in pipes; since 1988, thanks to the then President Mr. Reagan, who signed the “Safe Drinking Water Act”, the use of “Lead-free” alloys and pipes having less than 0,2% was imposed (in the past they contained 50%) and, as far as accessories, not more than 8%.

Afterwards the “National Primary Drinking Water Regulations” imposed some controls on piping corrosion and maintenance. According to this attachment lead levels in potable water were not admitted if more than 10% of the samples checked during monitoring operations exceeded 0,015 mg/l. EPA (Environmental Protection Agency) established this maximal of 15 μg/l as an acceptable limit (MAL).  

Law nr. 31 dated 2001 then modified into nr. 27/2002 will be effective in Italy in December 2003. According to this norm, the presence of lead in potable water has to be limited to 10 μg/l. As the actual lead value limit is of 50 μg/l, the new limit will have to be reached latest within 25/12/2013. During the period from 25/12/2003 to 25/12/2013, the value must be decrease to 35 μg/l. 

In the meantime, by the means of mandate M/136, the European Community entrusted CEN (Comité Européen de Normalization) the task of defining testing methods with respect to both potable water evaluation and materials in contact with the same.