Lead is a chemical chameleon. It resembles calcium so closely that the body smuggles it in as if it were a nutrient, and precisely where calcium is needed, in the nervous system and in the bones, it does its damage. At ETH Zürich we used lead isotopes as geological clocks: the ratio of the lead isotopes reveals the age of a rock. The same analysis answers a different question in a building, namely whether lead is present in paints, pipes and dust.
Where lead occurs in buildings
Three sources are typical, especially in buildings up to the 1970s:
- Lead paints: lead white (lead carbonate) in light-coloured paints, red lead (orange) as rust protection on metal, lead chromate in yellow and green tones. In Gründerzeit and Art Nouveau buildings they often lie beneath several newer layers. Intact, they are unproblematic; it becomes critical when they flake or when dust is created during work.
- Lead pipes: lead water pipes were installed in Austria into the early 1970s and are still regularly found in old buildings in Vienna, Graz, Salzburg and Innsbruck.
- Lead dust: the underestimated source. Weathering lead paint produces fine dust that accumulates on window sills, floors and in cracks, especially relevant in households with small children.
Why lead is dangerous
Lead is a neurotoxin. It disrupts signal transmission and the development of the brain. Babies and children under about six are most strongly affected, because their nervous system is still developing and they take up a considerably higher proportion of ingested lead into the body than adults; impairments of intelligence, attention and behaviour are described. In adults, high blood pressure and kidney damage are in the foreground. According to the WHO there is no safe threshold: even small amounts are considered harmful. The IARC of the WHO classifies lead and its inorganic compounds as probably carcinogenic (Group 2A).
Recognising lead pipes
A lead pipe can be identified visually by several features: it is grey and matt, soft (a key easily leaves a notch, a fresh scratch shimmers silvery), sounds dull when tapped, is not magnetic, and the joints are bead-soldered rather than screwed. Such pipes are most likely found at the house connection in the basement, on the riser pipes and on the last metres under the sink or washbasin. Important: this is only the visual identification. How much lead actually passes into the water is told only by an analysis.
How to determine lead reliably
The lead content of paint, plaster or dust cannot be judged with the naked eye. The reliable method is laboratory analysis by an accredited laboratory. For drinking water a stagnation sample is examined, that is, water taken after a defined standing time, because the lead concentration is highest after standing for longer. For paint, plaster and solder joints, material samples are evaluated layer by layer, and for dust, wipe samples. Sampling on one's own is not advisable, especially with lead paint: anyone scratching or sanding suspect paint creates exactly the lead-containing dust they want to avoid. Such work and the sampling belong in expert hands.
The legal framework
For drinking water, a lead limit of 10 micrograms per litre currently applies in Austria (0.01 mg/L, Drinking Water Ordinance). The EU Drinking Water Directive (EU) 2020/2184 lowers this value to 5 micrograms per litre by 12 January 2036. Since lead pipes often fail to meet even today's value after longer stagnation, this tightening amounts in practice to replacing all lead pipes. For the proper removal of lead-containing paints, the relevant ÖNORM specifications apply.
What to do
- Lead paint, intact: document and take into account at the next renovation. Do not sand, flame off or strip without protective measures. Painting over or sealing (encapsulation) is often the simplest solution.
- Lead paint, flaking, with children in the household: action needed. Professional removal or sealing by a specialist firm.
- Lead pipes: replacement is the only lasting solution; filters and coatings do not solve the problem. Until then the usual precautions apply: let the water run before use, use only cold water for cooking and drinking (warm dissolves more lead), and no water from lead pipes for baby food.
- Lead dust: wipe up damp rather than sweeping (sweeping spreads the dust), and eliminate the source.
Lead is not the only invisible pollutant in old buildings. Radon too can be neither seen nor smelled, and in buildings from before 1990 it is worth looking for asbestos.
Sources
- Drinking Water Ordinance (RIS): ris.bka.gv.at; EU Drinking Water Directive (EU) 2020/2184
- WHO, lead and health (no safe threshold, risk to children); IARC, classification of lead and inorganic lead compounds as Group 2A
- allum.de, „Blei: Gesundheitsrisiken": allum.de
Questions on the topic? Free Initial Consultation.