LEAD IN PAINTS

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There appears to be a great deal of confusion in the minds of the general public with regard to the role of lead in paints. Perhaps a review of the role that lead used to play and now plays in the surface coatings industry might put this into perspective and reassure the general public.

Lead is one of the commonest elements on earth and is very widely distributed. It is for t his reason that it is difficult to call anything "LEAD FREE" and some manufacturers prefer to use the term "NO ADDED LEAD" when referring to the subject. Small amounts of lead ingested by the body are generally excreted without problem. When larger amounts are ingested then levels can build up and this can be a problem. SANS and EC procedures require that preparations containing lead at levels >0.5% be labelled TOXIC. Lead is encountered in various forms and the toxic ones are those which are soluble, especially in acid. This is because the digestive system uses acids in the stomach and if the compound is soluble in acid, the body can take it up.

Leads compounds encountered in the paint industry, past and present, are:-
Oxides litharge and red lead High soluble
Carbonates white lead High soluble
Sulphate white lead (artists colours - historical) High Soluble
Chromates red, orange, yellow and green pigments. Low Soluble
Plumbates calcium plumbate Mod Soluble
Driers lead salts of various organic acids Low Soluble


When evaluating lead levels in paint this must be done on a basis of soluble lead and total lead. A further complication comes from the fact that paints are supplied in admixture with volatile solvents and so consideration has to be given to this and so lead levels are considered as. Total lead on total paint. Levels greater than 0.5 % require labels to warn users (SANS 10265/CHIP3) Total lead on solid paint. - Any paint containing >5% Soluble lead is classified by and its use is restricted by the "OHS Act - Lead Regulations". Any paint containing >0.15% total lead on paint as supplied should carry the warning "Contains Lead - not to be used on surfaces liable to be sucked or chewed by children." SAPMA mandatory label requirements.

Note for lead to be considered as toxic it must be in a form that can be assimilated by the digestive system. The digestive juices in the stomach are considered to be equivalent to given solution of hydrochloric acid. Lead itself and many of its compounds have very limited solubility at this level and so are not considered as toxic.

There are three ways in which lead can get into a surface coating by intent.
  • 1. The first is its use as a catalyst in the manufacture of the synthetic resin and its use as a catalyst to assist drying. Over the years these have been reduced or eliminated and if the level of lead is above 0.15% then the label should carry the warning "Contains Lead. Not to be used on surfaces likely to be sucked or chewed by children". Reputable manufacturers do not supply such paints for the domestic market. In any case the quantity of lead is extremely low - usually below 0,15% on solid paint
  • 2. The second is their use as primers. a. White lead has excellent preservative properties when used on wood. This is now only of historical interest, its use has been discontinued because of toxicity and only very old buildings will still have remains of these primers. The soluble lead content of the lead compound used is relatively high. With a total lead content of ±80% the soluble level is also ±80%.
    Besides its use in primer White Lead used to be used as a white pigment. This is no longer the case as it is more economical to use titanium oxide which is more effective in terms of colour, durability and cost. It began to be phased out in the 1940's and I doubt if it was still in use in this way in the 1950s. The only place where paints containing this lead pigment would be very old buildings - they would also probably be of wooden construction.
    b. Red lead has given excellent results when used upon steel structures. It use has also fallen away due to toxicity concerns not only due to manufacture and application but also in removal. One way to re-coat this type of structure is to remove the old coatings with abrasive (sand) blasting and containing the resultant dust. Some operators resort to wet sand blasting. This lowers the dust problem but the run off must be contained and disposed of as hazardous waste. This is difficult and costly. As in the previous case the soluble lead content of the lead compound used is relatively high. With a total lead content of ±90% the soluble level is also ±90%.
    It is doubtful that Red Lead was ever used as a colourant, too expensive compared to iron oxides.
    c. Calcium plumbate is still used as a substitute for red lead in primers especially for galvanised iron. As this is a very specialised application Its use is very limited. With a total lead content of ±60% the soluble level is also ±60%.
  • 3. Pigments. Lead pigments are still the best choice for Yellow, Orange, Red & Green (yellow/blue mix) and these are in the form of lead chromate complexes, often with molybdate ions. These pigments contain fairly high lead total lead levels but very low soluble lead levels. The toxicity is more related to the chromate content than the lead content and this makes them more hazardous in the powder form to the manufacturer rather than the end user. It must be borne in mind that the lead is encapsulated in the pigment and this is in turn encapsulated in the paint so risks to the paint user are relatively low unless sanded or abraded.

    • Nevertheless, mindful of the less than 0.15% rule, the use of these pigments in the decorative market has been virtually eliminated.
    As used in paints, pigments with a total lead content of ±60% only have a soluble level of less than 5%, in addition, as the quantity of pigment used in any paint is relatively low, considerable exposure and ingestion would be needed for any toxic effects to be shown.

    It is perhaps interesting that the presence of lead in a compound does not automatically make it toxic. The use of lead crystal glassware is a prime example.


    Les Fisher FTSC and Mike Russell FTC Feb 2004
    Last updated:

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