Lead in PVC

[Ferdinand.Engelbeen@ping.be (Ferdinand Engelbeen)]

Because of concerns of the use of lead as a stabiliser in PVC drinking
water pipe, we send you some data from the Nordic Pipes federation (Nordic
= Norway, Sweden, Denmark, Finland).

Although prepared for a debate on the use of lead as a stabiliser in PVC in
the Nordic countries, it can give you a feeling of the ratio of problems of
lead in PVC to lead in other uses.

Drinking water and pipe materials were tested for lead migration from PVC
to the water. Except for the first five days, when lead of the surface can
migrate to the water, there are no migrations seen and the water contains
no more lead at the tap than the natural lead content at the source. In the
first days, the pipe is tested for leakage and thouroughly flushed and
desinfected.

The surface of PVC pipes was tested with the same test, used for ceramics
in contact with food.
The first test did give 0.13 and 0.20 mg/dm2 lead
The second test did give less than 0.01 mg/dm2 that means that no lead is
migrating from the inside of the plastic.
The tightest EU test limit is 0.80 mg/dm2.

Lead consumption in Sweden in 1992 was:

Application:                     consumption (tonnes)

Accumulators, batteries:             22,000
Lead cable sheathing less than:       3,000
Crystal glass:                        1,300
Electronics:                          1,300
Ammunition:                           1,200
Weights:                              1,000
Metal alloys:                           900
Fishing weight, nets:                   600
Chimney plates:                         500
Plastic additives, excl. PVC pipes:     400
Leaded petrol:                          340
PVC pipes:                              225
Other usages:                           150
Rust protection, paint:                  90

Interesting, if lead in PVC pipes is a problem, why should the use of lead
in crystal glass be allowed, just for enjoying the art of glass blowing,
with no environmental benefit?

The annual emission of lead to the environment was calculated to be:

product                emission (tonnes)

Accumulators:               3,000
Ammunition:                 1,200
Fishing weights, nets:        600
Leaded petrol:                340
Rust protection paint:         90
PVC pipes:                      0.08

When incinerated, the amount of any metal used as stabiliser in PVC will
nearly not change the total amount of heavy metals that has to be washed
out of the stack gases.

No leaching has been seen from PVC pipes in soils or landfills, neither any
breakdown of rigid PVC itself. But, if we assume that PVC anyway will
breakdown in 100,000 years or so, that extra risk of lead leaching would be
neglible:

Natural lead content of soil:   20-50 mg/kg
Maximum allowed by different countries: 200-1000 mg/kg

When the lead content from one meter of 110 mm (4.3") PVC pipe migrates in
the adjacent soil that would augment the background lead content of soil
with:
0.4 mg/kg if only the surface layer breaks down and lead migrates within
0.5 m of the pipe
7 mg/kg if the entire lead content migrates in the adjacent 1 m3 of soil.

The migration speed of metals in general is less than 1.5 m in more than
600 years, with sandstone as exception: 4.5 m in 690 years.

Ferdinand Engelbeen
Chairman Chlorophiles

Ferdinand.Engelbeen@ping.be