PVC, Health and Environment

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Periodically in the press, attacks appear against PVC in general and more especially against PVC in packaging.

 

 

Traditionally, these attacks bear on 3 points :

 

         ·  The carcinogen power of PVC,

         ·  The non recyclability of PVC,

         ·  The production of toxic products during PVC incineration.

 

 

PVC carcinogen power

 

 

In this field, attacks often state that :

PVC contains significant quantities of chemicals likely to cause cancers and that therefore it is dangerous for people’s health.

 

This ambiguous form causes a reflex of fear to the reader. But this is the same problem with carcinogen products and toxic products, which are present by thousands, and it is necessary to know in which proportion they can be dangerous.

 

Among the products known as carcinogen, the state of California (a state which is very much advanced for the defense of health in the United-States) has established a list of products known to cause cancers, in a document concerning drinkable water.

 

We can find in it:

·   Vinyl chloride monomer (VCM) [present in PVC (p. 801)],

But also:

·     Acetaldehyde [present in apples and PET (p. 795)],

·     Cyclosporine [anti rejection drug used for organ grafts (p. 796)],

·     Testosterone [male hormone present in half of the inhabitants of the planets (p. 800)],

·     And probably many other products that every one of us meets everyday without knowing it.

 

An important thing would be to know the products which we are in contact with, what are the dangerous ones  and in which proportion they are present.

 

In fact, for PVC it is not the product itself that is carcinogen but its original monomer, vinyl chloride (VCM).

 

Vinyl chloride is a gas at ordinary temperature that becomes liquid at – 14° C. This product was first of all used as an anesthetic in dental surgery, and was then industrially produced from 1920. It is only at the end of the sixties that its carcinogen power was suspected, as one could notice among the personnel in charge of cleaning PVC polymerization autoclaves, higher rates of a very rare cancer type: angiosarcoma of the liver.

 

This discovery involved first of all the implementation of a legislation concerning working conditions in plants polymerizing PVC, as it is only in those plants that were evidenced these higher liver cancer rates.

 

Before the regulations, vinyl chloride contents in the atmosphere could exceed 300 ppm [1 ppm = 1 part per million = 1 g per (metric) tonne].

 

Surveys showed that 50-ppm contents could cause cancers.

 

The different regulations now impose contents lower than 1 ppm in working atmospheres. Regulations then extended to the VCM content in PVC packagings, then to the VCM content in foodstuffs.

 

In PVC, the maximum permissible content of VCM in Europe is 1 ppm. In PVC compounds produced by DORLYL, this content is lower than 0,05 ppm (I.e. : 20 times less than the limit).

 

In foodstuffs, the maximum allowed VCM content is 0,01 ppm in Europe and 0,002 ppm in the United-States. Measurements taken on foodstuffs packed in PVC made from DORLYL compounds, by using a method able to detect 0,0001 ppm, have not evidenced the presence of any VCM at all in the foodstuffs concerned. Contents are therefore lower 0,0001 ppm (0,0001 ppm represents 1 mg per 10 tonnes).

 

It is difficult to pretend that European and American regulations are latitudinarian, above all in the field concerning public’s health.

When these legislations limit the rate of certain products, limits are taken with a safety margin, in spite of this; we are well below set limits.

 

The utilisation of PVC as a foodstuff packaging product by international companies, world known wide for their seriousness, in the best proof of the harmlessness of PVC.

These companies, if they had the least doubt on the quality of their packaging materials, would not run the risk to go on using it and impairing their brand image, whereas documents concerning this subject have been known for over 20 years.

 

PVC non-recyclability

 

 

By closely studying the problem, one can notice that recycling problems are posed in similar terms for all plastic materials, and that it is more critical in the packaging field.

 

All thermoplastics are recyclable; on the other hand they are relatively little recycled. Why?

 

·     Because these products are very sensitive to the presence of dirt.

·     Because the different plastic materials are in incompatible with one another when mixed together.

·     Because packaging represents large waste volumes for relatively small weights.

 

Recycling operations require then sophisticated sorting and cleaning operations, resulting due to large volumes, in high costs per tonne thus making the treated product sometimes more expensive than the base stock, without having all the purity criteria.

 

What are the different recycling possibilities for used PVC bottles?

 

Re use in the same type of application:

 

The re-utilisation of PVC bottles (or plastics in general) requires a selective collection or a preliminary sorting of these packagings, their transport up to a place where packagings will be washed before being used again.

Obstacles are mainly the cost of transporting of empty packagings as well as, the uncertainty of the purity of washed packagings (plastic materials contrary to glass, can hold products in their material) also is the pollution created by the washing operation.

 

Re-utilisation in an other application:

 

Recycling this way is probably more realistic than the former. However, it is limited by the following problems:

 

·     Collection of packaging.

·     The sorting and purification which might be more or less advanced according to the final utilisation.

·     The creation of new outlets.

 

This activity is relatively recent. After its initial applications to produce bulky pieces, other more technical applications have been developed : tubes and multicoated sections – transformation into textile fiber. These applications are still too limited. However the cost of virgin materials that sometimes make the recycled product uncompetitive which limits the imagination of potential users.

 

Incineration with energy recovery:

 

Problems linked to incineration will be dealt with in the next chapter.

 

This way of recycling PVC packaging is now the most efficient as it does not require anymore the separation of packaging from garbage and it does not require sorting the different plastic materials. It saves injecting fuel oil into incinerators. This injection was necessary at the time when domestic garbage contained little or no plastic materials.

 

The incineration of garbage containing plastics with energy recovery cumulates three advantages:

 

·     It eliminates plastic waste.

·     It saves fossil fuels that would be used to incinerate garbage.

·     The energy produced saves the energy that would be necessary to produce by other means.

 

Biodegradability:

 

This concept applied to plastic materials seems to be attractive.

 

However, it must be handled with caution.

 

·     The fact that a plastic item is biodegradable may encourage users to throw it away anywhere and without judgment.

·     One must be absolutely certain than by-products resulting from biodegradation, are not more toxic than the original that has the disadvantage of being visible.

·     Finally, in the foodstuff-packaging field where for obvious reasons, a packaging material should be as inert as possible, both inertia and biodegradability concepts are opposed as far as present technologies are concerned.

 

The production of toxic products during incineration of PVC in garbage

 

 

Among the products listed as toxic, chlorine, hydrogen chloride, dioxin were quoted.

 

Chlorine (Cl2) is a particularly dangerous gas, but it is never given off during PVC incineration. Although sometimes named in certain articles, this is because of the confusion that certain people voluntarily make or by ignorance of chemistry, between chlorine (gas) and hydrogen chloride (commonly called hydrochloric gas or hydrogen chloride anhydrous).

 

Hydrogen chloride (HCl) or hydrochloric gas or hydrogen chloride anhydrous, is a suffocating gas that forms when chlorinated products are incinerated (such as PVC). This gas combines very rapidly with the water vapour to form a liquid, hydrochloric acid.

Hydrochloric acid is a strong, corrosive acid. It is the main component of gastric juices present in stomach.

It was common, at a time, when people spoke a lot about acid rains, to make PVC unjustly responsible for these acid rains on account of hydrochloric acid forming during incineration.

It is a fact that hydrochloric acid only represents in Western Europe 2,5 % of the potential acidity of human origin given off into the atmosphere, and that out of these 2,5 %, PVC (all origins taken into account) only accounts for half of it.

In France, when all municipal incinerators are upgraded to European standards (Community Directives 89/369/CEE and 89/429/CEE), at the latest on January 1^st 1996, the contribution of PVC to acid emissions in atmosphere will be lower than 0,1 %.

 

Dioxin: First of all, it is to be noted that this term is not correct. In fact dioxins are a family of 210 different compounds that are polychlorodibenzoparadioxins (PCDD – 75 different compounds) and polychlorodibenzofurans (PCDF – 135 different compounds).

 

Dioxins form when there is combustion of products containing chlorine.

The two main natural sources of dioxins being volcanic eruptions and forest fires. Dioxins then appeared well before man. Dioxins were detected in samples of 8,000 years old substances.

The toxicity of dioxins studied on animals is very variable from one species to the other (factor from 1 to 2,000). The toxicity of various dioxins is also very variable (factor from 1 to 10,000).

 

The most toxic product being probably 2,3,7,8 tetrachlorodibenzoparadioxin also called SEVESO dioxin.

It must be noted that, after SEVESO’s accident in 1976, a medical monitoring program was implemented and that 200,000 people were followed up. Today, specialists are in a position to declare that no long-term effect has been observed in the medically followed up population. Out of the 37,000 people potentially exposed, 400 had skin burns and 200 developed chlorine acne. All of them are now healed. Chromosomes examinations of most exposed people revealed no anomaly.

There was no reported death in SEVESO.

Professor Christoffer RAPPE, from the University of UMEA in Sweden, studied the formation of dioxins in the incinerator of the municipal treating 70,000 T/year of waste. The total dioxin emission from this incinerator is about 3 to 4 g a year and the emission of SEVESO dioxin is 0,07 g a year.

 

It was then clearly established that adding PVC in garbage did not increase the rate of dioxins given off. Authors have different views on the subject. One must admit that as quantities to be proportioned are very small, it is difficult to make accurate measurements allowing one to evidence differences.

 

The rates of SEVESO dioxin in gases coming out of incinerators are about 0,3 ng/Nm³ (1 ng = 10-9 g),

that is to say 0,0000000003 g per m³ gas.

 

By using the observed levels in burnt gases of the incinerator of UMEA, and by using weather data, the Swedish Weather Institute has calculated the dioxin concentrations in air in different points.

 

At the point where concentration is maximum, the content is about 0,05 pg/m³ (1 pg = 10-12 g),

be 0,00000000000005 g per m³ air.

 

The quantity of initial dioxin is under those conditions, about 0,02 pg/kg/d, to be compared with ADI which is 1,5 pg/kg/d (ADI = Admissible Daily Intake).

 

As an indication, a car driven with a lead free petrol engine gives off dioxins of 15 to 20 pg/m³.