An Evaluation of the Hazards of Toys and other Products made from Polyvinyl Chloride (PVC)
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An Evaluation of the Hazards of Toys and other Products made from Polyvinyl Chloride (PVC)

What is PVC?  Use of Lead and other stabilizers

October, 2005 
Important Update: Comparing the safety of all materials used for food and water

PVC Home Page

Summary & conclusions

Phthalate Plasticizers

July, 2002: Recent questions from our email inbox
Also -interview with a vinyl industry spokesperson. Read our comments!

Easy-to-print version of this report (26 sec @ 28k)

Other hazards

References

Authorship of this material

Most recent list of toys made with PVC (March 1999)

Update, Jan. '99:
Lead, Cadmium, Phthalates still found in Children's Products 

     Polyvinyl Chloride is a polymer, or large chain-like molecule, made up of repeating units of Vinyl Chloride (a monomer).   Commonly referred to as Vinyl or PVC, it is exceeded only by  polypropylene and polyethylene in the variety of  products which are made from it.   Other common commercial polymers used for familiar products are  polyurethane and polystyrene.   

     We find PVC in car interiors and trim, wall coverings, floor tiles, window frames, siding, water and sewer pipes, shrink wrap, packaging (including blister packs and food wraps), medical equipment   (tubing, transfusion bags, blood storage bags, respiration tubes),  electric and electronic cable insulation, textiles, both as trim and complete garments - and Toys.   

     PVC can be a tough, rigid material, or soft and flexible, depending on the use of additives.  It is denser than other plastics, and so preferred by food processors for packaging.  Additives include anti-oxidants (heat and light stabilizers) to extend the life of the plastic, and plasticizers to allow a precise degree of flexibility.

     All polymers, in a perfectly pure state, at room temperature, are completely non-toxic, since they are nearly inert and insoluble.   However, all commercial polymers require a variety of additives.   They all undergo degradation and decomposition when exposed to heat during formulation or molding into products.  They also tend to break down when subject to the mechanical stress of molding or extrusion.  

     Finally, all products made from polymers are degraded by the light, heat, stress, and air pollution encountered in everyday use.  For this reason, one or more stabilizers are required for each type of plastic.
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Stabilizers in PVC:    PVC has the special problem of forming HCl (Hydrochloric Acid) when it degrades, which causes a chain reaction which proceeds rapidly to complete loss of strength (and causes damage to manufacturing equipment).   The stabilizers for PVC have thus mostly been metal salts, which could react with the HCl.  These have included Lead, Cadmium, Barium, Calcium, Zinc, and organic Tin compounds.  (July 2000:  Organotin compounds found to interfere with immune system cell activity.)
Organotins, principally dibutyltin and monobutyltin, are used as stabilizers in Vinyl as an alternative to Lead and Cadmium.  Their principal use is in clear vinyl products.The first two are known poisons.  It appears that Cadmium is not much used any more.  There are varying accounts in the literature we have seen concerning the prevalence of Lead as a stabilizer.  According to an Australian document dated 1996, it is still quite widely used.  

Lead is not used where a clear Vinyl is required.  Window covering, food packages, tubing, etc, use Organic Tin Compounds (Organotins) or Calcium/Zinc.  There have been some findings linking Organotins to Reproductive and immune system problems.  A compound similar to ones used in PVC is used in marine antifouling paint, and has been blamed for  destruction of marine life in harbours.  Australia has banned the use of of this Organotin. 

Stabilizers are not chemically bound to the PVC polymer chains.   Only the amount of stabilizers which reacts with damaged parts of the polymer become chemically bound.  Whether mixed in during formulation, or into the melt during manufacturing, stabilizer molecules are held in place when the melt freezes, like objects in an ice cube.  Heat Stabilizers  are typically added at the rate of about .5 percent (.005) of the polymer.  Metal salts (like lead carbonate, etc) don't "like" to be mixed into an organic polymer, and so tend to clump and migrate when the polymer is heated, or in surface areas subject to weathering and stress.  For this reason, we expect the stabilizer to accumulate on the surface in normal use, especially if the product is exposed to heat, stress,  or light, particularly direct sunlight.  Smith (1996) cites the leaching of lead from new PVC pipe. 
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Availability of Lead in Toys:
  In 1995,  the Arizona Department of Health Services, responding to the lead poisoning of children in situations where no obvious source existed, found the source to be rigid Vinyl miniblinds in the children's rooms.   There were very large amounts of lead dust on the PVC blinds, as well as lead dust on the windowsills below. Two of the children had been chewing on the blinds themselves.   At first, the CPSC declined to identify the blinds as a hazard, but in June 1996 they agreed to do so.    Subsequently, sampling in North Carolina found miniblinds to be a lead hazard, with surface lead dust exceeding federal standards by as much as 100-fold.  No formal recall was ever issued, despite vigorous urgings by the authorities of both states.  The Window Covering Safety Council, throughout all this, put out press releases reassuring consumers that the lead found in the blinds did not constitute a hazard to children. 

Motivated by this finding, Greenpeace collected some popular  mass-market PVC toys, and contracted with two independent  laboratories to test for the presence of lead.   In short, they found that about 20 percent of the toys tested contained Lead, Cadmium, or both.  In many of the toys, the levels were high enough to exceed federal guidelines.  They repeated this process in several major U.S. urban areas, with similar results.  Their complete report is provided on this website (from link in section below).   The CPSC performed a small-scale replication of the study. They obtained roughly similar results, but concluded that the lead found on the surface of the tested toys did not constitute a health hazard to children.  Their conclusion was based on assumptions, definitions,  and interpretations, rather than substantially different quantitative findings. 
CPSC concluded that Greenpeace mis-interpreted its own results, by making errors in basic science, and wrong assumptions about children's behavior. They concluded the products tested, even ones containing Lead, were not hazardous to children, because the daily dosage of poisons ingested were below hazardous levels. Health Canada performed a similar evaluation, with identical conclusions and interpretation.   Environ Corporation, a think-tank hired by the Vinyl Industry Association, offered similar "findings", although did no actual laboratory work.  These reports are also posted on this website (see "links" below).    
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  CPSC,  Environ, and Health Canada, criticized the Greenpeace study principally on four grounds:
1. Accelerated aging tests using  exposure to ultraviolet light were not valid, because the toys tested by Greenpeace would not be exposed to ultraviolet radiation in normal use, unlike the miniblinds in the sunny windows.   
2. Great variations in city-to-city lead measurements, and variations from the CPSC results for the same toy indicates defects in Greenpeace's laboratory procedures.
3. A criticism of the Greenpeace study is inherent in CPSC's decision not to test the lead content of the electronic cables tested by Greenpeace, on the basis that children would not be expected to handle this material.
4. Estimates of amounts of lead a child would ingest by handling these toys were in error, since a child would not handle the entire object at once. Thus, amount of lead dust per unit area are a more correct measure than total dust on surface of item.   Assuming certain values for a child's hand size, amount of daily handling,   and correlations of blood levels with amounts ingested, the critics concluded that the resulting blood   lead levels would remain below established Federal standard of 10g/dl. 
Responding to the first comment:
The critics are incorrect on a point of basic scientific information, and deficient in simple observations of child behavior and demographics.  The miniblinds were exposed to light transmitted through glass, as well as the resulting heat.  "Glass in general is opaque to the ultraviolet and infrared". (Physics and Chemistry Handbook, 1964 edition ).  Carbon-carbon  and carbon-hydrogen bonds are broken far more readily by shorter than by longer wavelengths.  Any toy likely to be played with outdoors, or inadvertently left outside, would receive far more short wavelength   ultraviolet light,  available only in direct sunlight.  A number of the toys analyzed by Greenpeace are in that category; some might even be used as beach toys.    In a large sub-tropical  metropolis like Los Angeles or Miami,  the rapid disintegration of sun-exposed PVC, as well as rubber and other polymers,  is a familiar problem. 
Responding to the second comment:   The analysis was not performed by Greenpeace, but by two accredited and professionally staffed labs, specializing in lead analysis. The variations in percent lead content are far more likeley due to poor quality control at the manufacturing plants which processed the PVC resin. The very highest numbers, well over the theoretically useful quantities for metal salt stabilizers, are probably just due to gross over-use of the additives, which is something that would occur on a random basis.
Responding to the omission of testing of cable insulation:  It is not productive to make such assumptions about children's behavior.  Children can, and eventually will, handle everything in their daily surroundings.  We have an article   from Centers for Disease Control reporting the severe lead poisoning of adult electronics worker  who had developed the habit of chewing on lead-stabilized   PVC electric insulation.  Lead hazard is thus not just a problem for children; but the point is that children are especially at risk, due to their unpredictable behavior and greater sensitivity to the toxic effects of lead.
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Responding to the fourth criticism, we consider the toxicology of Lead:    In short, the daily intake of lead is not as important a determinant of ultimate harm as is the duration of exposure and the total lead ingested over time.  This is due to the cumulative nature of lead toxicity.  Lead at very low blood levels causes a very wide variety of changes in neural functioning.  It interferes with transmission of nerve signals both by disruption of Calcium ion balance along the nerve axon, and at the synapse, by bonding to Calcium receptor  sites.   Lead can modify gene expression and gene-regulated protein synthesis.  Lead exposure interferes in a variety of ways with the developing brain at the neuroanatomical level.  Prolonged exposure to low levels of lead changes the response of various neurotransmitter systems.  Consistent and reproducible behavioral effects have been seen with blood lead levels as low as 7 g/dl (micrograms of lead per tenth liter of blood), which is below the Federal standard of 10 g/dl.  
The CPSC suggests in its report that  "chronic ingestion of lead be limited to 15g per day" to prevent children of 6 years and younger from exceeding the 10 g/dl  blood lead level.  It is not clear from the CPSC report how the daily ingestion rate translates to the suggested maximum blood level. 
In any case, there is good reason to assert that the daily intake of lead for a child is not relevant to a discussion of the hazards of the material.  Lead is a uniquely cumulative poison.  Some of the kinds of neurological damage caused by lead are not reversible.  The period from 1 to 3 years of age in humans is critical for lead exposure, and neural damage occuring during this period is least likely to be reversible.  
Most important, children  excrete lead very slowly.  Lead behaves chemically very much like Calcium, and is similarly stored in bone.   Bone is in a dynamic equilibrium, biologically and chemically, with blood.  If the rate of lead intake is reduced, lead will enter blood from bone.  Thus, a daily exposure, however low, builds up a "savings account" of lead, which may persist for decades.   During periods of high calcium demand, as in lactation and pregnancy, lead enters the blood along with the calcium.  In older people, when bone mass is reduced by resorption, higher lead levels have been observed.  This is especially true of post-menopausal women, who are greater risk of osteoporosis.  (It thus seems that female children  are at particular risk from lead ingestion.)
It is also important to be aware that the lead available from the tested products would not be the only source of exposure in a child's environment.  Although substantial and very successful efforts have been made in the past twenty years to reduce environmental lead (removal of lead paint and banning its use in most applications, the elimination of leaded gasoline and lead plumbing solder), there are still other sources of lead exposure.  Due to the years of environmental accumulation, children are still exposed to other sources of lead beside toys.  Since all lead exposure is additive as well as cumulative, it is important to eliminate any source of exposure when it is within our power to do so.
For these reasons, we feel it is reasonable to assert that the series of calculations presented by CPSC to arrive at the conclusion that the lead found in some toys is not a hazard, is not helpful in ensuring safety for children.
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