[Also see: PVC: A Health Hazard From Production through Disposal Paul Goettlich 25oct01]
Materials made from chlorine resin, such as vinyl chloride and vinylidene chloride, are often thought of as environmental villains because they emit dioxin when burned under certain conditions. Recent reports that revealed plastic food wrap made of vinyl chloride emitted endocrine disruptors, or "environmental hormones," on incineration have worsened their image further. As a result, some companies have begun to replace some of the chemicals use in the manufacture of the wrap, and promote recycling.
In November, 21,000 rolls of plastic food wrap made of vinylidene chloride were returned to two major manufacturers of the product, Asahi Chemical Industry Co. and Kureha Chemical Industry Co. A nationwide citizens' group comprising nine organizations, including the Consumers' Union of Japan, collected the rolls from homes around the country after a campaign to raise awareness of environmental hormones.
Materials made with chlorine resin emit dioxin when they are burned at low temperatures, or are left smoldering.
About 80 percent of plastic food-wrap products for the home are made from this material. About 60,000 tons of plastic food wrap are produced annually.
"Although the figure may not seem so high, we have to remember that plastic food wrap usually goes straight from the home to the incinerator," said Keiko Mita, a secretariat member of the Consumers' Union of Japan. "If consumers change the way they use it, there will be a direct improvement in the environment."
After receiving the returned food wrap from the group, the manufacturers argued that poor incineration methods were to blame for excessive dioxin emissions, and reducing the number of products made from chlorine resin would not solve the problem. The two companies involved said they would continue producing plastic food wrap made from vinylidene chloride, even though other firms have introduced a similar product made from polyethylene.
There are two types of plastic food wrap currently being produced, one designed for home use and a stronger product for industrial use. More than 80 percent of the plastic food wrap produced for commercial use, as well as 10 percent of the rolls produced for home use, are made from vinyl chloride. Vinyl chloride film is cheaper and more elastic than similar products made from vinylidene chloride, so it is favored by supermarkets.
However, experiments conducted by the Consumers' Union of Japan revealed that rice balls and croquettes wrapped in this plastic film and heated in a microwave absorbed nonylphenol, which is believed to have characteristics similar to female hormones. A maximum of 800 parts per billion of nonylphenol was detected in the rice balls and 2,800 ppb in the croquettes.
Various additives are used to improve the performance of plastic food wraps, and the group believes that one of these additives--a substance used to stop phosphorus oxidation--is transformed into nonylphenol during the production process. No nonylphenol was detected in products made with vinylidene chloride.
Nine major manufacturers of plastic food wraps decided last year to replace the additive in question by the end of this month. It is the first time that the industry has conducted an across-the-board review of their operating practices since the dangers of environmental hormones became an issue of public concern.
"It is very hard for manufacturers to change the additives we use because it complicates the production process," said Kiyotaka Kinoshita of Shin-Etsu Polymer Co.'s general planning department. "But we decided that we should do this to alleviate the concerns of consumers." However, he added the names of the substances to be replaced will remain a trade secret.
"The quantities of nonyl phenol detected during the experiments were relatively large," said Yokohama City University Prof. Taisen Iguchi. "The prompt action taken by manufacturers was highly commendable."
Meanwhile, Mishima said the group will push for greater transparency from the industry in the future. "We haven't been told which additives are to be replaced," she said. "We need to keep the situation under close scrutiny."
Two million tons of vinyl chloride are used in Japan every year. Most of this is put to industrial use, including in agriculture, pipes and the construction industry. With the private sector pushing recycling efforts, the Association of Vinyl Environmental Council, estimates that 50 percent of vinyl used in agriculture and 70 percent of vinyl used in the manufacturing of pipes will be recycled in the next fiscal year.
With its relatively low production costs and its flexibility, vinyl chloride could be considered the most convenient material produced by mankind.
Iguchi commented, "If society as a whole can devise better ways to dispose of vinyl chloride, it would be possible to continue taking advantage of its benefits without damaging the environment."
Ministries and government agencies have already begun choosing construction materials that are free of vinyl chloride. And in Denmark and other European countries, strict regulations have been imposed on toys containing the substance.
Vinyl chloride resin is synonymous with mass production and mass consumption. With the nation poised to shift to a more recycling-oriented society, new policies governing the use of vinyl chloride materials are urgently required.
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