By Barry Densley
As consumers, we implicitly trust food manufacturers and government to maintain appropriate safeguards to prevent food contamination. Australian health officials recently ordered an investigation of locally manufactured baby milk formula following the discovery of plasticisers, or phthalates, in UK varieties.
The parliamentary secretary for health and family services, Senator Bob Woods, announced there was no immediate risk to Australians. "This situation in the United Kingdom does not mean we have any reason for concern ... we must quickly investigate to see if these substances are present at all in Australian products."
A by-product of the petroleum industry, phthalates were discovered in the 1850s and first developed commercially in the 1930s for the plastics industry. This industry manufactures an enormous range of PVC products for building, electrical, health care and transport applications. DEHP or di(2-ethylhexyl) phthalate accounts for up to 90% of annual global phthalate production (over 3.25 million tonnes).
Phthalates are potential carcinogens and may disrupt hormone function. Other possible effects include adversely affecting reproductive ability, developing embryos and reproductive ability of offspring, and disorders causing delay or lack of conception, such as menstrual disorders, hormonal problems, impotence, sperm abnormalities, uterine fibroid and tubal defects. Adverse birth effects may include spontaneous abortion, stillbirth, toxaemia, low birth weight, congenital defects and childhood cancer.
Phthalates are xenoestrogens: they mimic naturally occurring oestrogen and are thought to disrupt the body's complex chemical communications (endocrine) system. This system consists of a number of glands and part of the pancreas, testes and ovaries. Each gland secretes hormones to signal specific changes in cells affecting body function, development, mineral balance and metabolism. Natural hormones, including those we get from plants and vegetables (phytoestrogens), complete their tasks and then break down inside the body.
In 1987, Choice magazine reported high levels of phthalates in cheeses wrapped with PVC film (430 micrograms/kg in some brands). Following this, the National Health and Medical Research Council (NHMRC) set up a working group to examine phthalate levels in food.
Despite the group's toxicologists stressing that toxicology is not a definitive science and that further data or changed circumstances could lead to an entirely different conclusion, several recommendations were made. Phthalates migrating into food did not constitute a "toxic" risk, and there was no need for concern over daily intake levels. Minimising phthalates in food was, however, highly desirable.
A number of proposals were made regarding labelling regulations for PVC film. Representatives from the plastics industry stressed that self-regulation was desirable and that proposals to apply warning labels would be resisted.
In 1989, phthalates in PVC mattress covers were linked to cot death syndrome in studies by Penarth Research International. Subsequent studies refuted Penarth's findings, yet phthalates, particularly DEHP, have been implicated in fatal lung conditions in newborns using PVC ventilators.
An Australian Committee on Toxicity meeting in 1989 considered DEHP for the fourth time, to examine the possibility that DEHP may be responsible for congenital birth defects when combined with chemicals like caffeine. The Committee found there was no reason for concern over human exposure to DEHP and that no further action was required.
In 1992, Australian Standard "Plastics for Food Contact Use", AS 2070, reflected the findings of the NHMRC's 1987 report. AS 2070 contained a warning to food manufacturers of the dangers of biologically active substances (phthalates), migrating into food products via packaging or wrapping materials, including possible "toxic" or "chroni'c' effects to consumers:
"It is essential that the formulation of the plastics materials is such that any migration of substances into the food from the plastics packaging or wrapping materials is minimised and if migration occurs no known toxic hazard will exist to the consumer of the food ... Chronic effects ... are possible where small quantities of biologically active substances transfer from packaging materials and are ingested in small amounts over a long period of time."
AS 2070 first came into existence in 1977; yet it contained exactly the same warning as the 1992 standard.
The World Health Organisation (WHO) also published a report on DEHP in 1992. It found DEHP is readily absorbed in soil, is more soluble in blood than in water, is highly lipophilic (loves fat) and is persistent, accumulating in plants and animals. Atmospheric pollution was identified as the major source of contamination, industrial areas generally having the highest levels of DEHP. Blood transfusions and medical treatment using plastic devices were listed as a source of involuntary human exposure to DEHP.
A spokesperson for the Red Cross Blood Bank, Dr Richard Kimber, stated he was unaware of any problem associated with PVC blood bags and suggested contacting the manufacturers. Multinational Baxter HealthCare, suppliers of blood bags and plastic medical products to Australian hospitals and medical centres, have declined to comment on their use of PVC plastics.
The medical industry is well aware of the migration of DEHP into blood stored in PVC bags. DEHP migrates readily into red blood cell platelets, increasing shelf life of blood products. Long-term exposure to DEHP in the blood may also increase the risk of heart attack, as DEHP reduces contractile strength of heart muscle.
WHO recommended that disposal practices for DEHP be improved, that measures be taken to reduce the release of DEHP into the environment and that medical products that contribute to the body burden of DEHP be scrutinised to reduce exposure.
The UK Ministry of Agriculture, Fisheries and Food found phthalates present in every food sample taken since 1993, including meat, fish, eggs, milk and milk products. It estimated intake of phthalates in adults averaged between 0.8 mg and 1.6 mg per day.
Studies in 1995 found high levels of phthalates in infant formula, potato chips, chocolate bars, margarine, milk products and vegetable oils. Products packaged in paper and board, such as cakes, fats and confectionery, also contained high levels of phthalates. Gravy and vegetable burger mix, biscuits and vegetable fat had high concentrations.
Every baby milk formula tested contained phthalates. The most contaminated baby milk had concentrations that gave a total daily intake of 0.023 mg per kg of bodyweight. This is only four times lower than levels shown to reduce sperm count in rats. Safety levels in humans are normally a minimum of 100 times lower than levels shown to cause harm in animals.
In 1995, doctors from New York's Strang-Cornell Cancer Research Laboratory suggested that xenoestrogens found in plastics and pesticides increased breast cancer rates in women. Breast feeding has been shown to lower the risk of breast cancer by reducing high oestrogen levels associated with pregnancy. The Nursing Mothers Association voiced its concern about the lack of public awareness concerning phthalates.
A new book, Our Stolen Future, prompted the plastic industry to hold a seminar to discuss the implications of the book. "Our Stolen Future is so dramatic, persuasive and comprehensive, it is likely to become the foundation of dozens of attacks on industrial products and processes ... It is a comprehensive review of the potential impact of synthetic chemicals on human health", said an industry handout.
A spokesperson for the Plastics and Chemicals Industries Association (PACIA) denied there were any proven serious or long-term health issues associated with phthalates, but stated, "... if there is an issue, it's a potentially serious one". PACIA noted its commitment to programs such as "Responsible Care", aimed at improving its environmental performance.
Initiatives such as Responsible Care and the chemical and plastics industry self-regulation were recently assessed by the Australian Centre for Environmental Law. It noted that the failures of self-regulation far outnumber successes and concluded that Responsible Care "... is unlikely to substantially improve ... environmental performance of the chemical industry or regain the trust of the public in the industry's integrity".
PACIA recently commissioned the CSIRO to produce a confidential report on the side effects of xenoestrogens and hormone mimicry.
Recent studies have shown fish to change sex with long-term exposure to oestrogenic compounds. Many other chemicals containing phthalates, such as DDT, 2,4,5-T, 2,4-D and PCBs and dioxins, leave future generations with an unknown legacy.
Matt Ruchel, national toxics coordinator for Greenpeace, believes industry should stop using phthalates before it's too late. "Regulators and industry must adopt a precautionary approach and seek to eliminate pollution from these chemicals now, rather than wait for conclusive proof of harm ... this will mean ceasing the manufacture of PVC plastics ..."
The petrochemical industry insists there is no proof of any links or chronic health risks from the use of phthalates. Long-term research into phthalates would involve millions of dollars — money better spent on anti-cancer research, perhaps? If, as Senator Woods suggests, "there is no immediate risk", what of the risks to future generations?
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DEHP is used in such PVC-based products as acetates, adhesives, adhesive plaster foils, antiperspirants, air filters, automobile tyres, bandages, celluloid (film), carpets, casts, cosmetics, emulsion paints, engineering compounds, eyeglasses, filtration systems, food packaging, garden hose, hearing aids, inks, insect repellents, laminated cloth, lacquers, lubricants, packaging film, perfumes, pesticides, pharmaceuticals, pipes, plasticiser compounds, polyester fibres, protective gloves, PVC, resins, shower curtains, solvents, toys, vacuum pumps, vinyl flooring and upholstery, wallpapers and wire coatings for electrical cable.