Sunday, September 19, 2010

Plastic Puzzle

Plastic puzzle
Not all plastic containers are suitable for use or reuse. Moumita Chakrabarti gives the lowdown on what’s safe and what’s not. TT, 20 September 2010:Monalisa Sen was taken aback when her daughter’s class teacher told her that the plastic water bottle the child carried to school was unsafe. “She advised us not to reuse beverage bottles for drinking purposes,” says Sen
Sen is not the only one who is unaware of the fact that not all plastic bottles are safe for drinking or storing water. Many of us reuse plastic bottles in which beverages or mineral water is sold. And we also use plastic containers without giving a thought to whether or not they are safe for storing food. But health experts warn that this may have some adverse side effects.
So how does one know which plastic bottle or container is suitable for use and which is not? Well, there is a rule of thumb you can go by. Turn the bottle or container upside down and you will find a number embossed underneath. These numbers, ranging between 1 and 7, not only indicate the material the container is made of but also whether it is suitable for use.
In general, polyethylene terephthalate, commonly known as PET or PETE, which comes under Number 1, and is used in the manufacture of mineral water and beverage bottles, is considered safe. However, a few studies have shown that secretion of a toxic substance occurs when water is stored in a PET bottle for a considerable period of time.
Sunil Bhatnagar, senior manager (commercial), Pearl Polymers Ltd, which manufactures Pearlpet bottles, disagrees with this view. He says the material the company uses for manufacturing bottles has been thoroughly tested and approved and has been declared safe for food and other consumables by international health authorities. “Although most water and beverage bottles are lightweight and designed for single use, refillable and reusable Pearlpet bottles and jars are widely used.”
Not so, says a PepsiCo spokesperson. “PET bottles are not advisable for multiple use since they cannot be sterilised with hot water. If a bottle is not cleaned properly and used to store tap water, high TDS (total dissolve salts) might remain on the inner surface of the bottle and pose a health hazard. Ideally, these bottles should go back for processing,” the spokesperson says.
Concurs Sunil Pandey, fellow, Centre for Environmental Studies, “PET bottles used for long-term storage result in leaching (migration) of phthalates, a chemical compound of an acid used in making plastic, into water, which is harmful if ingested.” Phthalates can also cause infertility, obesity, breast and prostate cancer, heart disease and diabetes, adds Preeti Shah, director, Consumer Education Research Society (CERS), Ahmedabad.
The second (Number 2) type of plastic — high density polythylene (HDPE) — is not known to cause any health hazard and can be safely used for drinking water. It is also used in containers to store milk, cream and yogurt.
However, Number 3, which denotes polyvinyl chloride (commonly known as PVC), does pose some serious health risks. “This type of plastic contains plasticisers, which are used to soften hard materials, that can leach into food,” says Shah. Dr T.K. Joshi of the Centre for Occupational and Environmental Health (COEH), New Delhi, too says that bottles or plastic containers with Number 3 written on them should be avoided.
Ravi Agarwal, director, Toxic Links, New Delhi, points out that plasticisers added to PVC include phthalates and lead. “For this reason PVC is not used in children’s toys, teethers and even medical equipment in many countries,” he says. Lead impacts the nervous system and reduces the IQ level of children. It is one of the most toxic heavy metals, according to the World Health Organisation.
Though a Number 3 plastic container should be avoided, you can safely use containers with Numbers 4 (low-density polyethylene) and 5 (polypropylene) embossed on them. These are mainly used in take- away containers, those used for frozen food, bottles caps and food storage boxes.
In case you come across a Number 6 (polystyrene) type of plastic, that too should be given a wide berth. This kind of plastic is commonly used for making plastic cutlery, yogurt cups and coffee and tea cups. It is known to contain styrene, a chemical compound that is considered harmful.
The last type of plastic in the series, 7, contains bisphenol A (BPA), an organic compound that disrupts the endocrine system. This is not at all suitable for storing water and is mainly used for storing sauces and condiments. They can mimic the body’s natural hormones and thereby cause many health problems, say experts.
However, there are those who say that when it comes to the reuse of plastic mineral water or beverage bottles, the main danger lies not in any chemical contamination but in the fact that they may contain harmful bacteria. “If there is any risk from reuse, it probably comes from bacterial contamination as the bottle’s narrow neck makes it difficult to clean,” says Dr Joshi of COEH. He, however, agrees that not all plastic bottles can be used for drinking.
So do check the numbers beneath a plastic container before you use it. But, remember, even if it comes with the right number, it should not be used for too long. When it comes to plastics, use and throw seems to be the best option.