A number of different food products undergo a bleaching process for several reasons, such as enhancing the color of the food. In recent times there has been widespread debate about the saftey and potential health risks of bleaching foods. For example, white flour is known to undergo a stringent bleaching process to ensure that it is has an extremely white color. Similarly there has been widespread concern over bleaching of other foods such as tea.
DO BLEACHED TEABAGS REPRESENT A HEALTH RISK?
There has been significant public health concerns about the bleaching of tea in teabags. The fact is that during chlorine-bleaching some toxic substances, like dioxin, may be created. So, let’s find out if small amount of dioxin in chlorine-bleached teabags may actually be dangerous.
WHAT ARE TEABAGS MADE FROM?
First teabags were made from silk and muslin. Nowadays, teabags are mostly made from paper, produced from a blend of wood and vegetable (hemp) fibers. Both wood and vegetable pulp are usually chlorine-bleached, meaning that small amount of toxic chlorine compounds may end up in teabag paper.
To avoid chlorine toxicity, today some tea sellers use only teabags from non-chlorine (oxygen) bleached teabag paper, completely non-bleached paper, or teabags from synthetic fibers (1).
PAPER PRODUCTION AND BLEACHING
Wood consists of about 50% cellulose fibers, 30% lignin fibers, and 20% of other easily extracted substances (2). Lignin gives wood its strength and color. In order to get white paper (almost 100% cellulose), lignin and other substances have to be removed. Pulp cooking removes the most lignin from the pulp, and remaining lignin can be removed by bleaching.
The aim of using chlorine is to remove lignin from pulp (delignification), and thus bleach it.
Up until the late 1990s, elementary chlorine (Cl2) was used for pulp bleaching (3). Chlorine pulls lignin out from the pulp. Some chlorine binds to lignin, resulting in toxic organochlorine byproducts like chloroform, dioxin, furans etc.
CHLORINE DIOXIDE – ELEMENTAL CHLORINE FREE (ECF) BLEACHING
Nowadays chlorine dioxide (ClO2) is used in pulp bleaching instead of elementary chlorine. Chlorine dioxide does not bind to lignin but breaks it down, resulting in by far the less amount of dioxins in wood pulp (3). However, paper bleached with chlorine dioxide is still not completely chlorine free as some paper manufacturers may claim (3).
Extended delignification with ozone, oxygen or other non-chlorine whiteners, can furtherly reduce the amount of dioxins in the pulp (3).
PROCESSED CHLORINE FREE (PCF) BLEACHING
Processed Chlorine Free bleaching uses totally chlorine free processing, but includes recycled paper, which must be assumed as previously chlorine-bleached. Both the recycled fiber and any virgin fiber must be bleached without chlorine compounds (3). Before the fibers are made into new paper, they are thoroughly washed many times, so it is unlikely that chlorine will still be attached to the fibers after PCF bleaching. But minute amount of dioxins may still be expected to be found in the pulp.
TOTALLY CHLORINE FREE (TCF) BLEACHING
Totally Chlorine Free bleaching uses no chlorine compounds in bleaching procedure and only virgin wood pulp is used. Bleaching chemicals used – peracetic acid (CH3COOOH), oxygen (O2), ozone (O3) and hydrogen peroxide (H2O2) – produce no chlorine byproducts (3).
The chemical name for dioxin is 2,3,7,8- tetrachlorodibenzo para dioxin (TCDD). The name ‘dioxins’ is often used for the family of chemically related polychlorinated dibenzo para dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs), and dioxin-like polychlorinated biphenyls (PCBs). TCDD is the most toxic dioxin (4,11).
COMMON SOURCES OF DIOXIN
A human, in average, ingests most of dioxin with meat, dairy products, fish, shellfish and eggs (4,11).
DIOXIN IN TEABAGS
2,3,7,8-TCDD has been found in teabags at concentrations up to 4.79 ppt (6, page 83)
Bleached containers and filters can leach dioxins into milk, coffee, and other foods with which they come in contact (7).
HEALTH RISK OF DIOXIN EXPOSURE
Once dioxins have entered the body, they are absorbed by fat tissue. Their half-life in the body is estimated to be seven to eleven years (4). The study performed on Princeton University, USA, in y. 2003, has shown that there is no safe dose below which dioxin will not cause cancer (5).
After ingestion, dioxins accumulate in fatty tissues and disrupt the hormone system. EPA (US Environmental Protection Agency) scientists warned in 1994 that minute exposures to organochlorines can lead to cancer, loss of reproductive capabilities, endometriosis, developmental and behavioral disorders, learning disabilities, birth defects, and damaged immune systems (4). Fetus may absorb dioxins across the placenta and infant through their mother’s milk (8). However, TCDD does not affect DNA (4).
WHO IS SENSITIVE TO DIOXIN?
All people may be harmed by small amounts of dioxin, but at most risks are:
CHLORINE FREE PRODUCTS ASSOCIATION
The Chlorine Free Products Association certifies papers that meet their criteria for chlorine free. It awards its PCF symbol(Processed Chlorine Free) to papers that contain a minimum of 30% recycled fibers, have not been chlorine-rebleached, and use TCF (Totally Chlorine Free) virgin pulp that did not come from old growth forests. Its TCF symbol (Totally Chlorine Free) is awarded to virgin papers meeting the same criteria (3). PCF and TCF symbols may be found on some paper products including tea bags.
Because of increased customers awareness, many tea selling companies now use oxygen-bleached teabags instead of chlorine-bleached ones.
It is hard to say from the look of the teabag, is it bleached or not. If in doubt, and if you find this as an important issue, call the tea seller company and ask. They are usually willing to answer all questions.