Monday, 5 September 2016

BPA Exposure May Be Linked to Asthma

Previously I wrote about a new, vegan-friendly alternative to leather made from pineapple leaves. But that's not all it substitutes, as "vegan leather" used to only mean synthetics made from petrochemical products such as PVC, which can contain toxic chemicals including BPA. BPA is an increasingly unpopular chemical, with water bottles using a lack of BPA as a selling point. The most well-known effect of BPA exposure may be hormone disruption, but did you know that it may also increase the risk of asthma?

Just say no. Source: Aney.
Asthma is a chronic respiratory illness that has unfortunately been increasing in incidence. It is characterised by over-sensitive airways, which leads to airflow obstruction, and is inflammatory. Asthma is the third leading cause of hospitalisation for children and teenagers under the age of 15. I used to have asthma, but kicked it at the age of 8 by swimming in a heated pool. Others are not so lucky, as 75% of children still have symptoms of asthma when they reach adulthood. Asthma is caused by an interaction between genes and the environment, including BPA exposure. One study described in a review showed that higher prenatal levels of BPA was linked with a 20% higher risk of wheezing. 657 pregnant women were tested for their BPA levels during the first and third trimester. In another, urinary BPA levels were tested when mothers were 16 and 26 weeks pregnant, as well as at birth. Above average BPA levels was associated with more than double the risk of wheezing at 6 months, but not at three years old. It has also been demonstrated that every 10-fold increase in BPA levels was associated with a 55% increase in the risk of wheezing from birth to 5 years. A study that didn't show that BPA increased the risk of asthma only measured levels of the toxin during the first trimester of pregnancy. However, in two other studies, one involving almost 400 mothers, higher BPA levels 16 weeks into pregnancy was linked with higher risks of wheezing, one showing a 20% increase, the other showing a 79% increase. BPA exposure in childhood may or may not increase the risk of asthma too. One study found a 40-50% increase in asthma in children 3-7 years old. Two others, however, only found an increased risk in girls.

Why would a commonly used product cause diseases such as asthma? It's legal, so it must be safe, right? Well, even though BPA only has a six-hour half-life in the body, we are often in contact with it so much that little to no accumulation wouldn't make much difference. Many people also habitually use the same type of products, I have "my brand", you have "your brand". The way that BPA may cause asthma is by interfering with immune function, which may explain the mixed results in research. It may swing the immune response in favour of the T-helper 1 (Th1) cells; in naturopathic circles Th1 dominance is known to put our patients at risk of certain illnesses. Th2 dominance comes with its own risks. Others have shown that BPA could create Th2 dominance. BPA may increase the production of pro-allergic immune chemicals such as IL-4 and IgE, which tell a type of immune cell to start an inflammatory response. BPA may also cause oxidative stress, which has been known to promote diseases (including general aging) for many years. The well-known effects of oxidative stress is why popular health magazines and websites will tell you to drink green tea and eat brightly-coloured fruit and vegetables. It was the first thing I ever heard to do with antiaging, which was why even at 14 I drank green tea more than soft drinks. Overall, while human studies show mixed findings, because of individual differences, there is now more evidence, more reasons to avoid BPA.

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