The influence of plastic parts on human beings is underestimated? The exposure is still 44 times as expected.

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Plastic products can be seen everywhere in life. Many plastic products such as mineral water bottles, food packaging bags, cups and lunch boxes contain a substance called bisphenol A. It is generally believed that frequent contact with this chemical is safe for human body. But now, experts may have to re-examine this ingredient and related materials.

A recently published study found that the previous measurement methods adopted by regulatory agencies, including the FDA of the United States, were flawed, far underestimating the exposure of human body to BPA, and the actual BPA level in human body may be dozens of times higher than originally thought!

In order to understand the significance of this study, we should first look at why we need to pay attention to the problem of human exposure to bisphenol A.

On the one hand, BPA is very common, with an annual global output of about 9 million tons, which is widely used in plastic products, especially plastic drinks. Therefore, daily human contact is inevitable. For example, when the plastic containing polycarbonate is heated to about 60 degrees, it is easy to release BPA. Due to the stability of the material, it will slowly release BPA after long-term use.

On the other hand, previous animal studies have shown that BPA can interfere with endocrine system, including various biological pathways mediated by estrogen, androgen, progesterone and thyroid hormone; Fetal exposure to BPA is associated with an increased risk of growth, metabolism, behavior, reproduction and even cancer.

However, whether BPA exposure in daily life will cause health risks to human body is still controversial, especially it has not been confirmed by regulatory guidelines. For example, by evaluating the research data of measuring BPA in human urine, the FDA believes that the daily exposure level of human exposure to this chemical is very low and can be ignored.

Image source: Pixabay

New research challenges this. The discovery that affects our cognition stems from a more accurate measurement method of BPA. The metabolic rate of BPA in human body is relatively fast. Therefore, to accurately evaluate the exposure of bisphenol A, we should not only evaluate the content of bisphenol A in human body, but also determine its main metabolites. However, in the past, due to the lack of relevant standards, it was difficult to directly and accurately determine the content of the main metabolites of BPA, and most studies had to indirectly determine them. Professor Roy Gerona of the University of California, San Francisco and his team developed a new method to overcome this point and realize the direct measurement of BPA metabolites themselves.

The research team compared the old and new measurement methods and analyzed 39 urine samples. Considering the potential impact on the fetus and the physiological changes brought by pregnancy may affect BPA metabolism, the samples are from 29 pregnant women, 5 non-pregnant women and 5 men.

Through the analysis of pregnant women's samples, it is found that the BPA content measured by the new direct method is much higher, with an average of 5 1.99 ng/ml, which is 9 times that of the indirect method/kloc-0 and 44 times that of the national health and nutrition inspection report of the United States! With the increase of BPA exposure, the difference between the two methods is more obvious. In other words, the greater the exposure, the underestimation of the original method. By analyzing other 10 samples, the observed trends are consistent.

With the increase of exposure, the BPA content measured by the new method is obviously higher than that by the old method.

Professor Patricia Hunt, the author of the paper and a BPA expert at Washington State University, said: "Are we cautious enough about the safety of this chemical? This study is a serious reminder to us. The supervision of BPA by regulators may be based on inaccurate measurement results. "

The significance of this discovery is not limited to our understanding of BPA. Professor Gerona pointed out: "BPA is not the only chemical substance indirectly measured by NHANES that affects endocrine. If our findings are correct for BPA, then human exposure to other chemicals measured by similar methods may also be underestimated. "

At present, the research team is also using new methods to measure the human exposure of other applicable chemicals, such as benzoic acid esters, benzophenone and triclosan contained in many cosmetics and soaps, and phthalate esters, a common plasticizer in toys, food packaging and personal care products.

Image source: Pexles

Of course, it is difficult to subvert the existing regulatory standards by just one study, and what higher exposure dose means has not been answered yet. We need more research to reproduce and verify this problem. Professor Gerona said, "I hope this research will draw people's attention to the measurement method of BPA, and I also hope that more experts and experimental teams will independently evaluate it more carefully."

Before further scientific verification, what we can do is to use plastic products correctly under the existing guidance. Generally speaking, there is a triangular recyclable sign and number at the bottom of the plastic container, so you may wish to pay attention to and remember:

Image source: Pixabay

1 plastic is often used as the material of mineral water bottles and beverage bottles, and cannot be filled with hot water or heated, and cannot be recycled after 10 months;

No.2 plastic is often used as the container material of medicine bottles and toiletries, and cannot be used for food and recycling.

No.3 plastic is often used as raincoats, building materials, non-food containers and other materials. It can't hold food and can't be recycled. Toxic gases are produced when heated.

No.4 plastic is often used as plastic wrap and plastic film material and cannot be heated;

No.5 plastic is often used as the material of buckets and food containers, which can be heated by microwave oven and recycled.

No.6 plastic is often used as building materials, toys, instant noodle boxes in bowls, fast food boxes and other materials. Microwave heating is not allowed, and acidic drinks such as orange juice are not allowed.

No.7 plastic contains many kinds, and the details need further explanation. Among them, polycarbonate is often used as the material of kettle and baby bottle, which cannot be heated.

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