The San Francisco Department of Public Health has revealed that two people are critically ill and are now in the hospital after drinking toxic herbal tea that they bought at a Chinatown shop.

The patients, a woman and a man, became ill within an hour of drinking tea made from leaves they bought from Sun Wing Wo Trading Co. The two individuals quickly experienced weakness, which was followed by potentially fatal abnormal heart rhythms that required resuscitation and intensive hospital care.

Toxin Found In Tea Samples And Patients

Lab tests of the tea samples and the patients revealed the likely culprit of the poisoning as aconite, a plant that contains some toxic chemicals including strong and fast-acting poison that can cause severe side effects which include sweating, weakness or inability to move, nausea, breathing problems, heart problems and even death.

Aconite, an herbal medicine that has been used in Asia for thousands of years, is used as treatment for bruises, pains and other conditions. Although its plant's flowers are highly toxic in natural state, they can be safely consumed once properly processed. Poisoning incidents associated with aconite, however, still occur.

The city's health officer, Tomás Aragón, urged those who have purchased tea from the shop to not consume it and throw it immediately saying that aconite poisoning attacks the heart and can be deadly. Aconite poisoning also does not have an antidote.

Symptoms of poisoning tend to occur just a few minutes or up to several hours after consumption. Health officials likewise said that those who have consumed the tea but did not experience symptoms should still stop consuming it as a precautionary measure.

Other Risks Of Drinking Tea

Tea is a popular beverage around the world but while it has been associated with a number of health benefits, certain risks may come when sipping this popular brew.

As evidence by the incidents in San Francisco shows, tea can contain or absorb toxic compounds, which can be traced to the soil, environment, as well as manner of harvesting, storage and brewing.

In a 2013 study, researchers who tested 30 tea samples found that all contain high amount of lead, which is linked to increased risk for kidney, heart and reproductive issues. Another study published in 2015 likewise found that teas with added citric acid have increased levels of aluminum, lead and cadmium, with lemon tea bags found to produce up to 70 times higher levels of these heavy metals.

Researchers likewise found that economy teas have fluoride levels that exceed daily recommended levels. Too much fluoride has been linked to damaged teeth, joints and bones.

Staying Safe When Drinking Tea

Observing precautionary measures, however, can keep tea-drinkers safe when sipping their favorite drink. Health experts, for instance, advise avoiding tea from regions that are known to be more contaminated such as India, China and Sri Lanka.

"Tea from China has high levels of lead and aluminum, likely from contaminated soil due to coal fired power plants," said Gerry Schwarfenberg, from the University of Alberta, Edmonton in Canada.

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