Diet strongest source of mercury exposure in Guizhou province

China’s dietary staple is likely the primary source of inorganic mercury exposure in Guizhou province, even for those living in close proximity to mercury (Hg)  mines, a recent study found.

While rice has long been established as one of the major sources of mercury for residents in Guizhou,  little research has been done for those living in high-risk areas such as near Hg mines.

Seeking to better understand the risk of exposure, scientists from State Key Laboratory of Environmental Geochemistry with the Chinese Academy of Social Sciences tested urinary mercury levels of residents living within 3km of waste heaps from  the Wanshan Hg mining area in Guizhou.

Most suprisingly, they found that dietary intake, rather than fumes from the mine was still the main source of toxic exposure to Hg.

“By calculation of Probable Daily Intake from different routes, we found that dietary intake is the main pathway of IHg exposure for the local population, rather than inhalation of Hg vapor,” the study, Human inorganic mercury exposure, renal effects and possible pathways in Wanshan mercury mining area, China, said.

“It demonstrated a gradient of (urinary mercury) concentrations with the distance from the pollution sources,” the study said.

Testing the effects of exposure to mercury on eye sight, they found those in the area had impaired retinal function.

The study was published online by Environmental Research journal  on April 9.

Food allergies compared among SE Chinese and Russian children

Like many aspects of child development, environment plays a huge role in which foods children have an adverse reaction to.

A recent study tested more than 2000 children aged 7-10  in an attempt  to find how food sensitivities differ among children in the West Siberian city of Tomsk, south eastern China’s Guangdong province, rural Shaoguan city and Hong Kong.

“Compared to Europe, little is known about sensitization to food and inhalant sources in Russia and China,” the study said.

Scientists from 7 universities, including the Chinese University of Hong Kong and the Imperial College of London, found local diet and environment played a huge role in dictating allergies.

Shrimp and Crab were the most common sensitivities for Chinese children among the 27 foods and 8 inhalants tested, with  7-25% and  4-9% respectively of children showing reactions to the two foods.

Despite a heavy seafood diet,  Hong Kong children showed the most sensitivity to milk at 17% and to egg at 15%.

In Tomsk, Hazelnuts and fruits  – both common in the Russian diet – were the most prevalent allergens, with both around 6%. In Guangzhou, allergies to hazelnuts were virtually non-existant, the study said.

When testing inhalants, Chinese children showed an unexpectantly high sensitivity to house dust mites (HDM), with an overall average of ~39%.

In Hong Kong, a staggering 79% showed sensitivty to HDM, compared to just 13% in Tomsk.

“Sensitization profiles in Tomsk are dominated by birch pollen cross-reactivity, similar to what is common in Central and Northern Europe,” the study, Food sensitisation profiles in school-aged children from China and Russia, said.

“In contrast, sensitization to HDM and sea foods dominated the picture in China.”

“Whether house dust mite sensitization is (partly) at the basis of the high prevalence of seafood sensitization (e.g. via Der p 10/tropomyosin) or whether it is the seafood-rich diet, is currently under investigation.”

It was published in  Clinical and Translational Allergy 2015 on March 30.