Week 10: Environmental Health

This week we covered environmental health, focusing specifically on common toxins and toxicants in China and their health effects, the basics of epidemiology, air pollution, and the effects of acid rain. The prevalence of diseases such as chronic bronchitis, asthma, and other respiratory disorders amongst Chinese citizen are well-characterized, and have been directly linked to noxious emissions such as PM10. While the current emission standards in China are not as stringent as the standards proposed by the World Health Organization, the greatest contributing factor to chronic respiratory illness in China has been the failure of the Chinese national government to successfully implement and enforce the standards they have mandated. As a result, past and current levels of emissions in many Chinese cities such as Beijing, have been higher than these acceptable standards. The prevalence of chronic respiratory illness among the citizens of Beijing and the corresponding increase in mortalities has lowered the life expectancy in comparison to similarly developed cities such as Shanghai. Although Shanghai, in recent years, has met the Class II PM10 standard for residential and commercial areas and its citizens enjoy the highest life expectancy amongst all provinces of mainland China, residents of this city are still susceptible to respiratory illness. According to World Health Organization, the WHO AQG standards represent the minimum level of PM10 that is correlated with an increased risk of developing respiratory illness with 95% confidence. An increase in 10 µg/m of PM10 from these standards represents a 15% greater chance of developing respiratory illness. China Class II Standards for PM10 are 100 µg/m, 5 times higher than the WHO AQG standard. From this data, it is clear that current emissions standards in China are far from acceptable in terms of protecting citizens from respiratory disease.

Other air pollutants, such as NOx and SO2, contribute directly towards acid rain, whose devastating effects on forests and bodies of water are well-known. This week however, we also studied the lesser known health impacts of acid rain. Acid rain contributes to the buildup of mercury in fish, by favoring the ionic form of mercury in acidic water. Mercury ions can be converted into methylmercury by certain bacteria, and methylmercury is much more lipophilic and able to pass through body membranes than mercury. Acid rain also causes increased leaching of metals, including toxic heavy metals into waterways where people are more likely to be exposed to them. Cadmium in particular is dangerous because it can be taken up by crops, especially dark leafy greens and tobacco, which poses health hazards to the people who consume these goods.

In the face of such devastating environmental consequences, it is difficult to see how this situation can be reversed. However, there is a bright side: many technological changes have occurred that are not reflected in the current data, and motions have been made for China to increase the stringency of their emissions standards. Using a combined technological and policy-based approach, China has the potential to enjoy fresh air, clean water, and blue skies once more.