I recall a case study from uni where two epidemiologists studied respiratory hypersensitivity in East and West Germany in 1990 and 1991. The idea was that ethnically the two sample sets should be identical, but the environments in which the children grew up were different.
Here's the abstract:
We assessed the prevalence of asthma and allergic disorders in 9–11 year old children in Leipzig and Halle in East Germany, and Munich, West Germany. Both East German cities were heavily polluted due to private coal burning and industrial emissions, whereas Munich has moderate industry but heavy car traffic. All fourth grade pupils in Munich (n = 7445) were compared with those in Leipzig, 1990 (n = 1429) and Leipzig and Halle, 1991 (n = 3105). The prevalence of hay fever and skin test reactivity to common aeroallergens was considerably higher in West Germany as compared to East Germany. Furthermore, the prevalence of asthma was also higher in the West German study area. However, when atopy was taken into account, there was no longer a significant difference in the prevalence of asthma between the two parts of the country.
If you read the whole article (not free online unfortunately) the basic findings were that children who grew up exposed to some dirt and grime had better resistance to them, and were overall healthier than the kids whose well meaning parents ran after them with hand sanitizers, surface disinfectants, anti-bacterial swabs etc etc.
Such parents probably mean well, but they end up doing their children long term harm.
I'm with Amoud.
I recall a case study from uni where two epidemiologists studied respiratory hypersensitivity in East and West Germany in 1990 and 1991. The idea was that ethnically the two sample sets should be identical, but the environments in which the children grew up were different.
Here's the abstract:
We assessed the prevalence of asthma and allergic disorders in 9–11 year old children in Leipzig and Halle in East Germany, and Munich, West Germany. Both East German cities were heavily polluted due to private coal burning and industrial emissions, whereas Munich has moderate industry but heavy car traffic. All fourth grade pupils in Munich (n = 7445) were compared with those in Leipzig, 1990 (n = 1429) and Leipzig and Halle, 1991 (n = 3105). The prevalence of hay fever and skin test reactivity to common aeroallergens was considerably higher in West Germany as compared to East Germany. Furthermore, the prevalence of asthma was also higher in the West German study area. However, when atopy was taken into account, there was no longer a significant difference in the prevalence of asthma between the two parts of the country.
http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6TCR-3W0FBNM-K...
If you read the whole article (not free online unfortunately) the basic findings were that children who grew up exposed to some dirt and grime had better resistance to them, and were overall healthier than the kids whose well meaning parents ran after them with hand sanitizers, surface disinfectants, anti-bacterial swabs etc etc.
Such parents probably mean well, but they end up doing their children long term harm.