Why Getting Dirty Can Be Healthy for Children

To get the full value of joy， you must have someone to divide it with. 要想找到快樂的真諦，就該和人一起分享。

Everyone has a past， but don’t let it get in the way of how you build your future. 誰(shuí)都有過(guò)去，但不要讓過(guò)去妨礙了自己去創(chuàng)造未來(lái)。

“不干不凈，不會(huì)生病”，這本來(lái)是人們自我解嘲的托詞。但頂級(jí)美國(guó)科學(xué)家卻證明了它的合理性。

A new study suggests that early exposure to germsgerm：微生物；細(xì)菌。 strengthens the immune systemimmune：system 免疫系統(tǒng)。. That means letting children get a little dirty might be good for their health later in life.

The study involvedinvolve：包含，牽涉，牽連。 laboratory mice. It found that adult mice raised in a germfree environment were more likely to develop allergiesallergies：變態(tài)反應(yīng)性；過(guò)敏癥。， asthmaasthma：哮喘。 and other autoimmune disordersautoimmune disorders：自身免疫性疾病。. There are more than eighty disorders where cells that normally defend the body instead attack tissues and organs.

They include rheumatoid arthritisrheumatoid arthritis：類風(fēng)濕關(guān)節(jié)炎。， which attacks the joints; Crohn’s diseaseCrohn’s disease：克羅恩病。， an inflammatory bowel conditioninflammatory bowel condition：炎癥性腸病。; and juvenile diabetesjuvenile diabetes：青少年糖尿病。. Hay fever， a common allergy， is also an autoimmune disorder.

Richard Blumberg is a professor at Harvard Medical School in Boston， Massachusetts. He says in nineteen eightynine， medical researchers sought to explain these diseases with what they called the “hygiene hypothesishygiene hypothesis：衛(wèi)生假說(shuō)。.” They proposed that the increasing use of antibacterial soapsantibacterial soaps：抗菌肥皂。 and other products， especially early in life， could weaken immune systems.

RICHARD BLUMBERG: “The hypothesis has stated or suggested that earlylife exposure to microbesmicrobes：微生物。 is a very important determinantdeterminant：決定因素。 of later life sensitivity to allergic and socalled autoimmune diseases， such as hay fever， asthma， inflammatory bowel disease and others.”

Now， Dr. Blumberg and a team have what they say is the first biological evidence to link early exposure to germs to stronger adult immune systems. They say this exposure could prevent the development of some autoimmune diseases.

In the adult germfree mice， they found that inflammation in the lungs and coloncolon：結(jié)腸。 was caused by socalled killer T cells. These normally fight infection. But they became overactive and targeted healthy tissue—an autoimmune condition seen in asthma and a disease called ulcerative colitisulcerative colitis：潰瘍性結(jié)腸炎。.

Dr. Blumberg says the mice raised in a normal environment did not have the same reaction. He says their immune systems had been “educated” by early exposure to germs.

RICHARD BLUMBERG: “What was really most remarkable to us was the fact that once the education event provided by the microbes occurred in early life， it was durable and lasted throughout the life of the animal.”

Rates of autoimmune disorders are rising worldwide， but mostly in wealthier， industrialized countries.

RICHARD BLUMBERG: “I think one obvious question， for example， that’s raised by these studies is the early life use of antibioticsantibiotics：抗生素。 and whether we need to be more careful in their prescribingprescribing：開處方。.”

Rob Dunn is a professor of ecology and evolutionary biologyecology and evolutionary biology：生態(tài)學(xué)和進(jìn)化生物學(xué)。 at North Carolina State University in Raleigh. He says the new study does not mean people should stop washing.

ROB DUNN: “Wash your hands， but don’t do it with antimicrobial soap. Let your kids play in a reasonable amount of dirt and get outside and get exposed to a diversity ofa diversity of：多樣性的。 things.”