单选题
Is It Worth Eating an Organic Diet?
Organic or Inorganic A. Sales of organic food have been rising steadily over the past decade, reaching almost $30 billion in 2011, or 4.2% of all U.S. food and beverage sales, according to the Organic Trade Association. Many of the consumers who purchase these products say paying more for organic produce, milk and meat is a trade-off they are willing to make in order to avoid exposure to chemical pesticides and fertilizers and milk from cows given
bovine growth hormone (牛生长激素). Some experts say common sense should tell us that food grown without the help of synthetic chemicals is probably safer and healthier to consume than food containing those substances, even in trace amounts. They believe Americans should try to substitute organic products for conventional ones whenever possible.
B. However, other families, especially those whose food budgets may be more limited wonder if organic food is really worth its hefty price tag. Other experts point out that there isn't enough scientific evidence to say for sure that eating organic food leads to better health. As such, they say the most important dietary advice they can give Americans is to eat more fresh fruit and vegetables and less processed food.
C. Alex Leo, associate professor of environmental exposure biology at the Harvard School of Public Health, argues for eating more organic food. Janet H. Silverstein, a professor of
endocrinology (内分泌学) at the University of Florida and a co-author of an American Association of
Pediatrics (儿科学) study on the health benefits of an organic diet, takes the skeptic's view. So far, researchers haven't been able to provide them with a definitive answer.
Short Exposure to Pesticide D. Is there definitive scientific proof that an organic diet is healthier? 'Not yet,' said Leo. Robust scientific studies comparing food grown organically and food grown conventionally don't exist, thanks to a lack of funding for this kind of research. 'The lack of definitive evidence combined with the higher price of organic food has given skeptics a golden opportunity to argue that organic isn't worth the cost and effort,' he added.
E. While studies in recent years have delivered a decidedly mixed message about the healthfulness of organic food, those on both sides of the debate generally agree that organic produce typically contains fewer pesticides than conventional produce, and that people may be able to reduce or eliminate agricultural chemicals from their bodies by adopting an organic diet. This was illustrated in a study published in the journal
Environmental Health Perspectives in 2006. That study, which was led by Leo, showed that within five days of substituting mostly organic produce for conventional produce in children's diets, pesticides disappeared from the children's
urine(尿液).
Protective Effect F. Many say the pesticides found in our food are nothing to fear because the levels fall well below federal safety guidelines and thus aren't dangerous. Similarly, they say the bovine growth hormone used to increase cows' milk yield is perfectly safe. But federal guidelines don't take into account what effect repeated exposure to low levels of chemicals might have on humans over time. And many pesticides were eventually banned or restricted by the federal government after years of use when they were discovered to be harmful to the environment or human health.
G. Pesticides, in particular, are made to kill organisms, and the President's Cancer Panel in 2010 made clear that it sees them as a threat, advising Americans to 'reduce their cancer risks by choosing, to the extent possible, food grown without pesticides or chemical fertilizers.'
H. Recent field studies showed that organic produce, such as strawberries, leafy vegetables and wheat, not only tastes better but contains much higher levels of
phenolic acids(酚酸) than conventional produce. Phenolic acids can prevent cellular damage, and offer some protection against
oxidative stress (氧化应激), inflammation and cancer.
The Price Debate I. Yes, organic food typically costs more and can be harder to find than traditional food, but one could argue that the price of conventional food is artificially low because of all the subsidies that organic farmers don't get and that the government could do more to help organic farmers lower their costs. Nevertheless, when bought in-season, organic produce is often comparable in price to conventional produce.
J. A good strategy for consumers on limited budgets is to buy the organic versions of foods on the Environmental Working Group's 'Dirty Dozen' list, as they typically contain the most pesticides. Or, consumers could focus on buying the organic versions of the foods they eat most. Knowing that we could reduce our exposure to pesticides and increase our exposure to
antioxidants (抗氧化剂) by eating organic food, it makes great common sense to consume more of it.
K. Organic food is more expensive than conventional offerings, which could make it cost-prohibitive for families on limited food budgets. Given the lack of data showing that organic food leads to better health, it would be counterproductive to encourage people to adopt an organic diet if they end up buying less produce as a result. If families can afford to buy organic and still put a good amount of healthy food on the table, then the decision about whether to spend the extra money on organic produce, milk and meat should be based on a solid understanding of what we do and don't know about the benefits.
Pesticides and Safety L. It is difficult to compare the nutritional value of organic versus conventional food because the soil, climate, timing of harvest, and storage conditions all affect the composition of produce. Still, published studies have found no significant differences in nutritional quality between organic and nonorganic produce or milk. Similarly, there is no evidence that giving bovine growth hormone (BGH) to cows changes the composition of milk or affects human health. BGH is inactive in humans and degrades in the acidic environment of the stomach. As for pesticide exposure, the U.S. in 1996 established maximum permissible levels for pesticide residues in food to ensure food safety. Many studies have shown that pesticides levels in conventional produce fall well below those guidelines.
M. While it's true that organic fruits and vegetables in general contain fewer traces of these chemicals, we can't draw conclusions about what that means for health as there haven't been any long-term studies comparing the relationship between exposure to pesticides from organic versus nonorganic foods and adverse health outcomes. It may seem like 'common sense' to reduce exposure to these chemicals, but there are currently no good evidence-based studies to answer the question.
N. While awaiting definitive studies, families on limited budgets who are concerned about pesticide exposure can refer to the Environmental Working Group's list of the 'Dirty Dozen,' those foods with the highest pesticide residues, and the 'Clean 15', the foods with the lowest pesticide concentrations. A good strategy would be to focus on buying organic versions of the foods on the 'Dirty Dozen' listing.
Don't Trust Labels O. We would like to think that organic food is grown locally, put in a wheelbarrow and brought directly to our homes. However, much of it comes from countries where regulations might not be as tightly enforced as in the U.S., and labeling of the foods might be misleading.
P. And just because food is labeled organic doesn't mean it is completely free of pesticides. Contamination can occur from soil and ground water containing previously used chemicals, or during transport, processing and storage.
Organochlorine insecticides(有机氯杀虫剂) were recently found in organically grown root crops and tomatoes even though these pesticides haven't been used for 20 years.