You can cut your cancer risk by eating organic, a new study says

By Susan Scutti, CNN

Updated 1500 GMT (2300 HKT) October 22, 2018

Chat with us in Facebook Messenger. Find out what's happening in the world as it unfolds.

Fewer than 1% of avocados tested positive for pesticides. Best of all, only one pesticide of any kind was found on all the avocados tested. For these reasons, the Environmental Working Group ranked avocados as the No. 1 cleanest produce.

Photos: 2018's 'Clean 15'

Avocados – Fewer than 1% of avocados tested positive for pesticides. Best of all, only one pesticide of any kind was found on all the avocados tested. For these reasons, the Environmental Working Group ranked avocados as the No. 1 cleanest produce.

Hide Caption

1 of 15

Less than 2% of sweet corn, the second-cleanest produce, showed detectable levels of pesticides. Because a small portion of corn is grown from genetically modified seeds, the group suggests that those who wish to avoid genetically altered foods buy organic corn.

Photos: 2018's 'Clean 15'

Sweet corn – Less than 2% of sweet corn, the second-cleanest produce, showed detectable levels of pesticides. Because a small portion of corn is grown from genetically modified seeds, the group suggests that those who wish to avoid genetically altered foods buy organic corn.

Hide Caption

2 of 15

Nearly all the pineapples tested -- 90% -- showed no residual pesticides, while just five pesticides could be detected on any of the samples. For these reasons, pineapples fill position three on the clean list.

Photos: 2018's 'Clean 15'

Pineapples – Nearly all the pineapples tested -- 90% -- showed no residual pesticides, while just five pesticides could be detected on any of the samples. For these reasons, pineapples fill position three on the clean list.

Hide Caption

3 of 15

Overall, 86% of cabbage samples contained no detectable pesticides. Additionally, just two of more than 700 samples tested contained more than one pesticide. For these reasons, cabbage ranked fourth on the list of cleanest produce.

Photos: 2018's 'Clean 15'

Cabbage – Overall, 86% of cabbage samples contained no detectable pesticides. Additionally, just two of more than 700 samples tested contained more than one pesticide. For these reasons, cabbage ranked fourth on the list of cleanest produce.

Hide Caption

4 of 15

Photos: 2018's 'Clean 15'

Onions – Fifth-placed onions contained three or fewer pesticides overall, while fewer than one in 10 contained any pesticides.

Hide Caption

5 of 15

Frozen sweet peas ranked sixth on this year's clean produce list due to the fact that none of the tested samples contained more than two pesticides. Overall, about eight out of every 10 frozen sweet pea samples tested negative for pesticides.

Photos: 2018's 'Clean 15'

Frozen sweet peas – Frozen sweet peas ranked sixth on this year's clean produce list due to the fact that none of the tested samples contained more than two pesticides. Overall, about eight out of every 10 frozen sweet pea samples tested negative for pesticides.

Hide Caption

6 of 15

With no samples testing positive for more than three pesticides, papayas take seventh place on the list of clean fruits and veggies. The Environmental Working Group found that eight out of every 10 had no pesticide residues.

Photos: 2018's 'Clean 15'

Papayas – With no samples testing positive for more than three pesticides, papayas take seventh place on the list of clean fruits and veggies. The Environmental Working Group found that eight out of every 10 had no pesticide residues.

Hide Caption

7 of 15

Asparagus samples mostly tested negative for pesticides: Ninety percent were clean, according to the group, and no more than three pesticides were found on any one sample of this vegetable. Asparagus ranks eighth among the cleanest produce.

Photos: 2018's 'Clean 15'

Asparagus – Asparagus samples mostly tested negative for pesticides: Ninety percent were clean, according to the group, and no more than three pesticides were found on any one sample of this vegetable. Asparagus ranks eighth among the cleanest produce.

Hide Caption

8 of 15

Ninth-cleanest among all the different kinds of produce, mango samples showed no more than two pesticides when tested, while just over three-quarters tested negative for any and all chemical residue.

Photos: 2018's 'Clean 15'

Mango – Ninth-cleanest among all the different kinds of produce, mango samples showed no more than two pesticides when tested, while just over three-quarters tested negative for any and all chemical residue.

Hide Caption

9 of 15

Eggplant showed themselves guilty, at worst, of contamination with three types of pesticides, according to the group. Best of all, almost three out of every four tested eggplants contained no pesticides whatsoever. Thus, eggplants ranked last on the top 10 within the "Clean 15" list.

Photos: 2018's 'Clean 15'

Eggplant – Eggplant showed themselves guilty, at worst, of contamination with three types of pesticides, according to the group. Best of all, almost three out of every four tested eggplants contained no pesticides whatsoever. Thus, eggplants ranked last on the top 10 within the "Clean 15" list.

Hide Caption

10 of 15

Half of honeydew melons tested negative for pesticides, while no more than four pesticides were found on any of the honeydew samples. And so, honeydew melon slips into position 11 on the clean list.

Photos: 2018's 'Clean 15'

Honeydew Melon – Half of honeydew melons tested negative for pesticides, while no more than four pesticides were found on any of the honeydew samples. And so, honeydew melon slips into position 11 on the clean list.

Hide Caption

11 of 15

Lovely green kiwis were mostly pesticide free when tested: Sixty-five percent of all samples showed no chemicals, while only six pesticides could be found on any of the samples.

Photos: 2018's 'Clean 15'

Kiwi – Lovely green kiwis were mostly pesticide free when tested: Sixty-five percent of all samples showed no chemicals, while only six pesticides could be found on any of the samples.

Hide Caption

12 of 15

Overall, one out of 10 cantaloupe samples contained more than one pesticide, and more than 60% contained no pesticide residues. This orange melon ranked lucky 13 on the clean list.

Photos: 2018's 'Clean 15'

Cantaloupe melon – Overall, one out of 10 cantaloupe samples contained more than one pesticide, and more than 60% contained no pesticide residues. This orange melon ranked lucky 13 on the clean list.

Hide Caption

13 of 15

No pesticides were detected on about half of the cauliflower samples and none contained more than three separate chemicals. This is why cauliflower took the penultimate position on the "Clean 15" list.

Photos: 2018's 'Clean 15'

Cauliflower – No pesticides were detected on about half of the cauliflower samples and none contained more than three separate chemicals. This is why cauliflower took the penultimate position on the "Clean 15" list.

Hide Caption

14 of 15

Last but not least, broccoli found its way onto the list of cleanest produce. Seven out of 10 samples showed no pesticide residue, while only one in 10 contained more than one pesticide.

Photos: 2018's 'Clean 15'

Broccoli – Last but not least, broccoli found its way onto the list of cleanest produce. Seven out of 10 samples showed no pesticide residue, while only one in 10 contained more than one pesticide.

Hide Caption

15 of 15

06 clean 15 fruits and vegetables 2018 RESTRICTED

10 clean 15 fruits and vegetables 2018 RESTRICTED

11 clean 15 fruits and vegetables 2018 RESTRICTED

12 clean 15 fruits and vegetables 2018 RESTRICTED

Story highlights

More than 68,000 French adults took part in the study
Those who ate the most organic food were 25% less likely to develop cancer

(CNN)You can protect yourself from cancer by eating organic, a new study suggests. Those who frequently eat organic foods lowered their overall risk of developing cancer, a study published Monday in JAMA Internal Medicine finds. Specifically, those who primarily eat organic foods were more likely to ward off non-Hodgkin lymphoma and postmenopausal breast cancer compared to those who rarely or never ate organic foods.

Led by Julia Baudry, an epidemiologist at Institut National de la Sante et de la Recherche Medicale in France, a team of researchers looked at the diets of 68,946 French adults. More than three-quarters of the volunteers were women, in their mid-40s on average. These volunteers were categorized into four groups depending on how often they reported eating 16 organic products, including fruits and vegetables, meat and fish, ready-to-eat meals, vegetable oils and condiments, dietary supplements and other products.

Are there too many antibiotics in your fast food meat?

Follow-up time varied for each participant but lasted slightly more than four and a half years on average, and during that time, the study volunteers developed a total of 1,340 cancers. The most prevalent was breast cancer (459) followed by prostate cancer (180), skin cancer (135), colorectal cancer (99), and non-Hodgkin lymphomas (47).

The authors calculated cancer risk

Comparing the participants' organic food scores with cancer cases, the researchers calculated a negative relationship between high scores (eating the most organic food) and overall cancer risk. Those who ate the most organic food were 25% less likely to develop cancer. Specifically, they were 73% less likely to develop non-Hodgkin lymphoma and 21% less likely to develop post-menopausal breast cancer.

Even participants who ate low-to-medium quality diets yet stuck with organic food experienced a reduced risk of cancer, the authors found.

The authors theorize a "possible explanation" for the negative relationship between organic food and cancer risk stems from the "significant" reduction of contamination that occurs when conventional foods are replaced by organic foods.

Household disinfectants could be making kids overweight, study says

"If the findings are confirmed, promoting organic food consumption in the general population could be a promising preventive strategy against cancer," Baudry and her colleagues concluded.

Dr. Jorge E. Chavarro, an associate professor in the Department of Nutrition at Harvard T.H. Chan School of Public Health, said in a podcast that the new study is "incredibly important." He co-authored a commentary published with the study.

Most people who are not employed in agriculture are exposed to pesticide residues through food, said Chavarro, who was not involved in the study.

The new findings are consistent with those of the International Agency for Research in Cancer, which found pesticides are cancer causing in humans, noted Chavarro. They also align with those of another study that showed a negative relationship between eating organic food and non-Hodgkin lymphoma, he said.

Unsafe levels of a weed killer chemical in oat products, report says

However, Chavarro added that researchers designing future studies should be mindful of certain limitations in this new study.

Drawbacks of the study

"Assessing intake of diet is difficult, assessing intake of organic foods is notoriously difficult," said Chavarro. "That is because deciding to eat organic foods or not is a decision that has very strong social and economic determinants. Even though the authors had access to information of why people are choosing not to eat organic foods, they consider all non-consumers of organic foods the same."

Study ties pesticides in food to reduced fertility in women

For example, people who choose not to eat organic despite being able to afford to do so might have a poor attitude toward their health in general and that would likely influence the results.

Chavarro also said it is unclear that quantifying organic food consumption is really calculating what the study authors want to measure -- reduced exposure to pesticide residues through diet.

It's true that previous research, including one of Chavarro's own studies, have shown a correlation between organic food consumption and pesticide levels in urine, so the assumption is not incorrect. Still the authors need to show this, he said in the podcast about the study. And, different conventional foods are more "dirty" (contaminated with pesticides) than others, he said, so eating certain organic foods does a better job of protecting us against ingesting pesticides than others. Yet the study does not do a good job of sorting and evaluating these differences, he noted.

Get CNN Health's weekly newsletter

"At the current stage of research, the relationship between organic food consumption and cancer risk is still unclear," Chavarro and his co-authors wrote in the commentary.

In the end, the study's takeaway, according to Chavarro, is that we should all probably be paying more attention to how much organic food we eat and "we should probably be studying this more."