Researchers found that people exposed to higher levels of DINCH, a chemical used in plastics and consumer products, may have a higher risk of developing rheumatoid arthritis (RA), a disease where the immune system attacks joint tissues. The study analyzed data from over 4,000 American adults and discovered that those with higher levels of this chemical in their urine were more likely to have RA, especially if they had low vitamin D levels. While this doesn’t prove the chemical causes RA, it suggests a possible connection worth investigating further.

The Quick Take

  • What they studied: Whether a plastic chemical called DINCH that people are exposed to through everyday products is connected to rheumatoid arthritis, a painful joint disease.
  • Who participated: Over 4,000 American adults from a large national health survey conducted between 2013 and 2018. The group included people of different ages, backgrounds, and health statuses.
  • Key finding: Adults with higher amounts of DINCH in their urine were about 44% more likely to have rheumatoid arthritis compared to those with lower amounts. This connection was even stronger in people who didn’t have enough vitamin D in their blood.
  • What it means for you: This research suggests that reducing exposure to DINCH and maintaining healthy vitamin D levels might be worth considering, especially if you’re concerned about joint health. However, this is early-stage research, and you should talk to your doctor before making major changes based on this finding alone.

The Research Details

This was a cross-sectional study, which means researchers took a snapshot of a large group of people at one point in time and looked for connections between their DINCH exposure and whether they had rheumatoid arthritis. The researchers used data from the National Health and Nutrition Examination Survey (NHANES), a well-established program that tracks the health of Americans. They measured DINCH levels in urine samples and compared people with higher levels to those with lower levels, while accounting for other factors that might affect arthritis risk like age, weight, and smoking status. The researchers also looked at whether vitamin D played a role in this connection by analyzing how much vitamin D people had in their blood.

This type of study is useful for spotting potential health risks from everyday chemicals we’re exposed to. By using a large, representative sample of the American population, the findings are more likely to apply to real people rather than just laboratory conditions. The researchers also looked at vitamin D as a possible explanation for why DINCH might affect arthritis risk, which helps us understand the mechanism behind the connection.

The study used a large, nationally representative sample of over 4,000 people, which strengthens the findings. The researchers carefully controlled for other factors that could influence arthritis risk. However, because this is a cross-sectional study, it shows an association but cannot prove that DINCH actually causes arthritis. The study also relied on urine samples taken at one point in time, which may not fully represent someone’s long-term exposure to this chemical.

What the Results Show

Among the 4,263 participants with complete information, people with urinary DINCH levels higher than 1.0 nanograms per milliliter were 44% more likely to have rheumatoid arthritis compared to those with lower levels. This difference was statistically significant, meaning it’s unlikely to have happened by chance. When researchers looked at whether higher DINCH levels were connected to higher arthritis rates across the entire group, they found a clear trend: as DINCH levels went up, so did arthritis rates. The connection was particularly strong in people who had low vitamin D levels in their blood. In this subgroup, people with higher DINCH exposure were 79% more likely to have arthritis. The researchers also found evidence that vitamin D might partially explain how DINCH affects arthritis risk, accounting for about 4.7% of the connection.

The study found that the DINCH-arthritis connection was more pronounced in certain groups of people, particularly those with insufficient vitamin D levels. This suggests that vitamin D status might be an important factor in how this chemical affects joint health. The researchers tested their findings in different ways to make sure the results were reliable, and the connection held up across these different analyses.

While DINCH is a newer plastic chemical designed to replace phthalates (older chemicals that were found to be harmful), very little research has looked at its effects on arthritis. This study is among the first to examine this specific connection. Previous research has shown that other environmental chemicals can influence arthritis risk, so finding a link with DINCH fits with what we know about how outside factors can trigger or worsen this disease.

This study shows a connection between DINCH and arthritis but cannot prove that DINCH causes arthritis. The researchers measured DINCH only once, so they don’t know if people’s exposure levels stayed the same over time. The study is also observational, meaning people weren’t randomly assigned to different DINCH exposure levels—researchers just looked at what naturally occurred. Some people in the original survey didn’t have complete information, though the researchers did analyses to account for this. Additionally, the study cannot rule out that other unmeasured factors might explain the connection between DINCH and arthritis.

The Bottom Line

Based on this research, maintaining adequate vitamin D levels appears important for joint health, particularly if you’re concerned about arthritis risk. You might consider reducing unnecessary exposure to plastics and consumer products containing DINCH, though this chemical is difficult to completely avoid in modern life. If you have concerns about arthritis risk or vitamin D levels, talk to your doctor about testing and personalized recommendations. (Confidence level: Moderate—this is early research showing an association, not definitive proof of cause and effect.)

This research is most relevant to people concerned about arthritis prevention, those with a family history of rheumatoid arthritis, and individuals with low vitamin D levels. People already diagnosed with rheumatoid arthritis might also find this information useful for understanding potential contributing factors. However, this research doesn’t change current treatment recommendations for people who already have arthritis.

If you make changes based on this research, such as improving vitamin D levels, you wouldn’t expect to see dramatic changes in arthritis risk immediately. Vitamin D levels typically take several weeks to months to improve with supplementation or increased sun exposure. Any protective effects from reducing DINCH exposure would likely take much longer to become apparent, as arthritis develops over years.

Want to Apply This Research?

  • Track your vitamin D levels quarterly through blood tests, and log any joint pain or stiffness symptoms weekly using a simple 1-10 pain scale. Note any changes in plastic product use or dietary vitamin D intake.
  • Set a reminder to check vitamin D levels annually and discuss supplementation with your doctor if levels are low. Gradually reduce use of single-use plastics and choose glass or stainless steel containers when possible. Increase vitamin D-rich foods like fatty fish, egg yolks, and fortified dairy products.
  • Create a monthly dashboard showing vitamin D test results, joint symptom scores, and plastic exposure reduction efforts. Compare trends over 3-6 month periods to see if maintaining better vitamin D levels correlates with fewer joint symptoms. Share results with your healthcare provider during annual checkups.

This research shows an association between DINCH exposure and rheumatoid arthritis but does not prove that DINCH causes arthritis. This study should not be used to diagnose or treat any medical condition. If you have concerns about arthritis risk, vitamin D levels, or chemical exposure, please consult with your healthcare provider. Do not stop or change any current arthritis medications or treatments based on this research. This information is for educational purposes only and is not a substitute for professional medical advice.