DINCH was introduced as an alternative to controversial phthalates. Now a study of more than 6,600 pregnancies raises questions about whether the replacement is really safer.
The plastic wrapping around your food, the vinyl flooring beneath your feet and even some medical equipment may contain chemicals added to make plastic flexible. For years, manufacturers have been replacing controversial phthalates with alternatives advertised as safer. But what happens when the replacement turns out to have health concerns of its own?
A new study published in Environment International suggests that prenatal exposure to one such replacement, called DINCH, is associated with smaller babies at birth. Researchers led by Leonardo Trasande of NYU Langone Health examined 6,617 pregnancies across 22 American research cohorts. They found that higher levels of DINCH-related chemicals in pregnant women’s urine were associated with lower birth weights and an increased likelihood of babies being born small for their gestational age.
For every tenfold increase in one measured marker of DINCH exposure, babies weighed approximately 27 grams less at birth. Between 50% and 70% of the women studied had detectable levels of at least one DINCH breakdown product. The findings do not establish that DINCH causes smaller babies, but they raise questions about a chemical increasingly used in everyday consumer products.
Where is DINCH found?
DINCH, short for diisononyl cyclohexane-1,2-dicarboxylate, is a plasticizer. Manufacturers add plasticizers to certain plastics, particularly polyvinyl chloride (PVC), to make them softer and more flexible. Unlike the plastic itself, these additives are not necessarily permanently bound to the material. Under certain conditions, plasticizers can migrate out of products into food, dust or the surrounding environment. According to Health Canada and a scientific review of emerging plasticizers, DINCH is used in several categories of products:
- Food packaging: Certain flexible food-contact plastics, including some PVC films and packaging materials.
- Children’s toys: Soft plastic toys and other flexible plastic components.
- Medical equipment: Some flexible medical tubing, blood collection products and medical packaging.
- Vinyl flooring: Certain PVC flooring products and related materials.
- Coated textiles: Some flexible plastic coatings used in fabrics and other consumer products.
Not every product in these categories contains DINCH. Its presence depends on the manufacturer, formulation and applicable regulations, and it is not normally identified on consumer-facing packaging. But it’s starting to seem like NO PLASTIC IS SAFE.
DINCH is also distinct from PFAS, the group widely known as forever chemicals (Lululemon pants). Although both raise questions about chemical safety, they are different substances with different properties.
A safer replacement that may not be safer
Phthalates have long attracted scientific attention because some members of this chemical family can interfere with hormones and have been associated with reproductive and developmental problems. DINCH entered the market as an alternative intended to reduce those concerns. Its use expanded in products involving food contact, children and medical care.
But the new research suggests the replacement deserves closer scrutiny: “Our findings suggest that a chemical promoted as a safer replacement for phthalates and other plasticizers may affect how babies grow in the womb,” said Trasande in an NYU Langone statement.
The research also found differences depending on the baby’s sex. Associations with shorter birth length were stronger among boys, while girls were more likely to be classified as small for gestational age. Exposure during the third trimester appeared more strongly associated with reduced birth size than exposure earlier in pregnancy.
The study was observational, meaning researchers cannot rule out other factors that might explain the associations. It also did not demonstrate that DINCH exposure shortened pregnancies.
Are we replacing one problem with another?
Environmental scientists call this problem regrettable substitution. A chemical associated with health or environmental harm is phased out, only to be replaced by another substance that later raises similar concerns. The challenge extends far beyond plastic packaging. With thousands of chemicals used in consumer goods, researchers and regulators face the difficult task of understanding long-term health effects before substances become widespread.
“These results underscore the need for stronger oversight of chemicals used in food packaging and other household products by requiring they be tested before they are introduced to the market, instead of after they are connected to health concerns,” Trasande said.
For consumers seeking to reduce their exposure to plastic additives, practical steps include using glass or stainless steel food containers, avoiding heating food in plastic unless the container is specifically designed for that use, and choosing unpackaged fresh foods when practical.
The larger question is whether manufacturers should be required to establish the long-term safety of replacement chemicals before introducing them into products used by millions of people. And the even larger question is should manufacturers pay for damages?
