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Environmental Chemicals

Environmental Chemicals in U.S. Pregnant Women

chemicals in pregnant women

The number of chemicals detected in U.S. pregnant women out of 52 tested for, in 2003–2004. Each vertical bar represents one woman. Exposure is ubiquitous.
Do you know how many chemicals are in your body? At what levels? Probably not. I certainly don't. Every two years, the U.S. Centers for Disease Control and Prevention measures the levels of some environmental chemicals in a group of people that represent the general U.S. population, and publishes its findings in the National Report on Human Exposures to Environmental Chemicals. For most of the chemicals measured, so little research has been done on them that we do not know if the exposures found constitute a health concern. The most recent report confirms widespread exposure to some commonly used industrial chemicals, including many discussed here. Note that this project only tests for a couple of hundred chemicals; over 80,000 chemicals are in use in the U.S., and approximately 1000-2000 new ones are introduced each year. The U.S. government does not require safety testing for new or existing chemicals, and we know very little about how they act in combination with each other. Of critical concern is the ability of chemicals to cross the placenta and influence fetal development (Vandenberg et al. 2009). Worldwide, "over 350,000 chemicals and mixtures of chemicals have been registered for production and use, up to three times as many as previously estimated and with substantial differences across countries/regions... the identities of many chemicals remain publicly unknown because they are claimed as confidential (over 50,000) or ambiguously described (up to 70,000)." (Wang et al. 2020). Alarmingly, 99-100% of the pregnant women in this CDC sample have measurable levels of certain PCBs, organochlorine pesticides, PFASs, phenols, PBDEs, phthalates, polycyclic aromatic hydrocarbons (PAHs) and perchlorate in their bodies (Woodruff et al. 2011). People of minority backgrounds tend to be exposed to higher levels of many chemicals in the U.S. (Nguyen et al. 2020).
Scientists have long suspected that environmental chemicals could be involved in the development of type 1 diabetes, in part because certain drugs and chemicals could cause diabetes in laboratory animals. They have used these drugs, such as alloxan, streptozotocin (STZ), and cyclophosphamide to induce diabetes in animals for laboratory studies. Some other drugs have also been linked to the development of type 1 diabetes in humans. One example of a chemical inducing insulin-dependent diabetes in humans is the now-banned rat poison Vacor. In the late 1970s, a few people tried to kill themselves by eating Vacor, and ended up with diabetes instead. All of these compounds destroy beta cells, but all act via different mechanisms (Kraine and Tisch 1999; Lenzen 2008). Vacor and STZ both target beta cells, but have also been found linked to type 1-related autoimmunity: Vacor in humans (Karam et al 1980) and STZ in primates (Wei et al 2011). Numerous environmental chemicals can target beta cells (Hectors et al 2011); can they somehow provoke an autoimmune attack? We don't know.
Surprisingly, only a very few studies have directly examined the ability of the chemicals we encounter in the environment to affect the development of type 1 diabetes (Bodin et al. 2015; Howard 2019; Howard 2018Howard and Lee 2012). Thus, for many chemicals described here, I also included studies associating them with other types diabetes, or other autoimmune diseases. And, I included information on chemicals and how they can influence other factors that may influence the development of type 1 diabetes, such as increased insulin resistance or weight gain. I have also included information on chemicals that produce effects in the laboratory that could have ramifications for the development of type 1 diabetes, such as by inducing or accelerating autoimmunity, or causing beta cell dysfunction.
There is a ton of evidence that environmental chemicals may contribute to the development of type 2 diabetes, reviewed throughout this website. Sharp (2009), for example, focuses on Canadian Aboriginal people. Yet his review would be of interest to other communities, and may also be relevant for type 1. He concludes that some toxic chemicals interfere with the functioning of the beta cells, and affect insulin production, as well as obesity (see the height and weight page). The accepted risk factors for diabetes, including diet, lifestyle, and genetics, do not fully explain the high rates of diabetes in First Nation peoples.

Additional Chemicals

Sharyle Patton

Sharyle Patton directs the Biomonitoring Resource Center at Commonweal, helping people find out the levels of chemicals in their bodies.
Most chemicals analyzed in relation to diabetes/obesity warrant their own pages, as there are so many studies. A few are just beginning to be studied and do not warrant an entire page.


Parabens are often found in cosmetics and deemed "safe" by the FDA.

A long-term study from Spain found that people with higher propyl paraben levels had an increased risk of type 2 diabetes after 23 years of follow-up (Salamanca-Fernández et al. 2020). A prospective study from the Netherlands found that people with higher paraben levels lost less weight on a diet than those with lower levels, and had a higher BMI (van der Meer et al. 2020).

In U.S. adults, cross-sectional studies have found that levels of various parabens were associated with a lower risk of diabetes (Ward et al. 2020) and lower triglyceride levels (Pazos et al. 2020). In Canadian men, a cross-sectional study found that higher propyl paraben levels were associated with an increased risk of metabolic syndrome, while ethyl paraben levels were associated with a lower risk in women. Also in women, methyl paraben levels were associated with a lower risk of obesity, and methyl, propyl and ethyl parabens were associated with higher HDL cholesterol levels (Kim and Chevrier, 2019). Another cross-sectional study found that parabens are associated with an increased risk of obesity in Czeck women (Kolatorova et al. 2018). In Korean adults, those with higher paraben levels had a higher risk of diabetes and obesity (Lee et al. 2020). So there conflicting evidence so far.

Pregnant women

Exposure during pregnancy may be important for the woman (as well as the fetus), and contribute to gestational diabetes (Varshavsky et al. 2019). For example, higher paraben levels were associated with higher glucose levels in pregnant women (Bellavia et al. 2018), with gestational diabetes in overweight/obese pregnant women (Li et al. 2018), with higher weight gain during pregnancy (Wen et al. 2020), with lower blood pressure in pregnant women (Warembourg et al. 2018), and with various markers of metabolism in pregnant women (Zhao et al. 2020). But it also depends on the type of paraben; in Chinese women, ethyl paraben levels were positively associated with gestational diabetes, but not methyl paraben or propyl paraben (Liu et al. 2019). In general, the use of personal care products (which often contain parabens or other chemicals) is also linked to higher blood glucose levels in pregnancy (Bellavia et al. 2019). 


Prenatal exposure to parabens may also affect the growth of the fetus and child (Wu et al. 2018). A study that combines both human and animal evidence finds that in humans, maternal use of butyl paraben-containing cosmetics was associated with overweight in offspring in the first eight years of life, especially in girls (Leppert et al. 2020).

Laboratory Studies

 In mice, maternal butyl paraben exposure induces a higher food intake and weight gain in female offspring (Leppert et al. 2020). Exposure to methyl paraben during development affected the gut microbiota of rats in adolescence, although the changes diminished as the rats aged into adulthood (even when the exposure continued) (Hu et al. 2016).

In cell studies, low doses of methyl- and propyl- parabens increased fat cell development of white fat cells and increased glucose uptake in white fat cells, but did neither in brown fat cells (Elmore et al. 2020).

Nonionic Ethoxylated Surfactants

These are chemicals found in various consumer products, like household cleaning products. In the lab, they can promote the development of fat cells and the accumulation of triglycerides in fat cells (Kassotis et al. 2018).

Styrene and Polystyrene

In other laboratory studies, styrene causes higher glucose levels, higher insulin levels, and insulin resistance in rats (Niaz et al. 2017). In mice, polystyrene microplastics caused metabolic disorders in the mothers, along with changes in the gut microbiota and gut barrier dysfunction, as well as long-term metabolic consequences in the first and second generation offspring (Luo et al. 2019a), including affecting cholesterol and triglyceride levels (Luo et al. 2019b). (Changes to the gut microbiota and gut barrier are linked to type 1 diabetes; see the Diet and the Gut page).

Hexavalent Chromium

Another chemical barely researched is hexavalent chromium, a carcinogen and endocrine disruptor made famous in the movie Erin Brockovich. Gestational exposure to hexavalent chromium increased insulin levels and affected glucose uptake and in the offspring of rats (Shobana et al. 2017).

Benzo and Methane Chemicals

Exposure to certain benzotriazoles and benzothiazoles, widely-used chemicals, in early pregnancy were associated with impaired glucose tolerance and an increased risk of gestational diabetes in China (Zhou et al. 2019). 

Exposure to benzophenone-3 (BP-3), a chemical used in sunscreens, in pregnancy was associated with lower glucose levels and better glucose tolerance in Boston women with fertility problems (Wang et al. 2020).

Some studies have found that trihalomethanes, which are by-products of water chlorination (found in pools or drinking water), are not associated with increased rates of type 2 diabetes (Gängler et al. 2019), or with pre-diabetes (Ioannou et al. 2019). However, a different study found a possible link, and laboratory studies show that these chemicals might be linked to insulin resistance (Makris et al. 2016).

Mixtures and Other Industrial Chemicals

Chemical mixtures may act differently than chemicals individually (Le Magueresse-Battistoni et al. 2017), and these mixtures are linked to metabolic diseases such as diabetes (Le Magueresse-Battistoni et al. 2018). Mixtures of chemicals, for example, at low doses, affect body weight of rats in the lab (Docea et al. 2018). Mixtures of chemicals found in the environment, like raw sewage entering wastewater treatment plants, can cause fat accumulation in laboratory experiments (Barbosa et al. 2019). The complex mixtures of chemicals present in house dust induce biological activity related to fat accumulation in test tubes at levels found in normal houses (Kassotis et al. 2020).

Men who work in the plastic industry have a higher risk of type 2 diabetes and pre-diabetes, and the longer they have worked there, the higher the risk (Meo et al. 2018). People exposed to oil spills have been found to have higher glucose and cholesterol levels (Choi et al. 2017), while the chemicals found in fracking wastewater cause effects linked to weight gain in cells at levels that humans are exposed to (Kassotis et al. 2018). Some of these authors further found that developmental exposure to a mixture of 23 unconventional oil and gas chemicals altered energy expenditure and spontaneous activity in adult female mice, although it had no effects on glucose tolerance or body weight/composition (Balise et al. 2019a; reviewed by Nagel et al. 2020). However, a further study by the same authors found that when the mice were allowed to age, and had a short 3-day exposure to a high-fat, high-sugar diet, they developed increased body weight and higher fasting blood glucose levels (Balise et al. 2019b). Toads exposed to petrol (gasoline) developed high glucose levels after a couple weeks (Isehunwa et al. 2017). In Saudi Arabia, workplace exposure in wood, welding, motor mechanic, and oil refinery industries increased the risk of prevalence of prediabetes and type 2 diabetes among the workers, and affected diabetes development (Meo et al. 2020). 

Another issue that most studies do not address is that even the sequence of exposure may play a role-- the effects of chemicals can differ depending on which exposure occurs first (Ashauer et al. 2017).

Nanomaterials and Microplastics

Test tube screening of microplastic extracts from Italian waters showed potential effects on metabolism, including increased fat cell development and fat uptake and storage (Capriotti et al. 2020).

Additional substances with endocrine disrupting effects may also be linked to diabetes, including nanomaterials/nanoparticles (Ali 2019; Guo et al. 2019Mao et al. 2019Priyam et al. 2018). Titanium dioxide nanoparticles, for example, have been widely used in numerous applications and caused pancreatic tissue damage, including in islet cells, which became worse with increased duration of exposure. Decreased immune expression of the insulin protein together with decreased serum insulin and increased blood glucose levels indicated the alteration of beta cells (Abdel Aal et al. 2020).


For studies on specific chemicals, see the link on the bottom of each subpage. To see overall lists of studies of environmental chemicals and various types of diabetes/obesity, see these PubMed collections:

All environmental chemicals and diabetes/obesity (includes type 2, type 1, and gestational diabetes; insulin resistance; obesity/body size)
All chemicals and obesity and metabolic syndrome (includes studies on growth, height, weight, obesity, insulin resistance, lipids, and adipose (fatty) tissue)
All chemicals and type 1 diabetes
All chemicals and gestational diabetes
All chemicals and diabetes complications and blood glucose control