chemical information


Chemical Class:


Found in these people:

Anonymous Adult 2, Anonymous Adult 3, Anonymous Adult 5, Anonymous Adult 4, Anonymous Adult 6, Anonymous Adult 7, Anonymous Teen 1, Anonymous Adult 9, Anonymous Adult 12, Anonymous Adult 13, Anonymous Adult 11, Anonymous Adult 10, Anonymous Adult 14, Anonymous Adult 15, Anonymous Adult 16, Nicholas, Anonymous Adult 17, Anonymous Adult 18, Anonymous Adult 20, Anonymous Adult 21, Participant #1, Participant #10, Fred Gellert, Adelaide Gomer, Ann Hunter-Welborn, Jesse Johnson, Anonymous Adult, Winsome McIntosh, Judi Shils, Participant #18, Lynde Uihlein, Participant #2, Participant #20, Jessica Welborn, Alicia Wittink, Irene Crowe, Martha Davis, Emily Sayrs, Participant #6, Anonymous Adult RN7, Anonymous Teen 22, Anonymous Adult RN9, Sara Corbett, May, Anonymous Teen 20, Emma Spencer, Erin Schrode, Anonymous Teen 21, Sydney Blankers, Sarah Oswald, Asta Haman-Dicko, Laurie Mittelmann, Jenny Gilbertson, Anonymous Teen 11, Anonymous Teen 9, Christa Heffron, Caroline Burlingame, Monica Paulson, Donalin Cazeau, Natalie Klapper, Jessica Assaf, Hope Atkins, Rizza Alcaria, Alex Wells

Found in these locations:

Chicago, IL; Newton, MA; Fredericksburg, VA; Washington, DC; New York, NY; Lamont, FL; Atlanta, GA; Mountain View, CA; Stanford, CA; Palo Alto, CA; San Francisco, CA; Berkeley, CA; NY, USA; Alamo, CA; Fallbrook, CA; CA, USA; Belvedere, CA; Ithaca, NY; Encinitas, CA; Ross, CA; VA, USA; Milwaukee, WI; CO, USA; Littleton, CO; MD, USA; Austin, TX; Winchester, MA; Belmont, CA; Palm Beach Gardens, FL; San Leandro, CA; North Caldwell, NJ; Novato, CA; Los Angeles, CA; Portland, OR; Langhorne, PA; University Place, WA; Dorchester, MA; San Rafael, CA; Tuolumne, CA; Manteca, CA

Exposure routes:

Breakdown product of chemical used in cosmetics, paint, plastic, food packaging, and other common consumer products.


Found within many consumer products, phthalates are industrial plasticizers that impart flexibility and resilience to plastic, among other uses. Mono-butyl phthalates (mBuP, including mono-n-butyl phthalate and mono-isobutyl phthalate) are metabolites, or breakdown products, of dibutyl phthalates (di-n-butyl, di-isobutyl), industrial solvents or additives used in consumer products such as nail polish, cosmetics, some printing inks, adhesives, caulks, pharmaceutical coatings, and insecticides (EWG 2003; Wolff 2007). Mono-n-butyl phthalate is also a minor metabolite of butyl benzyl phthalate (CDC 2005). Exposure to dibutyl phthalates occurs through direct use of products containing these chemicals, as well as through inhalation of air containing these chemicals (CDC 2005).

In September 2000, scientists from the Centers for Disease Control and Prevention (CDC) conducted the first accurate measurements of human phthalate exposures, and reported finding phthalates in every one of 289 people tested, at surprisingly high levels (Blount 2000). The latest exposure study from CDC indicates that mBuP is a widespread contaminant of the human body (CDC 2005). Measurements of mBuP in the urine of over 2,500 Americans indicate that women are more exposed than men, and younger children (ages 6-11) are more exposed than older children (ages 12-19) and adults (CDC 2005). In a recent study of girls age 6 to 8 spearheaded by Mount Sinai School of Medicine, these particular phthalate metabolites were found in 88 of 90 girls tested (Wolff 2007). The European Union has banned use of some phthalates in cosmetics and other consumer products, in response to concerns about exposure as well as toxicity.

Phthalates are potent toxins to the male reproductive system. High levels of mBuP are associated with reduced levels of sperm motility and concentration, and alterations in hormone levels in adult men (Duty 2003, 2004, 2005). A recent study of 134 births found marked differences in the reproductive systems of baby boys whose mothers had the highest mBuP phthalate measurements during pregnancy (Swan 2005). A second study indicates that these mothers' phthalate exposures were not extreme, but rather were typical for about one-quarter of all U.S. women (Marsee 2006). Further research documented decreased testosterone levels among baby boys exposed to mBuP in their mother's breast milk (Main 2006). High levels of mBuP are also linked to altered thyroid hormone levels in pregnant women (Huang 2007).

In addition to this epidemiological research on humans, laboratory studies indicate phthalates cause a broad range of birth defects and lifelong reproductive impairments in animals exposed in utero and shortly after birth (Marsman 1995; Wine, 1997; Ema 1998; Mylchreest 1998; Gray 1999; Mylchreest 1999; Mylchreest 2000). Phthalate exposures damage the testes, prostate gland, epididymis, penis, and seminal vesicles in laboratory animals (e.g., Mylchreest 1998); most of these effects persist throughout the animal's life. MBuP in particular causes undescended testes, testicular lesions, feminization of the male fetus, extra nipples in male rats, deformed vertebrae, and cleft palate (CERHR 2000a). Parent compound DBP is neurotoxic, and may be developmentally neurotoxic (Grandjean 2006).

Mono-butyl phthalate

Formed from dibutyl phthalates, used in nail polish, cosmetics, and other consumer products; linked to birth defects and male reproductive issues.

Mono-butyl phthalate has been found in 74 of the 74 people tested in EWG/Commonweal studies. It has also been found in 7,916 of the 8,020 people tested in CDC biomonitoring studies.

Results for Mono-butyl phthalate

in urine

Showing results from Dateline NBC Families, Pets Project, EWG Study #10, cosmetic chemicals in teens, EWG Study #6, consumer product chemicals in mothers and daughters, EWG/Commonweal Study #7, consumer product chemicals in adults and teens, Dateline NBC Families, EWG Study #8, chemicals in mother and 2 children

EWG/Commonweal results

  • geometric mean: 54.6 ug/g creatinine in urine
  • found in 74 of 74 people in the group

CDC biomonitoring results

  • geometric mean: 20.3 ug/g creatinine in urine
  • found in 7916 of 8020 people in the group
0.267 ug/g creatinine in urine 6430

Mono-butyl phthalate results