The Motivation for the Study
The aim of the study was to understand to what extent phthalates are still used in plastic disposable food service gloves in the U.S. Disposable gloves are ubiquitous at every stage of food production. Gloves made of flexible polyvinyl chloride (PVC), or vinyl, are popular due to their durability and relatively low cost. Vinyl dominates the market for gloves used in handling, processing, and serving food. To make vinyl gloves flexible, manufacturers add high levels of plasticizer chemicals--typically around 30% by weight. These plasticizers migrate into foodstuffs touching the vinyl and people ingest them.
Among plasticizers, ortho-phthalate esters (“phthalates”) were historically dominant and have contaminated food for decades. While levels of many specific phthalates have declined, recent research shows that food remains the primary source of human exposure to these hazardous compounds.1 Phthalates in food likely come from multiple sources. In this study, we analyzed vinyl food-handling gloves for phthalate and non-phthalate alternative plasticizers.
Phthalates and Health
Phthalates may contribute to health and developmental problems in humans, especially children. In a review of epidemiological studies, researchers found a consistent connection between phthalates and specific poor health outcomes.2 Among girls and boys, phthalates are likely to increase the occurrence of allergies and asthma as well as behaviors related to attention deficit disorder. In boys, phthalates cause an increase in congenital malformations affecting the genitals, including decreased distance between anus and penis which can result in lower sperm quality, lower fertility, and increased risk of prostate cancer. Exposure to phthalates affects the level of hormones in men and women of reproductive age. Epidemiological studies show a connection between elevated phthalates and puberty timing—specifically early puberty in girls and male development of gynecomastia or enlargement or swelling of breast tissue.
Due to the toxicological and epidemiological studies, the U.S. Consumer Product Safety Commission (CPSC) convened a Chronic Hazard Advisory Panel (CHAP) “to study the effects of all phthalates and phthalate alternatives as used in children’s toys and childcare articles.”1 They recommended a permanent ban on certain phthalates, detailed in Table 1.
Table 1: Regulations on Phthalates
|Country||Regulatory Body||Name and Year enacted||Phthalates||Guidelines|
|United States||Consumer Product Safety Commission||Consumer Product Safety Improvement Act of 2008, 2014||DBP, BBP, DEHP, DINP||Banned from children’s toys and child care articles greater than 0.1%1|
|United States: California||California Office of Environmental Health Hazard Assessment||Proposition 65, 1988-2013 depending on phthalate||DEHP, BBP DIDP, DINP, DBP, DnHP||Warning of chemical use must be on the packaging3|
|European Union||European Chemicals Agency||2011, entry 51 of Annex XVII. Registration, Evaluation, Authorisation and Restriction of Chemicals (REACH)||DEHP, DBP, BBP, DIBP||Banned from children’s toys and childcare articles greater than 0.1% 4|
|European Union||European Chemicals Agency||REACH Authorisation for Substances of Very High Concern, 2011||DEHP, DBP, DIBP, BBP, and additional phthalates||All uses are banned unless specific uses have been exempted4|
|Japan||Ministry of Health, Labour and Welfare||On the Use of PVC Gloves for Foods, 2000||DEHP||Banned from PVC gloves5|
|Japan||Ministry of Health, Labour and Welfare||On the Plasticizer (DEHP) Eluted from PVC Medical Devices, 2002||DEHP||Banned from medical devices and gloves5|
|Japan||Ministry of Health, Labour and Welfare||Amendment to the standards for devices, containers package 2002||DEHP, DINP||Banned from food packaging materials in contact with fatty foods and toys that are held in the mouth5|
See Table A: Chemical Names and Acronyms for more information on the chemicals mentioned.
Phthalates and Food
The contamination of food by these endocrine-disrupting compounds is of particular concern. Phthalates migrate into food products from food contact materials used in food processing, in packaging or from food service gloves worn by workers. In general, phthalates in vinyl have been shown to leach, migrate, and off-gas into the environment.6–8
Although phthalates are present in many consumer products, food is believed to be the primary source of several phthalates.9–11 The CHAP report on phthalates tabulated the estimated daily exposures for pregnant women, women of reproductive age, infants, toddlers, and children.1 In each subpopulation, food, beverages, and drugs via direct ingestion--not children’s toys or personal care products--were the most significant contributors to phthalate exposure. A recent study has also shown that people who frequently eat at restaurants tend to have had higher phthalate levels in their bodies.11
Researchers have identified no single primary source of phthalates in the U.S. food supply chain, but our prior work and that of others suggest more highly processed foods tend to have higher phthalate concentrations.7,8,12–14 Food packaging, including printing inks and adhesives, may be a source for some foods, but processing equipment is probably a common source.15 Cao et al. detailed the following potential sources of phthalates in food in a review article: vinyl tubing, vinyl gaskets in metallic caps for glass jars, vinyl gloves, aluminum foil paper laminates, and coatings on cookware.7
It’s important to note that polymers other than vinyl can contain phthalates. Our 2018 report “Sources of Phthalates in Dairy Farm Equipment” found a high level of phthalates in a milking equipment part made of synthetic rubber called a teat cup liner or inflation.16 These liners go into a milking machine directly over a cow’s teat.
Previous Studies on Phthalates in Vinyl Gloves
A few researchers have studied the transfer of phthalates from food-handling gloves into food. Tsumura et al. investigated whether phthalates in vinyl food-handling gloves were a source of DEHP in packed lunches sold in Japanese convenience stores and restaurants.13 They found higher levels of phthalates in cooked food products (touched with vinyl gloves) than in uncooked food (not yet touched with vinyl gloves). They also found lower phthalate levels in packaged lunches at a factory where workers did not wear vinyl gloves compared to a factory where workers wore vinyl gloves. In another experiment, wearing vinyl gloves with phthalates, they handled food for 1 to 2 seconds and found an increase in the amount of phthalates in the food.17
Some studies have tested whether restrictions on phthalates have helped to decrease phthalate food contamination. To follow up on their previous research, Tsumura et al. analyzed meal samples from three hospitals in Japan for eight phthalates after Japan had passed a ban on gloves containing DEHP in 2000.18 Overall, they found hospital foods had one-third less DEHP after the ban. The same research group also tested baby food before and after the ban on DEHP in gloves and found similar results.17
Petersen and Jensen investigated whether food contact materials in the marketplace complied with phthalate limits that went into effect in the European Union (EU) on July 1, 2008.14 In addition to gloves, they tested conveyor belts, lids from packed foodstuff in glass jars, and tubes for liquid food. Out of twenty tested glove samples, five contained phthalates above EU limits. In a follow-up study in 2016, the researchers found five out of eight gloves tested did not meet the regulation.12
Previous studies of vinyl food-handling gloves are summarized in Table 2.
Table 2: Previous Studies on Phthalates in Vinyl Gloves
|Research Article||Phthalates Studied||Other Additives or Glove Types Studied||Results of Vinyl Glove Testing|
|Tsumura et al. 200113||
|Wakui et al. 200120||
||Polyethylene, natural rubber, and nitrile gloves. Reported on non-phthalate plasticizers, lubricants, antioxidant, vulcanizers and other chemicals||
|Petersen and Jensen 201019||
|Chao et al. 201321||
||Vinyl, nitrile and neoprene gloves tested for phthalates||
|Petersen and Jensen 201612||
See Table A: Chemical Names and Acronyms for more information on the chemicals mentioned
Some researchers have studied how phthalates on a person’s hands may expose them through hand-to-mouth contact or transdermal absorption.22 One set of experiments showed that DEHP on the skin chemically broke down into one of its metabolites, a known endocrine disruptor, which permeated human skin substantially.23,24 Earlier research found that skin absorption was highest for the lowest molecular weight phthalate studied (DEP) and decreased significantly with the higher molecular weight phthalates.25 In a study of phthalates in diapers, Ishii et al. found that depending on the phthalate, 0.006%-2.4% of the phthalates in diapers migrated into simulated sweat. In that study, due to the low levels of phthalates in the diapers, the authors determined that skin absorption did not pose a substantial risk to babies.26
The Danish Environmental Protection Agency studied the migration of phthalates into a sweat and saliva under various simulated conditions.27 They found the highest migration rates occurred during sucking (like a small child mouthing a toy) and during ultrasonic vibration (like for adult sex toys).
Skin wipe studies by Gong et al. have found consistent amounts of phthalates on the skin, highest on the hands, without the use of gloves.22 They estimated that transdermal absorption rates of the palm and back of hand vary between 0.09 and 0.21 (μg/kg)/day. In a similar study, Giovanoulis et al. found phthalates on hands as high as 100 μg/cm2 without the use of gloves.28
Food-handling gloves contain high levels of phthalates and are in intimate contact with the wearer’s skin. The transdermal absorption studies noted here allow us to infer that phthalates in gloves will enter the human body during wear. Workers wearing gloves are also likely to ingest phthalates when hands are not washed after glove use and before eating.
Aside from vinyl, food-handling gloves include nitrile (also known as nitrile butadiene rubber, NBR), polyethylene (PE), and latex (natural rubber). In Table 3 and Table 4 summarize chemical attributes of these common glove materials. Table 3 lists a chemical lifecycle assessment score for each material; Table 4 lists what is known about the migration of additives from each of the materials.
Table 3: Chemical Footprint of Food-handling Glove Materials
|Material||Chemical Footprint Score (100 is most benign)||Manufacturing Process Benchmark||Chemicals of Concern Used|
|Vinyl||0||Every manufacturing step involves the use of chemicals of high concern as defined by GreenScreen Benchmark 1||Chlorine, ethylene dichloride, and vinyl chloride monomer|
|Nitrile butadiene rubber||16.7||Some manufacturing steps include chemicals of high concern as defined by GreenScreen Benchmark 1, and others do not||The Benchmark 1 chemicals include 1,3-butadiene and acrylonitrile|
|Polyethylene||50||For each manufacturing step, no core chemical inputs are chemicals of high concern as defined by GreenScreen Benchmark 1||Ethylene, the monomer used to manufacture polyethylene, has received GreenScreen Benchmark 2|
Plastics Scorecard Version 1.0 is a method to evaluate plastics based on their lifecycle and use.29
Although latex gloves are commercially available, they are not a viable alternative. Natural rubber latex gloves are generally not recommended for food-handling because of the risk of users developing potentially life-threatening latex allergy. The U.S. Food and Drug Administration updated its food code in 2013, recognizing natural rubber latex gloves as an allergen.30 The average prevalence of latex allergies worldwide is 9.7% for healthcare workers, 7.2% for susceptible patients, and 4.3% among the general population.31 Arizona, Oregon, Rhode Island, Hawaii, and other states have bans on latex gloves used in the food service industry.32 National Institute for Occupational Safety and Health and Occupational Safety and Health Administration do not recommend latex gloves.33,34 Non-latex gloves only rarely cause allergic reactions, although nitrile gloves contain vulcanization accelerators that occasionally cause contact dermatitis.35
Table 4: Migration Studies of Polymers Used in Food-handling Gloves
|Polyethylene||Wakui et al., 2001||Low migration of antioxidants and a lubricant into n-hexane|
|Dopico-Garcı́a, López-Vilariño, González-Rodrı́guez, 2003||No migration of antioxidants from commercial samples of polyethylene packing into food simulants|
|Nitrile||Wakui et al., 2001||Moderate migration into n-hexane of two vulcanization accelerators and several antioxidants|
|Kawamura, Mutsuga, Wakui, Maitani, 2002||Moderate migration into n-hexane of two vulcanization accelerators and several antioxidants|
|Chao et al., 2013||Low levels of DEHP extracted, 17 times less than vinyl gloves|
See Table A: Chemical Names and Acronyms for more information on the chemicals mentioned
Product engineers should complete chemical hazard assessments on all plasticizers and other additives before their use in products. One option is Clean Production Action’s GreenScreen® For Safer Chemicals, a tool that uses authoritative lists and trained assessors to determine the hazard profile of a substance. GreenScreen assessments for the relevant phthalates are in the Appendix, Table B: Comparative Hazard Assessment of Chemical Plasticizers Used in Vinyl Food Service Gloves.