Analysis of the presence of benzophenone in industry, food and other consumer products

 Analysis of the presence of benzophenone in industry, food and other consumer products

 

1. Property analysis

Structure and molecular formula of benzophenone and relative molecular mass

 

C 13 H 10 O

Relative molecular mass: 182.22

 

Chemical and physical properties of the pure substance

►Description: colorless crystalline solid, with geranium or rose odor

►Boiling point: 305.4 °C

►Melting point: 48.5 °C (alpha type) and 26 °C (beta type)

►Density: 1.111 at 18 °C

►Vapor pressure: 1.93 × 10 -3 mm Hg at 25 °C

►Refractive index: 1.6077 at 19 °C

►Solubility: almost insoluble in water, but soluble in organic solvents such as ethanol, acetone, ether, acetic acid, chloroform and benzene.

►Flash point: > 110 °C

►Stability: decomposition by heat produces toxic gas; reacts with strong oxidizing agents.

►Octanol/water partition coefficient: log K ow , 3.18 ( LOGKOW, 2010 )

► Henry's law constant: 1.9 × 10 -6 atm.m 3 /mol at 25 °C

 

Analysis of benzophenone

(a) Air

The United States of America Occupational Safety and Health Administration (OSHA PV2130) reports a method for measuring benzophenone in air using a test tube containing chromosorb 106 (100/50-mg slice, 60/80 mesh) with a recommended maximum volume of 48 L and a maximum flow rate of 0.2 L/min. using an analytical solvent (99:1 carbon disulfide: N,N-dimethylformamide) to desorb chromosorb, and then measure the substance by gas chromatography with a flame ion detector.

(b) Food

Analysis of benzophenone in breakfast cereals using ultrasonic extraction coupled with gas chromatography-tandem mass spectrometry.

 

Production and use

Production

Benzophenone can be obtained in 66% yield by fucosylation of benzoyl chloride with excess benzene in the presence of anhydrous aluminum chloride. Benzophenone can also be produced by atmospheric oxidation of diphenylmethane in the presence of a metal catalyst, such as copper naphthenate.

According to the U.S. Environmental Protection Agency, it was classified as a high-volume chemical in 2003, with an annual production of more than 1 million pounds [453,000 kg] in the United States.

Utilization

Benzophenone is used as a fragrance ingredient, scent enhancer, perfume fixative, and additive in plastic, paint, and adhesive formulations; it is also used in the manufacture of insecticides, pesticides, hypnotics, antihistamines, and other drugs. Benzophenone is used in sunglasses as an ultraviolet (UV) curing agent and to prevent UV damage to odors and colors in products such as perfumes and soaps. In addition, it can be added to plastic packaging as a UV blocker, allowing manufacturers to package their products in clear glass or plastic rather than opaque or dark-colored packaging. It is also used in laundry and household cleaning products.

Benzophenone is widely used as a photoinitiator for UV-curable inks and varnishes. In addition to being a drying catalyst, benzophenone is an excellent wetting agent for pigments; it can also be used in printing to improve rheological properties and increase the flow of inks by acting as a reactive solvent.

 

Occupational exposure

Benzophenone can be absorbed by the body through inhalation, dermal and ingestion.

Industrial sectors with occupational exposure risks are the manufacture of paints (lacquers, varnishes and lacquers), plastic composites, and the manufacture and use of glues and adhesives. The National Occupational Safety and Health Institute conducted the National Occupational Exposure Survey in 1981-1983, which estimated that 41,516 workers (18,162 women) in 4,990 establishments (522 industry types employing approximately 1.8 million workers) surveyed in the United States were potentially exposed to benzophenone.

 

Occurred in food and dietary exposures

Dietary sources of benzophenone include its natural occurrence in foods, its presence as a contaminant in drinking water, its migration from food packaging, and its addition to foods as a flavoring agent.

(a) Food

The naturally occurring benzophenone in wine grapes ( Vitis vinifera L.) has been reported at concentrations of 0.08-0.13 ppm [mg/kg], and it is mainly present in Muscat grapes. Benzophenone was quantitatively detected in Passiflora species at 0.045 ppm and in black tea, Passiflora (Annona cherimola), mountain papaya (Carica pubescens) and spiny pandanus (Annona muricata L.). Concentrations below 0.01 ppm were reported in mountain papaya (C. pubescens and C. candamarcensis).

Based on its concentration in Muscat grapes, the working group estimated that consumption of 200 g of grapes would result in an exposure of approximately 20 µg of benzophenone, or 0.3 µg per kilogram of body weight (bw) for a 60 kg adult.

(b) Drinking water

Data on benzophenone in drinking water are limited; in 2001-02, the concentration in Japanese tap water was 8.8 ppb [μg/L], while the concentration in finished drinking water from a water filtration plant in the United States was 0.26 μg/L.

To assess exposure to contaminants through drinking water, WHO used a default consumption value of 2 liters of drinking water per capita per day for a typical adult of 60 kg body weight (WHO, 2008), assuming a total volume of water for consumption of 3 liters per capita per day, including water in food, which is a conservative estimate (WHO, 2003). However, this default assumption does not apply to all populations and climates. Under average conditions, the reference hydration value for infants (5 kg) is 0.75 liters, but for physically active people in warmer regions, it can be 4.5 liters for men, women and children, 4.8 liters for pregnant women and 5.5 liters for lactating women (World Health Organization, 2003).

The working group used available data on benzophenone concentrations in drinking water to assess dietary exposure for adults and infants (60 kg and 5 kg bw, respectively), assuming consumption of 2 and 0.75 liters of drinking water at 33 and 150 mL/kg bw, respectively. the infant scenario (in mL/kg bw) is equivalent to 9 liters of drinking water per day for a 60 kg adult, and would therefore include any The infant scenario (in mL/kg bw) corresponds to 9 liters of drinking water per day for a 60 kg adult and would therefore include any possible physically active person scenario in hot areas. Therefore, the estimated dietary exposure to benzophenone via drinking water for a standard 60 kg adult ranges from 0.52 to 17.6 µg/day, or 9 to 290 ng/kg bw/day, and for a 5-kg infant ranges from 0.2 to 6.6 µg/day, or 40-1320 ng/kg bw/day.

(c) Migration from food packaging

The main source of exposure to benzophenone through food packaging is related to its widespread use as a photoinitiator in UV-curable inks on the outer surface of cardboard packaging. Benzophenone is neither completely depleted nor removed during the printing process, nor is it irreversibly bound to the printed film layer. Therefore, it can migrate from the cardboard to the foodstuff either by direct contact or through the gas phase. When cartons are rolled up and compressed, the material on the outer surface of the package may contaminate the inner surface, a common practice in the food packaging industry, thereby contaminating the food through direct contact. Benzophenone may also contaminate food through the vapor phase, even from secondary packaging. Internal plastic bags used as a moisture barrier are not always effective. Benzophenone is known to migrate easily through polypropylene films, while aluminum and multilayer materials can effectively inhibit migration.

At low temperatures (-20 °C), benzophenone can migrate from cardboard to food during frozen storage, even if there is no direct contact between the package and the food or if the package has a polyethylene coating . In addition, the most common raw materials used for paperboard are recycled, so the products often contain photoinitiators, including benzophenone. Recycled board is usually used in direct contact with dry foods, such as flour and pasta, but also for fast food, i.e., foods with short contact times, such as pizza. Often, a functional barrier, such as plastic or aluminum foil, is used between the fatty or aqueous food and the recycled material to avoid direct contact.

Analytical data on the concentration of benzophenone in food packaging and food products are available. In particular, in a comprehensive survey conducted by the UK Food Standards Agency, benzophenone was detected in four of 115 food samples in printed plastic packaging (maximum concentration of 0.15 mg/kg) at concentrations of 60/296 directly or indirectly on printed paper or cardboard containing 0.05-3.3 mg benzophenone/dm 2 concentrations of 0.035-4.5 mg/kg (mean concentration, 0.9 mg/kg) and one of the 54 foods with printed adhesive labels (0.029 mg/kg). In this survey, most products in the categories of frozen foods (18/35), "jellies" (3/5) and "savory snacks" (15/40) tested positive for benzophenone. In the categories of "candy, chocolate cookies and chips" (5/35), "bakery products" (8/35) and "cereals" (4/25), the percentage of products testing positive for benzophenone was The percentage was low. Only one of the 20 "ready-to-eat meals" and 10 "desserts" did not test positive.

According to the UK Food Standards Agency, the potential dietary exposure to benzophenone for high level consumers is 1.2-1.5 µg/kg body weight. These estimates were calculated by combining the high consumption of foods that may contain benzophenone (449 g/day, 97.5th percentile in the UK National Adult Survey) with the two average levels (160 and 200 µg/day) at which it occurs. kg), depending on different assumptions about the value below the limit of quantification (45 µg/kg) for adults weighing 60 kg.

 

Updated but limited data on benzophenone concentrations in foods are available for other countries.

Samples of milk packaged in cartons available on the market in the People's Republic of China were tested: skim milk, whole milk, and partially skim milk. Benzophenone was detected at concentrations ranging from 0.94 to 1.37 μg/dm 2 in the packaging of all products and in five of the six milk products. Higher levels were found in milk with higher fat content, ranging from 2.84 to 18.35 μg/kg.

Migration of benzophenone into five selected dry foods (cakes, bread, cereals, rice and pasta) sampled in a Spanish supermarket was evaluated by Rodríguez-Bernaldo de Quirós et al. (2009). The highest concentration of benzophenone (12 mg/kg) was found in the cakes. Migration levels were positively correlated with porosity and fat content. These results correlate well with those reported by Anderson & Castle (2003), who analyzed 71 randomly selected food samples from a total of 143 items packaged in printed cardboard, in which benzophenone was detected. The highest value (7.3 mg/kg) was found in high-fat chocolate packaged in direct contact with cardboard.

In a study by Sanches-Silva et al. 36 samples of commercial beverages (fruit and vegetable juices, wines and soft drinks) were collected in 2005 and 2006 in Italy, Portugal and Spain, all of them packaged in multi-material multilayer boxes or aluminum cans. Benzophenone was detected in four packaging samples (one below the limit of quantification of 1.7 μg/dm 2 and three in the range of 3.6 to 12.3 μg/dm 2 ) and the beverage samples contained therein were analyzed. None of the extracts yielded positive results. However, according to the authors, although the juices contained small amounts of fat, the photoinitiators migrated and were adsorbed by the juice fibers (0.2% fiber content), thus contaminating the beverages.

In a study conducted by Koivikko et al. (EU), samples of printed panels for secondary packaging were collected from supermarkets together with the food contained therein (n = 22), and some were obtained from industrial production lines prior to the introduction of food products (n = 24). In addition, samples were taken from recycled cardboard collected from suppliers to assess background levels of benzophenone and other derivatives in it (n = 19). The most abundant photoinitiator found in the non-recycled product was benzophenone, which was detected in 61% of the samples. Traces of this compound were also found in 42% of the recycled non-printed board samples. The amount of benzophenone in these samples ranged from 0.57 to 3.99 mg/m 2 .

In Japan, benzophenone migrated from recycled paperboard used in contact with food into 95% ethanol, rather than from virgin paper. The migration range was 1.0 to 18.9 ng/mL for 8 of the 21 samples collected from recycled paperboard.

In 2009, the EU Rapid Alert System for Food and Feed (RASFF) notified high levels of 4-methylbenzophenone (another photoinitiator) detected in some breakfast cereal products (chocolate chip cereal) (European Commission, 2009). Further analysis conducted by the manufacturer showed high levels of this substance and up to 4210 μg/kg of benzophenone in these products.

(d) Addition to food as a flavouring

In the United States, the average reported level of benzophenone used as an additive ranged from 0.57 ppm [mg/kg] in non-alcoholic beverages to 1.57 ppm in baked goods, with the highest reported level ranging from 1.28 ppm in non-alcoholic beverages to 3.27 ppm in frozen dairy products. other reported uses were in fudge, gelatin and pudding.

The highest levels reported by the European Commission were generally 0.5 mg/kg in beverages and 2 mg/kg in food, without exception. Benzophenone is listed in the EU register of chemically defined flavourings. In the European Food Safety Authority (EFSA) Flavouring Group Assessment 69, dietary exposure to benzophenone in the EU was estimated at 23 µg/person/day based on weight data provided by industry, assuming that consumers represent 10% of the population. On the same basis, the U.S. dietary exposure was estimated at 11 µg per person per day.

As a flavoring agent at Toxicological Threshold of Concern Level III, assessed by EFSA under the Joint FAO/WHO Expert Committee on Food Additives (JECFA), industry provided the European Commission with investigated levels of refined additive use (IOFI-DG Sankoh, 2008). The single-serving exposure technique was developed by the Joint FAO/WHO Expert Committee on Food Additives (JECFA) to estimate the average level of use of one standard serving per day of a flavoured food or beverage containing a flavouring substance. Using this technique, the working group calculated an estimated exposure to benzophenone of 6 μg per person per day data when applied to IOFI-DG SANCO (2008) and 40 μg per person per day when applied to European Commission (2000) data.

 

Environmental Occurrence

Benzophenones are harmful to aquatic organisms. Benzophenones often have environmentally critical properties such as high lipophilicity and persistence, and are known to have adverse effects on fish reproduction and hormone function. According to, benzophenone is persistent, bioaccumulative and toxic (PBT).

Due to its high octanol:water partition coefficient and insolubility in water, benzophenone partitions in soil and sediment, and its adsorption to soil is proportional to the organic matter content therein.

(a) Water and sediment

Benzophenones are pharmaceuticals and personal care products known to occur in drinking water and reclaimed wastewater when the water source is influenced by effluents from wastewater treatment plants (Loraine & Pettigrove, 2006)). Removal of these compounds during wastewater treatment is not entirely effective, and wastewater-dominated streams represent a "worse case" scenario for studying personal care products and other organic wastewater contaminants. In these streams, even compounds with relatively short environmental half-lives, such as benzophenones, may act as "pseudo-persistent" compounds. As they are continuously introduced from wastewater treatment plants, these compounds are continuously released into the environment. As a result, aquatic organisms are exposed throughout their life cycle.

Another pathway for benzophenone to enter the aquatic environment is leachate from municipal solid waste landfills. Benzophenone was characterized in wastewater samples from municipal solid waste treatment plants in Reciplasa (Castellón province, Spain) between March 2007 and February 2009. Water samples were collected before and after the reverse osmosis treatment, which was performed before releasing the water into the environment. Benzophenone was detected in 38% of the treated samples and 55% of the raw leachate. In a study where submerged anaerobic membrane bioreactors were fed a simulated feedstock of the organic fraction of municipal solid waste, benzophenone was found as a contaminant in the leachate permeate.

Benzophenone was detected in surface water from sampling sites in rivers and effluent-dominated streams along the Han River (Seoul, Korea) in two of four river samples (detection limit, 50 ng/L) (mean, 52 ng/L; maximum, 59 ng/L) and all four effluent-dominated stream samples (mean, 102 ng/L; maximum, 130 ng/L) were the result of wastewater outfalls. Benzophenone was detected in surface water from the Ozark Plateau in northeastern Oklahoma, USA, at a site downstream of a municipal wastewater treatment plant outfall and in a hydrologically connected cave. It was present in wastewater from the main sewer of the city of Zagreb (Croatia), which was untreated at the time of the investigation and consisted of a mixture of wastewater from domestic and industrial sources.

Benzophenone was detected qualitatively in water from the Baltic Sea and Hamilton Harbour, Bermuda, and measured in two water samples from the Tama River, Japan, at concentrations of 21.0 and 22.8 ng/L. It was detected in water samples from the Venice Lagoon and the San Francisco Estuary at concentrations < 2.6-1040 ng/L and 14- in sediment samples concentrations of 200 μg/kg.

Benzophenone was detected in all 11 bluegill samples collected from a regional effluent-dominated stream (i.e., approximately 650 m downstream of the Hickory Creek Water Reclamation Plant effluent discharge in Denton County, TX, USA) at a mean concentration of 57 ng/g wet weight (standard deviation, 18 ng/g) with a range of 37-90 ng/g. Clear Creek (Denton County, TX, USA) had a mean concentration of 24 ng/g in three bluegill samples.Water, sediment and biota surveys in the Venice Lagoon, a highly urbanized coastal waters ecosystem receiving industrial and municipal wastewater discharges, detected benzophenone in lagoon sediments at concentrations ranging from 14-110 μg/kg .

A survey of raw and treated drinking water from four water filtration plants in San Diego County (California, USA) conducted in 2001-02 showed significant seasonal variation in benzophenone concentrations, with higher concentrations in summer than in winter, which may is because sunscreen is used more frequently in the summer. Benzophenone was detected at a concentration of 0.26 μg/L in one of 15 finished drinking water samples and 0.99 μg/L (range 0.56-1.35 μg/L) in four of six reclaimed wastewater samples.

 

Benzophenone has been used as a model hydrophobic contaminant. Due to their hydrophobicity, PBT contaminants can migrate out of the aqueous phase and bind to sediments. As a result, animals residing in or on top of these sediments are at risk of bioaccumulating PBT compounds and acting as carriers in transferring them to predators that may have limited direct contact with contaminated sediments. Predator species accumulate benzophenone from prey and exposure to narcotic organic contaminants such as benzophenone can lead to reduced activity, which may alter their ability to successfully capture such animals.

Benzophenones were found in surface sediment samples from the Havel and Spree rivers (Germany), characterized by high inputs of anthropogenic contaminants into eutrophic to hypertrophic river systems with very slow flow conditions. Benzophenone was detected and quantified in 10 out of 11 samples in the range of 0.5 to 4 ng/g dry matter concentrations from the 1979/80 to 1995 sediment records.

(b) Air

In 1988, benzophenone was characterized in the atmosphere of a 45-year-old spruce forest located at a height of 1 m in North Rhine-Westphalia (Germany), where severe forest damage was observed. We found benzophenone to be a component of standard residential oil burner emissions. Although benzophenone has been identified in the atmosphere, it is difficult to determine whether it is present because it is a direct product of combustion or a by-product of atmospheric degradation.

In an indoor air monitoring survey conducted by the Japanese Ministry of the Environment, benzophenone was detected in 67/68 samples analyzed. Therefore, human exposure through inhalation should be considered.

 

 

Other situations

Because benzophenone is used as an additive in fragrances, cosmetics, toiletries, pharmaceuticals, pesticides, and laundry and household cleaning products, exposure to benzophenone through the skin may be significant. The percutaneous absorption of benzophenone was measured in monkeys at approximately 70% of the dose used to seal the skin over a 24-hour period. Under unsealed conditions, skin penetration was reduced to 44%, probably due to evaporation from the application site.

Many dentures are typically prepared by polymerization reactions using benzoyl peroxide as an initiator, where benzophenone is a breakdown product that was found to elute from artificial saliva of four commercial soft denture liners (two plasticized acrylates and two silicone elastomers).

 

Total Human Exposure

Benzophenone ingested by humans is excreted in urine as metabolites, such as benzyl, so measuring benzophenone derivatives in urine provides an indication of total human exposure to benzophenone, which was detected in all urine samples in a study of 14 healthy volunteers. Benzyl alcohol concentrations ranged from 0.27 to 10.0 ng/mL, but the parent compound was not detected in any of the samples.

 

2. Cancer in experimental animals

Rats

In a 2-year carcinogenicity study, 50 males and 50 females were fed a diet containing 0, 312, 625, or 1250 ppm benzophenone (>99.5% purity; equivalent to an average daily dose of approximately 40, 80, or 160 and 35, 70, or 150 mg/kg body weight for males) to a group of B6C3F 1 mice at 8 weeks of age and females, respectively). 105 weeks. The feed consumption of exposed males and females was similar to that of the control group, but at the end of the study, the body weight of the 1250 ppm females was 14% lower than that of the control group. A positive trend in the incidence of hepatocellular adenomas was observed in males; the incidence in the 625 and 1250 ppm groups was significantly higher than in the control group and exceeded the historical control range of the feed study (12-30%). Hepatoblastoma was also observed in treated males, although the incidence in the 1250 ppm group (3/50, 6%) was not statistically significant and it exceeded the historical control range of the feed study (0-2%). 625 and 1250 ppm female mice had an increased incidence of hepatocellular adenoma, but the difference with the control group was not significant. A positive trend in the incidence of histiocytic sarcomas was observed in female mice in the liver, lung, ovary, uterus, spleen, adrenal gland, kidney, bladder and multiple lymph nodes; a significant increase in the incidence was observed in the 625 ppm group, and the incidence in the 625 and 1250 ppm groups exceeded the historical control range (0-2%) of the feed study (bladder and multiple lymph nodes were observed in female mice; 625 ppm group The incidence was significantly increased in the 625 and 1250 ppm groups and exceeded the historical control range (0-2%) of the feed study (bladder and multiple lymph nodes were observed in female mice; the incidence was significantly increased in the 625 ppm group and exceeded the historical control range (0-2%) of the feed study in the 625 and 1250 ppm groups). [The working group noted that hepatoblastoma and histiocytic sarcoma are rare tumors in mice].

Rats

In a 2-year carcinogenicity study, groups of 50 male and 50 female F344/N rats (6 weeks of age) were fed diets containing 0, 312, 625, or 1250 ppm benzophenone (>99.5% purity; equivalent to mean daily doses of approximately 15, 30, or 60 and 15, 30, and 65 mg/kg body weight for males and females, respectively) for 105 weeks. After week 70, feed consumption was lower in 1250-ppm males than in controls, whereas feed consumption in 1250-ppm females was generally lower than in controls throughout the study. survival time was significantly shorter in 1250-ppm males than in controls, which was attributed to increased severity of chronic progressive nephropathy in the kidneys. The incidence of renal tubular adenoma was increased in male rats exposed to 625 or 1250 ppm in both standard (single-segment) and extended (stepped-segment) assessments of the kidney, and the combined incidence of renal tubular adenoma (single-segment and stepped-segment) was also increased in males in these groups; the incidence was significantly higher in the 1250 ppm group than in the control group. Renal tubular carcinoma and metastatic epithelial carcinoma of the renal pelvis also occurred in men at 625 ppm. The incidence of monocytic leukemia was significantly increased in male rats exposed to 312 or 625 ppm, while the incidence in 1250 ppm males was slightly decreased compared with controls. This incidence and that of all treated female groups exceeded the historical control range of the feed study (30-68% for males and 12-38% for females). histocytic sarcoma incidence was lower in female rats at 625 and 1250 ppm (1/50 and 2/50, respectively). ntp, 2006; Rhodes et al. , 2007).

Skin application

Rats

Each group of 50 female Swiss mice received dermal application of 0, 5, 25, or 50% benzophenone [purity not specified] dissolved in acetone twice weekly for 120 weeks. Dermal application of benzophenone is not carcinogenic in mouse skin.

 

3. Other relevant data

Absorption and metabolism

Approximately 70% of benzophenone is absorbed by rhesus monkeys within 24 hours after percutaneous application. The gastrointestinal tract of Sprague-Dawley rats given a single dose (100 mg/kg bw) by gavage in corn oil rapidly absorbed benzophenone.

The metabolism of benzophenone in rabbits was initially shown to involve the reduction of ketone groups to produce benzohydrogen, which was excreted in the urine as a glucosinolate conjugate. In a subsequent study, 4-hydroxybenzophenone was isolated from the urine of Sprague-Dawley rats that had been given benzophenone in corn oil by tube feeding at approximately 1% of the administered dose. The urine samples were isolated after treatment with a β-glucuronidase/aryl sulfate lyase preparation.

Metabolism of benzophenone is recommended.

The 24-hour plasma time course of benzophenone, dibenzyl alcohol, and 4-hydroxybenzophenone was determined in Sprague-Dawley rats by corn oil tube feeding. The aromatic hydroxylation product 4-hydroxybenzophenone was identified after hydrolysis of the isolated metabolites with sulfate esterase. No dihydroxybenzophenone metabolite was identified in this study. Peak levels of benzophenone and its metabolites were reached approximately 4 hours after administration, and the elimination half-life of the parent compound was approximately 19 hours. In toxicokinetic studies, the plasma elimination half-life of benzophenone in F344 rats was approximately 4 hours after intravenous administration and 8 hours after administration via corn oil tube; in B6C3F 1 mice, the plasma elimination half-life was approximately 1 hour after intravenous administration and 1.5 hours after corn oil tube feeding.

Benzophenone was metabolized in isolated F344 rat hepatocytes to 4-hydroxybenzophenone, its sulfate conjugate, and dibenzyl alcohol. Pretreatment of hepatocyte suspensions with the sulfotransferase inhibitor 2,6-dichloro-4-nitrophenol resulted in increased concentrations of free 4-hydroxybenzophenone.

Exposure of aqueous benzophenone solutions to UV or sunlight produces bicyclic hydroxylated derivatives - 3-hydroxybenzophenone and 4-hydroxybenzophenone - along with hydrogen peroxide, and the formation of 4-hydroxybenzophenone by UV irradiation enhances the addition of hydrogen peroxide. The authors suggest that benzophenone may act as a photosensitizer, producing reactive oxygen species that can cause aromatic ring hydroxylation.

Genetic and related effects

Experimental systems

Benzophenone was not mutagenic in Salmonella typhimurium strains TA98, TA100, TA1535, or TA1537 in the presence or absence of a metabolic activation system. It did not increase the frequency of micronucleated multistained erythrocytes in bone marrow samples obtained from male B6C3F 1 mice given 3 intraperitoneal injections of benzophenone (200 to 500 mg/kg body weight) or the frequency of micronucleated normally stained erythrocytes in the peripheral blood of males or female B6C3F 1 mice given benzophenone (1250 to 20 000 ppm) in the diet (estimated daily dose range, 200-4200 mg/kg bw) for 14 weeks.

Neither benzophenone nor its metabolites - benzyl alcohol or 4-hydroxybenzophenone - induced umu gene expression in Salmonella typhimurium strain TA1535 in the presence or absence of rat or mouse liver microsomes. However, when E. coli membranes expressing recombinant human cytochrome P450 (CYP) 2A6, 1A1, 1A2, or 1B1 were added to cultures of Salmonella, umu gene expression induced by DNA damaging agents was triggered. The metabolites responsible for this genotoxic effect have not been identified.

Toxic effects

Experimental system

In a 2-year feed study, benzophenone treatment increased the severity of chronic kidney disease and the incidence of renal tubular hyperplasia and hepatocellular hypertrophy in rats, as well as nephropathy, olfactory epithelial chemosis, and splenic lymphoid follicular hyperplasia in mice. When treatment was initiated, animal 1s were 6 weeks (rats) or 8 weeks (mice); therefore, any potential endocrine-related effects associated with perinatal exposure were not captured in these studies.

Endocrine disrupting effects

In vitro effects

The benzophenone metabolite 4-hydroxybenzophenone induced proliferation of MCF-7 cells, an estrogen-responsive human breast cancer cell line, when cultured in medium without estradiol; this effect was also produced by 17β-estradiol, but not by benzophenone or dibenzyl alcohol.

4-Hydroxybenzophenone competed with 17β-estradiol for binding to human recombinant estrogen receptor alpha (ERα) encapsulated on 96-well plates (50% inhibitory concentration, ~5 × 10 -5 M), but neither benzophenone nor benzyl alcohol exhibited this competition. 4-Hydroxybenzophenone was approximately three orders of magnitude less potent than hexestrol for competition.

The bicyclic hydroxylated compounds (3- and 4-hydroxybenzophenone) produced upon exposure of benzophenone to sunlight competitively inhibit the binding of 17β-estradiol to human recombinant ERα and trigger ER-mediated transcriptional activity in yeast cells.

Some benzophenone derivatives that have been widely used as UV shields also possess estrogenic activity: benzophenone (2,2',,4,4',-tetrahydroxybenzophenone) also competes with 17β-estradiol for the binding of ERα and ERβ.

In addition, benzophenone-3 (2-hydroxy-4-methoxybenzophenone) triggers anti-androgenic activity in a human breast cancer cell line (MDA-kb2) by inhibiting dihydrotestosterone-induced androgen receptor activation, but there is no evidence of agonist activity. Nuclear receptor . It transcriptionally activates human ERα and ERβ in transfected human embryonic kidney cells (HEK293) and antagonizes the transcriptional activation of the androgen receptor by dihydrotestosterone and the progesterone receptor by synthetic progestin (ORG 2058) in a transfected human osteosarcoma cell line (U2)-OS).

Benzophenone and its metabolite 4-hydroxybenzophenone elicited estrogenic activity in MCF-7 cells and anti-androgenic activity in transfected rat fibroblast NIH3T3 cells. In both assays, 4-hydroxybenzophenone was more effective than benzophenone, but less effective than benzophenone-2.

In vivo effects

The in vivo estrogenic activity of benzophenone was confirmed in a uterotrophic assay. Subcutaneous injection of 4-hydroxybenzophenone (once daily for 3 days at 100, 200, or 400 mg/kg bw) into immature (21-day-old) female Sprague-Dawley rats produced absolute and relative dose-related increases in uterine weight. Morphological evaluation showed that treatment increased the height of the luminal epithelium and the thickness of the uterine stroma due to proliferation of the uterine luminal epithelium and increased the thickness of the vaginal epithelium and induced keratinization. The same uterotrophic effects were observed in de-ovulated Sprague-Dawley rats given benzophenone at doses of 100 and 400 mg/kg body weight in corn oil by gavage for 3 consecutive days. Uterine weight was also increased in de-ovulated female F344 rats that received intraperitoneal injections of benzophenone (300 mg/kg bw) for 3 days. [The estrogen-like effects of benzophenone in the female reproductive tract appear to be due to metabolism to 4-hydroxybenzophenone, which binds to ERα.]

 

3- and 4-hydroxybenzophenone induced an increase in uterine weight in immature female Sprague-Dawley rats exposed subcutaneously for 3 consecutive days. Pretreatment with the anti-estrogen ICI 182 780 (Faslodex) inhibited the effect on uterine weight. Thus, the estrogenic product of benzophenone can also be produced by photochemical activation. [This observation is important because benzophenone has been used as a UV filter in cosmetics].

The same uterotrophic effect as that of 4-hydroxybenzophenone was observed in ovariectomized Sprague-Dawley rats fed benzophenone in the diet for 2 3 months. In addition to the uterotrophic effects, in ovariectomized Sprague-Dawley rats given benzophenone-2 5 times by gavage in olive oil, expression of ER-related receptor 1 in the uterus and ERβ in the thyroid was increased and ERα expression in the uterus was decreased for days. At similar exposures, benzophenone 3 did not increase uterine weight, but decreased ERα expression in the pituitary and ERβ expression in the uterus. In addition to the estrogen-like effects induced by benzophenone 2 in multiple organs (including increased expression of insulin growth factor 1 in the vagina, decreased expression of insulin growth factor 1 in the liver, decreased pituitary synthesis of luteinizing hormone and decreased serum cholesterol HDL and LDL), 5 days of treatment resulted in decreased serum thyroxine and triiodothyronine levels via non-ER-mediated processes. The latter effect of benzophenone-2 appears to be due to interference with thyroid hormone biosynthesis by inhibition or inactivation of thyroid peroxidase.

Of the 17 benzophenone derivatives evaluated for anti-androgenic activity in vitro, the most potent (2,4,4',-trihydroxybenzophenone) also significantly inhibited the effects of testosterone on prostate and seminal vesicle weight gain in depressed male F344 rats (Hershberger test), confirming the in vivo anti-androgenic effects of this chemical. benzophenone-2 - an estrogen Benzophenone-2 - an estrogenic chemical - also induces hypospadias in male C57BL/6 mice treated by tube feeding from day 12 to day 17 of gestation. The authors conclude that this effect is dependent on ER signaling, as co-administration with an ER antagonist (EM-800) prevents benzophenone 2 from inducing hypospadias.

Benzophenone has also been shown to induce in vitro the interaction between the progesterone X receptor and steroid receptor coactivator 1 and to induce CYP2B1/2,-,2C11 and -, 3A1 gene expression in the liver of male Sprague-Dawley rats administered intraperitoneally 50, 100 or 250 mg/kg body weight daily for 3 days. Increased expression of [ CYP2B1 indicates the involvement of constitutive androstane-receptors]. Thus, benzophenone can also disrupt normal endocrine function through transcriptional activation of the pregnane X receptor and upregulation of the expression of genes encoding enzymes involved in endogenous steroid hormone metabolism.

The above studies suggest that benzophenone-derived chemicals with endocrine activity may alter normal development and affect the endocrine regulation of multiple organs through a variety of mechanisms.

4. Carcinogenic mechanisms

Although the mechanisms by which benzophenones induce tumors are not fully understood, they are likely to be complex. These effects may include the production of reactive oxygen species or endocrine disruption via multiple receptors, including estrogen-like effects due to benzophenone binding to ERα, altered endogenous steroid hormone metabolism, transcriptionally activated antagonistic androgen receptors, and possible activation of nuclear constitutive androstane and progesterone X receptors. [The working group noted that hydroxylation of benzophenone aromatics to transcriptionally active metabolites is likely to occur in humans].

4. Summary of data

Exposure data

Benzophenone is produced by the aromatization of benzoyl chloride with an excess of benzene. It can also be formed by atmospheric oxidation of diphenylmethane. Benzophenone is used as a UV curing agent, flavor component, aroma enhancer and perfume fixative, and as an additive in plastic, paint and adhesive formulations. Benzophenone is also used as a barrier to prevent UV damage to cosmetics. It is used in laundry and household cleaning products, as well as in the manufacture of pharmaceuticals, pesticides and agricultural chemicals. Benzophenone enters the environment through wastewater and municipal solid waste landfill leachate after washing from skin and clothing, and is ubiquitous in water, sediment and biota.

Occupational exposure may occur through inhalation and dermal contact during the manufacture of products containing benzophenone. Dietary exposure to benzophenone is due to its natural occurrence in foods or addition to foods as a flavoring agent, its presence in drinking water as a contaminant, and through its migration from food packaging, printing inks, or recycled cardboard. Exposure may also occur through inhalation of fragrances used in indoor air and through dermal contact with household cleaning and personal care products.

Human carcinogenicity data

No data were available for the working group.

Animal Carcinogenicity Data

The carcinogenicity of benzophenone was tested in a study in mice and rats by oral administration in the diet and in a study in mice by dermal application. Oral administration of benzophenone significantly increased the incidence of hepatocellular adenoma, hepatocellular adenoma, hepatocellular carcinoma and hepatoblastoma (combined) in male mice and histiocytic sarcoma in female mice. It increased the incidence of monocytic leukemia in male and female rats (not statistically significant in female rats), renal tubular adenoma in male rats and histiocytic sarcoma in female rats (not statistically significant). Dermal application of benzophenone did not induce tumors in mice.

Renal tumors, histiocytic sarcoma and hepatoblastoma are rare spontaneous tumors in experimental animals.

Other relevant data

No toxicokinetic data are available on benzophenone in humans. Benzophenone is absorbed by monkeys following dermal application and is rapidly absorbed from the gastrointestinal tract of rodents. It is metabolized by reduction to benzyl alcohol or by oxidation to 4-hydroxybenzophenone. The latter compound can also be formed by UV or sunlight exposure to benzophenone.

Benzophenone is not mutagenic to Salmonella and does not induce micronuclei in mice. In the presence of E. coli membranes expressing recombinant human cytochrome P450, benzophenone and its metabolites induce umu gene expression in Salmonella, an indicator of DNA damage.

The benzophenone metabolite 4-hydroxybenzophenone induces estrogenic activity and anti-androgenic activity in vitro, and the in vivo estrogenic activity of benzophenone has been demonstrated in various uterotropic assays. Benzophenone may alter endocrine signaling through multiple effects on receptors.

The evidence for a mechanism of tumor induction by benzophenone is weak, but the relevance of a tumor response in experimental animals to humans cannot be ruled out.