dichloromethane

Dichloromethane was detected in all 8 samples of mother's milk from 4 urban areas(1). Mother's milk in Soviet women manufacturing rubber articles - 74 ppb mean in 17 of 28 samples approx 5 hours after start of work, level declined after termination of work(2). Whole blood samples, 250 subjects, not detected to 25 ppb, 0.7 ppb average(3). Mean level of dichloromethane present in urine of workers at a pharmaceutical factory where this substance is used as a solvent was 190.8 ug/L during a 4-hr shift but appears to be nearly eliminated during the night break(5). Dichloromethane was detected in the urine of 9 of 20 humans, who were exposed in their workplaces, at levels of 0.001-0.045 ug/L(5). Personal air samples collected at homes of high school students in the Harlem area of New York Cit...

ATMOSPHERIC FATE: According to a model of gas/particle partitioning of semivolatile organic compounds in the atmosphere(1), dichloromethane, which has a vapor pressure of 435 mm Hg at 25 °C(2), is expected to exist solely as a vapor in the ambient atmosphere. Vapor-phase dichloromethane is degraded in the atmosphere by reaction with photochemically-produced hydroxyl radicals(SRC); the half-life for this reaction in air is estimated to be 160 days(SRC), calculated from its rate constant of 1.0X10-13 cu cm/molecule-sec at 25 °C(3). Dichloromethane does not absorb at wavelengths >290 nm(4,5) and, therefore, is not expected to be susceptible to direct photolysis by sunlight in the troposphere(SRC). A small fraction of the chemical is expected to diffuse to the stratosphere where it will rap...

Dichloromethane has reported experimentally derived Koc values of 28(1), 36(2), 48 and 8(3). According to a classification scheme(4), these Koc values suggest that dichloromethane is expected to have very high mobility in soil. Dichloromethane is adsorbed strongly to peat moss, less strongly to clay, only slightly to dolomite limestone, and not at all to sand(5).

ANAEROBIC: Dichloromethane exhibited 86-92% conversion to carbon dioxide (CO2) after acclimation using anaerobic digestion in wastewater(1). Under simulated conditions of a landfills, dichloromethane was degraded at a rate of 0.6 mg/cu m.hr(2). A half-life of 11 days has been reported in a 30-60 day laboratory study using anaerobic groundwater bacteria(3). A rate constant of 0.0064/day, half-life of 108 days, was observed from an initial dichloromethane concentration of 3500 ug/L over a 906 day period at a contaminated methanogenic site in Hawkesbury, Ontario, Canada(4). Biodegradation of dichloromethane in contaminated aquifers may occur under nitrate-reducing conditions via oxidation pathways(5). Dichloromethane is mineralized by various microbial mixed consortia and isolated single b...

Using carp (Cyprinus carpio) which were exposed over a 6-week period, a BCF range of 2.0-40 was determined for dichloromethane at initial concentrations of 25 and 250 ug/L(1). According to a classification scheme(2), this BCF range suggests bioconcentration in aquatic organisms is low to moderate(SRC).

The Henry's Law constant for dichloromethane is 3.25X10-3 atm-cu m/mole(1). This Henry's Law constant indicates that dichloromethane is expected to volatilize rapidly from water surfaces(2). Based on this Henry's Law constant, the volatilization half-life from a model river (1 m deep, flowing 1 m/sec, wind velocity of 3 m/sec)(2) is estimated as 2.9 hours(SRC). The volatilization half-life from a model lake (1 m deep, flowing 0.05 m/sec, wind velocity of 0.5 m/sec)(2) is estimated as 3.7 days(SRC). Half-lives for the evaporation from water of 3-5.6 hours have been determined at moderate mixing conditions(4). When released into an estuarine bay, all the chemical dissipated within 4 km of the release point in the spring and within 8 km in the winter under ice(5). Dichloromethane's Henry's...

The recommended IUPAC rate constant for the vapor-phase reaction of dichloromethane with photochemically-produced hydroxyl radicals is 1.0X10-13 cu cm/molecule-sec at 25 °C(1). This corresponds to an atmospheric half-life of about 160 days at an atmospheric concentration of 5X10+5 hydroxyl radicals per cu cm(2). The rate constant for the vapor-phase reaction of dichloromethane with atmospheric nitrate radicals, which occur predominantly in night-time air, has been measured as 4.8X10-18 cu cm/molecule-sec at 25 °C(3); this corresponds to an atmospheric half-life of about 16 years(SRC) at an atmospheric concentration of 2.8X10+8 nitrate radicals per cu cm(2). Dichloromethane does not absorb at wavelengths >290 nm(4,5) and, therefore, is not expected to be susceptible to direct photolysis...

RAIN/SNOW/FOG: Dichloromethane was detected in rain water samples collected from Japan in 1991 at a concentration of <0.10 ppb in urban and rural areas(1). In monitoring conducted between Nov 2000 and May 2001 at four sites along the Baltic Sea, Poland, dichloromethane was detected in precipitation samples at a range of 1-180 parts per trillion (average of 4 parts per trillion)(2).

Dichloromethane was detected in intermediate grain based food (1984); 9 varieties, 77.8% pos, 1.9-30 ppb (maximum concentration in bleached flour, followed by a fudge brownie mix; wheat, corn, oats (1984), 10, 2, and 1 samples, respectively: not detected(1). Table ready foods: 19 varieties, 42% pos, 1.4-71 ppb; maximum concentration in cheddar cheese; butter, 7 samples, 100% pos; 1.1-280 ppb; margarine, 7 samples, 100% pos, 1.2-81 ppb; cheese, 4 types 8 samples, 100% pos, 3.9-98 ppb, maximum concentration in Parmesan cheese(2).

Dichloromethane was detected in all 8 samples of mother's milk from 4 urban areas(1). Mother's milk in Soviet women manufacturing rubber articles - 74 ppb mean in 17 of 28 samples approx 5 hours after start of work, level declined after termination of work(2). Milk samples collected from 8 grocery stores in Las Vegas, NV in Jan-Feb 2002 contained average dichloromethane concentrations of 0.13, 0.02 and 0.06 ng/mL in whole milk, 2% milk and 1% milk respectively(3).

In 7 U.K. waste disposal facilities, concentrations of dichloromethane were found to range between 1 and 85 ug/cu m(1). Air samples were taken from 4 municipal landfill sites (3 old, 1 active) in southern Finland between 1989 and 1990, 100-250 meters from housing, concentrations ranged between 0.8-112 ug/cu m(2). Leachate samples taken from 3 hazardous wastes sites in Germany showed concentrations of dichloromethane ranging between 70 and 200,000 ug/L(3). In 1989, Dichloromethane was detected in air samples collected at 6 different sites. In 3 separate campaigns from sources such as vehicle exhaust, gasoline vapor, natural gas, industrial solvents, and drycleaning/ degreasing/wastewater at concentrations ranged from 0 to 48 ug/cu m, with an average of 1.5 ug/cu m(4). The City of Los Ang...

Dichloromethane is formed in the oceans with phytoplankton production of dichloromethane being one natural source(1). The quantity of dichloromethane in the global environment due to contribution from oceans is estimated between 190,000 and 200,000 tonnes per year(2). Dichloromethane has been detected in volcanic gases(3).

SOURCE DOMINATED: Dichloromethane was present 127 samples at an average of 270 parts per trillion(1) and in samples from 11highly industrialized locations at an average of 10-74,000 parts per trillion(2). Industrial sites in Newark, Elizabeth and Camden, NJ sampled during the summer 1981 contained dichloromethane at 230-720 parts per trillion, geometric mean, 10.2 ppb maximum(3). Estimated U.K. emissions in 1990 showed a concentration of 0.40% dichloromethane (by mass of total emissions)(4). In southern California and the Los Angeles area, 1.7% of total organic gas emissions was dichloromethane, due to industrial adhesive activities(5). 7-24% of dichloromethane was detected in approximately 50 air samples collected from the Lamato Reserve in Ivory Coast between Feb 9 and 18, 1991 and al...

Bottomfish were collected from Commencement Bay and adjacent waterways, Tacoma, WA in 1982. The highest average dichloromethane level was 0.53 ppm in English Sole (Parophrys vetulus) in 5 samples from the City Waterway, with the highest level of dichloromethane at 0.7 ppm(1). In a study on Lake Pontachartrain, New Orleans, dichloromethane concentration in oysters (Crassostrea virginica) from Inner Harbor Navigation Canal was 7.8 ng/g (ppb) wet weight. The concentration of dichloromethane in clams (Rangia cuneata) from Chef Manteur Pass was 27 ppb and from Rigolets, 4.5 ppb(2).

Dichloromethane is formed during the chlorination of water.

SEDIMENT: Bottom sediment near sewage outfall - Southern California - <4 ppb. In Lake Pontchartrain, New Orleans: 1.5 ppb wet weight in sediment from Inner Harbor Navigation Canal; 3.2 ppb in sediment from Chef Monteur Pass; and not detected in sediment from Rigolets(1-2). USEPA STORET database, 338 data points, 20.0% pos, 13.0 ppb median(3). Dichloromethane was not detected in sediments which were collected from mouths of several rivers and a port in Niigata Prefecture, Japan in September, 1995, detection limit= 120 ng/g(4).

Exposure levels between 1-69 mg/cu m (occupational exposure standard of 350 mg/cu m) were detected in 7 U.K. waste disposal facilities(1). Average worker exposure concentrations ranging between 0 and 25 ug/cu m were detected at various locations within municipal solid waste composting facilities(2). In Denmark, aerosol products were analyzed for dichloromethane, in 21 samples of cosmetics a concentration of 0.001-0.05%, in 3 samples of household and hobby products a concentration of 0.2-4.0%, 3 samples of paint and paint remover, a conc of 0.02-0.07%, 1 sample of lubricant and anti-rust products, a concentration of 55.8%(3). Exposure of dichloromethane was detected in 15 non-production departments of 3 mills at concentratuions ranging from 6.1 to 100 ppm, median concentration of 0 ppm(4).

Dichloromethane's production and use as a solvent in paint removers and other solvent applications, in degreasing and cleaning fluids, in aerosols and as a chemical intermediate may result in its release to the environment through various waste streams. Release to the environment also includes emissions from the oceans, biomass burning and volcanic gas emissions. If released to air, a vapor pressure of 435 mm Hg at 25 °C indicates dichloromethane will exist solely as a vapor in the ambient atmosphere. Vapor-phase dichloromethane will be degraded in the atmosphere by reaction with photochemically-produced hydroxyl radicals; the half-life for this reaction in air is estimated to be 160 days. Dichloromethane does not absorb at wavelengths >290 nm and, therefore, is not expected to be susce...

Breathing large amounts of methylene chloride causes dizziness, nausea, tingling or numbness of the finger and toes, loss of concentration, and reduced hand-eye coordination. Very high concentrations can lead to unconciousness, coma, and death. Skin contact with methylene chloride causes burning and redness of the skin. (L188, L189)

Treatment of methylene chloride exposure is mainly symptomatic. Ingested methylene chloride may be removed by emesis and/or gastric lavage, and activated charcoal. Hyperbaric oxygen may be used to treat the carbon monoxide poisoning that can result from inhalation of methylene chloride. (L190)

[in animals: lung, liver, salivary & mammary gland tumors]

The influence of different kinds of industrial solvents on the vestibular function of rats was studied by recording nystagmus, induced by accelerated rotation. The effect was related to the blood levels of the solvents. ...

Eyes, skin, cardiovascular system, central nervous system

LD50: 437 mg/kg (Intraperitoneal, Mouse) (T14) LD50: 6460 mg/kg (Subcutaneous, Mouse) (T14) LD50: 1600 mg/kg (Oral, Rat) (T32) LC50: 14 400 ppm over 7 hours (Inhalation, Mouse) (T14)

Exposure to methylene chloride may cause optic neuropathy and hepatitis. Very high concentrations can lead to unconciousness, coma, and death. It is metabolized to carbon monoxide, potentially leading to carbon monoxide poisoning. Methylene chloride also causes liver and kidney injury, and may be a carcinogen. (T10, L189)

ACGIH Carcinogen - Confirmed Animal.

Oral (L188); inhalation (L188); dermal (L188)

Methylene chloride targets the lungs, blood system, and nervous system. In the lungs its metabolites damage Clara cells. It is also metabolized into carbon monoxide, which binds to hemoglobin to produce dose-dependent increases in carboxyhemoglobin. This results in the reduced oxygen transport and neurological dysfunction characteristic of carboxyhemoglobinemia (carbon monoxide poisoning). Methylene chloride is also believed to cause neurotoxicity by interfering with signal transmission in a manner similar to general anesthetics. Certain metabolites, such as formaldehyde, may result in carcinogenic effects by causing DNA single strand breaks, DNA-protein crosslinks, and other mutations. (T10, L188) CDC-ATSDR Toxicological Profile

Acute Inhalation: 0.6 ppm (L134) Intermediate Inhalation: 0.3 ppm (L134) Chronic Inhalation: 0.3 ppm (L134) Acute Oral: 0.2 mg/kg/day (L134) Chronic Oral: 0.06 mg/kg/day (L134)

Oral Slope Factor Reference: IRIS Current

2A, probably carcinogenic to humans. (L135)

... patients with cardiovascular disease may be particularly susceptible to the effects of dichloromethane-induced carboxyhemoglobinemia.

Soil Saturation Concentration (mg/kg): 3.32e+03

Dichloromethane is reasonably anticipated to be a human carcinogen based on sufficient evidence of carcinogenicity from studies in experimental animals.

Advanced treatment: Consider orotracheal or nasotracheal intubation for airway control in the patient who is unconscious, has severe pulmonary edema, or is in severe respiratory distress. Positive-pressure ventilation techniques with a bag-valve-mask device may be beneficial. Consider drug therapy for pulmonary edema ... . Monitor cardiac rhythm and treat arrhythmias if necessary ... . Start IV administration of D5W /SRP: "To keep open", minimal flow rate/. Use 0.9% saline (NS) or lactated Ringer's (LR) if signs of hypovolemia are present. For hypotension with signs of hypovolemia, administer fluid cautiously. Watch for signs of fluid overload ... . Treat seizures with diazepam or lorazepam ... . Use proparacaine hydrochloride to assist eye irrigation ... . /Chlorinated fluorocarbons (C...

Soil Saturation Concentration (mg/kg): 3.32e+03

Reference: Smith, C.D. and Nowell, L.H., 2024. Health-Based Screening Levels for evaluating water-quality data (3rd ed.). DOI:10.5066/F71C1TWP