Lead Chromate

Metals -> Lead Compounds, Inorganic

Carcinogens

6.12 at 59 °F (NTP, 1992) - Denser than water; will sink

6.12 g/cu cm

6.3 g/cm³

6.12 at 59 °F

6.12 @25 °C

Yellow or orange-yellow powder

Yellow-orange monoclinic crystals

Orthorhombic: yellow crystals; monoclinic: orange crystals; tetragonal: red crystals

less than 1 mg/mL at 66 °F (NTP, 1992)

In water, 0.2 mg/L

In water, 0.17 mg/L at 20 °C

In water, 0.058 mg/L at 25 °C

Insoluble in acetic acid; soluble in dilute nitric acid and in solutions of fixed alkali hydroxides

Soluble in acid; insoluble in ammonia

Decomposes (NTP, 1992)

Decomposes

not available (decomposes when heated)

482 °F (decomposes)

1551 °F (NTP, 1992)

844 °C

844 °C

844 °C

1551 °F

844 °C

Danger

H350: May cause cancer [Danger Carcinogenicity]

P203, P260, P273, P280, P318, P319, P391, P405, and P501 (click each P-code to see the statement)

This chemical does not meet GHS hazard criteria for 0.3% (1 of 374) of reports.

Danger

H350 (99.7%): May cause cancer [Danger Carcinogenicity]

Chemical: Chromic acid (H2CrO4), lead(2+) salt (1:1)

Hazard Traits - Carcinogenicity; Reproductive Toxicity

SP - indicates a substance that is identified in a proposed Significant New Use Rule.

Restricted substance: Lead chromate

Substance: Lead chromate

Lead (II) chromate: HSNO Approval: HSR003009 Approved with controls

Flammability and Flash point data are unavailable; this compound is probably non-flammable. (NTP, 1992)

Not combustible. Gives off irritating or toxic fumes (or gases) in a fire. Risk of fire and explosion on contact with incompatible substances. See Chemical Dangers.

Despite the limited evidence for lead chromate causing cancer in humans, there is ample evidence in humans and animals that all Cr(VI) compounds, both soluble and insoluble, are capable of causing lung cancer. Lead poisoning can occur in exposed workers. [ACGIH] See Lead and linked occupational diseases. See Chromium and linked occupational diseases.

D008; A solid waste containing lead may or may not become characterized as a hazardous waste when subjected to the Toxicity Characteristic Leaching Procedure listed in 40 CFR 261.24, and if so characterized, must be managed as a hazardous waste. /Lead/

D007; A solid waste containing chromium may or may not become characterized as a hazardous waste when subjected to the Toxicity Characteristic Leaching Procedure listed in 40 CFR 261.24, and if so characterized, must be managed as a hazardous waste. /Chromium/

Pursuant to section 8(d) of TSCA, EPA promulgated a model Health and Safety Data Reporting Rule. The section 8(d) model rule requires manufacturers, importers, and processors of listed chemical substances and mixtures to submit to EPA copies and lists of unpublished health and safety studies. Chromic acid (H2Cr04 ), lead (2+) salt (1:1) is included on this list. Effective date: 2/28/2008; Sunset date: 4/28/2008.

This compound is not very flammable but any fire involving this compound may produce dangerous vapors. You should evacuate the area. All firefighters should wear full-body protective clothing and use self-contained breathing apparatuses. You should extinguish any fires involving this chemical with a dry chemical, carbon dioxide, foam, or halon extinguisher. (NTP, 1992)

In case of fire in the surroundings, use appropriate extinguishing media.

Fresh air, rest.

Rinse and then wash skin with water and soap.

Rinse with plenty of water (remove contact lenses if easily possible).

Rinse mouth. Give one or two glasses of water to drink.

EYES: First check the victim for contact lenses and remove if present. Flush victim's eyes with water or normal saline solution for 20 to 30 minutes while simultaneously calling a hospital or poison control center. Do not put any ointments, oils, or medication in the victim's eyes without specific instructions from a physician. IMMEDIATELY transport the victim after flushing eyes to a hospital even if no symptoms (such as redness or irritation) develop.

Suitable extinguishing media: Use water spray, alcohol-resistant foam, dry chemical or carbon dioxide.

Advice for firefighters: Wear self-contained breathing apparatus for firefighting if necessary.

NFPA recommends the use of water on fire.

From a secure, explosion-proof location, use water spray to cool exposed containers, If cooling streams are ineffective (venting sound increases in volume and pitch, tank discolors, or shows any signs of deforming), withdraw immediately to a secure position.

For more Fire Fighting Procedures (Complete) data for LEAD CHROMATE (6 total), please visit the HSDB record page.

Keep container tightly closed in a dry and well-ventilated place. Keep in a dry place. Storage class (TRGS 510): Non-combustible, acute toxic Cat.3 / toxic hazardous materials or hazardous materials causing chronic effects

Store in a secure poison location. ... Lead chromate must be stored to avoid contact with oxidizers (such as perchlorates, peroxides, permanganates, chlorates, and nitrates) and chemically active metals (such as potassium, sodium, magnesium, zinc and ferric ferrocyanide), since violent reactions occur. A regulated, marked area should be established where this chemical is handled, used, or stored in compliance with OSHA Standard 1910.1045.

PRECAUTIONS FOR "CARCINOGENS": Storage site should be as close as practical to lab in which carcinogens are to be used, so that only small quantities required for ... expt need to be carried. Carcinogens should be kept in only one section of cupboard, an explosion-proof refrigerator or freezer (depending on chemicophysical properties ...) that bears appropriate label. An inventory ... should be kept, showing quantity of carcinogen & date it was acquired ... Facilities for dispensing ... should be contiguous to storage area. /Chemical Carcinogens/

ACCIDENTAL RELEASE MEASURES: Personal precautions, protective equipment and emergency procedures: Use personal protective equipment. Avoid dust formation. Avoid breathing vapors, mist or gas. Ensure adequate ventilation. Evacuate personnel to safe areas. Avoid breathing dust; Environmental precautions: Prevent further leakage or spillage if safe to do so. Do not let product enter drains. Discharge into the environment must be avoided; Methods and materials for containment and cleaning up: Pick up and arrange disposal without creating dust. Sweep up and shovel. Keep in suitable, closed containers for disposal.

Evacuate persons not wearing protective equipment from area of spill or leak until cleanup is complete. Remove all ignition sources. Collect powdered material in the most convenient and safe manner and deposit in sealed containers. Ventilate area after cleanup is complete. It may be necessary to contain and dispose of this chemical as a hazardous waste. If material or contaminated runoff enters waterways, notify downstream users of potentially contaminated waters.

Cr(VI) cmpd in waste sludge are completely removed by redn by carbon at 600 °C. /Chromium VI/

Persons not wearing protective equipment and clothing should be restricted from areas of spills until cleanup has been completed. If chromic acid or chromates are spilled, the following steps should be taken: 1. Ventilate area of spill. 2. Collect spilled material in the most convenient and safe manner and deposit in sealed containers for reclamation or for disposal in a secured sanitary landfill. Liquid containing chromic acid or chromates should be absorbed in vermiculite, dry sand, earth, or a similar material. /Chromic acid and chromates/

PRECAUTIONS FOR "CARCINOGENS": A high-efficiency particulate arrestor (HEPA) or charcoal filters can be used to minimize amt of carcinogen in exhausted air ventilated safety cabinets, lab hoods, glove boxes or animal rooms ... Filter housing that is designed so that used filters can be transferred into plastic bag without contaminating maintenance staff is avail commercially. Filters should be placed in plastic bags immediately after removal ... The plastic bag should be sealed immediately ... The sealed bag should be labelled properly ... Waste liquids ... should be placed or collected in proper containers for disposal. The lid should be secured & the bottles properly labelled. Once filled, bottles should be placed in plastic bag, so that outer surface ... is not contaminated ... The plastic bag should also be sealed & labelled. ... Broken glassware ... should be decontaminated by solvent extraction, by chemical destruction, or in specially designed incinerators. /Chemical Carcinogens/

SMALL SPILLS AND LEAKAGE: Should a spill occur while you are handling this chemical, you should dampen the solid spill material with dilute acid or dilute alkali (e.g. dilute HNO3), then transfer the dampened material to a suitable container. Use absorbent paper dampened with the dilute acid or alkali to pick up any remaining material. Seal the absorbent paper and any of your clothing which may be contaminated in a vapor-tight plastic bag for eventual disposal. Solvent-wash all contaminated surfaces with dilute acid or alkali followed by washing with strong soap and water solution. Do not reenter the contaminated area until the Safety Officer (or other responsible person) has verified that the area has been properly cleaned.

Generators of waste (equal to or greater than 100 kg/mo) containing this contaminant, EPA hazardous waste number D007, must conform with USEPA regulations in storage, transportation, treatment and disposal of waste. /Chromium/

Generators of waste (equal to or greater than 100 kg/mo) containing this contaminant, EPA hazardous waste number D008, must conform with USEPA regulations in storage, transportation, treatment and disposal of waste.

Product: Offer surplus and non-recyclable solutions to a licensed disposal company. Contact a licensed professional waste disposal service to dispose of this material. Dissolve or mix the material with a combustible solvent and burn in a chemical incinerator equipped with an afterburner and scrubber; Contaminated packaging: Dispose of as unused product.

Chemical Treatability of Lead; Concentration Process: Biological Treatment; Chemical Classification: Metal; Scale of Study: Respirometer Study; Results of Study: Oxygen uptake inhibited.

For more Disposal Methods (Complete) data for LEAD CHROMATE (18 total), please visit the HSDB record page.

Personal protection: particulate filter respirator adapted to the airborne concentration of the substance. Do NOT let this chemical enter the environment. Vacuum spilled material with specialist equipment. If appropriate, moisten first to prevent dusting. Carefully collect remainder. Then store and dispose of according to local regulations.

ACCIDENTAL RELEASE MEASURES: Personal precautions, protective equipment and emergency procedures: Use personal protective equipment. Avoid dust formation. Avoid breathing vapors, mist or gas. Ensure adequate ventilation. Evacuate personnel to safe areas. Avoid breathing dust; Environmental precautions: Prevent further leakage or spillage if safe to do so. Do not let product enter drains. Discharge into the environment must be avoided.

Precautions for safe handling: Avoid contact with skin and eyes. Avoid formation of dust and aerosols. Further processing of solid materials may result in the formation of combustible dusts. The potential for combustible dust formation should be taken into consideration before additional processing occurs. Provide appropriate exhaust ventilation at places where dust is formed.

Appropriate engineering controls: Handle in accordance with good industrial hygiene and safety practice. Wash hands before breaks and at the end of workday.

Gloves must be inspected prior to use. Use proper glove removal technique (without touching glove's outer surface) to avoid skin contact with this product. Dispose of contaminated gloves after use in accordance with applicable laws and good laboratory practices. Wash and dry hands.

For more Preventive Measures (Complete) data for LEAD CHROMATE (20 total), please visit the HSDB record page.

13 lead chromate-based pigments were assayed for mutagenicity and toxicity using Salmonella typhimurium TA100. The compounds were assayed with and without S9, both in the presence and absence of the chelating agent, nitrilotriacetic acid (NTA). In general, the use of NTA to solubilize the compounds resulted in mutagenicity and/or toxicity being observed where it had not in the absence of NTA, or being observed at lower concentrations than when water alone was used. Encapsulation of pigments with amorphous silica rendered these pigments non-mutagenic and non-toxic, indicating that the active moieties were biologically unavailable to the bacteria. Varying the percentage of silica encapsulation on one pigment, medium chrome yellow, indicated that 5% encapsulation did not alter the mutagenicity while 10% encapsulation inhibited the mutagenicity without or with NTA.

Lead is a neurotoxin and has been known to cause brain damage and reduced cognitive capacity, especially in children. Lead exposure can result in nephropathy, as well as blood disorders such as high blood pressure and anemia. Lead also exhibits reproductive toxicity and can results in miscarriages and reduced sperm production. Hexavalent chromium is a known carcinogen. Chronic inhalation especially has been linked to lung cancer. Hexavalent chromium has also been know to cause reproductive and developmental defects. (A12, L21)

The substance can be absorbed into the body by inhalation of dust and by ingestion.

Oral (L136) ; inhalation (L136); dermal (L136)

IDENTIFICATION AND USE: Lead chromate is a yellow or orange-yellow powder. It is used as a pigment for paints and inks; in oil and water colors; printing fabrics; decorating china and porcelain; in chemical analysis of organic substances; and in traffic paints. HUMAN EXPOSURE AND TOXICITY: Lead chromate is toxic by ingestion and inhalation. Although no evidence has been found that lead-chromate causes lung cancer in lead chromate workers, it cannot be unequivocally stated that heavy exposures to lead chromate does not present a cancer hazard. One possible mechanism for lead chromate-induced carcinogenesis is through centrosome dysfunction, leading to the induction of aneuploidy. Lead in lead chromate could cause possible neurotoxicity. Increasing concentrations of lead chromate induced increasing amounts of cytotoxicity and clastogenicity in human skin cells. ANIMAL STUDIES: A single sc injection of 30 mg lead chromate(VI) oxide in water to 2 groups of 40 rats gave rise to 26/40 & 27/40 sarcomas, respectively, at site of injection within 117-150 weeks. No local sarcoma occurred in 60 vehicle-treated control rats. Lead chromate induced 14 fibrosarcomas & 17 rhabdomyosarcomas at the site of injection in 31/47 rats given monthly im injections of lead chromate. In addition, 3/24 lead chromate-treated rats had renal carcinomas. No such tumors appeared in a similar group of 22 controls injected with the vehicle. No lung tumors were found in rabbits and guinea pigs after intratracheal instillation. The potential mutagenicity of lead chromate was tested by following battery of microbial tests: the Escherichia coli pola+/pola- survival test; the Salmonella/microsome his+ reversion assay; the E coli trp+ reversion test plate assay; the E coli gal+ forward mutation test; & the Saccharomyces cerevisiae assay for mitotic recombination. Lead chromate was mutagenic in Salmonella & in Saccharomyces. Metabolic activation by rat liver homogenate (S9) was not required. Apparently, chromate ion is responsible for mutagenicity of lead chromate. An insoluble chromic compound, lead chromate (PbCrO4), was not cytotoxic nor mutagenic on V79 cells, probably because it is taken up by the cells very slowly. ECOTOXICITY STUDIES: Lead chromate was both cytotoxic and genotoxic to sea turtle cells. Concentrations of 0.1, 0.5, 1, and 5 ug/sq cm lead chromate induced 108, 79, 54, and 7% relative survival, respectively. Additionally, concentrations of 0, 0.1, 0.5, 1, and 5 ug/sq cm lead chromate induced damage in 4, 10, 15, 26, and 36% of cells and caused 4, 11, 17, 30, and 56 chromosome aberrations in 100 metaphases, respectively. Increasing concentrations of lead chromate induce increasing amounts of cytotoxicity and clastogenicity in sperm whale skin cells.

Lead mimics other biologically important metals, such as zinc, calcium, and iron, competing as cofactors for many of their respective enzymatic reactions. For example, lead has been shown to competitively inhibit calcium's binding of calmodulin, interferring with neurotransmitter release. It exhibits similar competitive inhibition at the NMDA receptor and protein kinase C, which impairs brain microvascular formation and function, as well as alters the blood-brain barrier. Lead also affects the nervous system by impairing regulation of dopamine synthesis and blocking evoked release of acetylcholine. However, its main mechanism of action occurs by inhibiting delta-aminolevulinic acid dehydratase, an enzyme vital in the biosynthesis of heme, which is a necesssary cofactor of hemoglobin. Hexavalent chromium's carcinogenic effects are caused by its metabolites, pentavalent and trivalent chromium. The DNA damage may be caused by hydroxyl radicals produced during reoxidation of pentavalent chromium by hydrogen peroxide molecules present in the cell. Trivalent chromium may also form complexes with peptides, proteins, and DNA, resulting in DNA-protein crosslinks, DNA strand breaks, DNA-DNA interstrand crosslinks, chromium-DNA adducts, chromosomal aberrations and alterations in cellular signaling pathways. It has been shown to induce carcinogenesis by overstimulating cellular regulatory pathways and increasing peroxide levels by activating certain mitogen-activated protein kinases. It can also cause transcriptional repression by cross-linking histone deacetylase 1-DNA methyltransferase 1 complexes to CYP1A1 promoter chromatin, inhibiting histone modification. Chromium may increase its own toxicity by modifying metal regulatory transcription factor 1, causing the inhibition of zinc-induced metallothionein transcription. (A12, L16, A34, A35, A36, T4, A20, A22, L136)

/AQUATIC SPECIES/ Sea turtles are a charismatic and ancient ocean species and can serve as key indicators for ocean ecosystems, including coral reefs and sea grass beds as well as coastal beaches. Genotoxicity studies in the species are absent, limiting our understanding of the impact of environmental toxicants on sea turtles. Hexavalent chromium (Cr(VI)) is a ubiquitous environmental problem worldwide, and recent studies show it is a global marine pollutant of concern. Thus, ...the cytotoxicity and genotoxicity of soluble and particulate Cr(VI) in hawksbill sea turtle cells /was evaluated/. Particulate Cr(VI) was both cytotoxic and genotoxic to sea turtle cells. Concentrations of 0.1, 0.5, 1, and 5 ug/sq cm lead chromate induced 108, 79, 54, and 7% relative survival, respectively. Additionally, concentrations of 0, 0.1, 0.5, 1, and 5 ug/sq cm lead chromate induced damage in 4, 10, 15, 26, and 36% of cells and caused 4, 11, 17, 30, and 56 chromosome aberrations in 100 metaphases, respectively. For soluble Cr, concentrations of 0.25, 0.5, 1, 2.5, and 5 uM sodium chromate induced 84, 69, 46, 25, and 3% relative survival, respectively. Sodium chromate induced 3, 9, 9, 14, 21, and 29% of metaphases with damage, and caused 3, 10, 10, 16, 26, and 39 damaged chromosomes in 100 metaphases at concentrations of 0, 0.25, 0.5, 1, 2.5, and 5uM sodium chromate, respectively. These data suggest that Cr(VI) may be a concern for hawksbill sea turtles and sea turtles in general.

/AQUATIC SPECIES/ Chromium (Cr) is a global marine pollutant, present in marine mammal tissues. Hexavalent chromium [Cr(VI)] is a known human carcinogen. In this study, we compare the cytotoxic and clastogenic effects of Cr(VI) in human (Homo sapiens) and sperm whale (Physeter macrocephalus) skin fibroblasts. Our data show that increasing concentrations of both particulate /lead chromate/ and soluble /sodium chromate/ Cr(VI) induce increasing amounts of cytotoxicity and clastogenicity in human and sperm whale skin cells. Furthermore, the data show that sperm whale cells are resistant to these effects exhibiting less cytotoxicity and genotoxicity than the human cells. Differences in Cr uptake accounted for some but not all of the differences in particulate and soluble Cr(VI) genotoxicity, although it did explain the differences in particulate Cr(VI) cytotoxicity. Altogether, the data indicate that Cr(VI) is a genotoxic threat to whales, but also suggest that whales have evolved cellular mechanisms to protect them against the genotoxicity of environmental agents such as Cr(VI).

Cough.

Redness.

See Effects of short-term exposure

Symptions of chronic lead poisoning include reduced cognitive abilities, nausea, abdominal pain, irritability, insomnia, metal taste in the mouth, excess lethargy or hyperactivity, chest pain, headache and, in extreme cases, seizures, comas, and death. There are also associated gastrointestinal problems, such as constipation, diarrhea, vomiting, poor appetite, weight loss, which are common in acute poisoning. Breathing hexavalent chromium can cause irritation to the lining of the nose, nose ulcers, runny nose, and breathing problems, such as asthma, cough, shortness of breath, or wheezing. Ingestion of hexavalent chromium causes irritation and ulcers in the stomach and small intestine, as well as anemia. Skin contact can cause skin ulcers. (L16, A2, L21)

... If environmental sampling and analysis show that environmental levels are at or greater than the recommended environmental levels, ... blood analysis shall be conducted quarterly ... until blood levels have returned to below the acceptable limit. ... If a blood level of 0.060 mg Pb/100 g or greater is found and confirmed by a second sample to be taken within two weeks, steps to reduce absorption of lead shall be taken as soon as the high levels are confirmed and a medical examination for possible lead poisoning shall be made available to workers with unacceptable blood lead levels. /Inorganic lead/

Medical records shall include information on all biologic determinations and on all required medical examinations. These records shall be available to the medical representatives of the employer, the Secretary of Labor, the Secretary of Health, Education, and Welfare and at the employee's request, to the employee's physician. /SRP: OSHA regs 1910.20 require that medical records be kept for duration of employment plus 30 years./ These records should be kept ... after the last occupational exposure to inorganic lead. /Inorganic lead/

... Comparative advantages of /the biological indicator/ delta-aminolevulinic acid dehydratase (ALAD) in typical (variable) occupational exposure conditions included: the highest sensitivity at low and relatively high lead exposure levels; better reflection of biologically active Pb as opposed to blood lead (PbB) (particularly compared to delta-aminolevulinic acid (ALAU) and coproporphyrin (CPU)); higher specificity compared to other indicators of lead effect; and generally higher reliability with regard to biologically and methodologically induced variations. ... /Inorganic lead/

The employer shall make available biological monitoring in the form of blood sampling and analysis for lead and zinc protoporphyrin levels to each employee who is or may be exposed above the action level for more than 30 days/yr. /Inorganic lead/

For more Medical Surveillance (Complete) data for LEAD CHROMATE (8 total), please visit the HSDB record page.

D008; A solid waste containing lead may or may not become characterized as a hazardous waste when subjected to the Toxicity Characteristic Leaching Procedure listed in 40 CFR 261.24, and if so characterized, must be managed as a hazardous waste. /Lead/

D007; A solid waste containing chromium may or may not become characterized as a hazardous waste when subjected to the Toxicity Characteristic Leaching Procedure listed in 40 CFR 261.24, and if so characterized, must be managed as a hazardous waste. /Chromium/

Pursuant to section 8(d) of TSCA, EPA promulgated a model Health and Safety Data Reporting Rule. The section 8(d) model rule requires manufacturers, importers, and processors of listed chemical substances and mixtures to submit to EPA copies and lists of unpublished health and safety studies. Chromic acid (H2Cr04 ), lead (2+) salt (1:1) is included on this list. Effective date: 2/28/2008; Sunset date: 4/28/2008.

... Substances for which a Federal Register notice has been published that included consideration of the serious health effects, including cancer, from ambient air exposure to the substance. Chromium is included on this list. /Chromium/

Listed as a hazardous air pollutant (HAP) generally known or suspected to cause serious health problems. The Clean Air Act, as amended in 1990, directs EPA to set standards requiring major sources to sharply reduce routine emissions of toxic pollutants. EPA is required to establish and phase in specific performance based standards for all air emission sources that emit one or more of the listed pollutants. Chromium compounds is included on this list. /Chromium compounds/

Toxic pollutant designated pursuant to section 307(a)(1) of the Federal Water Pollution Control Act and is subject to effluent limitations. /Lead and compounds/

Toxic pollutant designated pursuant to section 307(a)(1) of the Federal Water Pollution Control Act and is subject to effluent limitations. /Chromium and compounds/

Maximum contaminant level goal for inorganic contaminants: Contaminant: Chromium; MCLG 0.1 mg/L. /Chromium/

Maximum contaminant level goal for inorganic contaminants: Contaminant: Lead; MCLG 0 mg/L. /Lead/

Hexavalent chromium compounds are known carcinogens for the respiratory tract in humans. The mechanism of cell transformation by hexavalent chromium compounds is not fully understood although a role for intracellular reduction is sought. The aim of this study was to determine the distribution of Cr valence states in human cells after in vitro exposure to soluble or particulate chromium compounds. A synchrotron X-ray-based microprobe was used to investigate the cellular reduction of Cr(VI) and to image chromium oxidation states in cells. It was shown that soluble Cr(VI) compounds are fully reduced to Cr(III) in cells. Cr(III) is homogeneously distributed within the cell volume and therefore present within the nucleus. In the case of low solubility particulate chromate compounds, Cr(VI) can coexist in the cell environment, as particles in the perinuclear region, together with intracellular and intranuclear Cr(III). Chemical distribution maps also suggest that intracellular Cr(III) originates from extracellular dissolution and reduction of lead chromate rather than from intracellular engulfed particles. The possible stronger carcinogenicity of low solubility chromate vs soluble chromate compounds may derive from the combinative genotoxic effects of intranuclear Cr(III) and the persistent exposure to a strong oxidant, Cr(VI). /Soluble and particulate chromates/

Exposure to certain particulate hexavalent chromium [Cr(VI)] compounds, such as lead chromate (PbCrO4), has been associated with lung cancer and respiratory tract toxicity. Previous studies indicate that the solubility of Cr(VI)-compounds is an important factor in Cr(VI)-induced carcinogenesis. The present study investigates reactive oxygen species (ROS) generation by PbCrO4 particles and cellular responses using RAW 264.7 cells. A mixture containing PbCrO4 and RAW 264.7 cells generated hydroxyl radical ((.)OH), using cellularly generated H2O2 as a precursor, as measured by electron spin resonance (ESR) spin trapping in combination with H2O2 and (.)OH scavengers, catalase and sodium formate. The effect of ascorbic acid on (.)OH radicals was also measured using ESR. Confocal microscopy showed that particles could become either bound to the cell surface or engulfed over a 120 min time period. H2O2 generation and O2 consumption were also increased after treatment of the cells with PbCrO4. Both NF-kappaB and AP-1 were activated after exposure to PbCrO4 particles as measured by the NF-kappaB or AP-1 luciferase reporter plasmid assay. Our investigation thus demonstrated that the RAW 264.7 cells phagocytized the PbCrO4 particles leading to accumulation of the particles within vacuoles in the cytoplasm. These particles could induce chronic production of ROS and activation of NF-kappaB and AP-1. Such induction of transcription pathways may be involved in the inflammatory and carcinogenic responses induced by Cr(VI)-containing particles. /Lead chromate oxide/

Free radical reactions are believed to play an important role in the mechanism of Cr(VI)-induced carcinogenesis. Most studies concerning the role of free radical reactions have been limited to soluble Cr(VI). Various studies have shown that solubility is an important factor contributing to the carcinogenic potential of Cr(VI) compounds. Here, we report that reduction of insoluble PbCrO4 by glutathione reductase in the presence of NADPH as a cofactor generated hydroxyl radicals (.OH) and caused DNA damage. The .OH radicals were detected by electron spin resonance (ESR) using 5,5-dimethyl-N-oxide as a spin trap. Addition of catalase, a specific H2O2 scavenger, inhibited the .OH radical generation, indicating the involvement of H2O2 in the mechanism of Cr(VI)-induced .OH generation. Catalase reduced .OH radicals measured by electron spin resonance and reduced DNA strand breaks, indicating .OH radicals are involved in the damage measured. The H2O2 formation was measured by change in fluorescence of scopoletin in the presence of horseradish peroxidase. Molecular oxygen was used in the system as measured by oxygen consumption assay. Chelation of PbCrO4 impaired the generation of .OH radical. The results obtained from this study show that reduction of insoluble PbCrO4 by glutathione reductase/NADPH generates .OH radicals. The mechanism of .OH generation involves reduction of molecular oxygen to H2O2, which generates .OH radicals through a Fenton-like reaction. The .OH radicals generated by PbCrO4 caused DNA strand breakage.

Lead and chromium are absorbed following inhalation, oral, and dermal exposure. It is then distributed mainly to the bones and red blood cells. In the blood lead may be found bound to serum albumin or the metal-binding protein metallothionein. Organic lead is metabolized by cytochrome P-450 enzymes, whereas inorganic lead forms complexes with delta-aminolevulinic acid dehydratase. Lead is excreted mainly in the urine and faeces. Chromium distributes to nearly all tissues, with the highest concentrations found in kidney and liver. Bone is also a major storage site and may contribute to long-term retention. Hexavalent chromium's similarity to sulfate and chromate allow it to be transported into cells via sulfate transport mechanisms. Inside the cell, hexavalent chromium is reduced first to pentavalent chromium, then to trivalent chromium by many substances including ascorbate, glutathione, and nicotinamide adenine dinucleotide. Chromium is almost entirely excreted with the urine. (A12, L16, L136)

(51)Cr-labelled sodium, zinc and lead chromates were studied. Sodium chromate and the less soluble zinc chromate were absorbed by the blood, resulting in increased urinary excretion of chromium. ... The less water-soluble the chromate, the higher was its elimination via the feces. Absorbed chromium was retained in the spleen and bone marrow in all three cases, and also in the liver and kidneys in the case of sodium chromate. Chromium levels in blood and urine are not indicative of inhalation exposure to insoluble chromates.

Transmission electron microscopy (TEM) equipped with energy-dispersive x-ray analysis (EDX), electron spectroscopy for chemical analysis (ESCA), secondary ion mass spectrometry (SIMS), and laser microprobe for mass analysis (LAMMA) were used to follow the fate of chromium compounds deposited in the sheep tracheal lobe. Four chromium compounds were used: two chromium(VI) compounds (lead chromate and chromium trioxide) and two chromium(III) compounds (chronic oxide and chromium sulfate). Chromium trioxide is very soluble and the other three are slightly soluble. The compositions, concentrations, and sizes of particles were determined in the bronchoalveolar lavages (BAL) at d 2, 3, 5, and 30 after instillation and on the lung samples collected at d 31. The concentrations of particles in the BAL samples separated the chromium compounds in two groups where Cr2O3 and PbCrO4 (as Pb) were higher than Cr2(SO4)3, PbCrO4 (as Cr), and CrO3. The half-life for alveolar clearance of Cr2O3 and Cr2(SO4)3 has been calculated respectively at 11 and 80 d. Prismatic PbCrO4 particles break up in the lung and sustain a high concentration of isometric particles of lead chromate and another lead-containing compound in the BAL. The CrO3 instilled particles react with endogenous compounds or are transformed to insoluble hydroxyl complexes instead of diffusing very rapidly through the alveolar-capillary barrier. The alveolar clearance as measured in the BAL is not different from the control.

Used as a pigment; Chrome yellow is PbCrO4. Chrome green and chrome red also contain PbCrO4. [ACGIH] Used as a pigment in paints, ceramics, rubber and plastics, and fabric printing; [HSDB]

In 1977 the Consumer Product Safety Commission banned lead containing paint prohibiting the use of such paint on products to which consumers are exposed after sale. [ATSDR ToxFAQs, Toxicological Profile, Regulations and Advisories]

Painting (Pigments, Binders, and Biocides) [Category: Paint]

Pigment for paints and inks; in oil and water colors; printing fabrics, decorating china and porcelain; in chemical analysis of organic substances; in traffic paints.

Pigment in industrial paints, rubber, plastics, ceramic coatings; organic analysis

Lead chromate is used in pigments, as well as in some pyrotechnic compositions. (L53)

(1972) 3.06X10+10 G

(1975) 1.18X10+10 G (CHROME YELLOW & ORANGE)

Lead chromate (chrome yellow) can be produced by reacting sodium chromate with lead nitrate, or by reacting lead monoxide with chromic acid solution. By varying the proportion of reactants, either lead chromate (PbCrO4) or lead chromate oxide (basic lead chromate; PbO.PbCrO4) can be produced. High lead chromate content is associated with yellow pigments; increasing the lead chromate oxide content gives orange colors; and mixing with lead molybdate gives red pigments.

Chromic acid (H2CrO4), lead(2+) salt (1:1): ACTIVE

LEAD CHROMATE-BASED INKS ARE USED FOR PRINTING COLORED PAGES OF SOME CHILDREN'S MAGAZINES (COMICS). THIS PAPER REPORTS INVESTIGATIONS OF 48 UNITED KINGDOM, 9 SPANISH, & 5 AUSTRIAN COMICS.

Chrome yellows (containing 52-98% lead chromate) are considered to be the most versatile of the inorganic pigments and are therefore found in many formulations designed for a wide spectrum of uses.

Considerable energy is released by the mixture /of lead chromate and aluminum dinitronaphthalene/ derived from chromate-catalyzed exothermic decomposition of the nitro compound, coupled with a thermite-type reaction of the aluminum and chromate. It is useful for cracking concrete.