Summary of Initial Risk Assessment Report. Inorganic cyanide compounds (excluding complex salts and cyanates)

Transcription

1 Summary of Initial Risk Assessment Report Inorganic cyanide compounds (excluding complex salts and cyanates) This substance is assessed based on the Guideline for Initial Risk Assessment Version 2.0. >> Introduction << Inorganic cyanide compounds (except complex salts and cyanates) are the subject of this assessment report. Inorganic compounds exist as diverse chemical species which can change in the environment. These chemical species have different hazardous properties. However, very few measured environmental concentrations are available for each species. Taking that into consideration, risk assessments of inorganic compounds are conducted using slightly different procedures from those of organic compounds. Refer to the Guideline for more detail. In this report, units of concentrations and intake (e.g., mg/l, mg/kg-bodyweight/day) refer to the concentration or amount of CN. 1. General Information 1.1 Physico-chemical properties PRTR No. of Japan 108 Name (typical substance) Hydrogen cyanide Sodium cyanide Potassium cyanide Chemical formula HCN NaCN KCN CAS No Appearance Colorless gas or liquid White solid Colorless or white solid Melting point (degc) (degc) (degc) Boiling point (degc) 1,496 (degc) 1,625 (degc) Water solubility Miscible 582g/kg (20 degc) 716g/L (20 degc) 1.2 Environmental fate Bioaccumulation Biodegradation Bioaccumulation in the food chain probably does not occur. Bioconcentration factor (BCF): 0.50 (calculated based on logkow of -0.25) Cyanide can be biodegraded under specific conditions in which biological systems are acclimatized to cyanide. (In air) Stability and fate in the environment Cyanide is released into the environment mainly as HCN gas. As its degradation rate is relatively low, almost all HCN released into the atmosphere remains in the troposphere. Cyanide has the potential to be transported over long distances from its emission source. (In water) The alkali metal cyanides and hydrogen cyanide are very soluble in water. Biodegradation and volatilization are important transformation processes for cyanide in natural surface waters. 2. Sources of Release to the Environment 2.1 Annual production, import and domestic supply in 2001 The domestic supply of sodium cyanide was 24,508 tons in As for hydrogen cyanide, the sum of import and production was estimated to range from 1,000 to 100,000 tons

2 Listed industries R Uses Sodium cyanide: raw material of methionine, electroplating agent; raw material of agricultural chemicals Hydrogen cyanide: raw material of agricultural chemicals and organic synthetic chemicals 2.3 Release from industries within the scope of the PRTR system (in 2003) Release sources Air(ton) Water(ton) Soil(ton) Remarks Reported release <0.5 Release outside notification Release outside notification from non-listed industry Release into rivers: 36 tons Households (tobacco smoke) Mobile sources Total < Releases from other sources. Cyanide may be released through vehicle exhaust, combustion of coal and municipal waste, and during agricultural use of insecticides. 2.5 Main release routes The release of inorganic cyanide during use is greater than the release during production processes that use cyanide. The main release sources may be chemical industries and fiber industries

3 3. Exposure Assessment 3.1 Measured environmental concentration Media No. of points detected / No. of points measured No. of samples detected / No. of samples measured Detection range* 95th percentile Detection limit Year of investigation, Institution Air River water (microg/l) Drinking water (microg/l) 1022/ < /5541 -/11751 nd , Japan Water Works Association 2003, Japan Water Works Association Food (microg/g) -- 20/ , Kitada, et al. *nd: Not detected. For calculation of the 95th percentile, data less than the detection limit are replaced with a value equal to 1/2 of the detection limit. 3.2 Estimated environmental concentration Media Estimated concentration Description Air (microg/m 3 ) 4.4 River water (microg/l) 11 Calculated using the Atmospheric Dispersion Model for Exposure and Risk Assessment (AIST-ADMER) Ver Calculated using the Integrated River Model to predict the distribution of chemical concentration (IRM1) 3.3 Estimated environmental concentration in water (EEC) EEC(microg/L) The concentration estimated by mathematical model was used for the risk assessment because it is higher than the measured concentrations. 1)

4 Oral R Estimated human intake Intake route Concentration used for estimation of intake Estimated intake (microg/ person/ day) Estimated intake (microg/ kg-bodyweight (BW)/ day) Air 4.4(microg/m 3 ) The estimated concentration was used for the risk assessment because adequate measured data were not available. Drinking water Food (Umeboshi) 2(microg/L) The ninety-fifth percentile of measured concentrations was used for the risk assessment (microg/g) "Umeboshi " (pickled plum) is a popular food in Japan that is known to have relatively high concentrations of cyanide. Therefore, the intake of inorganic cyanide is derived from the average daily intake of "umeboshi " and the concentration of inorganic cyanide found in it (15.4 microg /g). Subtotal Total route ) This substance was assessed based on the Guideline for Initial Risk Assessment Version 2.0. Under Version 2.0, a measured concentration and an estimated concentration (calculated by mathematical model) are compared, and the higher concentration is used for the risk assessment. 4. Hazard Assessment 4.1 Effects on organisms in the environment Acute or Chronic/ Compounds Species Endpoint Concentration Algae Chronic (NaCN) Nitzschia linearis 72 hours LOEL Growth inhibition (mg/l) Crustacea Chronic (HCN) Gammarus pseudolimnaeus 83 days NOEC Growth inhibition, reproductive inhibition (mg/l) Fish Chronic (NaCN) Pimephales promelas 256 days NOEC Reproductive inhibition (mg/l) Key study Data of algae was used for the key study because effects on algae were observed at the lowest concentration in the hazard assessment

5 4.2 Human health toxicity Toxicity Exposure route Species Duration / Dose method Toxic effects (Key study is underlined) NOAEL or LOAEL (converted) (Epidemiologic data, for reference) (Human) (5-10 years/ occupational inhalation exposure) (Effect on neural system, thyroid adenoma, increased hemoglobin) (LOAEL: 6.4 ppm, equivalent to 0.65 mg/kgbw/day) Rat 6 months/ inhalation Decreased body weight NOAEL: 24mg/m 3 (equivalent to 3.2 mg/kgbw/day) Repeated dose toxicity Oral Rat 13 weeks/ drinking water (NaCN) Decreased body weight in males, decreased weight of cauda epididymis, epididymis and testes, decreased number of spermatid heads/testis, longer duration of proestrus and diestrus NOAEL: 100 ppm (equivalent to 4.5 mg/kgbw/day) Reproductive and developmental toxicity Carcinogenicity Genotoxicity Evaluation by IARC : This substance has not been evaluated by IARC Not considered to be genotoxic. 5. Risk Assessment 5.1 Environmental organisms Risk characterization EEC (microg/l) NOEC (mg/l) MOE Product of uncertainty factors Conclusion 11 LOEC: Substance of concern Product of uncertainty factors (UF): Extrapolation from laboratory test (10) * Additional factor based on assessor's judgment (2) = 20 Recommendation : The substance is considered to be of concern, and further investigation, analysis and assessment are necessary - 5 -

6 5.2 Human health Repeated dose toxicity Risk characterization Exposure route Intake (microg/kgbw/day) NOAEL (mg/kgbw/day) MOE Product of uncertainty factors Conclusion (Epidemiologic data for reference) (1.8) (LOAEL: 0.65) (360) (100) , Oral , No concern No concern immediate immediate Product of uncertainty factors (UF): (epidemiologic) - Intraspecies (10) * Use of LOAEL (10) = Interspecies (10) * Intraspecies (10) * Test duration (2) = 200 Oral - Interspecies (10) * Intraspecies (10) * Test duration (5) = Reproductive and developmental toxicity Carcinogenicity Recommendation for Human Health The substance is considered to be of no immediate concern for the moment and a low priority for further work. 6. Supplement