# Presentation: 270965

## •	Chemical Screeningat SRSby Wayne Davis

## Introduction

- SRS compared its chemical screening method to those used at three DOE sites where methods were found acceptable in recent OA-30 assessments. As a result of this comparison, SRS will implement Hanford’s screening (basically that proposed in the 2004 draft revision to DOE O 151.1).
- This presentation will give an overview of the four-site comparison, highlight work done on generating NFPA-equivalent Health Hazard ratings, and offer perspectives on exclusion criteria for dispersiblity, toxicity & volatility.

## Current SRS Identification & Screening

- Strict interpretation of DOE O 151.1
- Single decision: If ≥ TQ/TPQ, include in EPHA
- Otherwise, address in Base Program

## Y-12 Identification & Screening

- If ≥ TQ/TPQ, address in EPHA
- If ≥ RQ or specified NFPA criteria, retain for screening
- If release could exceed PAC @ 30 m, address in EPHA
- Otherwise, address in Base Program

## LANL Identification & Screening

- LANL TQs are consequence-based (trip PAC @ 30 m)
- If ≥ LANL TQ, address in EPHA
- Exemptions based upon common use, low dispersiblity, and low inventory(< 1 lb)
- Otherwise, address in Base Program

## Hanford Identification & Screening

- If ≥ TQ/TPQ, address in EPHA
- If not, make qualitative estimate of hazard potential
- Exemptions based upon common use, low dispersiblity, low toxicity (NFPA H<3), and low inventory(< lab-scale)
- Otherwise, address in Base Program

## Key Attributes of Reviewed Processes

- Uses screening criteria from latest draft DOE O 151.1
- Uses NFPA Health Hazard rating as a screening criteria
- Y-12
- Includes anything that could trip PAC
- Includes fire byproducts
- Additional NFPA Hazard criteria (fire & instability)
- LANL
- Developed site-specific thresholds based on ability to trip PAC (many threshold quantities are very low)

## Vapor Pressure

**40 CFR 796.1950 *****Vapor Pressure***
- -	Volatilization, the evaporative loss of a chemical, depends upon the vapor pressure of the chemical and environmental conditions... Vapor pressure values provide indications of the tendency of pure substances to vaporize in an unperturbed situation, and thus provide a method for ranking the relative volatilities of chemicals... Chemicals with relatively low vapor pressures... are less likely to vaporize and become airborne than chemicals with high vapor pressures... On the other hand, **non**volatile chemicals are less frequently involved in atmospheric transport, so that concerns regarding them should focus on soil & water.

## Vapor Pressure

## Vapor Pressure

- Typical Binning of Vapor Pressures:
- < 1 mm Hg: 	VERY LOW
- 1-10 mm Hg: 	LOW
- 10-100 mm Hg: 	MEDIUM
- 100-760 mm Hg: 	HIGH
- > 760 mm Hg: 	VERY HIGH (gas at room temperature)
- Water:
- 17.53 mm Hg @ 20oC (68oF)
- Gasoline:
- 220 - 450 mm Hg @ 20oC

## Partial Pressure

- Pressure of gas mixture equals sum of pressures of each constituent alone
- PTotal = P1 + P2 +... Pn  (Dalton’s Law)
- When dealing with aqueous solutions, subtract contribution of water to arrive at partial pressure of the material with which we are concerned.
- For example, MSDS for sodium hydroxide solution typically show that material has a vapor pressure approximately equal to water. This is because the NaOH contributes no significant vapor pressure

## NFPA 704 Health Hazard

| Degree of Hazard | Criteria  |
| --- | --- |
| 4 —Materials that, under emergency conditions, can be lethal. | Gas: LC50 for acute inhalation toxicity is ≤ 1000 ppm.	
Liquid: saturated vapor concentration at 20°C (68°F) is≥ ten times its LC50 for acute inhalation toxicity, if its LC50 is≤ 1000 ppm.	
Dust & mist: LC50 for acute inhalation toxicity is ≤ 0.5 mg/L.
Material whose LD50 for acute dermal toxicity is ≤ 40 mg/kg.
Material whose LD50 for acute oral toxicity is ≤ 5 mg/kg. |

## NFPA 704 Health Hazard

| Degree of Hazard | Criteria  |
| --- | --- |
| 3 —Materials that, under emergency conditions, can cause serious or permanent injury.  | Gas: LC50 for acute inhalation toxicity is> 1000 ppm but ≤ 3000 ppm.
Liquid: saturated vapor concentration at 20°C (68°F) is ≥ its LC50 for acute inhalation toxicity, if its LC50 is ≤ 3000 ppm and that does not meet the criteria for degree of hazard 4.
Dust & mist: LC50 for acute inhalation toxicity is> 0.5 mg/L but ≤ 2 mg/L.
Materials whose LD50 for acute dermal toxicity is> 40 mg/kg but ≤ 200 mg/kg.
Materials corrosive to the eye, skin, or respiratory tract.
Cryogenic/compressed gases that cause frostbite / irreversible tissue damage.
Materials whose LD50 for acute oral toxicity is> 5 mg/kg but ≤ 50 mg/kg. |

## NFPA 704 Health Hazard

- Note that all materials given a health hazard rating of 4 are toxic (either by inhalation, ingestion, or skin absorption). Some material given a health hazard rating of 3 may not be toxic at all but corrosive or very cold.
- We propose that if a material receives a rating of 3 ***only*** because it is corrosive or cryogenic, it may be screened out – preferably in the Hazards Survey. This would allow cryogenic liquids and some dilute acids/bases to be screened out.

## “Extraordinarily High Toxicity”

- DOE O 151.1 (latest draft) reads:Substances that are both dispersible and have extraordinarily high toxicity (substances having an ERPG-3 or equivalent value of 3 ppm or less) must be analyzed in an EPHA if the quantity is greater than 1 pound.
- If threshold is specified, units should be in mg/m3 (or both) rather than ppm only as TEEL list converts all values to mg/m3. About 10% of listed substances have no conversion back to ppm (e.g., asbestos)

## “Extraordinarily High Toxicity”

- Based upon review of several AEGLs, threshold of 3 ppm is too high. AEGL-3 values for nerve gases range from 0.00091 ppm [0.01 mg/m3] for VX to 0.039 ppm [0.26 mg/m3] for Tabun. Several other materials of interest fall into this range (e.g., AEGL-3 for beryllium & methyl mercury is 0.1 and 0.2 mg/m3 respectively).
- I suggest a value consistent with high range for nerve gases be used (i.e., ~ 0.3 mg/m3); otherwise, sites could trip 1 lb limit with many substances (e.g., asbestos TEEL-3 = 2.5 mg/m3).