Emerging Pollutants. Decamethylcyclopentasiloxane (D5)

Transcription

1 Emerging Pollutants Decamethylcyclopentasiloxane (D5) Julia Quint, PhD, HESIS, DHS WRPPN Conference, Granlibakken, CA October 16, 2003

2 Hazard Evaluation System & Information Service (HESIS) Established by CA Legislature in 1979 in response to DBCP-induced sterility of workers Collect and evaluate information to establish harmful effects on health Provide early warnings and reliable information to prevent hazards to workers Recommend protective occupational health standards to Cal/OSHA 2

3 How HESIS Identifies Chemical Hazards Peer-reviewed journal articles NTP, IARC, Cal/EPA, etc. reports Industry toxicity reports, TSCA 8(e) Medical case reports HESIS Helpline 3

4 HESIS Health Advisory n-hexane 4

5 HESIS Hazard Alert 1-BP 5

6 6

7 Decamethylcyclopentasiloxane (D5) What is it? volatile methylsiloxane oily liquid flammable special equip. needed highly lipid soluble low solubility in water can bioconcentrate not ozone-depleting not listed as HAP low odor 7

8 D5 How It s Used Industrial Drycleaning GreenEarth (Dow 245 Fluid) Automotive dressings Bumper Brite (Malco) Beauty/Personal Care Cosmetics African Essence (Univ.Beauty) Shower gels, Deodorants Healthcare Scar Therapy 8

9 D5 Toxicity Testing EPA & Dow Corning MOU Background MOU signed in 1996 PSP covers 6 siloxanes FDA - I.D d data needs ( 92) EPA - required data for 56 silicones under TSCA ( 93) EPA required D4 studies ( 89) MOU Elements New data development Communication of H&S data P2/waste minimization Environmental responsibility 9

10 D5 Toxicity / Health Data Summary of Major Studies Dow two-year chronic toxicity/oncogenicity study* Tumor 0 ppm 10 ppm 40 ppm 160ppm Endometrial adenocarcioma Endometrial adenoma Endometrial adenomatous polps Total Tumors Number rats in group *Preliminary results reported to the EPA under TSCA Section 8(e) on February 4,

11 D5 Chronic Toxicity/Oncogenicity Study Interpretation of Preliminary Results Dow Corning Progression of hyperplasia to adenoma to adenocarcinoma was not observed. A statistically significant increase in adenocarcinomas alone is lost when other tumors added in. OEHHA (Cal/EPA) A statistically significant increase in a malignant tumor (adenocarcina) due to D5*, a chemical that is bioconcentrated and is a candidate to replace perchloroethylene, indicates a potential hazard for workers in the dry cleaning industry and perhaps for the general public. *p=0.029 when compare 0/60 in controls vs 5/60 in 160 ppm grp. 11

12 D5 Toxicity / Health Data Summary of Major Studies (Cont d) Burns-Nass et al. subchronic toxicity study* Effects of inhalation of increasing D5 levels in female rats D5 (ppm) Liver wt (g) Triglycerides Gamma GT (U/L) ±0.46 # 42.88± ± ± ± ± ±0.60 ** 33.25±3.5 ** 1.49 ±0.37 ** ± ±3.5 ** 1.56 ±0.53 ** ±0.59 ** ± ±0.51 ** (mg/dl) # mean ±standard deviation; ** p<0.01 *Toxicological Sciences 1998 May;43(1):28-38 (from Dow Corning) 12

13 D5 Subchronic Toxicity Study Interpretation & Follow-Up Actions Dow Corning Statistically significant increases in liver weight for female rats exposed to 46 and 86ppm, and female and male rats exposed to 224 ppm. Dose related increase in gamma glutamyltransferase (gamma-gt) in female rats. Recommended an exposure guideline of 10 ppm on MSDSs OEHHA (Cal/EPA) Increases in liver weight in rats of both sexes. Increase in gamma-gt in both sexes at 224 ppm; dose-related in females between 46 and 224 ppm. Female rat is more sensitive to actions of D5 on liver. Calculated a reference exposure level of 46 ppb (0.046 ppm) 13

14 Communication of D5 Toxicity Data Dow Corning (R) 245 Fluid MSDS 14

15 Dow Corning (R) 245 Fluid Section 3 MSDS Information (4/7/2003) Section 3 Effects of Overexposure Acute Effects Eye: Direct contact may cause temp. redness and discomfort. Skin: No sig. irrit. expected from single short-term exposure. Inhal: Same as above. Oral: Low ingestion hazard in normal use. Prolonged/Repeated Exposure Effects Skin: No known applicable information. Inhalation: No known applicable information. Oral: No known applicable information.. 15

16 Dow Corning (R) 245 Fluid Section 11 MSDS Information (4/7/2003) Section 11 Toxicological Information Repeated inhalation or oral exposure of mice and rats to decamethylcyclopentasiloxane produced an increase in liver size. No gross histopathological or significant clinical chemistry effects were observed. An increase in liver metabolizing enzymes, as well as a transient increase in the number of normal cells (hyperplasia) followed by an increase in cell size (hypertrophy) were determined to be the underlying causes of liver enlargement. The biochemical mechanisms producing these effects are highly sensitive in rodents, while similar mechanisms in humans are insensitive. Good industrial hygiene practice minimizes inhalation exposure to any chemical. Dow Corning has set an exposure guideline of 10 ppm TWA for this material. 16

17 Dow Corning (R) 245 Fluid Section 11 MSDS Information (4/7/2003) Section 11 Toxicological Information A 2 year combined chronic/carcinogenicity assay was conducted on decamethylcyclopentasiloxane (D5). Fischer-344 rats were exposed by whole-body vapor inhalation 6 hrs/day, 5 days/week for up to 24 months to 0, 10, 40, or 160 ppm of D5. A statistically significant increase in the trend for uterine endometrial tumors was observed in female rats exposed for 24 months at 160 ppm. Whether or not this increase in incidence is truly related to the exposure to D5 is questionable and yet to be determined. The 160 ppm exposure concentration greatly exceeds workplace or consumer exposure. It is unlikely that industrial, commercial or consumer uses of products containing D5 would result in a significant risk to humans. The exposure guideline will be re-evaluated when a better understanding of 17 the significance of this new data is developed.

18 Communication of D5 Toxicity / Health Data US EPA Fact Sheet Focus on dry cleaning use Concluded results indicate D5 may be cancer hazard No screening level or formal risk assessment Cannot characterize human/environmental risks Final results due in 2004 Interested in human exposure data 18

19 D5 Some Next Steps Assessment of risks to humans and the environment if warranted by final study results Dissemination of health hazard information Regulation of D5 to protect workers and environ. Evaluation of CARB s Dry Cleaning Airborne Toxic Control Measure (in progress) Evaluation of alternative dry cleaning solvents by IRTA (in progress) 19

20 New Chemical Substitutes / New Hazards New Substitute Hazard Reg. Status Replaced Chem. 1-Bromopropane Repro; Unregulated TCA; Freons; Perc Neurologic n-methyl Pyrrolidone Repro. Prop. 65 Meth. Chloride Polymeric Isocyanates Asthma Unregulated TDI; HDI; MDI D5 or Green Earth Liver; Unregulated Perc?Cancer 20

21 Protecting Health & the Environment Some Long-Term Strategies A chemical policy that requires toxicity testing to ensure safety prior to marketing and use Effective enforcement of TSCA Dedicated funding for the development & testing of effective, safer alternatives Incentives for the marketing & use of proven, safer alternatives 21