Detaljerad miljöinformation

Environmental Risk Classification

Predicted Environmental Concentration (PEC)

Currently, estradiol is marketed in Sweden as estradiol hemihydrate and estradiol valerate. Estradiol is the active pharmaceutical ingredient (API) and marketed volumes need to be adjusted to this moiety for PEC calculation.

Estradiol varieties	Molecular weight	Conversion factor	Sale volume (2022)	API amount (2022)
Estradiol	272.4 g/Mol	1.00	---	---
Estradiol hemihydrate*	562.8 g/Mol	0.97	28.56	27.70
Estradiol valerate	356.5 g/Mol	0.76	16.87	12.82
Total sale volume API (kg/year)				40.52
* contains two moieties of estradiol

PEC is calculated according to the following formula:

PEC (μg/L) = (A*10⁹*(100-R))/(365*P*V*D*100) = 1.37*10^-6*A*(100-R) = 0.00102 μg/L

Where:

A = 40.52 kg (total sold amount API in Sweden year 2022, data from IQVIA / LIF

R = 81.69 % removal rate (due to loss by adsorption to sludge particles, by volatilization, hydrolysis or biodegradation)

P = number of inhabitants in Sweden = 10 *10⁶

V (L/day) = volume of wastewater per capita and day = 200 (ECHA default) (Reference I)

D = factor for dilution of wastewater by surface water flow = 10 (ECHA default) (Reference I)

Predicted No Effect Concentration (PNEC)

Ecotoxicological studies*

Algae (green algae, Desmodesmus subspicatus):

NOEC 72 hours (growth rate) ≥ 3100 μg/L, E_rC₅₀ 72 hours (growth rate) > 3100 μg/L. Guideline OECD 201. (Reference II)

Crustacean (waterflea, Daphnia magna):

Chronic toxicity

NOEC 21 days (reproduction) ≥ 139 μg/L. Guideline FDA TAD 4.09. (Reference III)

Fish (rainbow trout, Oncorhynchus mykiss):

Acute toxicity

LC₅₀ 96 hours (survival) ≥ 500 μg/L. Guideline FDA TAD 4.11. (Reference IV)

Fish (fathead minnow, Pimephales promelas):

Chronic toxicity

EC₁₀ 56 days (weight) = 0.008 μg/L. Guideline EPA FIFRA Subdev. E, 72-5. (Reference V)

Fish (Japanese rice fish, Oryzias latipes):

Chronic toxicity

Besides the OECD studies complying with GLP documentation requirements, there is a published fish full life-cycle study, that was conducted with the Japanese rice fish (Oryzias latipes). The test setup is exploratory but the publication was considered sufficiently reliable for derivation of the environmental quality standard (EQS) and therefore is included here. The study started with fish embryos 12 hours after fertilization and continued for up to 101 days including filial fish generation (spawned at day 98, 99, and 100) and assessed various endpoints. Fish were exposed continuously (flow-through system) at 0.939, 2.86, 8.66, 27.9, and 92.4 ng/L. Most endpoints showed no concentration-response related effects of estradiol. However, sex differentiation, induced vitellogenin (VTG; yolk protein), and reproductive impairment were observed with concentration-response relationship in the parent fish generation, coming up with a NOEC of 2.86 ng/L. There were no effects in the filial fish generation at concentrations below 8.66 ng/L.

NOEC 101 days (fertility) = 2.86 ng/L = 0.00286 μg/L. Fish full life-cycle exploratory study. (Reference VI)

The PNEC was calculated by division of the lowest effect level (NOEC) of the most sensitive taxonomic group considering an appropriate assessment factor (AF). The most sensitive taxonomic group were fish and the lowest effect level was reported as NOEC = 0.00286 µg/L. The regulatory default standard AF of 10 was used, which is applicable when there are chronic aquatic toxicity studies representing the three trophic levels (algae, crustaceans, and fish).

PNEC = 0.00286 µg/L / 10 = 0.000286 µg/L

Environmental risk classification (PEC/PNEC ratio)

The risk quotient PEC/PNEC was calculated as 0.00102 µg/L / 0.000286 µg/L = 3.57.

Justification of chosen environmental risk phrase:

A risk quotient above 10 qualifies for the phrase “Use of estradiol has been considered to result in moderate environmental risk.”.

Degradation

Biotic degradation

Ready degradability:

Ready biodegradation of estradiol was determined in three studies, one in accordance with OECD 310B and two according to FDA TAD 3.11. The studies reported more than 60 % biodegradation of estradiol in 28 days. Guideline OECD 301. (Reference VII, VIII, IX)

Abiotic degradation

Hydrolysis:

This study reported that estradiol is stable. Guideline FDA TAD 3.09. (Reference X)

SimpleTreat modelling – elimination in sewage treatment plants

The SimpleTreat model (v4.1) was used to estimate the fraction of estradiol that is retained in sewage treatment plant and does not enter the surface water compartment. The calculation is based on experimental physico-chemical data of estradiol. Molecular weight: 272.4 g/mol, octanol-water partition coefficient (K_OW): 4.03, vapour pressure: 0.00000003 Pa at 25 °C, water solubility: 1.7 mg/L at 20 °C, organic carbon partition coefficient (K_OC): 2511 and biodegradation: readily biodegradable, failing 10-day window. (Reference VIII, XI, XII, XIII)

SimpleTreat calculated the release to surface water after sewage treatment as 18.31 %, i.e., 81.69 % are eliminated by ready biodegradation or binding to sludge. The PEC calculation was refined taking account of this elimination.

Justification of chosen degradation phrase:

The high ready biodegradation and elimination in sewage treatment plants qualifies for the phrase “Estradiol is slowly degraded in the environment.”.

Bioaccumulation

Partitioning coefficient:

The log D_ow was reported as 4.03. Guideline FDA TAD 3.02. (Reference XI)

Bioconcentration factor (BCF):

In addition, a bioaccumulation study according to OECD TG 305 was conducted. 20 fish (Lepomis macrochirus) were exposed to¹⁴C labeled estradiol as well as 40 fish in the tap water control and exposed for an uptake period of 22 days, followed by 8 days depuration. There were 2 replicates per treatment and 1 for the control.

The test substance solution was delivered continuously to the tanks. The nominal concentration of estradiol in the water was 276 ng/L. The concentration of the test substance in the fish and in the water was determined in the uptake and depuration phase of the test. The ¹⁴C concentration in the fish was analyzed by liquid scintillation after oxidative degradation of the fish in samples taken on day 4, 6, 10, 14, 21, 24, 26, and 30. The ¹⁴C concentration in the water was analyzed by liquid scintillation in samples taken at the same time points. The bioconcentration factor in fish (BCFss) was calculated as the ratio of the mean values of the ¹⁴C concentration in fish and in water.

The BCFss was 108.8 (normalized to 5 % lipid: 71.58). The uptake rate constant (k1) was 1.1, the depuration rate constant (k2) was -2.2. The DT₅₀ for depuration was determined with 3.2 days, indicating a rapid turnover of estradiol. This finding could be expected, since estradiol is an endogenous hormone metabolized rapidly during normal physiological processes.

The study reported a BCF of 71.58. Guideline OECD 305. (Reference XIV)

Justification of chosen bioaccumulation phrase:

As the BCF was < 500 estradiol is not considered bioaccumulative which qualifies for the phrase “Estradiol has low potential for bioaccumulation.”.

Excretion (metabolism)

Estradiol valerate are readily cleaved into estradiol and valeric acid. Estradiol undergoes the same metabolic pathways as endogenous estrogen, i.e. it is further metabolized into the major metabolites estrone, estriol, estrone sulfate and estrone glucuronide.

Despite the high metabolization this was not considered for refinement of the PEC calculation, as the primary metabolites are estrogenic as well, although to a lesser extent (Reference XV, XVI, XVII)

References

1. Guidance on information requirements and Chemical Safety Assessment Chapter R.16: Environmental exposure assessment. V3.0, Feb. 2016.

2. Growth inhibition test with estradiol (ZK 5018) on the green algae Desmodesmus subspicatus. Experimental Toxicology, Schering AG, study no. TXST20020260, report no. A30506 (2006)

3. Reproduction and chronic immobilization study of estradiol in Daphnia magna. Experimental Toxicology, Schering AG, study no. TX96156, report no. AQ94 (2001)

4. Acute toxicity of 17β-estradiol with the rainbow trout. Experimental Toxicology, Schering AG, study no. TX95070, report no. A05662 (2001)

5. Evaluation of the reports entitled: [14C]Ethinylestradiol – Early life-stage toxicity test with fathead minnow (Pimephales promelas). Experimental Toxicology, Schering AG, study no. TXST19960143, report no. No. B945 (1999)

6. Seki M, Yokota H, Maeda M, Kobayashi K. Fish full lifecycle testing for 17β-estradiol on medaka (Oryzias latipes). Environmental Toxicology and Chemistry 24, 1259-1266 (2005)

7. Study of aerobic biodegradability of estradiol. Experimental Toxicology, Schering AG, study no. TX95270, report no. A05658 (2001)

8. Study on the biodegradability of estradiol in the CO2-evolution test (Modified Sturm-Test). Experimental Toxicology, Schering AG, study no. TXST19970041, report no. A05659 (2001)

9. Study of aerobic biodegradability of estradiol. Experimental Toxicology, Schering AG, study no. TX96181, report no. A05814 (2001)

10. Estradiol/ZK 5018/Report on physicochemical properties/Rate of hydrolysis. General Physical Chemistry, Schering AG, study no. 0353, report no. N408 (2001)

11. Estradiol, ZK5018, Report on physicochemical properties, Water solubility, N-octanol/water partition coefficient. General Physical Chemistry, Schering AG, Berlin, report no. A02014.

12. Estradiol/ZK 5018/Report on physicochemical properties/ Vapour pressure. General Physical Chemistry, Schering AG, Berlin, study no. 0121, report no. M963EY10.

13. Estradiolhemihydrat/ ZK 5018/Report on physico-chemical properties/ Estimation of the adsorption coefficient (KOC) on soil and sewage sludge (HPLC method). Analytical Development Physical Chemistry, Schering AG, Berlin, study no. 07100160, report no. A39007.

14. Bioconcentration flow-through fish test with estradiol [BAY 86-5435 (14-C)]. Nonclinical Drug Safety, Bayer Schering Pharma AG, study no. TOXT7082197, report no. A52549 (2011)

15. Hobkirk, R., Mellor, J. D., Nilsen, M.: In vitro metabolism of 17β-estradiol by human liver tissue. Can. J. Biochem. 53, 903-906 (1975). (1.6.1.3.1 Hobkirk et al. 1975)

16. Lievertz, R.W.: Pharmacology and pharmacokinetics of estrogens. Am. J. Obstet. Gynecol. 156, 1289-1293 (1987). (1.6.1.3.1 Lievertz 1987)

17. Slaunwhite, R.W, Kirdani, R.Y., Sandberg A.A.: Metabolic aspects of estrogens in man. In: Greep, R. O., Astwood, E. B. (Eds.): Handbook of Physiology, Section 7: Endocrinology, Vol. 2, Female Reproductive Sytem, part 1, Chapter 21, American Physiology Society, Washington DC, 1973, pp. 485-523. (1.6.1.3.1 Slaunwhite et al. 1973)