California Code of Regulations
Title 27 - Environmental Protection
Division 4 - Office of Environmental Health Hazard Assessment
Chapter 1 - Safe Drinking Water and Toxic Enforcement Act of 1986
Article 8 - NO Observable Effect Levels
Section 25803 - Assessment

Universal Citation: 27 CA Code of Regs 25803

Current through Register 2024 Notice Reg. No. 38, September 20, 2024

(a) A quantitative risk assessment which conforms to this section shall be deemed to determine the level of exposure to a listed chemical which will have no observable effect, assuming exposure at one thousand times the level in question. The assessment shall be based on evidence and standards of comparable scientific validity to the evidence and standards which form the scientific basis for listing the chemical as known to the state to cause reproductive toxicity. In the absence of principles or assumptions scientifically more appropriate, based upon the available data, the following default principles and assumptions shall apply in any such assessment:

(1) Only studies producing the reproductive effect which provides the basis for the determination that a chemical is known to the state to cause reproductive toxicity shall be utilized for the determination of the NOEL.

(2) Where multiple reproductive effects provide the basis for the determination that a chemical is known to the state to cause reproductive toxicity, the reproductive effect for which studies produce the lowest NOEL shall be utilized for the determination of the NOEL. The NOEL shall be the highest exposure level which results in no observable reproductive effect, expressed in milligrams of chemical per kilogram of bodyweight per day. This may be the no observed effect level in a scientific study or, alternatively, may be calculated by means of a generally accepted scientific methodology such as the benchmark dose methodology. Where a study (e.g., epidemiological publication) reports a range of exposure levels associated with no observed effect, the NOEL may be selected from within the range or calculated by benchmark dose or other accepted scientific methodology.

(3) The quality and suitability of available epidemiologic data shall be appraised according to generally accepted scientific principles to determine whether the study is appropriate as the basis for an assessment. Factors for consideration in this appraisal include but are not limited to: the identification and selection of study subjects (e.g. cases, controls, exposed, unexposed), validity and reliability of the ascertainment of exposure, completeness of follow-up, assessment of outcomes, and appropriateness of the statistical analysis and power of the study to detect an effect. Biases and confounding factors shall be identified, quantified, or otherwise considered, as appropriate.

(4) Animal bioassay studies for assessment shall meet generally accepted scientific principles, including the thoroughness of experimental protocol, the degree to which dosing resembles the expected manner of human exposure, the temporal exposure pattern, the duration of study, the purity of test material, the number and size of exposed groups, and the route of exposure and the extent of occurrence of effects.

(5) The NOEL shall be based on the most sensitive study deemed to be of sufficient quality.

(6) The results obtained for the most sensitive study deemed to be of sufficient quality shall be applicable to all routes of exposure for which the results are relevant.

(7) When available data are of such quality that anatomic, physiologic, pharmacokinetic and metabolic considerations can be taken into account with confidence, they may be used in the assessment.

(8) When data do not allow the determination of a NOEL, the lowest observed effect level shall be divided by 10 to establish a NOEL for purposes of assessment.

(b) In the absence of principles or assumptions scientifically more appropriate based upon the available data, the following default principles or assumptions shall apply in any such assessment. The NOEL shall be converted to a milligram per day dose level by multiplying it by the assumed human body weight. When the applicable reproductive effect is upon the adult male, human body weight of 70 kilograms shall be assumed. When the applicable reproductive effect is upon the adult female or conceptus, human body weight of 58 kilograms shall be assumed. When data indicate that exposure of the neonate, infant, child or adolescent results in the applicable reproductive effect, the bodyweights specific below shall be assumed:

Adolescent (age 11-18 years) 40 kg
Child (age 2-10 years) 20 kg
Infant (age 29 days-1 year) 10 kg
Neonate (age 0-28 days) 3.5 kg

1. New section filed 2-24-88 as an emergency; operative 2-27-88 (Register 88, No. 11). A Certificate of Compliance must be transmitted to OAL within 120 days or emergency language will be repealed on 6-27-88.
2. New section refiled 6-27-88 as an emergency; operative 6-27-88 (Register 88, No. 27). A Certificate of Compliance must be transmitted to OAL within 120 days or emergency language will be repealed on 10-25-88.
3. New section refiled 10-17-88 as an emergency; operative 10-25-88 (Register 88, No. 44). A Certificate of Compliance must be transmitted to OAL within 120 days or emergency language will be repealed on 2-22-89.
4. New section refiled 2-21-89 as an emergency; operative 2-22-89 (Register 89, No. 10). A Certificate of Compliance must be transmitted to OAL within 120 days or emergency language will be repealed on 6-22-89.
5. Certificate of Compliance including amendment transmitted to OAL 6-9-89 and filed 7-10-89 (Register 89, No. 30).
6. Amendment of subsection (a) filed 1-7-2003; operative 2-6-2003 (Register 2003, No. 2).
7. Change without regulatory effect renumbering title 22, section 12803 to title 27, section 25803 filed 6-18-2008 pursuant to section 100, title 1, California Code of Regulations (Register 2008, No. 25).
8. Amendment of subsection (a)(1), new subsection (a)(2), subsection renumbering and amendment of newly designated subsections (a)(3) and (a)(8) and subsection (b) filed 3-17-2011; operative 4-16-2011 (Register 2011, No. 11).

Note: Authority cited: Section 25249.12, Health and Safety Code. Reference: Sections 25249.5, 25249.6, 25249.9, 25249.10 and 25249.11, Health and Safety Code.

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