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Diss Factsheets
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EC number: 234-363-3 | CAS number: 11120-22-2
- Life Cycle description
- Uses advised against
- Endpoint summary
- Appearance / physical state / colour
- Melting point / freezing point
- Boiling point
- Density
- Particle size distribution (Granulometry)
- Vapour pressure
- Partition coefficient
- Water solubility
- Solubility in organic solvents / fat solubility
- Surface tension
- Flash point
- Auto flammability
- Flammability
- Explosiveness
- Oxidising properties
- Oxidation reduction potential
- Stability in organic solvents and identity of relevant degradation products
- Storage stability and reactivity towards container material
- Stability: thermal, sunlight, metals
- pH
- Dissociation constant
- Viscosity
- Additional physico-chemical information
- Additional physico-chemical properties of nanomaterials
- Nanomaterial agglomeration / aggregation
- Nanomaterial crystalline phase
- Nanomaterial crystallite and grain size
- Nanomaterial aspect ratio / shape
- Nanomaterial specific surface area
- Nanomaterial Zeta potential
- Nanomaterial surface chemistry
- Nanomaterial dustiness
- Nanomaterial porosity
- Nanomaterial pour density
- Nanomaterial photocatalytic activity
- Nanomaterial radical formation potential
- Nanomaterial catalytic activity
- Endpoint summary
- Stability
- Biodegradation
- Bioaccumulation
- Transport and distribution
- Environmental data
- Additional information on environmental fate and behaviour
- Ecotoxicological Summary
- Aquatic toxicity
- Endpoint summary
- Short-term toxicity to fish
- Long-term toxicity to fish
- Short-term toxicity to aquatic invertebrates
- Long-term toxicity to aquatic invertebrates
- Toxicity to aquatic algae and cyanobacteria
- Toxicity to aquatic plants other than algae
- Toxicity to microorganisms
- Endocrine disrupter testing in aquatic vertebrates – in vivo
- Toxicity to other aquatic organisms
- Sediment toxicity
- Terrestrial toxicity
- Biological effects monitoring
- Biotransformation and kinetics
- Additional ecotoxological information
- Toxicological Summary
- Toxicokinetics, metabolism and distribution
- Acute Toxicity
- Irritation / corrosion
- Sensitisation
- Repeated dose toxicity
- Genetic toxicity
- Carcinogenicity
- Toxicity to reproduction
- Specific investigations
- Exposure related observations in humans
- Toxic effects on livestock and pets
- Additional toxicological data
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Exposure related observations in humans: other data
Administrative data
- Endpoint:
- exposure-related observations in humans: other data
- Type of information:
- other: Communication regarding IQ
- Adequacy of study:
- supporting study
Data source
Reference
- Reference Type:
- publication
- Title:
- What is the meaning of non-linear dose-response relationships between blood lead concentrations and IQ?
- Author:
- Bowers TS & Beck BD
- Year:
- 2 006
- Bibliographic source:
- NeuroToxicology. 27(4): 520-524
Materials and methods
- Type of study / information:
- This communication addresses the purported existence of a supra-linear dose-response relationship between environmental measures such as blood lead concentrations and IQ. It explores the mathematical requirements placed on such dose-response relationships when the environmental measure, or independent variable, is lognormally distributed and the effect, or dependent variable, is normally distributed.
- Endpoint addressed:
- neurotoxicity
Test guideline
- Qualifier:
- no guideline followed
- Principles of method if other than guideline:
- Communication regarding mathematical dose-response relationships
Test material
- Reference substance name:
- Lead
- EC Number:
- 231-100-4
- EC Name:
- Lead
- Cas Number:
- 7439-92-1
Constituent 1
Method
- Ethical approval:
- not applicable
Results and discussion
- Results:
- While recent literature has suggested the existence of a supra-linear dose-response relationship between blood lead concentration and IQ, the authors found no convincing evidence from animal studies supporting this relationship. Blood lead concentrations in the general population are lognormally distributed, whereas raw scores from various IQ tests are standardized to a normal distribution. The authors demonstrate that a supra-linear slope is a required outcome of correlations between data distributions where one is lognormally distributed and the other is normally distributed. The required supra-linear nature of the IQ-blood lead relationship will not necessarily change when confounders are included in the analysis if the confounders themselves are also normally distributed.
Applicant's summary and conclusion
- Conclusions:
- The authors conclude, "The analysis shows that caution should be taken in assigning biological significance to supra-linear dose-response relationships in these instances. Detailed analyses of such data sets should be conducted to determine if the magnitude of supra-linear slopes are more or less than mathematically required, and from there to consider biological significance."
- Executive summary:
This communication addresses recent literature that purports the existence of a supra-linear dose-response relationship between environmental measures such as blood lead concentrations and IQ. The authors found no convincing evidence from animal studies supporting this relationship. Blood lead concentrations in the general population are lognormally distributed, whereas raw scores from various IQ tests are standardized to a normal distribution. The authors demonstrate that a supra-linear slope is a required outcome of correlations between data distributions where one is lognormally distributed and the other is normally distributed. The required supra-linear nature of the IQ-blood lead relationship will not necessarily change when confounders are included in the analysis if the confounders themselves are also normally distributed. The authors conclude, "The analysis shows that caution should be taken in assigning biological significance to supra-linear dose-response relationships in these instances. Detailed analyses of such data sets should be conducted to determine if the magnitude of supra-linear slopes are more or less than mathematically required, and from there to consider biological significance."
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