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Phthalate Di-butyl phthalate

6. Does DBP pose risks to human health?

  • 6.1 Are workers at risk from exposure to DBP?
  • 6.2 Are consumers at risk from exposure to DBP?

6.1 Are workers at risk from exposure to DBP?

The source document for this Digest states:

Workers

Assuming that oral exposure is prevented by personal hygienic measures, the risk characterisation for workers is limited to the dermal and respiratory routes of exposure. Furthermore, it is assumed that adequate risk reduction measures are taken to prevent accidental exposure. If applicable, quantitative risk characterisation is performed by calculation of the MOS (ratio between NOAEL/LOAEL and exposure levels) and comparison of this value with the minimal MOS. The minimal MOS is established via assessment factors, taking into account inter- and intraspecies differences, differences between experimental conditions and the exposure pattern of the worker, type of critical effects, dose-response relationship, confidence of the database and correction for route-to-route extrapolation. A risk is indicated when the MOS is significantly lower than the minimal MOS.

Acute toxicity, irritation and sensitisation

Given the low toxicity observed in the acute oral, inhalation, and dermal studies, the effects observed in the irritation and sensitisation studies and the anticipated occupational exposure levels it is concluded that DBP is of no concern for workers with respect to acute effects, irritation, and skin sensitisation (conclusion (ii)). There are no data available on the possible respiratory sensitisation.

Repeated dose toxicity

There are no suitable dermal repeated dose toxicity studies available. The risk assessment for dermal repeated exposure is therefore based on route-to-route extrapolation. Based on the MOSs (10-20) between the NOAEL from the repeated dose study by inhalation in rats (146.6 mg/kg bw/day calculated based on the NOAEC of 509 mg/m3) and the anticipated dermal exposure levels (420-975 mg/day) it is concluded that for occupational exposure Scenario 3 (use of products containing DBP; subscenario “aerosol forming activities”) adverse systemic health effects due to repeated dermal exposure cannot be excluded (minimal MOS 3.6) (conclusion (iii)). No concern for systemic health effects is indicated for other occupational scenarios. There is no suitable information available to determine the risk for local skin effects after repeated dermal exposure.

Based on the MOSs (51-102) between the NOAEC for systemic effects from the repeated dose study by inhalation in rats (509 mg/m3) and the anticipated inhalation exposure levels (5-10 mg/m3) it is concluded that there is no concern for systemic health effects due to repeated inhalation occupational exposure in all scenarios (minimal MOS 90) (conclusion (ii)). Based on the MOSs (0.1-0.2) between the NOAEC for local effects from the repeated dose study by inhalation in rats (1.18 mg/m3) and the anticipated inhalation exposure levels (5-10 mg/m3) it is concluded that there is concern for local effects due to repeated inhalation occupational exposure in all scenarios (minimal MOS 27) (conclusion (iii)).

The conclusions about the risk for systemic health effects derived for the individual routes of exposure are also applicable after combined occupational exposure (i.e. conclusion (iii) for Scenario 3 (use of products containing DBP; subscenario “aerosol forming activities”) after dermal exposure and conclusion (ii) for all other occupational scenarios). A risk assessment for combined exposure is not applicable for local toxicity.

Mutagenicity and carcinogenicity

From the results of the mutagenicity studies it is concluded that DBP may be considered as a non-genotoxic substance (conclusion (ii)). No adequate carcinogenicity studies with DBP are available. There are no urgent reasons for concern for workers with regard to carcinogenicity (conclusion (ii)).

Toxicity for reproduction

Based on the MOSs (3.7-8.6) between the LOAEL for reproductive toxicity (52 mg/kg bw/day) and the anticipated dermal exposure levels (420-975 mg/day) and the MOSs (36-73) between the LOAEL for reproductive toxicity (52 mg/kg bw/day) and the anticipated inhalation exposure levels (5-10 mg/m3) it is concluded that there is no concern with respect to reproduction toxicity due to repeated dermal or inhalation exposure for any occupational scenario (minimal MOS 7.2 and 80, respectively) (conclusion (ii)).

Occupational limit values

The available current occupational exposure limit values for DBP amount to 5 mg/m3, and are based on different oral toxicity studies. However, in the present report reference is made to additional oral and inhalation toxicity studies in which among others a LOAEC for local respiratory effects below the present OELs of 5 mg/m3 was established, based on which there is a need to reconsider the current occupational exposure limits.

Source & ©: "Environmental Health Criteria for Fluorides", (EHC 227), Summary of the Report, Chapter 1.8: Effects on other organisms in the laboratory and field  

For more information, see the full IPCS document,
Chapter 9: Effects on other organisms in the laboratory and field  

The same information on
DIDP-DINPDEHP

6.2 Are consumers at risk from exposure to DBP?

The source document for this Digest states:

Consumers

Starting points for the risk assessment for the scenarios with repeated exposure (I, III and IV) are the exposure estimates and the NOAEC of 509 mg/m3 from the 28-day inhalation study in rats (the highest concentration tested) or the overall oral LOAEL of 52 mg/kg bw/day from the 2-generation reproduction study in rats with a continuous breeding protocol.

The MOS between the inhalation exposure estimate for scenario I and the inhalation NOAEC is 6x1010. The MOSs between the oral exposure estimates and the overall oral LOAEL are 1,925 and 65,00 for scenario III and IV, respectively. These MOSs indicate no concern for consumers (conclusion (ii)).

For scenario II the use will be occasionally and exposure is acute. Toxic effects in humans after acute exposure have not been described, in rats the 4h LC50 is ≥15,680 mg/m3. The MOS of 5,000 between this value and the estimated human exposure indicates no concern for consumers (conclusion (ii)).

Humans exposed via the environment

Inhalation exposure

The MOSs between the inhalation NOAEC of 509 mg/m3 from the 28-day inhalation study in rats (the highest concentration tested) and the inhalation exposure levels at local as well as at regional scale are all >2x105. From these high MOSs it is concluded that there is no concern for humans indirectly exposed via the environment by inhalation (conclusion (ii)).

Total daily intake (from air, drinking water and food)

For the risk characterisation, the estimated total daily intakes for the different scenarios at local scale and for the regional scale are compared with the overall oral LOAEL of 52 mg/kg bw/day. For all local scenarios the MOSs (562-66,000) indicate no concern for humans indirectly exposed via the environment (conclusion (ii)).

For the regional scale the MOS of 1.45x105 also indicates no concern (conclusion (ii)).

Breast milk

Comparing the maximum infant exposure via breast milk (6 µg DBP/kg bw/day) with the overall oral LOAEL of 52 mg/kg bw/day, a MOS of 8,667 can be calculated. This MOS, even when realizing that a LOAEL instead of a NOAEL was used, is considered sufficiently high to conclude that there is no concern for breast-fed babies (conclusion (ii)).

HUMAN HEALTH (PHYSICO-CHEMICAL PROPERTIES)

Flammability, explosive properties and oxidizing properties are not considered to form a hazard. There is no need for further information and/or testing with regard to physico-chemical properties (conclusion (ii)).

Source & ©:  "2003 Risk Assessment Report (RAR 003) on Dibutyl Phthalate (DBP), Summary of the Report, chapter 4: Human Health

For more information, see the full ECB Risk Assessment Report:
 Chapter 4: Human Health

The same information on
DIDP-DINPDEHP

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