EPA’s Draft Risk Evaluation of Di-Isobutyl Phthalate (DIBP): What It Means for Industry, Workers, and the Environment
In July 2025, the U.S. Environmental Protection Agency (EPA) released its draft risk evaluation for di-isobutyl phthalate (DIBP) under the Toxic Substances Control Act (TSCA). This marks an important step in the agency’s ongoing efforts to assess the safety of high-priority chemicals used in U.S. commerce. The evaluation, supported by extensive technical documentation, opens the door for public comment and is expected to inform regulatory actions that may affect manufacturers, workers, and environmental stakeholders alike.
What is Di-Isobutyl Phthalate (DIBP)?
Di-isobutyl phthalate is part of the phthalate family of chemicals, widely used as plasticizers to increase flexibility in polymers and other materials. DIBP specifically has been found in:
🧴 Adhesives and sealants
🎨 Paints and coatings
🖨️ Printing inks
🛍️ Consumer goods such as flexible plastics
🏗️ Automotive and construction products
Like other phthalates, DIBP has raised toxicological concerns, particularly around its potential to interfere with endocrine and reproductive development. Research indicates that prenatal exposure to phthalates may disrupt normal hormone function, leading to developmental and reproductive effects.
EPA’s Draft Findings: Where the Risks Lie
The draft risk evaluation represents EPA’s scientific analysis of DIBP across multiple conditions of use (COUs), ranging from industrial processing to potential consumer exposures. The highlights include:
👷♂️ Human Health Risks (Workers)
a. EPA found unreasonable risks to workers under two conditions of use.
b. These conclusions were made without assuming the use of personal protective equipment (PPE)—a deliberate choice under TSCA evaluations to ensure protection across all scenarios, including facilities where PPE may not be adequately enforced.
c. Importantly, the evaluation acknowledged that PPE such as gloves, respirators, and local exhaust ventilation could mitigate risks, but the baseline assumption is risk exists if exposures are uncontrolled.
🌍 Environmental Risks
a. The draft also identifies unreasonable risk to the environment under four conditions of use.
Environmental releases during manufacturing, processing, and disposal are of concern, particularly for aquatic ecosystems.
b. Like other phthalates, DIBP is persistent in certain environmental compartments and can accumulate, raising questions about long-term ecological impact.
✅ No Consumer Risk
a. Interestingly, EPA determined no unreasonable risks to consumers or the general population from any of the evaluated conditions of use.
b. This contrasts with some other phthalates (like DEHP), which have shown consumer-level risks in past evaluations.
The Technical Backbone: How EPA Reached These Conclusions
The draft risk evaluation isn’t just a policy document—it’s supported by hundreds of pages of technical analysis. Key elements include:
📊 Occupational Exposure Limits
i. EPA derived an occupational exposure benchmark of 1.5 mg/m³ (0.13 ppm) based on developmental toxicity studies showing decreased fetal testicular testosterone levels. This level was calculated as an 8-hour time-weighted average (TWA).
🔍 Systematic Review Approach
i. EPA used a “systematic review” methodology to identify, screen, and evaluate available studies.
ii. Technical appendices cover:
⚗️ Physical-chemical properties
💨 Dermal absorption and inhalation data
🌊 Environmental fate and transport
👷♂️ Worker and environmental exposure scenarios
🧬 Human health hazard data
📈 Exposure Scenarios Modelled
i. Industrial settings (manufacturing, processing, formulation)
ii. Downstream use (coatings, adhesives, plastics)
iii. Disposal and waste streams
❓ Uncertainty Factors
i. To ensure protection, EPA applied uncertainty factors when extrapolating from animal studies to humans and when addressing variability in worker populations.
Timeline and Regulatory Context
The release of this draft risk evaluation is not the end of the process—it’s the beginning of a public engagement and regulatory cycle.
⚠️ High-Priority Substance Designation (2019)
a. DIBP was designated as a high-priority chemical in December 2019, making it one of the first 20 chemicals slated for detailed risk evaluation under amended TSCA.
📝 Draft Risk Evaluation (July 2025)
a. EPA has now released its draft evaluation, supported by technical documents and a docket for public comment.
🗣️ Public Comment Period (60 Days)
a. Once formally noticed in the Federal Register, stakeholders will have 60 days to submit comments via docket EPA-HQ-OPPT-2018-0434 at Regulations.gov. A Federal Register notice dated August 6, 2025 confirmed that the comment period ends on October 6, 2025
👨🔬 Science Advisory Committee on Chemicals (SACC)
a. Although SACC is not reviewing DIBP directly, it is reviewing related phthalates such as DBP, DEHP, and DCHP. Because these evaluations rely on similar exposure methodologies, input on them could indirectly shape EPA’s final approach to DIBP.
✅ Final Risk Evaluation (Expected 2026)
a. EPA will review public input, revise the draft, and issue a final risk evaluation.
🛡️ Risk Management (TSCA Section 6)
a. If the final evaluation confirms “unreasonable risk,” EPA will be required to move into risk management rulemaking. This could involve restrictions, bans, labelling requirements, or substitution mandates—depending on the scope of identified risks.
Why This Matters for Stakeholders?
The draft risk evaluation has far-reaching implications across different groups:
🏭 For Industry and Employers
i. Workplace Controls: The clear message is that workers face risks from DIBP exposure, so employers should assess whether current ventilation, PPE programs, and work practices are sufficient.
ii. Anticipating Regulation: If EPA finalizes these findings, companies may need to prepare for stricter handling requirements, reporting obligations, or even phase-outs of DIBP in certain applications.
🌿 For Environmental Advocates
i. Ecological Concerns: The finding of unreasonable environmental risks could fuel calls for tighter restrictions on phthalate releases.
ii. Community Right-to-Know: Advocates will likely push for transparency in reporting releases and promoting safer alternatives.
🔬 For Researchers and Academics
i. Data Gaps: The draft provides a roadmap of where science is still developing. For example, long-term ecological effects and low-dose endocrine disruption remain areas needing more clarity.
ii. Peer Input: Researchers have the chance to influence EPA’s evaluation by submitting comments or highlighting overlooked studies.
🏛️ For Policymakers and Regulators
i. Consistency Across Phthalates: Because EPA is reviewing several phthalates in parallel, the DIBP draft could serve as a template for how similar chemicals will be handled.
ii. Balancing Risks vs. Uses: Policymakers will eventually need to weigh the availability of safer substitutes against the utility of DIBP in industrial applications.
Looking Ahead
The draft evaluation of DIBP shows how science-based policy unfolds under TSCA. By identifying risks without factoring in PPE, EPA sets a conservative baseline that ensures protection for the most vulnerable workplaces. At the same time, the absence of consumer risks suggests the chemical’s hazards are most acute in industrial and environmental contexts rather than in direct consumer use.
The next several months will be critical:
🏭 Industry voices will likely emphasize existing controls and argue against over-regulation.
🌿 Advocates may call for stronger restrictions and accelerated substitution with safer alternatives.
⚖️ EPA will balance these inputs, refine its analysis, and issue a final determination in 2026.
EPA’s July 2025 draft risk evaluation of di-isobutyl phthalate (DIBP) is a pivotal moment in U.S. chemical safety regulation. By flagging unreasonable risks to workers and the environment, the agency has put industries on notice while inviting public participation in shaping the path forward.
For now, the message is clear: DIBP use carries risks that must be managed. Whether that management takes the form of stricter workplace controls, environmental safeguards, or eventual substitution will depend on the outcome of the public comment process and EPA’s final evaluation.
One thing is certain—the scrutiny on phthalates is not going away, and companies, advocates, and regulators alike should be preparing for the next phase of this regulatory journey.
Reach out to our regulation experts on chemical and product regulatory compliances