Laredo, Texas (Midwest Sterilization Corporation)
Midwest Sterilization Corporation is located at 12010 General Milton, Laredo, TX. The facility uses ethylene oxide (EtO) to sterilize medical equipment and materials.
EPA scientists and analysts recently completed a risk assessment to understand the impact of EtO emissions from the Midwest Sterilization Corporation facility. As part of this risk assessment, we used the most recent available information about how much EtO the company emits into the air and we modeled estimated cancer risks to people living nearby. The risk assessment identified elevated cancer risk in the Laredo community. EPA is committed to working with state and local agencies, facilities, and communities to reduce this risk.
NOTE: The risk information on this map, from July 2022, is no longer current. EPA is archiving this map because it no longer portrays everything we know about risk. In a number of cases, commercial sterilizers have made improvements or changes to operations that have reduced risks to residents.
EPA has proposed two new actions to address emissions of ethylene oxide from commercial sterilizers and to reduce risks for people who live, work, or go to school near these facilities. Learn about these actions.
Midwest Sterilization Corporation
This map shows EPA’s estimates of lifetime cancer risks from EtO near Midwest Sterilization Corporation in Laredo, TX. As you can see from the map risk decreases with distance from the facility.
The area in blue shows estimated lifetime cancer risks of 100 in a million or greater from breathing air containing EtO emitted from the facility (or the same as 1 additional cancer case in 10,000 people). A lifetime cancer risk of 100 in a million means that, if 1 million people were exposed to this level of EtO in the air 24 hours a day for 70 years, 100 people would be expected to develop cancer from that exposure. EPA cannot predict whether an individual person will develop cancer.
View a larger version of the map and legend in a new browser tab.
For this risk assessment, we looked at excess cancer risk attributable to a single chemical, EtO. This estimated risk is in addition to the risk of developing cancer from other causes. This is a worst-case scenario that assumes a person stays in the highest risk area 24 hours a day continuously for 70 years. EPA takes this approach because we want to be protective of the most exposed and most vulnerable individuals from risk associated with EtO emissions from this facility.
- Read additional information on EtO, including information on our current understanding of risks from ethylene oxide.
Midwest Sterilization Corporation (MSC) is an ethylene oxide sterilization plant that has been operating since 2005 in Laredo. MSC provides commercial sterilization services using ethylene oxide as the sterilizing agent for medical equipment and supplies. With its two facilities (Jackson, MO and Laredo, TX), Midwest Sterilization Corporation is the largest privately owned contract ethylene oxide sterilizer in the United States.
Additional Technical Information:
Midwest Sterilization in Laredo, TX is comprised of twenty-four pre-conditioning rooms, ten sterilization chambers, and forty aeration rooms. Ethylene oxide usage is limited by Texas Commission on Environmental Quality (TCEQ) to a maximum daily rate of 7,007 pounds per day and a maximum annual rate of 2,557,555 pounds per year. All sterilizing chambers are vented to a wet acid scrubber with a control efficiency of no less than 99.63 percent. Emissions from the chamber exhaust vents (back vents) of the sterilizers are routed to the Chamber Exhaust Vent Control System that reduces ethylene oxide by at least 99 percent. Ethylene oxide emissions from the aeration rooms are routed to two Safe Cell Systems that reduce the ethylene oxide concentration to 1 ppm or less.
Permit Details and Additional Requirements:
Midwest’s permit from TCEQ requires the facility to perform compliance stack sampling and/or other testing. These procedures establish the actual pattern and quantities of air contaminants being emitted into the atmosphere from the Acid Scrubber and Safe Cell control devices. TCEQ’s Executive Director has the discretion to require compliance testing at the facility as necessary, and TCEQ’s permit does contain ongoing compliance conditions that the facility must meet. The facility’s current permitted maximum allowable emissions of ethylene oxide are 6.31 tons per year. TCEQ has completed eight routine compliance investigations at this facility from 2016-2021.
Information on Controls: The sterilization chamber vent (vacuum pump) emissions (where the bulk of the ethylene oxide goes) are treated using two different wet scrubbing systems. The first system is a Croll-Reynolds wet gas scrubber that consists of two towers working in parallel. In series to these two towers is a third tower and wet scrubbing system (Advanced Air Technologies Wet Gas Acid/Water Packed Tower Scrubber). This Advanced Air Technologies Scrubber has been permitted since April of 2020 and MSC recently completed installation in 2021.
What EPA is Doing to Address Ethylene Oxide
Now: The Agency is reviewing controls on regulated equipment and processes that emit EtO to determine whether additional air pollution controls are needed. This review includes examining new developments in practices, processes and control technologies, considering cost and feasibility, as well as addressing any previously unregulated emission points.
Soon: Later this year, EPA will propose strengthening current regulations for Ethylene Oxide Commercial Sterilizers. EPA will consider risk as part of the proposed regulations.
- Learn more about regulation for EtO Sterilization Facilities.
- For more information about actions you can take.
Follow-Up Questions from Community Meeting on Sept. 15
Below are follow up questions that were asked at the community meeting held in Laredo, Texas on September 15. If you have additional questions please email email@example.com.
What type of handheld instrument did ECAD use during the inspection at Midwest Sterilization to check for emissions and/or fugitives/leaks?
Inspectors used Toxic Vapor Analyzers (TVAs), configured as a Flame Ionization Detector (FID) analyzers. The TVA is a commonly used instrument for conducting Method 21 compliance monitoring and other LDAR (Leak Detection and Repair) applications. Inspectors were also equipped with an Infrared optical gas imaging camera, that can scan broad sections of equipment rapidly and survey process areas to detect leaks from gases that might otherwise go undetected.
What is the maximum amount of penalty (per day) or does EPA’s penalty policy look like if the company is found in violation by EPA? If Midwest were found in violation can the penalty be distributed or used in the community? Is there any disincentive (civil or criminal) to comply with EPA rules?
If EPA finds a facility to be in violation of the Clean Air Act, EPA may order it to comply and may assess monetary penalties under Section 113 of the Clean Air Act. Civil Penalties are monetary assessments paid to the US Treasury by a regulated entity due to a violation or noncompliance. The threat of a civil penalty acts as an incentive for coming into compliance and staying in compliance with the environmental statutes and regulations. Civil penalties are designed to recover the economic benefit of noncompliance and to compensate for the seriousness of the violation. While EPA generally applies its Stationary Source Civil Penalty Policy (Oct. 25, 1991), available at https://www.epa.gov/enforcement/clean-air-act-stationary-source-civil-penalty-policy-october-25-1991, when determining appropriate penalties for Clean Air Act violations, the Penalty Policy does not constrain EPA’s ability to seek civil penalties up to the statutory maximum set forth in 42 U.S.C. 7413, as adjusted for inflation. The maximum statutory penalty amounts in 42 U.S.C. 7413 have been adjusted for inflation under Federal Civil Penalties Inflation Adjustment Act of 1990, as amended through 2015, the Debt Collection Improvement Act (“DCIA”), 31 U.S.C. § 3701, and 40 C.F.R. 19.4.
Supplemental Environmental Projects (SEPs) and Mitigation can be part of an enforcement settlement. SEPs are environmental improvement projects that a violator voluntarily agrees to perform. These projects are in addition to actions required to correct the violations specified in the settlement. Mitigation is additional injunctive relief to reduce or offset harm caused by past or ongoing violations.
Persons who knowingly violate the Clean Air Act and/or provide false information to EPA, or those who negligently release hazardous pollutants that endanger others, are subject to criminal penalties under the CAA and other statutes.