2026 ICD-10-CM Diagnosis Code T53.7X1AToxic effect of other halogen derivatives of aromatic hydrocarbons, accidental (unintentional), initial encounter

ICD-10-CM Codes›S00–T88›T51-T65›T53

ICD-10-CM T53.7X1A
CMSSource: CMS FY 2026 ICD-10-CM dataset · Effective Oct 1, 2025 – Sep 30, 2026

T53.7X1A is a billable ICD-10-CM diagnosis code for toxic effect of other halogen derivatives of aromatic hydrocarbons, accidental (unintentional), initial encounter. The 7th character A marks it as an initial encounter code, used while the patient is receiving active treatment. It is valid on HIPAA claims for fiscal year 2026 (October 1, 2025 through September 30, 2026) and groups to MS-DRG 917 through 918. Coders also document this condition as methoxychlor poisoning. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under External cause codes: intent of injury, accidental/unintentional; External cause codes: poisoning by non-drug; and Toxic effects, initial encounter.

Code Identity

ICD-10-CM Code
T53.7X1A
Billable Status
Yes — Valid for Submission
Code Describes
Toxic effect of other halogen derivatives of aromatic hydrocarbons, accidental (unintentional), initial encounter
Short Description
Toxic effect of halgn deriv of aromatic hydrocrb, acc, init
Parent Code
T53.7X1
Toxic effect of other halogen derivatives of aromatic hydrocarbons, accidental (unintentional)

Code Classification

ChapterS00–T88Injury, poisoning and certain other consequences of external causes
SectionT51-T65Toxic effects of substances chiefly nonmedicinal as to source
CategoryT53Toxic effect of halogen derivatives of aliphatic and aromatic hydrocarbons
This CodeT53.7X1AToxic effect of other halogen derivatives of aromatic hydrocarbons, accidental (unintentional), initial encounter

Approximate SynonymsGuidance

Alternate terms and clinical phrases that map to this code.

  • Methoxychlor poisoning
  • Porphyria caused by chlorinated phenol
  • Porphyria caused by toxic effect of substance
  • Secondary porphyria
  • Tetrachlorodibenzodioxin poisoning

Coding GuidelinesGuidance

The appropriate 7th character is to be added to each code from block Toxic effect of halogen derivatives of aliphatic and aromatic hydrocarbons (T53). Use the following options for the applicable episode of care:

  • A - initial encounter
  • D - subsequent encounter
  • S - sequela

Source: ICD-10-CM Official Guidelines for Coding and Reporting, FY 2026, published by CMS and the National Center for Health Statistics.

Clinical ClassificationClinical

AHRQ’s CCSR groups this code into broader clinical categories.

CCSR EXT020
External cause codes: intent of injury, accidental/unintentional
Default principal diagnosis: inpatient No · outpatient No
CCSR EXT015
External cause codes: poisoning by non-drug
Default principal diagnosis: inpatient No · outpatient No
CCSR INJ023
Toxic effects, initial encounter
Default principal diagnosis: inpatient Yes · outpatient Yes

Clinical InformationClinical

  • Methoxychlor

    an insecticide. methoxychlor has estrogenic effects in mammals, among other effects.

Table of Drugs and ChemicalsClinical

Substances in the Table of Drugs and Chemicals that reference this code family. Always confirm in the Tabular List before coding.

SubstanceAccidentalSelf-harmAssaultUndeter­minedAdverse
Effect		Under­dosing
Chlorbenzene, chlorbenzolT53.7X1T53.7X2T53.7X3T53.7X4––
ChloroanilineT53.7X1T53.7X2T53.7X3T53.7X4––
Chlorobenzene, chlorobenzolT53.7X1T53.7X2T53.7X3T53.7X4––
ChlorodinitrobenzeneT53.7X1T53.7X2T53.7X3T53.7X4––
Chlorodinitrobenzene::dust or vaporT53.7X1T53.7X2T53.7X3T53.7X4––
ChlorodiphenylT53.7X1T53.7X2T53.7X3T53.7X4––
ChloronitrobenzeneT53.7X1T53.7X2T53.7X3T53.7X4––
Chloronitrobenzene::dust or vaporT53.7X1T53.7X2T53.7X3T53.7X4––
ChlorophenolT53.7X1T53.7X2T53.7X3T53.7X4––
DichlorobenzeneT53.7X1T53.7X2T53.7X3T53.7X4––
DioxinT53.7X1T53.7X2T53.7X3T53.7X4––
MethoxychlorT53.7X1T53.7X2T53.7X3T53.7X4––
Methoxy-DDTT53.7X1T53.7X2T53.7X3T53.7X4––
MonochlorobenzeneT53.7X1T53.7X2T53.7X3T53.7X4––
OrthodichlorobenzeneT53.7X1T53.7X2T53.7X3T53.7X4––
PentachloronaphthaleneT53.7X1T53.7X2T53.7X3T53.7X4––
TCDDT53.7X1T53.7X2T53.7X3T53.7X4––
2,3,7,8-Tetrachlorodibenzo-p-dioxinT53.7X1T53.7X2T53.7X3T53.7X4––

Convert T53.7X1A to ICD-9-CMHistory

The closest ICD-9-CM equivalents under the General Equivalence Mappings.

ICD-9-CM
982.3 Tx ef cl-hydcarb slv NEC
ApproximateCombination The match is approximate, and more than one code can be needed to describe the source diagnosis. Confirm with contextual judgment.
ICD-9-CM
E869.8 Acc poison-gas/vapor NEC
ApproximateCombination The match is approximate, and more than one code can be needed to describe the source diagnosis. Confirm with contextual judgment.

Code HistoryHistory

FY 2016AddedAdded to the ICD-10-CM code setEffective October 1, 2015, the first year of ICD-10-CM.
FY 2017–2025No changes
FY 2026CurrentCurrent code set, no changesEffective October 1, 2025 through September 30, 2026.

Questions About T53.7X1AOverview

Is T53.7X1A a billable code?

Yes. This is a billable ICD-10-CM code, specific enough to report toxic effect of other halogen derivatives of aromatic hydrocarbons, accidental (unintentional), initial encounter on HIPAA-covered claims from October 1, 2025 through September 30, 2026.

What does the 7th character A in T53.7X1A mean?

The final character A marks the initial encounter: use it while the patient is receiving active treatment for toxic effect of other halogen derivatives of aromatic hydrocarbons, accidental (unintentional), such as an emergency visit or first evaluation.

What MS-DRG does T53.7X1A group to?

When toxic effect of other halogen derivatives of aromatic hydrocarbons, accidental (unintentional), initial encounter is the principal diagnosis on an inpatient stay, it groups to MS-DRG 917, 918, with relative weights from 0.8571 to 1.5684 depending on complications. Higher weights mean higher Medicare reimbursement.

What is the ICD-9 equivalent of T53.7X1A?

Under the General Equivalence Mappings, toxic effect of other halogen derivatives of aromatic hydrocarbons, accidental (unintentional), initial encounter converts to ICD-9-CM 982.3 (tx ef cl-hydcarb slv NEC) and E869.8 (acc poison-gas/vapor NEC). The mapping is approximate, so confirm the match fits the documentation.

Footnotes

[1] Not chronic - A diagnosis code that does not fit the criteria for chronic condition (duration, ongoing medical treatment, and limitations) is considered not chronic. Some codes designated as not chronic are acute conditions. Other diagnosis codes that indicate a possible chronic condition, but for which the duration of the illness is not specified in the code description (i.e., we do not know the condition has lasted 12 months or longer) also are considered not chronic.