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T53.5 vs T59.821D

T53.5 (Toxic effects of chlorofluorocarbons) compared with T59.821D (Toxic effect of hexamethylene diisocyanate, accidental (unintentional), subsequent encounter), from the official CMS tabular data. Do not report these codes together: the official tabular list marks them Excludes1.

Relationship

Conflict

Excludes1 conflict

T59.821D
Toxic effect of hexamethylene diisocyanate, accidental (unintentional), subsequent encounter
↔
T53.5
Toxic effects of chlorofluorocarbons

Not coded here — these two are mutually exclusive.

“chlorofluorocarbons (T53.5)”

An Excludes1 note means the two conditions cannot occur together, so the pair should not be reported for the same encounter. The sole exception is when the conditions are documented as unrelated to each other.

Source: CMS ICD-10-CM tabular instructional notes; ICD-10-CM Official Guidelines, Section I.A.12.a

Can these codes be reported together?

No — do not report together. T59.821D carries an Excludes1 note covering T53.5: “chlorofluorocarbons (T53.5)”

Sole exception: when the two conditions are documented as unrelated to each other (ICD-10-CM Official Guidelines, Section I.A.12.a).

Side by side

T53.5Toxic effects of chlorofluorocarbonsT59.821DToxic effect of hexamethylene diisocyanate, accidental (unintentional), subsequent encounter
Billing statusNon-billable header

Report instead: T53.5X1A, T53.5X1D, T53.5X1S, T53.5X2A, T53.5X2D

Billable
ClassificationS00-T88 — Injury, Poisoning and Certain Other Consequences of External Causes (S00-T88)S00-T88 — Injury, Poisoning and Certain Other Consequences of External Causes (S00-T88)
DefinitionToxic effects of chlorofluorocarbons is a non-billable ICD-10-CM category code (T53.5).—
7th characterThe appropriate 7th character is to be added to each code from category T53The appropriate 7th character is to be added to each code from category T59
Includes—
aerosol propellants
Toxic effects of hexamethylene diisocyanate NOS
Use additional code
code(s):
for all associated manifestations of toxic effect, such as: respiratory conditions due to external agents (J60-J70)
personal history of foreign body fully removed (Z87.821)
code(s):
for all associated manifestations of toxic effect, such as: respiratory conditions due to external agents (J60-J70)
personal history of foreign body fully removed (Z87.821)
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Derived from the official CMS ICD-10-CM tabular data (FY2026). Not billing advice; verify sequencing rules for the encounter. All data sources