diff --git a/py/src/braintrust/env.py b/py/src/braintrust/env.py
index 90ab2a44b..f08afb668 100644
--- a/py/src/braintrust/env.py
+++ b/py/src/braintrust/env.py
@@ -230,6 +230,11 @@ class BraintrustEnv:
     DISABLE_ATEXIT_FLUSH = EnvVar("BRAINTRUST_DISABLE_ATEXIT_FLUSH", EnvParser.BOOL)
     CAPTURE_USER_AUDIO_ATTACHMENTS = EnvVar("BRAINTRUST_CAPTURE_USER_AUDIO_ATTACHMENTS", EnvParser.BOOL)
     CAPTURE_AGENT_AUDIO_ATTACHMENTS = EnvVar("BRAINTRUST_CAPTURE_AGENT_AUDIO_ATTACHMENTS", EnvParser.BOOL)
+    MAX_GENERATOR_ITEMS = EnvVar("BRAINTRUST_MAX_GENERATOR_ITEMS", EnvParser.INT)
+    PROMPT_CACHE_MEMORY_MAX_SIZE = EnvVar("BRAINTRUST_PROMPT_CACHE_MEMORY_MAX_SIZE", EnvParser.INT)
+    PROMPT_CACHE_DISK_MAX_SIZE = EnvVar("BRAINTRUST_PROMPT_CACHE_DISK_MAX_SIZE", EnvParser.INT)
+    PARAMETERS_CACHE_MEMORY_MAX_SIZE = EnvVar("BRAINTRUST_PARAMETERS_CACHE_MEMORY_MAX_SIZE", EnvParser.INT)
+    PARAMETERS_CACHE_DISK_MAX_SIZE = EnvVar("BRAINTRUST_PARAMETERS_CACHE_DISK_MAX_SIZE", EnvParser.INT)
     OTEL_COMPAT = EnvVar("BRAINTRUST_OTEL_COMPAT", EnvParser.BOOL)
     # Opt out of the default OpenTelemetry-compatible hex span/trace IDs and use
     # legacy UUID-based IDs (and V3 span-component export) instead.
diff --git a/py/src/braintrust/logger.py b/py/src/braintrust/logger.py
index bf7df50b0..a63487d01 100644
--- a/py/src/braintrust/logger.py
+++ b/py/src/braintrust/logger.py
@@ -626,27 +626,23 @@ def default_get_api_conn():
         self.reset_login_info()
 
         self._prompt_cache = PromptCache(
-            memory_cache=LRUCache(
-                max_size=int(os.environ.get("BRAINTRUST_PROMPT_CACHE_MEMORY_MAX_SIZE", str(1 << 10)))
-            ),
+            memory_cache=LRUCache(max_size=BraintrustEnv.PROMPT_CACHE_MEMORY_MAX_SIZE.get(1 << 10)),
             disk_cache=DiskCache(
                 cache_dir=os.environ.get(
                     "BRAINTRUST_PROMPT_CACHE_DIR", f"{os.environ.get('HOME')}/.braintrust/prompt_cache"
                 ),
-                max_size=int(os.environ.get("BRAINTRUST_PROMPT_CACHE_DISK_MAX_SIZE", str(1 << 20))),
+                max_size=BraintrustEnv.PROMPT_CACHE_DISK_MAX_SIZE.get(1 << 20),
                 serializer=lambda x: x.as_dict(),
                 deserializer=PromptSchema.from_dict_deep,
             ),
         )
         self._parameters_cache = ParametersCache(
-            memory_cache=LRUCache(
-                max_size=int(os.environ.get("BRAINTRUST_PARAMETERS_CACHE_MEMORY_MAX_SIZE", str(1 << 10)))
-            ),
+            memory_cache=LRUCache(max_size=BraintrustEnv.PARAMETERS_CACHE_MEMORY_MAX_SIZE.get(1 << 10)),
             disk_cache=DiskCache(
                 cache_dir=os.environ.get(
                     "BRAINTRUST_PARAMETERS_CACHE_DIR", f"{os.environ.get('HOME')}/.braintrust/parameters_cache"
                 ),
-                max_size=int(os.environ.get("BRAINTRUST_PARAMETERS_CACHE_DISK_MAX_SIZE", str(1 << 20))),
+                max_size=BraintrustEnv.PARAMETERS_CACHE_DISK_MAX_SIZE.get(1 << 20),
                 serializer=lambda x: x.as_dict(),
                 deserializer=RemoteEvalParameters.from_dict_deep,
             ),
@@ -2951,7 +2947,7 @@ async def wrapper_async_gen(*f_args, **f_kwargs):
                     _try_log_input(span, f_sig, f_args, f_kwargs)
 
                 # Get max items from environment or default
-                max_items = int(os.environ.get("BRAINTRUST_MAX_GENERATOR_ITEMS", "1000"))
+                max_items = BraintrustEnv.MAX_GENERATOR_ITEMS.get(1000)
 
                 if trace_io and max_items != 0:
                     # Collect output up to limit
@@ -2992,7 +2988,7 @@ def wrapper_sync_gen(*f_args, **f_kwargs):
                     _try_log_input(span, f_sig, f_args, f_kwargs)
 
                 # Get max items from environment or default
-                max_items = int(os.environ.get("BRAINTRUST_MAX_GENERATOR_ITEMS", "1000"))
+                max_items = BraintrustEnv.MAX_GENERATOR_ITEMS.get(1000)
 
                 if trace_io and max_items != 0:
                     # Collect output up to limit
diff --git a/py/src/braintrust/test_logger.py b/py/src/braintrust/test_logger.py
index 9745c17be..1749f8d73 100644
--- a/py/src/braintrust/test_logger.py
+++ b/py/src/braintrust/test_logger.py
@@ -2838,6 +2838,47 @@ async def large_async_generator():
             os.environ["BRAINTRUST_MAX_GENERATOR_ITEMS"] = original
 
 
+@pytest.mark.parametrize("value", ["", "  ", "not-a-number"])
+def test_traced_generators_ignore_invalid_max_items_env(with_memory_logger, monkeypatch, value):
+    """An empty or non-numeric BRAINTRUST_MAX_GENERATOR_ITEMS falls back to the default instead of raising."""
+    init_test_logger(__name__)
+    monkeypatch.setenv("BRAINTRUST_MAX_GENERATOR_ITEMS", value)
+
+    @logger.traced
+    def sync_generator():
+        yield from range(3)
+
+    @logger.traced
+    async def async_generator():
+        for i in range(3):
+            yield i
+
+    async def collect():
+        return [v async for v in async_generator()]
+
+    assert list(sync_generator()) == [0, 1, 2]
+    assert asyncio.run(collect()) == [0, 1, 2]
+
+    logs = with_memory_logger.pop()
+    assert [log.get("output") for log in logs] == [[0, 1, 2], [0, 1, 2]]
+
+
+@pytest.mark.parametrize(
+    "name",
+    [
+        "BRAINTRUST_PROMPT_CACHE_MEMORY_MAX_SIZE",
+        "BRAINTRUST_PROMPT_CACHE_DISK_MAX_SIZE",
+        "BRAINTRUST_PARAMETERS_CACHE_MEMORY_MAX_SIZE",
+        "BRAINTRUST_PARAMETERS_CACHE_DISK_MAX_SIZE",
+    ],
+)
+@pytest.mark.parametrize("value", ["", "not-a-number"])
+def test_state_ignores_invalid_cache_size_env(monkeypatch, name, value):
+    """An empty or non-numeric cache size variable keeps the default instead of failing state creation."""
+    monkeypatch.setenv(name, value)
+    logger.BraintrustState()
+
+
 def test_traced_sync_generator_zero_limit_drops_output(with_memory_logger):
     """Test sync generator with limit=0 drops all output but still yields values."""
     init_test_logger(__name__)